Milan Prodanovic

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Verified

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• PhD
• Head of Department at Madrid Institute for Advanced Studies

To address the reduction of system inertia, transmission system operators are now requesting converter-interfaced generators (CIGs) to participate in frequency support services. Microgrids (MGs) and virtual power plants have been used as a solution for aggregation of small CIGs. It has been recently considered they may use their combined actions to...

Grid synchronization algorithms are important in control systems of power electronic converters. These algorithms must ensure proper synchronization even in the case of disturbances such as voltage-sags and phase-jumps, which are common in high-voltage and low-voltage ride-through applications. Therefore, the development of robust synchronization a...

Converter-interfaced generation (CIG) has been used to transfer energy from solar irradiation and wind to electricity networks. Until now, power plants based on CIG have been used solely to inject power from the primary source whenever it is available. As the share of CIG increases, its impact on the power system operation has become more relevant...

Virtual synchronous machine (VSM) control is commonly used to control power converters in islanded microgrids (MGs). Frequently, the dynamic model of the MG is unknown and, therefore, the estimation-based, impedance criterion is preferred to design the control parameters. However, the original impedance criterion does not consider the fundamental f...

This paper proposes a recursive, virtual admittance based, secondary controller for DG units that improves the voltage profile in distribution networks. First, the adaptation of the virtual admittance concept for the goal of voltage regulation is explained. Then, a recursive secondary controller is developed to periodically update the virtual admit...

In recent years, the massive integration of converter-interfaced devices to electrical distribution networks has lead to appearance of poorly-damped subsynchronous interactions in the grid. These oscillation modes amplify electrical disturbances originated from the grid and may cause an interaction between grid elements threatening the system stabi...

The grid synchronisation block is a key component of power electronics converters and their control systems. In some cases, synchronisation algorithms are based on non-linear oscillators and, therefore, their stability boundaries should be analysed by using non-linear techniques. However, as this topic is relatively novel, it has been seldomly addr...

The increased number of distributed generation sources in distribution networks in recent years has emphasized the importance of their accurate and computationally efficient modelling. The development of efficient models becomes more difficult and complex with the introduction of novel controllers that aim to support the grid, often emulating the o...

In this paper the dynamic response of the virtual impedance control loop for power electronic converters is studied using the recently proposed concept of complex frequency. This quantity captures bus frequency variations due to changes in both the phase angle and the amplitude of the voltage and current. The paper analytically derives the link bet...

Low-frequency oscillations in power systems have been commonly damped by power system stabilisers based on lead-lag transfer functions. These stabilisers can be implemented in the control loops of synchronous generators or converter-interfaced generation (CIG). Commonly, pole placement techniques are used to design power oscillation damping (POD) c...

In this paper the dynamic response of the virtual impedance control loop for power electronic converters is studied using the recently proposed concept of complex frequency. This quantity captures bus frequency variations due to changes in both the phase angle and the amplitude of the voltage and current. The paper analytically derives the link bet...

The increased number of distributed generation sources in distribution networks in recent years has emphasized the importance of their accurate and computationally efficient modelling. The development of efficient models becomes more difficult and complex with the introduction of novel controllers that aim to support the grid, often emulating the o...

Stability of power electronic converters connected to power grids is commonly assessed by using the impedance criterion. On the contrary, stability of power grids is typically analysed by using network state-space representation and system eigenvalues. It has been already reported in the literature that the impedance criterion may lead to erroneous...

The ever-increasing level of converter interfaced generation in the network has an important impact on the power system stability. To address this issue, transmission system operators are requesting network support services from newly integrated devices. The batteries are seen as a suitable solution with this respect, as the available energy is not...

In recent years, transmission system operators have started requesting converter-interfaced generators (CIGs) to participate in grid services such as power oscillation damping (POD). As power systems are prone to topology changes because of connection and disconnection of generators and electrical lines, one of the most important requirements in th...

Low-frequency oscillations are an inherent phenomena in transmission networks and renewable energy plants should be configured to damp them. Commonly, a centralised controller is used in PV plants to coordinate PV generators via communication channels. However, the communication systems of PV plants introduce delays of a stochastic nature that degr...

Power system stabilisers (PSSs) are commonly used in synchronous generators for damping low-frequency oscillations. However, many of these machines have been replaced by converter-interfaced generators (CIGs), such as those used in solar power plants. This means that CIG-based power plants should also contribute to oscillation damping. Moreover, CI...

This paper proposes a taxonomy of power converter control schemes based on the recently proposed concept of complex frequency . This quantity captures local frequency variations due to the change of both the phase angle and amplitude of bus voltages and current injections. The paper derives the analytical expressions of the link between complex p...

Low-frequency oscillations are an inherent phenomena in transmission networks and renewable energy plants should be configured to damp them. Commonly, a centralised controller is used in PV plants to coordinate PV generators via communication channels. However, the communication systems of PV plants introduce delays of a stochastic nature that degr...

This paper proposes a recursive, virtual admittance based, secondary controller for DG units that improves the voltage profile in distribution networks. First, the adaptation of the virtual admittance concept for the goal of voltage regulation is explained. Then, a recursive secondary controller is developed to periodically update the virtual admit...

The penetration of renewable energy sources~(RES) is changing the characteristics of electrical distribution networks. One of the most affected aspects is the network stability. Thus, the system operators are imposing new requirements on RES to provide grid support services. Significant part of these services focuses on the system stability improve...

The presence of distributed energy sources in distribution networks has been steadily increasing in the past few years, causing important changes in the voltage profiles. For this reason, distributed generators are expected to contribute to the voltage regulation. Recently, novel controllers have been proposed that emulate the dynamic properties of...

Microgrids (MGs) facilitate the integration of distributed energy resources (DERs) in electrical grids. To coordinate the operation of these DERs, a three-level hierarchical control is commonly used. In general, different control layers are designed with sufficient bandwidth separation between them to avoid unwanted dynamic interactions, resulting...

The presence of distributed energy sources in distribution networks has been steadily increasing in the past few years, causing important changes in the voltage profiles. For this reason, distributed generators are expected to contribute to the voltage regulation. Recently, novel controllers have been proposed that emulate the dynamic properties of...

This paper proposes a taxonomy of power converter control schemes based on the recently proposed concept of complex frequency. This quantity captures local frequency variations due to the change of both the phase angle and amplitude of bus voltages and current injections. The paper derives the analytical expressions of the link between complex powe...

The aim of this paper is to analyse the parameter stability and power transfer limits of active distribution networks with power converters and load tap changers by using bifurcation theory. First, the nonlinear model of a representative distribution grid with mixed loads and power converters is derived. Frequently neglected effects of converter ca...

In recent years, Microgrids (MGs with renewable energy sources, diesel gen-sets and droop-controlled converters have been increasingly used to guarantee the continuity of power supply in remote areas. Renewable energy sources have been typically connected to MGs by using an electronic converter that features the two controllers: a current-control l...

In recent years, power electronic converters have been increasingly used for integration of different generation technologies to electricity networks. However, due to their fast control loops and non-ideal grid conditions, these devices are prone to interact with each other. This can lead to an unstable grid operation with possible catastrophic res...

The level of penetration of distributed energy sources in distribution networks has been steadily increasing in the recent years causing significant changes and fluctuations in the voltage profiles. For this reason, distributed generators are being asked to participate in the voltage regulation. This task is commonly achieved by applying additional...

Low-frequency oscillations in power systems have been commonly damped by using additional loops in the control system of synchronous generators. With the massive integration of converter-interfaced generators (CIGs), power system operators have recently started requesting the same power oscillation damping (POD) capability from those power plants a...

Within electrical distribution networks, substation constraints management requires that aggregated power demand from residential users is kept within suitable bounds. Efficiency of substation constraints management can be measured as the reduction of constraints violations w.r.t. unmanaged demand. Home batteries hold the promise of enabling effici...

Within electrical distribution networks, substation constraints management requires that aggregated power demand from residential users is kept within suitable bounds. Efficiency of substation constraints management can be measured as the reduction of constraints violations w.r.t. unmanaged demand. Home batteries hold the promise of enabling effici...

In recent years, the importance of DC networks has increased with further development of railway systems, urban electricity networks, and high-voltage direct current (HVDC) systems, to name some examples. Breaking energy recovery, energy storage integration, and flexible management of power flows with the existing AC grids represent some challenges...

Renewable energy sources have been commonly connected to the grid by using current-controlled voltage source converters (CC-VSCs) based on phase-locked loops (PLLs). This approach simplifies the design and implementation of control algorithms and it has been well studied in the literature. Nevertheless , the massive integration of CC-VSCs in electr...

Power electronics converters are typically used in microgrids and local power network to interface renewable energy sources, energy-storage systems (ESSs) and loads. In the case of an ESS, its active power capacity can be used to compensate subsynchronous oscillations produced by the massive integration of converter-interfaced applications. However...

By using small computing devices deployed at user premises, Autonomous Demand Response (ADR) adapts users electricity consumption to given time-dependent electricity tariffs. This allows end-users to save on their electricity bill and Distribution System Operators to optimise (through suitable time-dependent tariffs) management of the electric grid...

Model-based predictive power control (MPPC) is a well-known and useful technique for control of electric drives and renewable energy generation systems. However, this strategy relies on the knowledge of accurate system models and parameter values and would otherwise lead to tracking errors in applications because of inevitable parameter uncertainti...

This paper presents an improved model based predictive current control for surface permanent magnet synchronous generator (SPMSG) where the dynamic response time can be adjusted according to the characteristics of the application and that can operate in the over-modulation region. Moreover, the steady-state errors typically observed in other model...

Hybrid microgrids (MGs) with both renewable energy sources (RESs) and diesel-generator sets are used to guarantee the continuity of power supply in remote areas with no access to electricity networks. RESs are commonly interfaced by using electronic power converters with their control system based on a current controller and phase-locked loop (PLL)...

The concepts of power system stability have been under review by both researchers and system operators because of the massive introduction of converter-interfaced power sources and loads to electrical grids. Power converters are mainly connected to networks that have a low short-circuit ratio (i.e. weak grids), where the power-transfer capability i...

Active Network Management (ANM) technologies represent an effective tool for increasing the penetration of Distributed Generators (DGs) in electrical distribution systems. Under normal operating conditions, these technologies allow a massive integration of renewable generation without exceeding rated values of electrical equipment. In addition to t...

This paper presents a control approach for HVDC interconnections that provides damping of frequency oscillations in asynchronous ac grids by introducing a virtual friction for coupling their inertial dynamics. The HVDC interconnection is modelled by using the concept of common and differential power flow, allowing for independent control of the dc...

This paper presents a technique for damping of oscillations in ac grids by control of VSC-HVDC links. The effect of the proposed controller is equivalent to a mechanical friction between two asynchronous networks (modelled as rotating masses) interconnected by the HVDC link. Therefore, the dynamics of the ac grids will be coupled, and the virtual f...

Multi-Terminal Direct Current (MTDC) links are increasingly used to integrate large offshore wind farms to electricity grids and synchronous machines emulation represents an attractive option for control of their power-conversion terminals. Virtual Synchronous Machine (VSM) facilitates the connection of wind turbines based on different technologies...

Modern power distribution networks assume the connection of Distributed Generators (DGs) and energy storage systems as well as the application of advanced demand management techniques. After a network fault these technologies and techniques can contribute individually to the supply restoration of the interrupted areas and help improve the network r...

Virtual Synchronous Machine (VSM) term commonly refers to the emulation of synchronous machines operation by using power electronics converters. However, a wider application of this control technique is still pending on further refinement of its design aspects and digital implementation. In this paper a systematic approach to design of the VSM para...

Recent advances in energy storage technologies and their increased deployment in power systems have improved the network flexibility and brought a number of economic benefits. Apart from typical energy storage applications during the network nominal operation, energy storage can significantly improve the quality of service under fault conditions an...

The emulation of synchronous machines is becoming an attractive solution to provide virtual inertia and voltage support to weak grids and microgrids, representing an alternative to conventional current-injection control strategies. However, synchronverters operate as voltage sources and this makes it difficult to limit the current when an event lik...

A wide scale deployment of energy storage systems in power networks for energy balancing applications will lead to network reliability improvements. After a fault occurs in a network, energy storage will be able to help restore supply in the network areas isolated from the primary substation or in those re-connected to adjacent feeders of limited t...

Electronic power interfaces are commonly used in microgrids for renewable energy integration and a control method based on a Virtual Synchronous Machine (VSM) represents an attractive alternative to conventional approaches. This control method has several advantages, however, a number of issues still need to be properly addressed, including those o...

Most Renewable Energy Sources (RES) are interfaced to electricity grids via Voltage Source Converters (VSCs). To facilitate the integration, the controllers based on emulation of synchronous generators have been increasingly used. This control technique is commonly referred to as Virtual Synchronous Machine (VSM) and recent studies have shown that...

Emulation of inertia has drawn much attention in recent years due to the growing demand for network services from systems operators. In this scenario, the converter control method Virtual Synchronous Machine (VSM) has gained importance because of its inertial properties. However, in its original form VSMs do not have a current-controller and, there...

The energy storage systems have been frequently used to facilitate the integration of variable, renewable energy to distribution power networks. The improvement of the reliability of supply is another possible benefit of storage integration. However, energy storage technologies represent a costly solution that require optimisation based methods and...

Two different methods for implementing inertial damping on a Virtual Synchronous Machine (VSM) and their potential for attenuating power system oscillations when utilized in a VSC HVDC terminal are investigated in this paper. As a reference case, the VSM is considered with only a frequency droop providing damping in the virtual swing equation. Then...

Most electronic devices are connected to the grid by using power electronics converters and, in order to reduce the filter size and cost, novel filter topologies are being proposed in the literature. For high-power applications, LTCL filters are an attractive solution since the size of inductors can be reduced while maintaining a low switching freq...

The Back-to-Back (BTB) converter is one of the most popular converter topologies for the control of electrical machines, power transmission systems, and power quality applications. The conventional cascade control structure is commonly used due to its simple design procedure and reliable operation. However, the bandwidth of the DC-link voltage cont...

Railway systems are one of the most energy-efficient ways of land transportation. In order to reduce their dependence on fossil fuels they are being massively electrified introducing new technical challenges. Multi-terminal Medium-Voltage-DC (MVDC) networks represent an attractive solution for this task as the DC-networks can be readily used to int...

STATCOMs are widely used to provide voltage support in electrical distribution systems. However, if the grid voltage is distorted, the output current of a STATCOM may also be distorted unless a harmonic current controller is added to the control system. Repetitive controllers (RCs) provide an attractive solution for harmonic control in electronic p...

In recent years the penetration of distributed generators (DGs) with power electronics interfaces has rapidly increased and this fact has created new challenges for the operation of power systems. In some cases, when DGs are connected via long distribution cables an interaction between their control systems and the network may produce undesired res...

Creation of microgrids in distribution networks under fault conditions is a well-known solution for improving network reliability. In order to provide operation in islanded mode, microgrids require advance control functionalities and an adequate level of distributed energy resources. However, variable renewable generation introduces several constra...

Power electronics interfaces are commonly used for renewable energy integration in microgrids and their control as synchronverters represents an alternative to typical control configurations. This control technique introduces many advantages, but several issues need to be properly addressed including power quality and harmonic current sharing. In t...

The emulation of synchronous machines is becoming an attractive solution to provide virtual inertia and voltage support to weak grids and microgrids, representing an alternative to conventional current-injection control strategies. However, synchronverters operate as voltage sources and this makes it difficult to limit the current when an event lik...

In recent years synchronverters have become a preferred control solution for integration of renewable energy sources and battery systems to power networks. In this control strategy the converter acts as a fundamental frequency voltage source and, as such, is unable to deal with harmonic power quality issues. In the literature the harmonic control i...

Reliability assessment tools are of crucial importance for planning and modernisation of distribution power systems. In recent years there has been an increased deployment of renewable energy, distributed generation, energy storage, electric vehicle, protection device automation and demand response schemes in the distribution networks. All these te...

This paper deals with the short-term forecasting of electrical energy demands at the local level, incorporating Advanced Metering Infrastructure (AMI), or “smart meter" data. It provides a study of the effects of aggregation on electrical energy demand modelling and multi-nodal demand forecasting. This paper then presents a detailed assessment of t...

The high penetration of renewable energy sources in electrical distribution networks is giving rise to new challenges in the low voltage network operation. Power electronics converters are widely used to connect these energy resources to the grid, and the control technique that emulates the operation of synchronous generators is attracting the atte...

An increased deployment of distributed generation in recent years has contributed to creation of meshed power networks usually seen as a way to improve power flow management capability. Also, power electronics converters have been commonly used to interface distributed resources to the grid, yet their impact on the network stability has not been su...

The increasing trends of energy demand and renewable integration call for new and advanced approaches to energy management and energy balancing in power networks. Utilities and network system operators require more assistance and flexibility shown from consumers in order to manage their power plants and network resources. Demand response techniques...

This paper introduces an automated and reconfigurable laboratory environment for rapid prototyping of DC and AC microgrids. The laboratory includes seven fully programmable power converters, 47.5 kWh lithium-ion battery, configurable AC loads, a set of AC busbars with configurable network impedances between them, a set of DC busbars and relevant mo...

Efficient integration of Distributed Generation (DG) and Energy Storage Systems (ESS) to distribution networks can help improve the reliability of supply. In order to evaluate the impact of these technologies on reliability several Monte Carlo simulation techniques have been proposed in recent years, yet none of the analytical methods that are know...

In recent years, the energy sector has undergone an important transformation as a result of technological progress and socioeconomic development. The continuous integration of renewable technologies drives the gradual transition from the traditional business model based on a reduced number of large power plants to a more decentralized energy produc...

In modern societies buildings largely contribute to the energy demand and account in some countries for up to 45% of the primary energy consumption. Detailed consumption data can be used to offer advanced services and provide new business opportunities to all participants in the energy supply chain. In recent years, the intensified research effort...

This paper presents the real-time (RT) powerhardware- in-the-loop (PHIL) emulation of the two most popular variable-speed wind turbines (WT): the doubly-fed induction generator (DFIG) WT with partial-scale power converter and the permanent-magnet synchronous machine (PMSM) WT with full-scale power converter. RT-PHIL emulation offers a realistic, co...

A novel modelling method and a stability analysis procedure for weak power networks with high penetration of power electronics converters are proposed in this paper. The modeling approach can be applied to any network topology and in order to model of the complete network it introduces small-signal state-space models for each network component incl...