EPE Association: EPE 2019 - DS3i: Other Grid Issues

EPE 2019 - DS3i: Other Grid Issues
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2019 - DS3i: Other Grid Issues

   [return to parent folder]

   A New Harmonic Optimization Strategy for Modular Multilevel Converters
By Yang GAO [View]
[Download]

Abstract: This paper proposes a new harmonic optimization strategy for Modular Multilevel Converter (MMC). To verify the strategy, a typical offshore wind power DC integration using MMC model is established in the software PSCAD/EMTDC, and the total harmonic distortion (THD) of the point of common coupling (PCC) is compared before and after using the new harmonic optimization strategy. Simulation results show the effectiveness of the optimization strategy.

   A Novel Bi-directional Hybrid High Voltage DC Fault Current Limiter Based on Superconding Material and Power Electronic Devices
By Chaoran ZHUO [View]
[Download]

Abstract: Compared with traditional AC transmission system, the development of DC transmission system is constrained by the amplitude limitation of fault current, since there is no natural zero crossing. This paper provides a new high voltage directional current hybrid fault current limiter topology which can be used to limit bi-directional fault current. The new hybrid fault current limiter topology uses the topology including fully-controlled electrical power switches and superconducting materials, which works together to limit the fault DC current. Superconducting material in this hybrid fault current limiter topology is being applied during the time when fault current is losing control, especially in time delay of sensing and judging the fault current by electrical power switches. As long as fault current is conformed, the part of power switches will take the rest of the works. Compared with other types of fault current limiter typologies, it provides a better fault current limitation results and at the mean time with much simpler control strategy.

   Analytical design considerations for MVDC solid-state circuit breakers
By Sondre J. K. BERG [View]
[Download]

Abstract: This paper investigates the design principles of a solid-state circuit breaker (SS CB) for medium voltagedirect current (MVDC) grids. The emphasis is given on the design of the required active and passivecomponents that employed in a SS DCCB based on analytic methodology. Several cases related tothe characteristics of the current technology of power semiconductor devices have been investigated andevaluated in terms of maximum short-circuit current, maximum switch current, maximum switch voltage,clearance time, as well as, passive elements requirements. It has been shown that potential improvementsof the current power semiconductor technology could lead to improved performance of SS DCCB withlower requirements for passive elements. In particular, the most significant characteristic that improvesthe overall SS breaker performance was found to be a potential reduce of the falling time (or increase ofpower dissipation) of the switches used in SS breaker.

   Continuous Higher Order Sliding Mode Controller for LCL-Type Grid-Connected Shunt Active Filters
By Mohamad Alaaeddin ALALI [View]
[Download]

Abstract: A LCL grid connected three-phase and three-wire shunt active filter (SAF) is studied andcontrolled. It is known that SAFs generate distortive components caused by a high switchingfrequency of a voltage source inverter (VSI). In order to prevent spreading these distortivecomponents to the grid, the LCL filter (usually controlled by a linear control feedback) is used;while a parasitic phase shift/lag between the reference and injected currents emerges andseverely deteriorates the filtration quality. On the other hand, the use of a sliding modecontroller (SMC) reduces phase shift effects and consequently ensures good filtration qualityof the SAF while improving robustness to system's disturbances. A side effect of SMC is ingenerating discontinuous very high switching frequency control command that can severelyhurt the switching elements of the VSI. In this work, the robust continuous higher order slidingmode controller (C-HOSM), whose output is processed by pulse-width modulators (PWM), isstudied for controlling the SAF. The proposed robust control set up provides a fixed givenfrequency of control switching, required for the VSI safe operation. The proposed approachwas validated on industrial nonlinear load via simulations carried out using Matlab, Simulink,and Simscap-Sim\_Power\_System code.

   Coordinated Control of Parallel Power Conditioners Synthesizing Resistive Loads in Single-Phase AC Microgrids
By Augusto Matheus DOS SANTOS ALONSO [View]
[Download]

Abstract: Without proper coordination, power conditioners within microgrids are prone to suffer from resonance phenomena due to the complex and dynamic interactions among the main grid, nonlinear loads and distributed converters. In addition to the detriment of grid-connected devices and loads, harmonic voltage resonances may also lead to microgrid instability. As a consequence, the steering of distributed power conditioners to diminish voltage distortions and suppress undesired currents has been playing a key role on enhancing the operational stiffness of microgrids. In general, such conditioners are driven by the synthesis of sinusoidal currents independently on the status of voltage waveforms, which may not adequately damp harmonic resonances and still jeopardize system stability. Thus, this work proposes the coordination of multiple parallel power conditioners, which are driven as controlled current sources, through a current-based approach that synthesizes resistive loads, enhancing the system capability to damp voltage resonances, as well as improving power quality within microgrids. Simulation results comprising a single-phase microgrid with resonant and nonlinear loads, as well as two distributed power conditioners, are presented to demonstrate the effectiveness of the approach.

   Fast Power Flow Calculation Method for Grid Expansion Planning
By Mirko WAHL [View]
[Download]

Abstract: Distribution grid operators in Germany are facing major challenges. The increasing share of decentralized generation units over the last years are followed by a foreseeable increase in demand and peak load. This will be caused by an electrification of the mobility and heating sectors, therefore more electric vehicle (EV) and heat pumps (HP), for instance, will be connected to the grid. Due to their inherent storage capacity EV and HP provide a certain time shifting possibility of their demand. This flexibility can be used by grid operators to postpone or avoid grid reinforcement. To do so, the grid expansion planning must simulate the grid operation more comprehensive via time series. Since a time series based simulation comes with a high increase in computing time a fast power flow calculation is required. In this paper we present a fast power flow calculation method for weakly meshed grids such as medium and low voltage grids.

   Impact of the phase-angle detection inaccuracies on the performance of a three-phase grid-tied system
By Vinícius BACON [View]
[Download]

Abstract: Grid voltage information, such as voltage amplitude, frequency, as well as phase-angle have been commonly estimated by employing phase-locked loop (PLL) schemes. However, supposing the estimated phase-angle signal is generated with some distortion, which can be caused by disturbances present in the mains voltages, very likely the control reference signals will also be distorted and can interfere in the performance of grid-connected systems.This paper evaluates the impacts caused by inaccurate detection of the utility phase-angle on the static performance of a three-phase parallel active power filter (P-APF). Taking into account that grid-connected system like P-APF uses the utility phase-angle to compute the compensation current references, inaccuracies in the phase-angle detection can cause not suitable operation and, hence, deteriorate its active filtering performance.By means of several experimental tests, which are performed under grid voltage distorted conditions, the performance of a three-phase P-APF is evaluated considering the interference of PLL schemes.

   Optimization of Hybrid Current-Injection Circuit Breakers including Mechanical Switch Limitations
By Andreas JEHLE [View]
[Download]

Abstract: Circuit breakers with current injection enable fast interruption of fault currents in DC grids. Independent of the topology, a high number of semiconductors and capacitors is required. The minimum required number of semiconductors and capacitors depend mainly on the system voltage and the maximum fault current. However, also the MS characteristics have considerable influence on the required number of semiconductors and capacitors. Therefore, in this paper the influence of the MS characteristics on the arc extinction and the influence of the arc voltage on the DC-CB design is presented. In addition, optimization procedures for current injection circuit breaker are presented, which include the MS characteristics and four different possibilities to include the arc voltage. Finally,three DC-CB topologies are compared in terms of number of semiconductors and capacitors.

   Performance Analysis of Counter-Current Injection based DC Circuit Breaker with Improved Capacitor Charging Circuit
By Ali VIRDAG [View]
[Download]

Abstract: In this paper, a hybrid DC breaker topology based on counter current injection method [1], [2] withimproved charging circuit of the capacitor is proposed and analyzed. Instead of using an external sourceto pre-charge the capacitor, the proposed charging circuit uses the system voltage. The charging circuitis implemented with only one semiconductor switch compared to two switches charging circuitry thatis used in general to isolate both positive and negative terminal of the source voltage from the capacitorterminals. The paper proposes a modified snubber circuit to avoid overvoltage across the circuit-breaker.Effect of snubber capacitance and snubber resistance on the circuit performance is also analyzed.

   Performance evaluation of high power semiconductor devices employed in solid-state circuit breakers for MVDC grids
By Andreas GIANNAKIS [View]
[Download]

Abstract: This paper presents a performance evaluation of power losses of three high-power and high-voltage power semiconductor devices, namely, IGBTs, BIGTs, and IGCTs operating in solid-state DC circuit breakers for medium voltage Direct Current grids. The performance of each breaker is evaluated for a wide range of DC voltages and load conditions under steady-state operation, whereas the criteria are the conduction losses associated with the switches and the corresponding junction temperature. The IGCT-based solid-state breaker achieved the lowest power losses, while the IGBT-based performed the highest losses under all the investigated cases. Last but not least, a comparative study regarding the transient responses of the three devices when a short-circuit occurs is also examined and presented. The superiority of BIGT-based breaker in terms of minimizing the short-circuit current is revealed.

   The Influence on Drive Inverters under the Effects of Short Circuits in an Open Industrial DC grid
By Simon PULS [View]
[Download]

Abstract: An open industrial DC grid has many advantages. The exchange of energy and lower costs for semiconductors due to the elimination of rectifiers are excellent arguments. This paper presents relevant faults for drive inverters during operation in the DC grid. It is shown where electrical faults can occur during operation of an open industrial DC grid. In particular, short-circuit faults are described. It is explained how the faults affect electrolytic capacitors and the free-wheeling diodes built in drive inverters. Both components are heavily stressed in the event of a short-circuit fault. Furthermore, it is mentioned out which role solid-state / hybrid circuit breakers and melting fuses can play.

   Verification of Simplification of Traction Substation System by Energy Storage System
By Kota MINAMINOSONO [View]
[Download]

Abstract: We developed control logic demanded for ESS to simplify SS facilities, replacing SS with Battery Post. We report the verification test results about ESS for stable railway operation use in order to compensate for voltage drops, and control logic using train data to reduce battery size and extend battery life.

EPE 2019 - DS3i: Other Grid Issues
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2019 - DS3i: Other Grid Issues
	[return to parent folder]

	A New Harmonic Optimization Strategy for Modular Multilevel Converters By Yang GAO	[View] [Download]
Abstract: This paper proposes a new harmonic optimization strategy for Modular Multilevel Converter (MMC). To verify the strategy, a typical offshore wind power DC integration using MMC model is established in the software PSCAD/EMTDC, and the total harmonic distortion (THD) of the point of common coupling (PCC) is compared before and after using the new harmonic optimization strategy. Simulation results show the effectiveness of the optimization strategy.

	A Novel Bi-directional Hybrid High Voltage DC Fault Current Limiter Based on Superconding Material and Power Electronic Devices By Chaoran ZHUO	[View] [Download]
Abstract: Compared with traditional AC transmission system, the development of DC transmission system is constrained by the amplitude limitation of fault current, since there is no natural zero crossing. This paper provides a new high voltage directional current hybrid fault current limiter topology which can be used to limit bi-directional fault current. The new hybrid fault current limiter topology uses the topology including fully-controlled electrical power switches and superconducting materials, which works together to limit the fault DC current. Superconducting material in this hybrid fault current limiter topology is being applied during the time when fault current is losing control, especially in time delay of sensing and judging the fault current by electrical power switches. As long as fault current is conformed, the part of power switches will take the rest of the works. Compared with other types of fault current limiter typologies, it provides a better fault current limitation results and at the mean time with much simpler control strategy.

	Analytical design considerations for MVDC solid-state circuit breakers By Sondre J. K. BERG	[View] [Download]
Abstract: This paper investigates the design principles of a solid-state circuit breaker (SS CB) for medium voltagedirect current (MVDC) grids. The emphasis is given on the design of the required active and passivecomponents that employed in a SS DCCB based on analytic methodology. Several cases related tothe characteristics of the current technology of power semiconductor devices have been investigated andevaluated in terms of maximum short-circuit current, maximum switch current, maximum switch voltage,clearance time, as well as, passive elements requirements. It has been shown that potential improvementsof the current power semiconductor technology could lead to improved performance of SS DCCB withlower requirements for passive elements. In particular, the most significant characteristic that improvesthe overall SS breaker performance was found to be a potential reduce of the falling time (or increase ofpower dissipation) of the switches used in SS breaker.

	Continuous Higher Order Sliding Mode Controller for LCL-Type Grid-Connected Shunt Active Filters By Mohamad Alaaeddin ALALI	[View] [Download]
Abstract: A LCL grid connected three-phase and three-wire shunt active filter (SAF) is studied andcontrolled. It is known that SAFs generate distortive components caused by a high switchingfrequency of a voltage source inverter (VSI). In order to prevent spreading these distortivecomponents to the grid, the LCL filter (usually controlled by a linear control feedback) is used;while a parasitic phase shift/lag between the reference and injected currents emerges andseverely deteriorates the filtration quality. On the other hand, the use of a sliding modecontroller (SMC) reduces phase shift effects and consequently ensures good filtration qualityof the SAF while improving robustness to system's disturbances. A side effect of SMC is ingenerating discontinuous very high switching frequency control command that can severelyhurt the switching elements of the VSI. In this work, the robust continuous higher order slidingmode controller (C-HOSM), whose output is processed by pulse-width modulators (PWM), isstudied for controlling the SAF. The proposed robust control set up provides a fixed givenfrequency of control switching, required for the VSI safe operation. The proposed approachwas validated on industrial nonlinear load via simulations carried out using Matlab, Simulink,and Simscap-Sim\_Power\_System code.

	Coordinated Control of Parallel Power Conditioners Synthesizing Resistive Loads in Single-Phase AC Microgrids By Augusto Matheus DOS SANTOS ALONSO	[View] [Download]
Abstract: Without proper coordination, power conditioners within microgrids are prone to suffer from resonance phenomena due to the complex and dynamic interactions among the main grid, nonlinear loads and distributed converters. In addition to the detriment of grid-connected devices and loads, harmonic voltage resonances may also lead to microgrid instability. As a consequence, the steering of distributed power conditioners to diminish voltage distortions and suppress undesired currents has been playing a key role on enhancing the operational stiffness of microgrids. In general, such conditioners are driven by the synthesis of sinusoidal currents independently on the status of voltage waveforms, which may not adequately damp harmonic resonances and still jeopardize system stability. Thus, this work proposes the coordination of multiple parallel power conditioners, which are driven as controlled current sources, through a current-based approach that synthesizes resistive loads, enhancing the system capability to damp voltage resonances, as well as improving power quality within microgrids. Simulation results comprising a single-phase microgrid with resonant and nonlinear loads, as well as two distributed power conditioners, are presented to demonstrate the effectiveness of the approach.

	Fast Power Flow Calculation Method for Grid Expansion Planning By Mirko WAHL	[View] [Download]
Abstract: Distribution grid operators in Germany are facing major challenges. The increasing share of decentralized generation units over the last years are followed by a foreseeable increase in demand and peak load. This will be caused by an electrification of the mobility and heating sectors, therefore more electric vehicle (EV) and heat pumps (HP), for instance, will be connected to the grid. Due to their inherent storage capacity EV and HP provide a certain time shifting possibility of their demand. This flexibility can be used by grid operators to postpone or avoid grid reinforcement. To do so, the grid expansion planning must simulate the grid operation more comprehensive via time series. Since a time series based simulation comes with a high increase in computing time a fast power flow calculation is required. In this paper we present a fast power flow calculation method for weakly meshed grids such as medium and low voltage grids.

	Impact of the phase-angle detection inaccuracies on the performance of a three-phase grid-tied system By Vinícius BACON	[View] [Download]
Abstract: Grid voltage information, such as voltage amplitude, frequency, as well as phase-angle have been commonly estimated by employing phase-locked loop (PLL) schemes. However, supposing the estimated phase-angle signal is generated with some distortion, which can be caused by disturbances present in the mains voltages, very likely the control reference signals will also be distorted and can interfere in the performance of grid-connected systems.This paper evaluates the impacts caused by inaccurate detection of the utility phase-angle on the static performance of a three-phase parallel active power filter (P-APF). Taking into account that grid-connected system like P-APF uses the utility phase-angle to compute the compensation current references, inaccuracies in the phase-angle detection can cause not suitable operation and, hence, deteriorate its active filtering performance.By means of several experimental tests, which are performed under grid voltage distorted conditions, the performance of a three-phase P-APF is evaluated considering the interference of PLL schemes.

	Optimization of Hybrid Current-Injection Circuit Breakers including Mechanical Switch Limitations By Andreas JEHLE	[View] [Download]
Abstract: Circuit breakers with current injection enable fast interruption of fault currents in DC grids. Independent of the topology, a high number of semiconductors and capacitors is required. The minimum required number of semiconductors and capacitors depend mainly on the system voltage and the maximum fault current. However, also the MS characteristics have considerable influence on the required number of semiconductors and capacitors. Therefore, in this paper the influence of the MS characteristics on the arc extinction and the influence of the arc voltage on the DC-CB design is presented. In addition, optimization procedures for current injection circuit breaker are presented, which include the MS characteristics and four different possibilities to include the arc voltage. Finally,three DC-CB topologies are compared in terms of number of semiconductors and capacitors.

	Performance Analysis of Counter-Current Injection based DC Circuit Breaker with Improved Capacitor Charging Circuit By Ali VIRDAG	[View] [Download]
Abstract: In this paper, a hybrid DC breaker topology based on counter current injection method [1], [2] withimproved charging circuit of the capacitor is proposed and analyzed. Instead of using an external sourceto pre-charge the capacitor, the proposed charging circuit uses the system voltage. The charging circuitis implemented with only one semiconductor switch compared to two switches charging circuitry thatis used in general to isolate both positive and negative terminal of the source voltage from the capacitorterminals. The paper proposes a modified snubber circuit to avoid overvoltage across the circuit-breaker.Effect of snubber capacitance and snubber resistance on the circuit performance is also analyzed.

	Performance evaluation of high power semiconductor devices employed in solid-state circuit breakers for MVDC grids By Andreas GIANNAKIS	[View] [Download]
Abstract: This paper presents a performance evaluation of power losses of three high-power and high-voltage power semiconductor devices, namely, IGBTs, BIGTs, and IGCTs operating in solid-state DC circuit breakers for medium voltage Direct Current grids. The performance of each breaker is evaluated for a wide range of DC voltages and load conditions under steady-state operation, whereas the criteria are the conduction losses associated with the switches and the corresponding junction temperature. The IGCT-based solid-state breaker achieved the lowest power losses, while the IGBT-based performed the highest losses under all the investigated cases. Last but not least, a comparative study regarding the transient responses of the three devices when a short-circuit occurs is also examined and presented. The superiority of BIGT-based breaker in terms of minimizing the short-circuit current is revealed.

	The Influence on Drive Inverters under the Effects of Short Circuits in an Open Industrial DC grid By Simon PULS	[View] [Download]
Abstract: An open industrial DC grid has many advantages. The exchange of energy and lower costs for semiconductors due to the elimination of rectifiers are excellent arguments. This paper presents relevant faults for drive inverters during operation in the DC grid. It is shown where electrical faults can occur during operation of an open industrial DC grid. In particular, short-circuit faults are described. It is explained how the faults affect electrolytic capacitors and the free-wheeling diodes built in drive inverters. Both components are heavily stressed in the event of a short-circuit fault. Furthermore, it is mentioned out which role solid-state / hybrid circuit breakers and melting fuses can play.

	Verification of Simplification of Traction Substation System by Energy Storage System By Kota MINAMINOSONO	[View] [Download]
Abstract: We developed control logic demanded for ESS to simplify SS facilities, replacing SS with Battery Post. We report the verification test results about ESS for stable railway operation use in order to compensate for voltage drops, and control logic using train data to reduce battery size and extend battery life.