EPE Association: EPE 2025 - DS1f: Smart Grids, DC Networks and Components, Hybrid AC/DC Networks

EPE 2025 - DS1f: Smart Grids, DC Networks and Components, Hybrid AC/DC Networks
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2025 - Conference > EPE 2025 - Topic 02: Smart Grids and Renewable Energy > EPE 2025 - DS1f: Smart Grids, DC Networks and Components, Hybrid AC/DC Networks

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   A Multi-Agent Reinforcement Learning-based Secondary Control for Voltage Restoration and Current Sharing in DC Microgrids
By Shima SHAHNOOSHI, Javad EBRAHIMI, Alireza BAKHSHAI [View]
[Download]

Abstract: Microgrids are designed for sustainable energy generation and the efficient use of Distributed Generators (DGs). DC microgrids face challenges such as current sharing and voltage restoration, commonly addressed using droop control. Despite its simplicity, droop control can lead to voltage deviations and inefficient current sharing. This paper develops a Multi-Agent Reinforcement Learning (MARL) based secondary control method using Deep Q-Networks (DQN) to improve voltage restoration and current sharing in DC microgrids. The proposed method leverages centralized training to utilize comprehensive environmental information, integrating both the voltage restoration and current sharing objectives into each agent's local reward function. Simulation results demonstrate the effectiveness of the MARL approach in addressing the limitations of droop control, ensuring stable current flow and enhancing overall system performance.

   An overview of grid code possible requirements for an interoperability MVAC/MVDC systems - Focus on fault detection for a future PV power plant
By Nicolas LIM, Van-Sang NGUYEN, Seddik BACHA, Quoc Tuan TRAN [View]
[Download]

Abstract: An AC/DC interoperability is expected to be part of the future grid but is not currently developed at medium voltage level. Standardization efforts are necessary to develop medium voltage DC (MVDC) systems. This article discusses the existing grid code for medium voltage (MV) applications, providing an overview of the existing requirements and the future requirements expected for the development of MVDC applications. Behaviour of a hybrid AC/DC system during fault situations through PLECS based simulation has been provided.

   Comprehensive model of a synchronous generator for single-node studies
By Guillermo BAUTISTA, Miguel GARCÍA, Javier MARCOS, Íñigo DE LA PARRA, Luis MARROYO [View]
[Download]

Abstract: As power electronics increasingly replaceSynchronous Generators (SGs), the focus on system frequencystability has grown. To study frequency dynamicsduring disturbances, time-domain models, such as thesimple single-node model, are used. The commonly usedsingle-node models lack sufficient representation of electricpower dynamics, simplifying converter-interfaced generation(CIG) behavior as reduced system inertia. However,control strategies, such as Power System Stabilizers(PSS) on SGs or Power Oscillation Dampers (POD) onCIG, can modify the system-wide frequency response.This paper presents a comprehensive state-space modelof a SG for single-node studies, offering flexibility toanalyze electrical interactions involving the AutomaticVoltage Regulator (AVR) and PSS, while facilitating theinclusion of power electronics. Additionally, the modelprovides a mathematical framework for understanding therelationships between system parameters through statespacerepresentation and could be used to explore othercritical interactions.

   Development of an Integrated Transmission-Distribution Simulation Model for Coordinated TSO-DSO Interface Management
By Mohamed Nadir BOUHADDA, Mohamed Moez BELHAOUANE, Arnaud DAVIGNY, Abdelhadi QASIMI, Vincent BARBESANT, Sebastien HAYE, Benoit ROBYNS [View]
[Download]

Abstract: This paper presents a comprehensive methodology for integrated TSO/DSO modeling, aimed at enhancing coordinated management of transmission and distribution networks. The proposed approach allows to perform a unified numerical load-flow model that effectively integrates both transmission and distribution electrical systems, accounting for technical constraints of each grid operator. The validation of the detailed joint TSO/DSO model is carried out using real-world scenarios provided by grid operators, ensuring its practical applicability.

   Distribution Network Reconfiguration Including OLTC Limits and Variable Shunt Reactors
By Aghyles GRAINE, Jean-Paul GAUBERT, Didier LARRAILLET [View]
[Download]

Abstract: Networks often suffer from overvoltageproblems. The On-Load Tap Changers (OLTCs) may notalways be able to regulate the voltage. Distribution net-work reconfiguration and variable shunt reactors can helpmitigate these issues. In this paper, OLTCs are modeledand incorporated into the optimization. The results showan improvement in the accuracy.

   Enhanced Current-Limiting Strategy of Grid-Forming Converter Considering Grid-forming Capability
By Junyeol MAENG, Shenghui CUI [View]
[Download]

Abstract: Recently, Grid-forming (GFM) converters have gained significant attention for their ability to enhance power system stability during disturbances. However, conventional current-limiting strategies lack sufficient consideration for preserving GFM capability under current-limited conditions. To address this issue, this paper proposes a novel current-limiting strategy that simultaneously ensures accurate current limitation and preserves GFM capability. The proposed method minimizes deviations in the converter terminal voltage by incorporating a PCC voltage-based current-limiting condition in real time. This approach allows the GFM converter to preserve its natural response-driven GFM capability to the greatest extent possible within a given current limit. Experimental results validate the superior performance of the proposed method compared to existing methods.

   Enhancing Optimal Power Flow Feasibility: A Novel Comparative Study of Approximation Techniques
By Sarah ALIBHAI, Maxim CIOBANU, Wiktor WIEJAK, David PETERS, Sajad FATHI HAFSHEJANI, Daya GAUR, Robert BENKOCZI [View]
[Download]

Abstract: This experimental study investigates three approximation methods (quadratic, linear, and logarithmic) of the Optimal Power Flow problem (OPF) in comparison to traditional DC-OPF approximations using benchmark cases from the MATPOWER library. The quality and efficiency of each method is assessed using novel error metrics in respect to the AC-OPF baseline, with a focus on phase angle, voltage magnitude and generation costs. Results demonstrate promise in outperforming DC-OPF while maintaining computational efficiency, especially in the case of the quadratic approximation. Findings indicate an attainable balance between accuracy and complexity and contribute to power system modeling with implications for real-time power system management and the integration of sustainable energy.

   Handling Ground Faults in Meshed MVDC Grids by Fast Redistribution of Power Flow
By Tuan Minh NGUYEN, José-Luis MARQUÉS-LOPEZ, Claus HILLERMEIER [View]
[Download]

Abstract: In case of ground faults, the power flows within multiterminal DC grids must be redistributed to drive the current in faulty lines to zero. This paper completes a previously presented method for generating such transitions by a central component, a new feedback control to correct undesirable deviations from the desired behavior.

   Modular Clamping Circuit for High Speed Solid State Circuit Breakers
By Florian KAPAUN, Christopher DAHMEN, Gerhard STEINER, Michael WITTI [View]
[Download]

Abstract: The aviation industry is on the cusp of a revolutionary transformation with the advent of zero-emission aircraft. These innovative aircraft, powered by cutting-edge technologies such as electric propulsion and hydrogen fuel cells, promise to significantly reduce the environmental impact of air travel. As global awareness of climate change and sustainability grows, the development and adoption of zero-emission aircraft are becoming increasingly vital. However, the integration of these advanced technologies necessitates robust electrical network protection to ensure safety and reliability. This leads to the need for advanced protection circuits, such as Solid-State Circuit Breakers (SSCBs) and clamping circuits, which are essential for managing the complexities of modern electrical systems. This paper focuses on an advanced clamping circuit that enables efficient voltage clamping for high-speed SSCBs. The method effectively clamps overvoltage in failure cases, realizing almost no voltage overshoot and a minimum time to clear the fault current. Due to its complete analog nature it is very suitable for safety critical applications where active digital control circuits have to be avoided. The proposed method is very efficient, ensuring the stability and safety of electrical networks in zeroemission aircraft.

   Protection design for pole-to-pole faults in DC networks
By Fabian Benedikt WITT, Melanie HOFFMANN, Michael KURRAT [View]
[Download]

Abstract: Fault protection is one of the primary challenges impeding the widespread adoption of DC and hybrid AC/DC grids. A structured planning process for protection systems is necessary with regard to standardization. In this paper, a novel three-step protection system design process is proposed building upon the CENELEC (CLC/TS 50654-1) approach. The proposed planning process is separated into concept, system and component level. On concept level, the operational modes 'continued operation', 'temporary stop' and 'permanent stop' according to CENELEC are used to define desired system behaviour in the event of a fault. On system level, protective action sequences are defined to realize the system behaviour defined on concept level. Finally on component level, protective devices are dimensioned and tripping thresholds are determined.

   SiC Solid-state Power Contactors SSPC`s in comparison to E-Fuses and Solid-state Circuit breakers
By Maik HOHMANN [View]
[Download]

Abstract: In this work, the novel approach of a DC protection system based on an all-solid-state semiconductor PCB solution was presented. The switching element, called the 'solid-state power contactor - SSPC', is implemented as a circuit board. Modern system integration technologies are used here. The focus is on circuit board technologies that distribute the power losses of the semiconductors in a targeted manner on the circuit board and can very quickly reduce high temperature gradients in the semiconductors in critical operating conditions. There are fundamental differences between the three systems E-Fuse, SSCB and SSPC, depending on their intended use. This is why E-Fuse is primarily considered a fuse replacement system, SSCB as an on/off switching device and the SSPC presented here as a protective device for functional safety must enable 'safe disconnection and switching'. In addition, the naming E-Fuse, SSCB or SSPC are not absolute.

   Three port converter control with automatic mode transition for interconnected and standalone DC microgrids
By Athanasios VASDARIS, Georgios SALAGIANNIS, Emmanuel TATAKIS [View]
[Download]

Abstract: Various Three-Port Converters (TPCs) are proposed in literature, usually operated in standalone networks without their control clearly discussed. In this paper, a new control scheme, offering smooth and automatic mode transitions in standalone and interconnected DC Microgrids operation, is presented. The control is applied in a TPC that consists of a boost and a bidirectional buck-boost converter, integrating a PV string and a battery with the DC Microgrid. In contrast to other proposed control systems, the one suggested here guarantees the required function of maximum power point tracking and output regulation in all corresponding modes. The proper operation of the system is evaluated through simulation studies.

   Ultra-Fast Bidirectional SiC Solid-State Circuit Breaker for 800V / 400A Aircraft Applications
By Christopher DAHMEN, Florian KAPAUN, Gerhard STEINER, Hubert RAUH, Florian BAYER [View]
[Download]

Abstract: The shift toward electric propulsion in aircraft brings unique challenges to power distribution and protection systems, requiring the advancement of technologies like solid-state circuit breakers (SSCBs). This paper explores the pivotal role of SSCBs in electric aircraft, highlighting their potential to improve safety, reliability, and efficiency in 800V high-power environments. However, their integration in aviation also presents challenges, such as ultra-fast fault isolation within complex electrical architectures, efficient thermal management, enhanced reliability and safety, and the demand for lightweight, compact designs. This paper addresses these challenges by analyzing current technological limitations, exploring potential solutions, and presenting experimental results from a bidirectional silicon carbide (SiC) SSCB that successfully detects a 1kA fault current with a response time of less than 1µs. The results emphasize the need for continued innovation in SSCB technology to meet the stringent demands of next-generation electric aircraft.

EPE 2025 - DS1f: Smart Grids, DC Networks and Components, Hybrid AC/DC Networks
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2025 - Conference > EPE 2025 - Topic 02: Smart Grids and Renewable Energy > EPE 2025 - DS1f: Smart Grids, DC Networks and Components, Hybrid AC/DC Networks
	[return to parent folder]

	A Multi-Agent Reinforcement Learning-based Secondary Control for Voltage Restoration and Current Sharing in DC Microgrids By Shima SHAHNOOSHI, Javad EBRAHIMI, Alireza BAKHSHAI	[View] [Download]
Abstract: Microgrids are designed for sustainable energy generation and the efficient use of Distributed Generators (DGs). DC microgrids face challenges such as current sharing and voltage restoration, commonly addressed using droop control. Despite its simplicity, droop control can lead to voltage deviations and inefficient current sharing. This paper develops a Multi-Agent Reinforcement Learning (MARL) based secondary control method using Deep Q-Networks (DQN) to improve voltage restoration and current sharing in DC microgrids. The proposed method leverages centralized training to utilize comprehensive environmental information, integrating both the voltage restoration and current sharing objectives into each agent's local reward function. Simulation results demonstrate the effectiveness of the MARL approach in addressing the limitations of droop control, ensuring stable current flow and enhancing overall system performance.

	An overview of grid code possible requirements for an interoperability MVAC/MVDC systems - Focus on fault detection for a future PV power plant By Nicolas LIM, Van-Sang NGUYEN, Seddik BACHA, Quoc Tuan TRAN	[View] [Download]
Abstract: An AC/DC interoperability is expected to be part of the future grid but is not currently developed at medium voltage level. Standardization efforts are necessary to develop medium voltage DC (MVDC) systems. This article discusses the existing grid code for medium voltage (MV) applications, providing an overview of the existing requirements and the future requirements expected for the development of MVDC applications. Behaviour of a hybrid AC/DC system during fault situations through PLECS based simulation has been provided.

	Comprehensive model of a synchronous generator for single-node studies By Guillermo BAUTISTA, Miguel GARCÍA, Javier MARCOS, Íñigo DE LA PARRA, Luis MARROYO	[View] [Download]
Abstract: As power electronics increasingly replaceSynchronous Generators (SGs), the focus on system frequencystability has grown. To study frequency dynamicsduring disturbances, time-domain models, such as thesimple single-node model, are used. The commonly usedsingle-node models lack sufficient representation of electricpower dynamics, simplifying converter-interfaced generation(CIG) behavior as reduced system inertia. However,control strategies, such as Power System Stabilizers(PSS) on SGs or Power Oscillation Dampers (POD) onCIG, can modify the system-wide frequency response.This paper presents a comprehensive state-space modelof a SG for single-node studies, offering flexibility toanalyze electrical interactions involving the AutomaticVoltage Regulator (AVR) and PSS, while facilitating theinclusion of power electronics. Additionally, the modelprovides a mathematical framework for understanding therelationships between system parameters through statespacerepresentation and could be used to explore othercritical interactions.

	Development of an Integrated Transmission-Distribution Simulation Model for Coordinated TSO-DSO Interface Management By Mohamed Nadir BOUHADDA, Mohamed Moez BELHAOUANE, Arnaud DAVIGNY, Abdelhadi QASIMI, Vincent BARBESANT, Sebastien HAYE, Benoit ROBYNS	[View] [Download]
Abstract: This paper presents a comprehensive methodology for integrated TSO/DSO modeling, aimed at enhancing coordinated management of transmission and distribution networks. The proposed approach allows to perform a unified numerical load-flow model that effectively integrates both transmission and distribution electrical systems, accounting for technical constraints of each grid operator. The validation of the detailed joint TSO/DSO model is carried out using real-world scenarios provided by grid operators, ensuring its practical applicability.

	Distribution Network Reconfiguration Including OLTC Limits and Variable Shunt Reactors By Aghyles GRAINE, Jean-Paul GAUBERT, Didier LARRAILLET	[View] [Download]
Abstract: Networks often suffer from overvoltageproblems. The On-Load Tap Changers (OLTCs) may notalways be able to regulate the voltage. Distribution net-work reconfiguration and variable shunt reactors can helpmitigate these issues. In this paper, OLTCs are modeledand incorporated into the optimization. The results showan improvement in the accuracy.

	Enhanced Current-Limiting Strategy of Grid-Forming Converter Considering Grid-forming Capability By Junyeol MAENG, Shenghui CUI	[View] [Download]
Abstract: Recently, Grid-forming (GFM) converters have gained significant attention for their ability to enhance power system stability during disturbances. However, conventional current-limiting strategies lack sufficient consideration for preserving GFM capability under current-limited conditions. To address this issue, this paper proposes a novel current-limiting strategy that simultaneously ensures accurate current limitation and preserves GFM capability. The proposed method minimizes deviations in the converter terminal voltage by incorporating a PCC voltage-based current-limiting condition in real time. This approach allows the GFM converter to preserve its natural response-driven GFM capability to the greatest extent possible within a given current limit. Experimental results validate the superior performance of the proposed method compared to existing methods.

	Enhancing Optimal Power Flow Feasibility: A Novel Comparative Study of Approximation Techniques By Sarah ALIBHAI, Maxim CIOBANU, Wiktor WIEJAK, David PETERS, Sajad FATHI HAFSHEJANI, Daya GAUR, Robert BENKOCZI	[View] [Download]
Abstract: This experimental study investigates three approximation methods (quadratic, linear, and logarithmic) of the Optimal Power Flow problem (OPF) in comparison to traditional DC-OPF approximations using benchmark cases from the MATPOWER library. The quality and efficiency of each method is assessed using novel error metrics in respect to the AC-OPF baseline, with a focus on phase angle, voltage magnitude and generation costs. Results demonstrate promise in outperforming DC-OPF while maintaining computational efficiency, especially in the case of the quadratic approximation. Findings indicate an attainable balance between accuracy and complexity and contribute to power system modeling with implications for real-time power system management and the integration of sustainable energy.

	Handling Ground Faults in Meshed MVDC Grids by Fast Redistribution of Power Flow By Tuan Minh NGUYEN, José-Luis MARQUÉS-LOPEZ, Claus HILLERMEIER	[View] [Download]
Abstract: In case of ground faults, the power flows within multiterminal DC grids must be redistributed to drive the current in faulty lines to zero. This paper completes a previously presented method for generating such transitions by a central component, a new feedback control to correct undesirable deviations from the desired behavior.

	Modular Clamping Circuit for High Speed Solid State Circuit Breakers By Florian KAPAUN, Christopher DAHMEN, Gerhard STEINER, Michael WITTI	[View] [Download]
Abstract: The aviation industry is on the cusp of a revolutionary transformation with the advent of zero-emission aircraft. These innovative aircraft, powered by cutting-edge technologies such as electric propulsion and hydrogen fuel cells, promise to significantly reduce the environmental impact of air travel. As global awareness of climate change and sustainability grows, the development and adoption of zero-emission aircraft are becoming increasingly vital. However, the integration of these advanced technologies necessitates robust electrical network protection to ensure safety and reliability. This leads to the need for advanced protection circuits, such as Solid-State Circuit Breakers (SSCBs) and clamping circuits, which are essential for managing the complexities of modern electrical systems. This paper focuses on an advanced clamping circuit that enables efficient voltage clamping for high-speed SSCBs. The method effectively clamps overvoltage in failure cases, realizing almost no voltage overshoot and a minimum time to clear the fault current. Due to its complete analog nature it is very suitable for safety critical applications where active digital control circuits have to be avoided. The proposed method is very efficient, ensuring the stability and safety of electrical networks in zeroemission aircraft.

	Protection design for pole-to-pole faults in DC networks By Fabian Benedikt WITT, Melanie HOFFMANN, Michael KURRAT	[View] [Download]
Abstract: Fault protection is one of the primary challenges impeding the widespread adoption of DC and hybrid AC/DC grids. A structured planning process for protection systems is necessary with regard to standardization. In this paper, a novel three-step protection system design process is proposed building upon the CENELEC (CLC/TS 50654-1) approach. The proposed planning process is separated into concept, system and component level. On concept level, the operational modes 'continued operation', 'temporary stop' and 'permanent stop' according to CENELEC are used to define desired system behaviour in the event of a fault. On system level, protective action sequences are defined to realize the system behaviour defined on concept level. Finally on component level, protective devices are dimensioned and tripping thresholds are determined.

	SiC Solid-state Power Contactors SSPC`s in comparison to E-Fuses and Solid-state Circuit breakers By Maik HOHMANN	[View] [Download]
Abstract: In this work, the novel approach of a DC protection system based on an all-solid-state semiconductor PCB solution was presented. The switching element, called the 'solid-state power contactor - SSPC', is implemented as a circuit board. Modern system integration technologies are used here. The focus is on circuit board technologies that distribute the power losses of the semiconductors in a targeted manner on the circuit board and can very quickly reduce high temperature gradients in the semiconductors in critical operating conditions. There are fundamental differences between the three systems E-Fuse, SSCB and SSPC, depending on their intended use. This is why E-Fuse is primarily considered a fuse replacement system, SSCB as an on/off switching device and the SSPC presented here as a protective device for functional safety must enable 'safe disconnection and switching'. In addition, the naming E-Fuse, SSCB or SSPC are not absolute.

	Three port converter control with automatic mode transition for interconnected and standalone DC microgrids By Athanasios VASDARIS, Georgios SALAGIANNIS, Emmanuel TATAKIS	[View] [Download]
Abstract: Various Three-Port Converters (TPCs) are proposed in literature, usually operated in standalone networks without their control clearly discussed. In this paper, a new control scheme, offering smooth and automatic mode transitions in standalone and interconnected DC Microgrids operation, is presented. The control is applied in a TPC that consists of a boost and a bidirectional buck-boost converter, integrating a PV string and a battery with the DC Microgrid. In contrast to other proposed control systems, the one suggested here guarantees the required function of maximum power point tracking and output regulation in all corresponding modes. The proper operation of the system is evaluated through simulation studies.

	Ultra-Fast Bidirectional SiC Solid-State Circuit Breaker for 800V / 400A Aircraft Applications By Christopher DAHMEN, Florian KAPAUN, Gerhard STEINER, Hubert RAUH, Florian BAYER	[View] [Download]
Abstract: The shift toward electric propulsion in aircraft brings unique challenges to power distribution and protection systems, requiring the advancement of technologies like solid-state circuit breakers (SSCBs). This paper explores the pivotal role of SSCBs in electric aircraft, highlighting their potential to improve safety, reliability, and efficiency in 800V high-power environments. However, their integration in aviation also presents challenges, such as ultra-fast fault isolation within complex electrical architectures, efficient thermal management, enhanced reliability and safety, and the demand for lightweight, compact designs. This paper addresses these challenges by analyzing current technological limitations, exploring potential solutions, and presenting experimental results from a bidirectional silicon carbide (SiC) SSCB that successfully detects a 1kA fault current with a response time of less than 1µs. The results emphasize the need for continued innovation in SSCB technology to meet the stringent demands of next-generation electric aircraft.