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Hello, I have a real problem statement from wind industry. Does, anyone suggest the solution.
We have power converters for 2-3MW wind turbine and their failures are a cause of concern, I know there is peak wind season is going on which may be the one of the reason of failures.
Can anyone suggest the other causes of failures and possible solutions? Please share if any case study available in public domain.
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It would be useful to read the paper entitled "Exploring the Causes of Power-Converter Failure in Wind Turbines based on Comprehensive Field-Data and Damage Analysis."
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Any researcher who is interested in working together in the field of Powers Electronics & Drives, Converter & Inverter Design, MPPT Techniques, Solar Photovoltaic Systems, Microgrid, EV Charging Stations. And also interested in publishing good quality paper. Kindly contact me. And also here Give your suggestion and feedback.
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Yes sir, I'm interested..
I would like to work on Multi-level converters
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I have designed a Buck converter hardware setup, using MITSUBISHI IGBT MODULES
CM150DU-12H, L=2mH, C=1000uH, Dutycycle=50%, input voltage = 30, in this scenario am getting output voltage same as input voltage, even though by changing the duty cycle????  any solutions for this?
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followed
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Hi everyone, I am writing my master thesis in grid forming controllers and I am analyzing Power Synchronization Control as one of the Grid forming control methods. I am dealing with some problems when connecting the current limitation so I wanted to as if there is someone here that simulated the same control method and can help me to clarify some questions.
Thank you !
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Who has a simulation model of a wind turbine based on a dual-fed asynchronous generator for high power that takes into account grid-side power converter control and generator-side power converter control?
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Hi everyone
I'm trying to control a pmsm current using finite control set MPC using the book (PID and Predictive Control of Electrical Drives and Power Converters using MATLAB / Simulink), when I'm using PMSM model in simscape everything is fine and currents can track id and iq (currents in dq reference frame) but the problem is PMSM model is based on modified park transform (90 degree behind phase a) and our calculations are based on original park.
when I change the PMSM model park transform to original park results change and FCS-MPC does not work properly.
does anybody have this problem?
Thank you in advance
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The answer is you can not control the current of PMSM without controlling the SPEED ! because you are using synchronius frame(DQ) you have to consider speed control. The reason behind your model is that you are using different models for plant and controller so the speed is zero actually and you think you are controlling the current without controlling the speed.
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Hello Everyone,
I want help to evaluation efficiency of DC-DC power converter with Matlab/Simulink. Is there any block for the calculation? Please share any ideas regarding this.
Thanks
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In general, the efficiency of a power converter (AC-DC or DC-DC) is assessed by comparing its input power to its output power. To be more specific, the converter's efficiency is determined by dividing its output power (Pout) by its input power (Pin).
For MATLAB, these tutorials might help:
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Hi,
(I have asked this questions previously, but I believe it was too general. I have tried to be more specific here)
I am trying to establish an islanded microgrid with 2 inverters running in parallel to supply a single load. I want to use droop control so I can then adjust the power sharing between them.
I am struggling to get 2 inverters to synchronise. I can get them to supply the same voltage, but the currents work against each other in the load.
What I have tried:
1. Grid forming and Grid feeding. When I add the Grid feeding inverter, I can not control the voltage that it injects the current at. If I give it it a Reactive power reference, it will inject current into the grid at that power level, it doesn't regulate the voltage. Therefore, it pushes the voltage of the load up I get instability in the system.
2. Grid supporting Voltage x 2. I have tried to put 2 Grid supporting Voltage sources in parallel. The problem here, is that if each inverter supplies a different power, this then adjusts the frequency that is injects its power into the grid and the miss match between the two frequencies of the inverters causes instability.
3. Grid supporting Voltage and Grid supporting Current. This has the same issue as point number 1. As there is no way to pin the voltage to anything, it is simply a current source that cant control the voltage it injects at. This causes instability in the microgrid I created.
Am I doing something wrong ?
The following paper has exactly what I am trying to achieve, but I get different results:
Does anyone have a Simulink model of 2 parallel inverters supplying a load in islanded mode?
Attached is the model of the Grid Supporting Voltage inverters in parallel that I have been working on. You can see that the currents of each inverter are working against each other.
Thank you
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Synchronization is to agree in time. So, in order to synchronize multiple sources such as the power inverters you have to choose the strongest one as the reference synchronization source. This source is better to be referenced to a crystal controlled oscillator for high stability.
Then every other inverter is to be synchronized by the reference taken from the microgrid as I proposed in the first part of my answer.
This means the local oscillator of the inverter must be synchronized to the reference by means of phase locked loop.
In summary my proposal is to take the strongest power fed to the grid is to be taken as a reference for all other source fed to the grid.
To synchronize any inverter to the grid please refer to the papers in the links:
Best wishes
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Hi,
I am currently working on my PhD in Control Engineering. I have run into a brick wall and it has consumed months of my time. I understand the following:
There are 4 types of configurations for a power converter:
Grid Forming
Grid Supporting Current
Grid Supporting Voltage
Grid Feeding
I am using the following paper to try and establish a microgrid of parallel converter:
1. When I establish a Grid Forming power converter, I set the w and v of the grid. I am then using a second Grid Supporting Current power converter, but the voltage of the grid become unstable. I have read in other threads that Grid Forming power converters cannot run in parallel with any other converters. I assume this is why this started.
2. I then try to establish 2 Grid Supporting Current power converters to run in parallel with each other. However, there doesn't really seem to be a way that I can synchronise them. I can get them to run when the power on the droop controller is the same, therefore the w are both the same and they synchronise. I tried to switch one of them for a Grid Feeding power converter, again this did the same as in part 1, it adjusted the voltage and it became unstable.
3. All of the models I have come across take the inner current loop voltage readers before the Capacitor but after the Inductor, as in the paper mentioned above. However, Simulink gives me an error about zero crossings, when I override it the AC output has major distortion in it.
How can I create a Simulink model with two parallel converters to run together ?
My goal is to create two or more parallel converters providing a single load so that I can create a controller that provides stability under actuator attacks.
The other papers I have based this off are:
You can see from these articles that the current reading is taken before the capacitor bank.
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Dear Sandford:
You can benefit from this valuable Link about your topic:
I hope it will be helpful...
Best regards....
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Is it sampling frequency of control loop or some kind of resonance frequency of the system ??
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The frequency response, or variations in magnitude and phase as a function of frequency, is depicted using Bode graphs. This is accomplished using two semi-log scale charts. The top plot is usually magnitude or "gain" in decibels (dB). The bottom plot represents a phase, which is usually expressed in degrees.
A Bode plot /ˈboʊdi/ is a graph representing a system's frequency response in electrical engineering and control theory. It is frequently a mix of a Bode magnitude plot, which expresses the amplitude of the frequency response (usually in dB), and a Bode phase plot, which expresses the phase shift.
In electronics, frequency response is a quantifiable measure of a system's or device's output spectrum in response to a stimulus that is used to define the system's dynamics. It is a measure of the amplitude and phase of the output in relation to the input as a function of frequency.
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I am looking for information that mentions the control strategies in direct current to direct current converters, which can facilitate a summary of the state of the art. Any information is welcome.
If you know of some control methods / strategies and can mention it, it would be helpful.
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Hi all, I am looking for literature on the topic of Power converter layout. Does anybody have recommendations for thier favourite and most usefull books, articles, application notes?
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Due to the increasing penetration of distributed energy resources (DERs), various inertia emulation methods have been recently proposed for the interfaced power converters. These methods intentionally slow down the converter frequency response speed. In this case, the power converters are able to keep pace and play well with conventional synchronous generators.
However, it is also envisioned that a 100% DER penetration level may be realized in the future. In that case, is it meaningful to pursue the "inertia" concept? especially when all the power converters can maintain synchronization and frequency stabilization within an extremely short period of time.
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I would recommend reading the deliverables available at https://www.h2020-migrate.eu/downloads.html.
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Rotational loads are definitely linked to the reactive power readings in distribution network.
Are there any direct or indirect relationships derived between the two?
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In LV distribution networks, reactive power is not efficient in modifying electrical parameters due to X/R ratio of conductors. Although works discuss the effects on voltage in LV, IM tends to generate voltage problems like undervoltage.
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LCL filter are used for grid connected three phase inverters. The design of LCL filter is tricky as it can effect the stability of the system. During the design of LCL filter, to calculate converter side inductor, first maximum current ripple is calculated as
∆i_max=V_dc/(6L_i f_sw )
In above equation both ∆i_max and Li are unkown, so some authors[1] suggest to use 10% of Imax for this ripple current. On the other hand, other paper for example [2] and [3] use a relatively complex method to calculate the value of ∆i_max.
My first question is how accurate is use of 10%*Imax approximation? Are there any other quick way or approximations according to standards to find ∆i_max.
My second question is how to find the right attenuation factor δ for particular value of THD?
[1]M. Dursun and M. K. DÖŞOĞLU, "LCL Filter Design for Grid Connected Three-Phase Inverter," 2018 2nd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT), 2018, pp. 1-4, doi: 10.1109/ISMSIT.2018.8567054.
[2]Said-Romdhane, M.B.; Naouar, M.W.; Belkhodja, I.S.; Monmasson, E. An Improved LCL Filter Design in Order to Ensure Stability without Damping and Despite Large Grid Impedance Variations. Energies 2017, 10, 336. https://doi.org/10.3390/en1003033
M. Ben Saïd-Romdhane, M.W. Naouar, I. Slama. Belkhodja, E. Monmasson,
[3]Simple and systematic LCL filter design for three-phase grid-connected power converters,
Mathematics and Computers in Simulation, Volume 130,2016,Pages 181-193,ISSN 0378-4754,
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Indeed you could benefit from this valuable article about your topic:
"Design Space Optimization of a Three-Phase LCL Filter for Electric Vehicle Ultra-Fast Battery Charging" .. September 2020.
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hello, i try to model my boost and buck-boost converter in simulink using the state space averaging technique, but what I see in the literature that the dynamic equations differs depending on the conduction mode if it is continuous or discontinuous.. My question is if I want to do my simulation, should I suppose that I am working in only one conduction mode for ex in CCM and then continue working based on that ? if yes, what are the consequences of not considering the other conduction mode ?
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Just make sure you have higher value of inductor or there is critical load resistance up to which the system stays at continuous conduction mode.
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Hi friends
Why Current control( inner loop) is faster than voltage control ( outer loop) in power converters ?
Can you explain me deep level.
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I'm simulating different modulation techniques based on the mentioned topology.
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IGBT
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Dear Colleagues,
In a typical multi-loop digital control scheme for power converters, generally, there is an inner current control loop that provides the reference for PWM gate generation. Also, an outer loop control is used to produce the current reference (DQ current for a three-phase system) for the current controller. A designer can select either voltage or power controller as the outer control loop.
My question is what are the criteria to select a controller between voltage and power as the outer loop? Can anyone please enlighten me when we should select a power controller as the outer loop? When we should select a voltage controller instead of a power controller as the outer loop?
Thanks a bunch in advance for your time and suggestion :) .
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Thanks, everyone for your time and suggestions.
From other colleagues, I have received a high-level view of the answer. The selection of power/voltage controller as the outer loop depends on control objectives and the role of power converters. I have known two terminologies that define the role of power converters: 1) grid following converter and 2) grid forming converter. If I have a strong grid with stable and regulated voltage and frequency and need to operate a power converter to inject whatever power is available, then it is necessary to select a power controller as the outer loop. In this case, the converter would be grid following converter and the outer loop would control P and Q. On the other hand, if I have a local grid or small weak grid and the control objective is to regulate the bus voltage and frequency, then it is necessary to select a voltage controller as the outer loop. In this case, the converter would be grid forming converter and the outer loop control V and f.
Now, this is a grid-connected converter example, but the principles would be similar if it was for other applications, such as internal DC buses of back-to-back converters, etc.
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When mosfet is turned off there is a reverse voltage across body diode and the depletion region of drain-source diode(Cds) gets charged. As for the diode, it is forward biased and there is no stored charge across its depletion capacitance(Cj). When we turn on the mos the stored charge in Cds gets dumped into the channel of mosfet and gets wasted and the Cj gets charged. During the turn off transition of mos the Cds gets charged now and the charge stored in Cj gets discharged through the load. Here it is said that the energy lost during turn on transition is 0.5(Cds+Cj)(Vg^2). From my understanding I think that the lost energy is of the energy stored in Cds and Cj discharges its energy back to the load(during the turn off transition of mos). But that doesn't add up with the result given here. Please correct me if I am wrong and explain what is going on.
Thanks in advance
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You are being deceived by an inaccurate and incomplete model. There are two capacitances associated with the diode, D: 1) the depletion/junction/transition capacitance, Cj, which only exists when the diode is zero and reverse biased; and 2) the diffusion capacitance, which stores the minority carrier charge, but only exists when the diode is forward biased. These two capacitances are both in parallel with the diode. Note the caveat given in the diagram: "assuming linear capacitances". That is referring to the fact that Cj should actually be written as Cj(V) because it is a nonlinear function of the reverse voltage difference across the diode.
When the MOSFET is turned on, it shock excites the LCR circuit into a damped oscillation. The circuit oscillates because of L and C, and it is a dampled oscillation due to the load resistor R. In order to prevent a negative voltage difference from appearing across the load R, a clamping diode D is in the circuit. When the damped oscillation attempts to reverse direction, the clamping diode becomes forward biased and essentially stops the oscillation.
Now, as you mentioned, when the MOSFET is turned off, its Cds is charged to the voltage difference, vg. The clamping didoe, D, will have its diffusion capacitance charged to a value somewhat less than vg, depending on the degree of damping from the load R, when the damped oscillation attempts to reverse direction. At this point, the MOSFET is turned on, again, discharging Cds, and reverse biasing diode D which discharges its diffusion capacitance - not its diffusion/transition/junction capacitance.
There is a lot being left out of the description of the boost converter.
Regards,
Tom Cuff
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In this circuit the capacitor is junction capacitance of diode and ringing takes place here. The third plot is voltage across diode. As the stored minority charge inductor is stored with negative current and it need a path to flow. My doubt is where does this current actually(physically) flow? I mean the junction capacitance is modelled from the depletion region meaning that it will flow through diode again but diode cant conduct in negative direction. Please explain me what is exactly going on here and tell me where am I going wrong.
Thanks in advance
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Please provide us with a better picture of your circuit and better pictures of your three waveforms. As it stands, it is very difficult to see any details.
Regards,
Tom Cuff
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I am working on a project in which I need to control the duty cycle of the pulse given to mosfet in an AC to DC converter.The mosfets are connected to LCL filter to give a regualted 5V.The output voltage and a reference of 5V error is taken and a compensator is connected.The output is compared using PWM and then sent to mosfet.Do we need mosfet driver in between?What kind of mosfet driver should I use in multisim?Can I get any reference?Should we solve this using bode plot?Should I use PID controller to decrease the error and should I simulate in MATLAB using PID controller ?As I find it easy
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Hi,
It would be that this reference can help:
PD: Matlab implementation codes are available.
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Dealing with LLC resonant converter simulation and would like to plot the efficiency curve. How Can I do that ? eff = Pout/Pin ( Pout I can calculate from Output voltage and current but input current seems to be partial sinusoidal and cannot deal with any calculation !)
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You can use the following link:
Copy the IGBT model from here and use it with your DC converter. You can use any IGBT's datasheet to update the library. Efficiency calculation and plotting is also shown in the given model. Hope it will help.
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I am designing a control for bi-directional LLC-SRC DC-DC converter. The converter charges a battery from the grid. But during reverse operation, i.e when the current flows from battery towards the grid, what may be the impacts of current on the resonant capacitor (Cs as attached)? Do I need to wait for the discharge of DC link capacitors (fast/slow anyhow) on both sides? I cannot see any abnormal change or fluctuations during simulations. For practical approach, I am not sure. Any suggestions?
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Good question, follow
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Hello Technician and Academician
Can somebody please inform me, what is actually the type/topology of power converter available at the market for small wind turbines (below 10kW) with PMSG? especially for the rectifier part, is it just simple rectifier or controlled rectifier, with thyristor or MOSFET?
what are the dominant topology people used? for offgrid and ongrid
if you check IEEExplore, then soo many types, but I cannot find the reality in the market
what people recently use actually?
Best Regard
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Yes, as you mentioned in your answer, the back-to-back converter and the switch mode rectifier + inverter are the most commonly used for the WTs coupled PMSG.
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Can anyone recommend good tutorial materials and literature on 'grid forming and grid following converter models'?. I will appreciate your recommendations and suggestions. Thanks.
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Check the following interested book:
Jamil, M., Rizwan, M., & Kothari, D. P. (2017). Grid Integration of Solar Photovoltaic Systems. Crc Press.
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If I have a grid with 5KV nearly .. with RCL load ..
how to mention the power value of shunt active power filter in that case ?
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i think Ehtisham Lodhi's answers are enough.
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Mostly, PLL is mostly employed to generate the phase angle of PCC voltage in grid-following controlled converter. However, the phase angle can also be directly computed from abc voltage (first do the clark transformation to alpha-beta than calculate the anti-trigonometric). The fluctuations of the result caused by harmonics can be filtered someway, i suppose. Isn't it an easier and more reliable way than PLL?
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Hi Zhaoshun Deng,
The method of Clarke transformation can be used for grid synchronization assuming sinusoidal grid voltages. As you mentioned, low pass filters can be used for taking out the harmonics. The method can give the correct phase information in steady-state operation. However, this method as you can see is an open-loop technique with no feedback signal about the accuracy of the calculated angles.
For a converter operating in the grid following mode, it is very essential that the phase angle of the grid is precisely tracked at all times in spite of any harmonics and in the presence of transient disturbances. The Clarke transformation method suffers from a poor transient response during grid disturbances, mainly due to the use of low pass filters in the forward path without negative feedback.
The PLL essentially does a similar job, but it uses a closed loop technique. The loop filter in the forward path of the PLL performs the job of eliminating the effect of unwanted harmonics. At the same time, the feedback from the output VCO in the PLL makes sure that dynamic response is not compromised.
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I'm developing a Bachelor Teases about the economic impact of inserting a BESS into a MV level load. One of the requirements is to include a step-by-step on how to buy a commercial inverter for the required Energy Storage Systems composed of Li-Ion batteries. Any kind of material would be highly appreciated! Thanks!
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Hej,
I think SMA has some comercially available inverters in their sortiment for this purpose. I ll guess you ll find also some prices.
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For a switched-mode power supply, can volt second balance be applied to capacitor voltages too at different operating modes or is it only restricted to inductors?
Is it technically correct to express capacitor voltages in terms of the inductor, so as to apply VSB?
Please explain in detail!
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Afaq Hussain thanks for nicely putting it up. As an additional understanding exercise, would recommend you, P. Arvind, to study the waveform of current through the inductor in an SMPC device. You will see, that during one mode (ON/OFF), the current rises and during the other mode, it falls down. Now, in steady-state, the average current through an inductor is constant. This means, the amount of rise and fall of current in the two different modes should be equal in magnitude, thereby canceling the overall change in current. Note that the rise and fall of the inductor current would be equal to the rate of rise multiplied with time of rise and rate of fall multiplied with time respectively. But, we know that rate of rise/fall of inductor current is proportional to the voltage across the inductor. So basically, the product of voltage across inductor during ON mode and rise time, and the product of voltage across inductor during OFF mode and the fall time, add up to zero, in other words, "Balance" out. Hence the name, inductor volt-second balance. Now, it is important to note that this 'balancing-out' happens only in steady-state when the average current through the inductor is constant. It might interest you to know, that during the transient state, inductor volt-second balance is not a valid phenomenon. I hope this helps. Thanks for reading.
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- While I am doing MMC design simulation, I always find that all capacitors of MMC work in the same time.
is there away to sort them but without one by one condition ?
- Do MMC need P&ID for capacitor voltages?
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Hi,
Regarding batteries, there is always one concern that I will share.
(a) When you use a capacitor, your voltage balancing logic keeps the voltage in check, as a result you only draw reactive power from cap.
(b) When you have a battery, you might forgo the need of a balancing logic, this means you 'might' draw active power from the battery. This also means that you might be pumping active power into the battery, right? It's a possibility that cannot be easily ruled out.
So how do we proceed? If you want to avoid caps and use batteries, you must at least ensure that you draw active power from the auxiliary batteries that replace caps. Otherwise, you might pump power into a battery, overcharging it beyond rated limits. You can refer my Article on IEEE that discusses a similar scenario at length. Thanks.
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I am working in the area of DC Microgrid in this regards I need a DC-DC converter. I will be thankful for this act of kindness.  
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Data Current Controlled Voltage Source Inverter (CCVSI) Simulation and Design using Simulink (in Persian)
regarding
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I want to validate control scheme using DSP and Hardware setup, which i design in MATLAB simulink. So is there any reference guide book, which can guide me through every step from prototyping to generating code in Simulink or PSIM and test it on prototype.
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In PSIM it is very easy to interface your power converter whith TI28f335 using Processor in the Loop (PIL) provided in PSIM (This capability is provided in PSIM10 and higher versions). PSIM added another power full and low cost target which can also be used in PIL tests (28F379D: PSIM ver.12). In my opinion its a powerfull tool to test your control algorithm whithout having the physical system ( actual power converter). You can visit PSIM home page for further information and guidance.
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I have a tank of lube oil which is not insulated and top of tank is a compartment, in other words, tank is the bottom of the auxiliary compartment. The volume of tank is 25.000 liters. Because we will flush the pipes with lube oil pump (90 KW), the temperature of oil will increase by time. I assumed 50% of pump power will be converted into heat in oil and the oil will increase 4 celcius/hour. But i dont know how to calculate the heat exchange between oil in tank and ambient. Does anyone know a simple formula to calculate hourly heat exchange (Celcius/Hour) of mass oil inside a tank and ambient ?
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Nice Dear Hakim Abbasov
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I have been trying to simulate an MMC in a rectifier-mode using PWM.
First, I modeled a single phase MMC on PSIM software and simulated it in an inverter-mode, and made sure it worked. Then I connected a voltage source on the AC side and loaded the converter on the DC side (effectively making it operate as a rectifier), using the same PWM scheme. I get a zero voltage at the DC side as the AC source seems to be shorted through both the upper and lower arms, hence there is no voltage between the positive and the negative output DC terminals. Is there any difference in terms of modulation, structure, or any other, between an MMC rectifier and an MMC inverter? Most research papers seem to talk about an MMC inverter, never touching on the MMC rectifier.
Thanks in advance for your contribution.
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Hello Ayoub Mbogela , I'm performing the same setup in simulation and I have got the results in Inverting mode of operations but am unable to operate the converter in rectifying mode of operation and was wondering if you had any success in doing so. If yes, then please tell me the appropriate switching scheme.
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I want to understand the basic difference between these two converters. Also, how is a grid forming converter supposed to improve the voltage quality of the grid as it requires the voltage reference from the grid itself ? (Correct me if i am wrong).
Moreover, can a converter be both (grid forming and grid supporting) at the same time or one or another in the same structure with conditions like transition ?
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The inverter is connected at a bus in the network. The grid is "seen" by inverter at that bus, and this perception is in the form of voltage and frequency. Question is, who is responsible for maintaining that voltage/frequency? Whether V/f will still be maintained if inverter under consideration is disconnected? Every type of inverter injects power into the bus it's connected, however the key deciding factor of its role as grid forming/feeding/supporting is maintaining V/f.
Technically, if inverter control structure directly incorporates voltage tracker/regulator and its frequency is auto-generated (not sensed from bus), then it's a grid forming inverter.
On contrary, if voltage tracker is not employed and frequency reference is obtained from sensed/measured/estimated frequency locked to the corresponding bus by mechanism like PLL or FLL, then it's grid following.
Grid support is an "additional" feature, a grid supporting inverter can be of both types: grid forming or feeding. If the references/set-points of inverter (set-points includes voltage, frequency, active/reactive power, virtual flux, virtual torque, injected currents etc.) are adjusted based on "additional" inputs from information of other buses/loads in the network, for serving extra ancillary features (apart from local v/f regulation and power injection), then the inverter is said to "support the grid". The additional support include: power quality enhancement, stability support, reserve provision, event ride-through, economic dispatch etc.
See below examples:
1) Single inverter feeding standalone network: It is alone responsible for producing and maintaining V/f at all buses in network, thus "Grid Forming". If it adjusts its V/f setpoints for other purposes (like brown-out, current limiting for overloads/faults, improving voltage profile of a remote bus, loss reduction etc.), then it is also "Grid Supporting", it is supporting the grid formed by itself! Otherwise, if V/f are regulated at constant values, it is not grid supporting.
2) Parallel connected droop controlled inverters: All inverters contribute or participate in process of grid formation by means of droop coefficients. They serve additional purpose of power sharing, hence they are both grid forming and grid supporting.
3) PV inverters always operated at MPP: Irrespective of V/f of the bus it's connected, it only injects available peak power into grid, hence only grid feeding.
4) PV inverters with derated MPP: They inject certain fraction of available peak power to grid, and power reference is adjusted as per reserve requirement of the grid. Hence, it's an example of both grid feeding and grid supporting.
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My 500-page book Power Electronics-Enabled Autonomous Power Systems: Next Generation Smart Grids (Wiley - IEEE) is now available at
Enjoy reading ...
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Can't we design the MPC Control for a system whose model is not known, but all the quantities are measurable? I am working on a bidirectional DC-DC converter which involves switching of power electronic devices and the exact model of the system is not known. Can't we design MPC for this system in MATLAB, if the quantities associated with the system can be measurable? Please give specific suggestions in this regard.
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Agree with Gusius Gus
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How I implement control system when I model the rectifier in PSCAD? 
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The following point briefly addresses your concerns to perform the abc-to-dq0 transformation:
1. The fundamental reason to transform the three-phase instantaneous voltages and currents into the synchronously rotating reference dq0 frame is to make computations much easier. Secondly, it allows the system operator to independently control the active (d-axis) and reactive (q-axis) components of the currents. Similarly, in machine, the flux and torque can be independently controller. This way, the coupling effect can be minimized to certain extent.
2. Additionally, in the dq0-frame, the mutual inductance is constant. Thus, it allows the system operator to achieve the desired output as the inductance dependent quantities are constant.
3. Further, the various feedback controller including proportional-integral (PI) and proportional-integral-derivative (PID) practically offers an effective and reliable control solution when the quantities are DC (i.e., constant) in nature. On the contrary, if the input quantities to these feedback controllers are of periodic or sinusoidal then the integrator term of these controllers typically fail to introduce the infinite gain. As a result, the steady-state error will not be forced to zero.
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Hi
I am trying to design an optimal fractional order PID controller for a buck converter. Can anyone suggest how to decide the time integral performance criteria to be selected? Can an ITSE error of zero be achieved?Also, can anyone suggest any books or papers which clearly explain the procedure of optimization of PID and FOPID controllers? Thanks in advance.
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It is well known that each one of these criteria leads to a solution with certain characteristics.
as far as i remember, the ISE and ITSE lead to solutions with low damping.
That's just an example.
ITAE is most commonly used. IAE may lead to slower response, and so on.
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I was looking for an active-bridge rectifier. The active-bridge is superior in terms of efficiency if compared with the conventional diode-bridge rectifier. The only solution I found was IR1161L which is a synchronous FET controller in secondary side rectification in power converters such as flyback and resonant half-bridge converters. For active-bridge rectifier, we can use 4 of IR1161L to drive the four FETs of the active-bridge. Unfortunately, Infineon doesn't offer a spice model for this IC and there is no way to test it's performance.
If there is an alternative solution that has a spice model please suggest.
Thanks
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There is the LT4320 but it only goes up to 600Hz so I guess too slow for what you need. I have also thought to use a programmable analog chip such as the Silego parts (now Dialog). They have analog comparators in them and logic so you could make a rectifier controller.
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Dear All,
I am an Electrical Engineer in a Dutch startup, & looking for the research team who is working on some electronics project, well that's a very big topic by naming just Electrical or Electronics. But any project related to the subject I would be interested to join.
Pls, let me know if group/individual would like to join me in their group or individual who wants to work with me on some project(can discuss separately).
I have done some research/projects in my current company like reducing Inrush current in television, Circuit design for a small oven, Design of LED batten, Programming of Power converter through a USB port etc.
Thank you.
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Please contact me to see if any of my new designs can be implemented.
Sharaf Energy Systems Inc. Canada
especially
green plugs
SFC filters and EE devices for pumping an d A/ C -
Air Circulation cyclical loads.
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As far as I know, the control structures of grid-forming converters can be classified into 2 categories: one is single-loop without current control loop; the other includes a voltage loop and an inner current loop. What's the advantages and disadvantages between them two? Which one is more promising?
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I would definitely prefer the 2nd strategy because of its control over limiting the current. This also insures that that the bus voltage under autonomous mode is regulated at 120 Vrms.
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Please suggest me suitable power electronics converter which can extract current of a particular frequency from a multi-frequency voltage bus at high power level.
Multi-frequency bus voltage
V = V1sin(w1t+phi1)+V2sin(w2t+phi2)+V3sin(w3t+phi3)+V4sin(w4t+phi4)
and I want a power electronics converter and load to connect across this voltage, but the converter should draw current of particular frequency only, say for example: i =I3sin(w3t+theta3), (see attached figure)
Please suggest me suitable power converter for this.
Is it possible to do so, without using passive LC filters?
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Dear Varun,
What are the frequencies for the power to be separated. If the frequency is relatively high you can use band pass passive filters. If the frequency of low you can use active power filters. For using active power filters please follow the paper in the link:
Best wishes
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Good morning, regarding synch of power converters to grid I note that the basic approach for PLL is trying to reduce the phase error i.e the difference between the real and estimated phase angle.
To that end a Park transformation is applied to convert the abc voltages to dq voltages via Park transformation.
I note that in several papers the Vq component is used to compute the phase error while in others Vp is used.
Would you kindly advice which option is preferable in your opinion.
Thanks in advance a Merry NY2K20!
Juan Cabeza
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Dear Juan,
As both Vp and Vq are synchronized to each other, then any one of them is suitable to perform as reference for the phase locked loop.
This is a conceptual question concerning the operation of the PLL and the relationship between Vp and Vq.
Best wishes
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I need to provide an isolated voltage sensing for control circuitry of a DC-DC power converter (it needs to sense the 350 VDC output voltage). Does anyone have any recommendation about selecting an appropriate voltage sensor IC? Requirements:
  • High common-mode transient immunity (preferably above 50 Kv/us)
  • Very Low Delay
Thank you!
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ISO224B isolated sensor from TI, with an appropriate voltage divider on the high voltage side.
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How to calculate the settling time for the PV MPPT controller?
I mean for example if the operating conditions are changed: solar radiation, the duty cycle, etc.
How much time the does system need to reach the steady-state condition?
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In testing the MPPT controller speed of response one applies normally a unit step change of the Irradiance and see how it takes to reach steady state condition. The settling time is time taken by the processor from instant of application of stimuli till it reaches almost steady state value. The almost steady state value is considered to be reached when the power reaches its 90 percent of its steady state value.
Best wishes
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I want to design the filter for DC-AC converter topology which is half bridge. I'm using SiC MOSFET for that. Input voltage = 560V, Output voltage = 500V. I'm using Plecs + MATLAB for designing the Circuit. I want to reduce the losses so that it will be less that 200W overall.
#powerelectronics #electrical #semiconductor #powerengineering #Convertertopology
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I would presume you have a basic 3-phase VSI inverter, grid-tied by an L-C filter, to answer this question. In this case, choosing the inductive reaction at the grid frequency is a popular practice to be 5-10% of your base impedance rating (= Vgrid / Igrid). For example, if your grid voltage is 230 V(ph) and the rated AC inverter current is 23 A per phase, then 10 Ohm (= 230/23) is your base impedance. Now you can calculate the inductance you need. Once you have the inductance value, the capacitance value can be calculated on the grid side (usually less than 5 percent) depending on the THD requirement.
If you don't have L-C and you only have ' L, ' then the value depends entirely on the current grid THD-higher the inductance value, lower the THD value. And the inductance is going to be much bigger in this situation.
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The increase in the trend of distributed generation has led to the formation of community microgrids. What is the best possible solution to connect single-phase loads to a microgrid with 2 level voltage source converter?
I feel one possible solution to connect single-phase loads is to use a 3-phase 4 -wire transformer.
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You can use the split DC link which includes two series capacitor in parallel with a large balancing resistor for each of them . This a simple way to provide a neutral point which its voltage clamped at half of the DC link voltage .
Special PWM generating schemes can be used for balancing of the capacitors voltages. But where the neutral current is large, it flows through the capacitors and, hence, bulky capacitors are needed to make the voltage ripple on the capacitors. Also the neutral point usually drifts and becomes unbalanced when it includes DC component. So different strategies for neutral point balancing are reported, usually using the Space Vector Pulse Width Modulation or MPC control.
A better way to provide a neutral line is to add an additional fourth leg, called a neutral leg, to the conventional three-leg converter. The neutral current can be controlled to flow through the inductor so that the neutral point is maintained at the mid-point of the DC link. This allows the phase legs and the neutral leg to be controlled independently, which means the three phases can be controlled independently as well.
Ref :
Control of Power Inverters in Renewable Energy and Smart Grid Integration https://ieeexplore.ieee.org/book/6381785
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Hi
my question is why and how fuzzy logic can perform better than conventional MPPT methods such as : P&O method ?
I found that fuzzy logic can eliminate the slow tracking speed and the oscillation around Maximum power point (MPP)which are the two common drawbacks of the P&O method.
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The P&O method calculates the duty cycle and hence the MPP point depending on the irradiation levels. However, the fuzzy method has been trained in advance which directly operates at the MPP point. This might be the reason for less/no oscillations in Fuzzy controller compared to P&O.
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Well .. my question is too simple.
I need to know how to model rectifier circuit in state space model [A B C D]
rectifier circuit simply consists of: voltage source, MAYBE line inductane, 3phase rectifier diode, load (resistive .. if I can make a model reliable for different type of loads, that's a plus ! ).
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Build the model in MATLAB as per your state space equations,
and cheak the responce of model and give parameter values as per your numerical example.
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Power converters for rural electrification comes on all shapes and sizes. However, in the OwnPower project we seek to develop converters which are multi-functional and multi-tier.
If you could wish for a power converter that could take care of all of your field problems, which functions would you like this converter to have?
(DC/DC, DC/AC, step-up, step-down, isolation, high-power, etc...)
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all types of shape are possible
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This might be a too general question, but:
In power electronics applications (such as DC-DC converters and such) and for switching frequencies of "a few hundred KHz", in general which one has lower core losses as a core of a power inductor (say for example an output filter inductor) : a "ferrite core" or a " powder core" ?
or is there any new material that can outperform those materials in terms of core losses (that can also handle power levels from a few kW to a few tens of kW)?
Thanks!
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The best cores for high frequencies are the ferrite cores because ferrites are electrically insulating. Therefore they will be no eddy current in the core. The limiting frequency is limited by the magnetization losses.
Ferroelectric based cores whether laminated or powder will still have eddy current losses but very suppressed. So, they normally used at lower frequencies.
As an advice you can survey the commertial coils that satisfy your requirements and specifications.
Best wishes
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in a 3 phase application, SVPWM output is gates S1S3S5 .. but If I made modeling to my system in dq frame, HOW I can convert S1S3S5 to dq frame to suit my modeling system?
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Dear Akram
please go through this below links, this links may be helpful for you
Thank you
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I am new to simulink and am simulating a PV module with a buck converter. As you see from the equation of the output current eq(1), there will be algebraic loop. I tried a unit delay and memory to break it, it works when I test the PV module alone with a variable resistance at the output and it yeled correct results. But a unit delay or memory blocks can change the dynamic behavior of the system, so is there a way to get around the algebraic loop problem ?
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When you load the solar module by an inverter, then for a given load you have to adjust the PULSE WIDTH of the inverter to operate the module at the maximum power point under the the specified temperature and simulation condition.Then you have to get the maximum power point Vom and Iom, then you apply Vom on the inverter and vary its PULSE WIDTH till the input current to the inverter reaches Iom.
Best wishes
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I am using HCPL 316J IC as gate driver for matrix converter application. The system is running completely fine on RL load. But on running a motor load from the converter, it is observed that as soon as the motor accelerates, the gate pulses are withdrawn by driver ICs which then require manual resetting to re-issue gating signals. An obvious guess would be overcurrent DESAT protection getting enabled...but i have disabled the DESAT pin in the PCB design by grounding it.
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I suspect high Common Mode Noise disturbances.
Check out again with the following:
1) DSAT pin 14 to be connected to VE pin 16.
2) Ensure a resistance of about 10k to 33k connected between gate and emitter of IGBT as close to device pins as possible
3) Ensure connection of Ceramic disc capacitors (not polyester capacitors) of 0.1uF (apart from about 47uF to 100uF electrolytic capacitors) across supply pins of IC to output common, ie., between pins (12+13) & 16 and between pins (9+10) & 16, as close as possible to the IC.
4) Instead of a single gate resistance in series with gate, split the resistance into two: 2/3 of original value remains in series with gate and 1/3 of original value be put in series with track from VE (pin 16) & common of supplies to actual Emitter of IGBT.
5) In case wires are used to connect from pcb to the IGBT gate & emitter, they should be as short as possible (preferably less than 6inches in length) and the two wires to be twisted together.
Best wishes.
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Dear friends,
in these days, SiC power electronic devices are being popular in different applications. For medium voltage direct current (MVDC) converters based on SiC technology, there are some effects imposed SiC converters due to load and supply variations. My question is that, How do these variations affect the switching performance of SiC based power converters in MVDC systems?
Thank you in advance,
Amir.
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Hi Ali.
Thank you for you response.
But I think that it is incomplete.
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(1)How can we calculate tail current duration and magnitude of an IGBT ?
(2) What are the ways to minimize the tail current ?
Attached is datasheet of an IGBT : IKW75N60T , reference for further discussion.
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I am opening a serious discussion for the validity of implementing the SHE modulation for a specific three phase converters controlled by Vector Control and regulating the DC-Link. Implementing SHE as open loop control (fixed modulation index and arbitrary phase shift) is visible and easy. Also, single phase implementation is easy and really visible for open loop (99% of research using open loop).
Here is the issue for 3-phase converter: to eliminate the harmonics, the pulse pattern must be produced for a complete period (20 ms for 50 Hz) for each phase. this means the sampling time for the control loop should be 20 ms ( too slow). in other words, let us check only for Phase A. the pattern need to be ready each period (20 ms) and the SHE will not update the its reference angles during executing the full pattern with takes 20 ms. This concept is also applied for phase B and C. Otherwise, if we contentiously update the modulation index and the converter vector phase shift (relative to grid vector), the SHE becomes some sort of random PWM pattern.
The Question is: Is SHE valid for controlling three phase converters using vector control method in a closed loop control strategy?
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Whatever harmonics orders, this is not the issue. The issue is the closed loop control where the modulation index is conteneously changling.
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I want to use a single circuit for accelerating the motor in bi-direction ,and also want the same circuit to provide dynamic braking for the motor. Will a buck-boost converter be helpful when I am using a micro-controller as a master control for the circuit?
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Go for the class C chopper
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Dvr, dstatcom and upqc
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55% of them are installed by ABB only. Kindly see the website of ABB for more details
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I want to charge series connected 4 lead acid batteries (all of them are the same ) from a solar panel using a power converter with MPPT. Since these 4 are connected in series, they will charge and discharge at different rate (voltage for each will be different). Hence, I need a resistive attenuator for
Charge equalization. Now the issue with that is, I am working with 250W panel (high power), which causes a problem. Now:
1- I cannot know the voltage drop for each since it has to be above the rated voltage for charging.
2- Connecting them in parallel with a diode for each branch, but I cannot grantee that there will be no circulation of current in them.
I thought about charging these batteries individually based measurement of currents/ voltages that will be the job of a controller. So:
1-Is there something like a changeover (switching circuit) I can implement to overcome this issue?
2-Which connection of these batteries is best for impedance matching?
any advice or help is appreciated.
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Dear respected Fahad Abu Khald,
The nominal battery voltage must be less than the solar panel voltage for charges to flow from the solar panel to the battery. Since the battery is to store charges, the solar batteries should be connected in parallel in order to maximize charges stored by the batteries not voltage...
Please check my profile for more information..
Best regards.
Kifilideen.
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Can MPPT techniques applied to ZVS,ZCS and soft switching converters?
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Based on the literature, yes it is possible to achieve soft switching with MPPT. Maria Teresa Outeiro has achieved soft switching with MPPT for fuel cell with SRC application. Try to go trough the authors article:
1- Design, Implementation and Experimental Validation of a DC-DC Resonant Converter for PEM Fuel Cell Applications
2- Resonant power converters applications: LsCsLpCp circuit for renewable energy sources as case study
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Dear Ms,
I have been thinking in how to Speed up the performance in DC-DC Power Converter?, because I have a systems which has 2 DC-DC converters, the first one is working in order to obtaing the highest solar harvesting under a MPPT control and recharging a battery bank, but after it there is a second one DC-DC converter which is aimed to maintain the output voltage within the safe values range. Notwithstanding, I have noticed that the simulation go slower than I would like, in many cases it take bout a week for running a 24 hours simulation.
Could you help me with this issue?.
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I think you should check your simulation status, in powerGui, in continous time, it takes time, you should descritze it, and reduce the samples. Also check if there are any zero crossings, becoz matlab hangs when perofrming differentials while executing such probs, as such kinds of probs are prominemt in switching convrts.
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What are the expressions inside High voltage reactive current logic and Low voltage active current logic blocks? Only two parameters are given:VHVRCR (High voltage reactive current voltage ) and CURHVRCR (max.reactive current at VHVRCR).
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I agree with Mr. L.T.G. Lima
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Hi Professor,
In these days, I am studying MPC control on inverters. I do the model predictive control of a grid connected inverter with LCL filter, to be more specific , finite set MPC control with long predictive horizon.
I would like to tell you why I want to implement MPC method to the gird inverter. When I entered my supervisor's team, they focus on control method on power electronics. At that time, my supervisor, Mr Long, told me MPC control is pretty popular in recent years, and suggested me to value such a control method to do a further study. So firstly, I read the book Model Predictive Control of High Power Converters and Industrial Drives written by Tobias Greyer, and found FSMPC with long horizon is much better than that with short horizon. As a result, after understanding the principle in that book, I want to do some simulations to see whether I can implement such control method into the inverter. But during simulation, I faced some troubles. . Everyday I suffered finishing all kinds of troubles. At these days, I constructed the whole simulation and wrote the code for mpc block, but it doesn't work.
So I'd like to get your hand to solve the problems. Below, I show you what I have done in these two weeks.
best regard,
Jin Pengxin
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Implementing long-horizon FCS-MPC with sphere decoding is not trivial. Implementing it for a system with an LCL filter is even more difficult. I would recommend to first get it to run for a simple RL load with a voltage source. Make sure you have good debugging at hand and plot your predictions. It certainly took me many weeks to get these things running. Two weeks is much too short a time frame for this.
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Hi All,
I am working on the prototype of a three phase bidirectional dual active bridge DC DC converter?I am having DC offset in the current on the primary side of the transformers which is causing loss of efficiency.I would be grateful if any one in this community can shed some light on the potential causes of DC offset?
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did you solve your problem. i am having same problem in DAB.
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Good Day all,
I started learning SMC for power converters and got some basic principles of it. However, If I am not wrong, MPC is also becoming popular these days. So, please clarify me " what are the performance differences between the two control methods and when to use the specific controller? "
Thanks in Advance.
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Dear Lokesh,
SMC was initially built for nonlinear systems, while MPC was designed for linear systems to anticipate for desired control and after that there have been developments for nonlinear system. in fact each method has a specific domain or it can gives excellent performance. Also we can add the two method in same application.
For more information about this subject, i suggest you to see links on topic.
Comparison between Predictive Sliding Mode control ... - ResearchGate
Comparison Between Predictive Sliding Mode Control ... - ResearchGate
Application of MPC and sliding mode control to IFAC benchmark models
Recent Advances in Electrical Engineering and Control Applications
Robotics and Mechatronics for Agriculture
Best regards
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I am currently studying grid-tied converters and in order to have accurate simulation results I would like to the know the impedance value of the low voltage distribution grid ( Vrms= 260V , f=50 Hz)
Is there anyone who his field of study is related to electrical power systems and knows the typical impedance values?
Thanks in advance.
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Ioannis, you are correct. A transformer does not have a fault level input.
I provided a range of 11kV network fault levels so that you can use to model it as an equaivalent Thevenin's Voltage source i.e. Infinitly stiff voltage source behind a series impedance. This is also referred to as "External Grid" in network modelling tools.
For 1a 00 MVA fault level in a 11kV network, your Thevenin voltage source value will be 11,000/(sqrt(3) = 6350V (Ph-n) and your series impedance (usually assumed reactance) = j1.21 Ohm. Your distribution transformer - say 11/0.415kV 300KVA Dyn11 Z=5% will be connected to this series impedance in your model.
Above is reasonably accurate representation of a 11kV network and a distribution transformer model for basic load flow and short circuit analysis.
In case you are planning to investigate Z(f) - impedance of the grid as function of frequency, than you will need to add equivalent shunt capacitance to the 11kV terminal of the Thevenin impedance. However, this may not be as easy to get as Thevenin equivalent series impedance. You will also have to model your LV cable as a PI model with series impeadnce and shunt capacitance.
Trust above is helpful.
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The are many devices for wave energy extraction like offshore devices, onshore devices and near shore devices. I want to know from you the name of wave power converters from off shore devices.
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1. Oscillating Water Column (OWC)
2. Hinged Contour Device
3. Floating Device
4. Hydraulic Device
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There are many publications about HVDC and MMC converters, and there are also different tunings for the classical PI controllers for the current controllers. 
If there are hundreds of submodules, what would the typical values for the time responses of the circulating currents (also called differential currents)?
Thanks, 
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The circulating current controller’s dynamic response usually affected by the sampling time, switching freqency, etc.
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It was seen from the simulation , that a PI controlled DC-DC boost converter is having ringing effect when an input line variation is applied. The ringing amplitude is high. And the ringing frequency is found to be less than the cut off frequency of the open loop transfer function. Is there any method by which I can reduce the effect of ringing amplitude as well as the ringing oscillations?
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Try using improved PID like Fractional pid controller or used Anti-windup technique with pi to reduce the integral effect
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Hi,
I want to use comsol software to simulate provskite solar cells, I dont know what kind of information is needed to simulate different layers and finally extract the best power converting effeciency ( PCE%)
Please guide me.
sincerely yours
mohsen
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thank you very much