EPE Association: EPE 2018 - DS3j: Power Quality Issues; Fault Coordination and Protection of DC grids

EPE 2018 - DS3j: Power Quality Issues; Fault Coordination and Protection of DC grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2018 - DS3j: Power Quality Issues; Fault Coordination and Protection of DC grids

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   Analysis of Low-Frequency-Oscillations in Single-Phase AC Systems by LTP Theory
By Valerio SALIS [View]
[Download]

Abstract: The paper presents the analysis of a single-phase active rectifier, with DC constant power load, affected by Low-FrequencyOscillation (LFO) behaviour. Conventional LTI analysis tools might fail to reveal the LFO phenomenon, whereas the LTP(Linear Time Periodic) approach, here exploited with analytical derivation and detailed simulations, provides superior results.

   Comparison of Energy Dissipation Concepts for DC Circuit Breakers
By Andreas JEHLE [View]
[Download]

Abstract: In DC grids, DC circuit breakers (CB) are used to interrupt currents in case of a fault and to dissipate the remaining energy in the line. Independent of the actually DC CB concept, different energy dissipation concepts can be used, which also influence the performance of the DC CB. In this paper, the energy dissipation with different circuit arrangements, where the energy is dissipated in a single loop, in two loops or in two coupled loops, are discussed and compared. Additionally, the effect of different voltage waveforms across the DC CB and the distribution of the current limiting inductance on the input and the output side of the DC CB are investigated.

   Design considerations of power semiconductor devices employed in VSCs under short-circuit fault conditions in MVDC distribution grids
By Andreas GIANNAKIS [View]
[Download]

Abstract: Electric energy distribution using medium voltage DC (MVDC) enables an advantageous performance compared to the state-of-the-art MVAC counterparts. Among others, a crucial challenge currently is related to the need for developing high-performance protection schemes against DC short-circuits and, thus, to prevent severe conditions of electric and thermal stress in the involved power electronics equipment. This paper presents an evaluation of design requirements and performance of four types of active rectifiers employed in MVDC grids under a DC short-circuit condition when using either an AC circuit breaker (AC CB) or a solid-state DC CB. The focus is on freewheeling diodes and the evaluation is performed in terms of power semiconductors stress, fault handling capability and chip area requirements by using simulations and calculations. The superior performance of DC CB over AC counterparts for all rectifier types is highlighted.

   Electric Vehicle Charging Station Load Analysing Based on Monte-Carlo Method
By Maksims VOROBJOVS [View]
[Download]

Abstract: Taking into account the technological leap and the increased demand and production of electric vehicles, a study on the use of free power for charging of electric vehicles of the Riga Technical University, at the Faculty of Power and Electrical Engineering was conducted within the presented document. Also, a computer model of load demand for one charging unit was created to analyze quality of network parameters. This study uses statistics of load demand of charging unit for probabilistic forecasting of the load on a substation of 400 kVA and 630 kVA and determining the most optimal conditions of charging units for a particular station, using algorithm based on the Monte Carlo method. The algorithm described in detail is described in detail. Simulation was conducted on the basis of which it was concluded that if the charging station is located in a university campus or office center. It is necessary to organize switching on and off of charging points.

   Large Signal Stability Analysis of More Electric Aircraft Power System
By Yalu SHEN [View]
[Download]

Abstract: The electric load amount and power capacity impact the stability of the aircraft power grid and bringchallenges to the design. With Lyapunov stability theorems in large-signal model based stabilityanalysis, this paper establishes the system state equation, obtains the scalar function according to themixed potential function theory, and determines the system stability region. The theoretical analysisresults are verified by simulation of a single-channel grid.

   MVDC distribution grids and potential applications: Future trends and protection challenges
By Andreas GIANNAKIS [View]
[Download]

Abstract: This paper presents the fundamental system components of medium-voltage direct current (MVDC) grids, including an overview of power electronic converters and protection schemes against DC fault currents. In addition to this, the lack of standardization and the development of efficient and reliable circuit breakers (CBs), which are today considered as showstoppers, are also analyzed in detail. The performances of three DC CBs, namely mechanical breaker with active current injection, solid state CB and hybrid CB are evaluated in terms of clearance times, fault peak current, residual energy dissipation and power losses using simulations. Last but not least, an overview of potential onshore and offshore future applications of MVDC grids is also presented by identifying targeted voltage and power ratings.

   Single-Phase Fundamental Component Estimation and Frequency Tracking under Time-varying Harmonic Distortion Operation
By Eder KAPISCH [View]
[Download]

Abstract: A scheme for combined fast frequency tracking and fundamental component estimation is proposed.Comparison of performances under time-varying harmonic distorted grid measurements operation isalso discussed. The approach is based on a modification of the so-called Adaptive Quadratic SignalsGenerator Phase-Locked Loop, adding a pre-filtering stage in order to attenuate the influence of thetime-varying harmonics. The time discretization strategy is also presented. Experimental tests of thealgorithms are carried out using a dSPACE platform, and measurements validate the proposals.

   Surge Current Simulation in a Half Bridge using a Thermal Model
By Fabian HOHMANN [View]
[Download]

Abstract: In this paper an IGBT half bridge with an antiparallel press-pack diode is examined for MMC use. Stateof-the-art half bridges use a bypass thyristor in order to protect the lower diode during a DC-short. Thispaper investigates prediction methods to calculate the stress of diode 2. Furthermore, it deals with thepossibility to substitute the bypass thyristor with a press-pack diode (PP-diode) to enhance to use of theequipped semiconductor area.

   The Research on Characteristics of DC Arc Fault Based on FRFT
By Yaojia ZHANG [View]
[Download]

Abstract: This paper studies the Fractional Fourier Transform to extract the frequency domain characteristics of AC components of the current. Compared with traditional FFT method, the arc fault and normal are differed clearly by the FRFT (p=0.95) method. It has higher arc fault detection rate and important engineering application value.

   VOLTAGE DIPS DETECTION USING KALMAN FILTER IN A MICROGRID WITH HIGH LEVEL OF DISTRIBUTED GENERATION
By Aleksandar STANISAVLJEVIC [View]
[Download]

Abstract: The paper addresses the problem of fault detection in microgrid with high level of distributed generation, using an algorithm based on Kalman filter. Modified IEEE 13 bus system with high level of distributed generation was used. Fast Fourier Transform and half cycle RMS was implemented and tested to be used for comparison. Algorithms are applied and tested in advanced laboratory setup as part of inverter control. Simulations were carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with distributed generation was used. Algorithm based on Kalman filter shows good performance and fast detection of voltage dips in specific applications, slightly better than FFT, tested for 5 different types of faults.

EPE 2018 - DS3j: Power Quality Issues; Fault Coordination and Protection of DC grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2018 - DS3j: Power Quality Issues; Fault Coordination and Protection of DC grids
	[return to parent folder]

	Analysis of Low-Frequency-Oscillations in Single-Phase AC Systems by LTP Theory By Valerio SALIS	[View] [Download]
Abstract: The paper presents the analysis of a single-phase active rectifier, with DC constant power load, affected by Low-FrequencyOscillation (LFO) behaviour. Conventional LTI analysis tools might fail to reveal the LFO phenomenon, whereas the LTP(Linear Time Periodic) approach, here exploited with analytical derivation and detailed simulations, provides superior results.

	Comparison of Energy Dissipation Concepts for DC Circuit Breakers By Andreas JEHLE	[View] [Download]
Abstract: In DC grids, DC circuit breakers (CB) are used to interrupt currents in case of a fault and to dissipate the remaining energy in the line. Independent of the actually DC CB concept, different energy dissipation concepts can be used, which also influence the performance of the DC CB. In this paper, the energy dissipation with different circuit arrangements, where the energy is dissipated in a single loop, in two loops or in two coupled loops, are discussed and compared. Additionally, the effect of different voltage waveforms across the DC CB and the distribution of the current limiting inductance on the input and the output side of the DC CB are investigated.

	Design considerations of power semiconductor devices employed in VSCs under short-circuit fault conditions in MVDC distribution grids By Andreas GIANNAKIS	[View] [Download]
Abstract: Electric energy distribution using medium voltage DC (MVDC) enables an advantageous performance compared to the state-of-the-art MVAC counterparts. Among others, a crucial challenge currently is related to the need for developing high-performance protection schemes against DC short-circuits and, thus, to prevent severe conditions of electric and thermal stress in the involved power electronics equipment. This paper presents an evaluation of design requirements and performance of four types of active rectifiers employed in MVDC grids under a DC short-circuit condition when using either an AC circuit breaker (AC CB) or a solid-state DC CB. The focus is on freewheeling diodes and the evaluation is performed in terms of power semiconductors stress, fault handling capability and chip area requirements by using simulations and calculations. The superior performance of DC CB over AC counterparts for all rectifier types is highlighted.

	Electric Vehicle Charging Station Load Analysing Based on Monte-Carlo Method By Maksims VOROBJOVS	[View] [Download]
Abstract: Taking into account the technological leap and the increased demand and production of electric vehicles, a study on the use of free power for charging of electric vehicles of the Riga Technical University, at the Faculty of Power and Electrical Engineering was conducted within the presented document. Also, a computer model of load demand for one charging unit was created to analyze quality of network parameters. This study uses statistics of load demand of charging unit for probabilistic forecasting of the load on a substation of 400 kVA and 630 kVA and determining the most optimal conditions of charging units for a particular station, using algorithm based on the Monte Carlo method. The algorithm described in detail is described in detail. Simulation was conducted on the basis of which it was concluded that if the charging station is located in a university campus or office center. It is necessary to organize switching on and off of charging points.

	Large Signal Stability Analysis of More Electric Aircraft Power System By Yalu SHEN	[View] [Download]
Abstract: The electric load amount and power capacity impact the stability of the aircraft power grid and bringchallenges to the design. With Lyapunov stability theorems in large-signal model based stabilityanalysis, this paper establishes the system state equation, obtains the scalar function according to themixed potential function theory, and determines the system stability region. The theoretical analysisresults are verified by simulation of a single-channel grid.

	MVDC distribution grids and potential applications: Future trends and protection challenges By Andreas GIANNAKIS	[View] [Download]
Abstract: This paper presents the fundamental system components of medium-voltage direct current (MVDC) grids, including an overview of power electronic converters and protection schemes against DC fault currents. In addition to this, the lack of standardization and the development of efficient and reliable circuit breakers (CBs), which are today considered as showstoppers, are also analyzed in detail. The performances of three DC CBs, namely mechanical breaker with active current injection, solid state CB and hybrid CB are evaluated in terms of clearance times, fault peak current, residual energy dissipation and power losses using simulations. Last but not least, an overview of potential onshore and offshore future applications of MVDC grids is also presented by identifying targeted voltage and power ratings.

	Single-Phase Fundamental Component Estimation and Frequency Tracking under Time-varying Harmonic Distortion Operation By Eder KAPISCH	[View] [Download]
Abstract: A scheme for combined fast frequency tracking and fundamental component estimation is proposed.Comparison of performances under time-varying harmonic distorted grid measurements operation isalso discussed. The approach is based on a modification of the so-called Adaptive Quadratic SignalsGenerator Phase-Locked Loop, adding a pre-filtering stage in order to attenuate the influence of thetime-varying harmonics. The time discretization strategy is also presented. Experimental tests of thealgorithms are carried out using a dSPACE platform, and measurements validate the proposals.

	Surge Current Simulation in a Half Bridge using a Thermal Model By Fabian HOHMANN	[View] [Download]
Abstract: In this paper an IGBT half bridge with an antiparallel press-pack diode is examined for MMC use. Stateof-the-art half bridges use a bypass thyristor in order to protect the lower diode during a DC-short. Thispaper investigates prediction methods to calculate the stress of diode 2. Furthermore, it deals with thepossibility to substitute the bypass thyristor with a press-pack diode (PP-diode) to enhance to use of theequipped semiconductor area.

	The Research on Characteristics of DC Arc Fault Based on FRFT By Yaojia ZHANG	[View] [Download]
Abstract: This paper studies the Fractional Fourier Transform to extract the frequency domain characteristics of AC components of the current. Compared with traditional FFT method, the arc fault and normal are differed clearly by the FRFT (p=0.95) method. It has higher arc fault detection rate and important engineering application value.

	VOLTAGE DIPS DETECTION USING KALMAN FILTER IN A MICROGRID WITH HIGH LEVEL OF DISTRIBUTED GENERATION By Aleksandar STANISAVLJEVIC	[View] [Download]
Abstract: The paper addresses the problem of fault detection in microgrid with high level of distributed generation, using an algorithm based on Kalman filter. Modified IEEE 13 bus system with high level of distributed generation was used. Fast Fourier Transform and half cycle RMS was implemented and tested to be used for comparison. Algorithms are applied and tested in advanced laboratory setup as part of inverter control. Simulations were carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with distributed generation was used. Algorithm based on Kalman filter shows good performance and fast detection of voltage dips in specific applications, slightly better than FFT, tested for 5 different types of faults.