Nicholas S Gurule's research while affiliated with Sandia National Laboratories and other places

Publications (10)

Article
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By strategically curtailing active power and providing reactive power support, photovoltaic (PV) systems with advanced inverters can mitigate voltage and thermal violations in distribution networks. Quasi-static time-series (QSTS) simulations are increasingly being utilized to study the implementation of these inverter functions as alternatives to...
Conference Paper
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In order to address the recent inclement weather-related energy events, electricity production is experiencing an important transition from conventional fossil fuel based resources to the use of Distributed Energy Resources (DER), providing clean and renewable energy. These DERs make use of power electronic based devices that perform the energy con...
Conference Paper
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Renewable energy has become a viable solution for reducing the harmful effects that fossil fuels have on our environment, prompting utilities to replace traditional synchronous generators (SG) with more inverter-based devices that can provide clean energy. One of the biggest challenges utilities are facing is that by replacing SG, there is a reduct...
Conference Paper
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The high penetration of photovoltaic (PV) distributed energy resources (DER) facilitates the need for today's systems to provide grid support functions and ride-through voltage and frequency events to minimize the adverse impacts on the distribution power system. These new capabilities and its requirements have created concerns that autonomous unin...
Conference Paper
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With inverter-based distributed energy resources (DERs) becoming more prevalent in grid-connected or islanded distribution feeders, a better understanding of the performance of these devices is needed. Increasing the amount of inverter-based generation, and therefore reducing conventional generation, i.e. rotating machines and synchronous generator...
Conference Paper
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In 2016, 1.2 GW of photovoltaic (PV) power tripped off in California during the "Blue Cut Fire" when PV inverters miscalculated the grid frequency during a line-to-line fault. In response, the 2018 edition of the IEEE 1547 interconnection standard was updated to mandate distributed energy resource (DER) devices "ride-through" voltage phase angle ch...
Conference Paper
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During the last decade, utility companies around the world have experienced a significant increase in the occurrences of either planned or unplanned blackouts, and microgrids have emerged as a viable solution to improve grid resiliency and robustness. Recently, power converters with grid-forming capabilities have attracted interest from researchers...
Conference Paper
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Power outages are a challenge that utility companies must face, with the potential to affect millions of customers and cost billions in damage. For this reason, there is a need for developing approaches that help understand the effects of fault conditions on the power grid. In distribution circuits with high renewable penetrations, the fault curren...
Conference Paper
Full-text available
The Ideal Transformer Method (ITM) and the Damping Impedance Method (DIM) are the most widely used techniques for connecting power equipment to a Power-Hardware-in-the-Loop (PHIL) real-time simulation. Both methods have been studied for their stability and accuracy in PHIL simulations, but neither have been analyzed when the hardware is providing g...
Conference Paper
Full-text available
Historically, photovoltaic inverters have been grid-following controlled, but with increasing penetrations of inverter-based generation on the grid, grid-forming inverters (GFMI) are gaining interest. GFMIs can also be used in microgrids that require the ability to interact and operate with the grid (grid-tied), or to operate autonomously (islanded...

Citations

... The power curtailment is employed into the gridtied inverter for many applications such as zero energy exporting [8] which the PV system is only produces enough power for the local load and never injects power into the distribution network; over-voltage and thermal violation mitigations [9], [10]; solving grid congestion problems in power system planning [11]; improving power quality and providing frequency control in the microgrid systems with multi-energy sources [12], [13], [14]; improving a distributed power system control for multi-microgrid networks [15] and enhancing distribution system resiliency [16]. This paper introduces a particular power curtailment controller, which enables the grid-tied PV inverter to assist power generation during islanding operations rather than the solar hybrid on/off grid inverter alone. ...
... PHIL schemes tend to incorporate commercial power electronic devices such as inverters for photovoltaic or battery energy systems. Such PHIL testbeds provide insightful information of the dynamics of the EUT prior to commission it into the actual grid [69][70][71][72][73][74][75]. ...
... GSFs provide a benefit to both grid voltage and frequency stability while at the same time reducing the need of costly grid upgrades [1], [2]. However, GSFs can cause deviation in voltage and frequency during ride-through operations [3]. Also, variation in voltage and frequency during the ride-through process can make islanding detection more difficult for PV inverters. ...
... The DETL provides power electronics testing capabilities including islanded and campus microgrids as well as scaled portions of utility feeders and the transmission infrastructure using PHIL implementation [109,[136][137][138][139]. "DETL includes a 480 V, 3-phase microgrid, with interconnections to the utility grid and to various distributed energy resources including PV inverters, energy storage inverters with grid-forming capability, microturbines, fuel cells, reciprocating engine-generators, and electrical energy storage systems" [135]. ...
... This is mainly because the majority of DUTs are current sources such as renewables-based DERs using grid-following inverters [52]. Grid-following inverter control regulates active and reactive power output and ties into the grid to match the local voltage and frequency and requires a voltage reference to synchronize their internal phase locked loop (PLL) [109][110][111]. This makes grid-following inverters well-suited for grid-tied operation, but not under islanded conditions as they do not provide grid-forming capabilities needed to sustain microgrids [109]. ...
... The fault behavior of GFM inverters during (un)balanced faults has received little attention in the literature [24]. GFM fault behavior has been studied using simulations and experiments in [25][26][27]. GFM inverters are susceptible to changes in grid voltage and commonly malfunction during grid disturbances due to low short circuit capacity compared to SGs. Inverters may typically be tripped to avoid damage from huge fault current. ...
... The fault behavior of GFM inverters during (un)balanced faults has received little attention in the literature [24]. GFM fault behavior has been studied using simulations and experiments in [25][26][27]. GFM inverters are susceptible to changes in grid voltage and commonly malfunction during grid disturbances due to low short circuit capacity compared to SGs. Inverters may typically be tripped to avoid damage from huge fault current. ...
... Results for the IEEE Std 1547.1 UI Test 5B are obtained for a commercially available PV inverter using a Power-Hardwarein-the-Loop (PHIL) platform [20], [21]. The PV inverter is tested operating with GSFs (VVC, FWC and VWC set to DFLT) [22]. ...
... The stability of the closed-loop PHIL de-pends on the transfer function of the power amplifier, the transport and feedback delays in the loop, the IA used, and the device-under-test (DUT). Various stabilization methods have been reported in the literature [2], [4], [5] for the different IAs. The Ideal-Transformer-Method (ITM) is among the most commonly used ones [2], [4]. ...