EPE Association: EPE 2016 - LS6f: Protection in DC and AC Grids; Smart Grids

EPE 2016 - LS6f: Protection in DC and AC Grids; Smart Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 06: Grids and Smart Grids > EPE 2016 - LS6f: Protection in DC and AC Grids; Smart Grids

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   HVDC Grid Protection with Integrated Fault Categorization for Selective Tripping
By René SANDER [View]
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Abstract: HVDC Circuit Breakers require adequate fault detection for selective breaking. In terms of tripping commands, general fault categorization is necessary and, where appropriate, even short circuit localization. Wave propagation phenomena from switching operations, blocking MMCs, lightning strikes and short circuits must be clearly distinguished, which is fundamentally examined here. Analyses have been undertaken by accompanied simulations in MATLAB Simulink.

   Unidirectional hybrid circuit breaker topologies for multi-line nodes in HVDC grids
By Andreas JEHLE [View]
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Abstract: Interest in HVDC transmission increases, but still fault handling is difficult because fault currents rise faster than in HVAC transmission. Therefore concepts for a fast turn off of DC lines, especially in case of a short circuit fault, are needed. Turning the complete DC-transmission system off is too slow and not suitable for large grids. To overcome this, several bidirectional HVDC circuit breaker topologies have been developed. However, fast bidirectional circuit breakers contain a huge number of semiconductors. As alternative unidirectional circuit breakers can be used, which have a lower number of semiconductors. This paper focuses on the applicability of unidirectional hybrid circuit breakers, which are derived from four bidirectional circuit breaker concepts. In addition, a detailed comparison of the unidirectional circuits breaker topologies is presented.

   Virtual inertia with PV inverters using DC-link capacitors
By Eberhard WAFFENSCHMIDT [View]
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Abstract: Soon, virtual inertia for grid control must be covered by photovoltaic inverters. It is suggested to use DC link capacitors for this task. This requires 5 W, 50 J and a capacitor size of about 200 cm³ per installed kW, corresponding to the size of single phase DC link capacitors. It is shown that the additional power ripple (and thus current ripple) is in the order of 0.1\% and the voltage ripple of the intermediate voltage will typically remain between +/-3.6\%. The related control can be easily extended by adding a voltage signal to the control voltage, which is proportional to the frequency deviation. Then, the existing controller inherently sets the required additional power fluctuation required for the virtual inertia function.

   Wide Frequency Range Medium-Voltage Grid Impedance Analysis by Current Injection of a Multi-MW Power Converter
By Frederik HAHN [View]
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Abstract: More and more energy is fed especially by decentralized converters from renewable energy sources into the grid. Therefore, it is important to know the grid behavior at a wide frequency range from the fundamental frequency up to the kHz-range. This paper presents an advanced impedance mediumvoltage measurement system with a high frequency range for an electrical medium-voltage grid. A sinusoidal current of a predefined frequency is injected into the grid. With this, the grid impedance is calculated from the measured magnitude and phase of the injected current and the resulting voltage. The measurements will be executed at different frequencies to produce approximate continuous impedance versus frequency characteristic of the grid at the measured coupling point. Results of a ready to use, low-voltage impedance measurement system are discussed, and the design considerations the basic concept and first simulation results of the developed medium-voltage system are presented in this paper.

EPE 2016 - LS6f: Protection in DC and AC Grids; Smart Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 06: Grids and Smart Grids > EPE 2016 - LS6f: Protection in DC and AC Grids; Smart Grids
	[return to parent folder]

	HVDC Grid Protection with Integrated Fault Categorization for Selective Tripping By René SANDER	[View] [Download]
Abstract: HVDC Circuit Breakers require adequate fault detection for selective breaking. In terms of tripping commands, general fault categorization is necessary and, where appropriate, even short circuit localization. Wave propagation phenomena from switching operations, blocking MMCs, lightning strikes and short circuits must be clearly distinguished, which is fundamentally examined here. Analyses have been undertaken by accompanied simulations in MATLAB Simulink.

	Unidirectional hybrid circuit breaker topologies for multi-line nodes in HVDC grids By Andreas JEHLE	[View] [Download]
Abstract: Interest in HVDC transmission increases, but still fault handling is difficult because fault currents rise faster than in HVAC transmission. Therefore concepts for a fast turn off of DC lines, especially in case of a short circuit fault, are needed. Turning the complete DC-transmission system off is too slow and not suitable for large grids. To overcome this, several bidirectional HVDC circuit breaker topologies have been developed. However, fast bidirectional circuit breakers contain a huge number of semiconductors. As alternative unidirectional circuit breakers can be used, which have a lower number of semiconductors. This paper focuses on the applicability of unidirectional hybrid circuit breakers, which are derived from four bidirectional circuit breaker concepts. In addition, a detailed comparison of the unidirectional circuits breaker topologies is presented.

	Virtual inertia with PV inverters using DC-link capacitors By Eberhard WAFFENSCHMIDT	[View] [Download]
Abstract: Soon, virtual inertia for grid control must be covered by photovoltaic inverters. It is suggested to use DC link capacitors for this task. This requires 5 W, 50 J and a capacitor size of about 200 cm³ per installed kW, corresponding to the size of single phase DC link capacitors. It is shown that the additional power ripple (and thus current ripple) is in the order of 0.1\% and the voltage ripple of the intermediate voltage will typically remain between +/-3.6\%. The related control can be easily extended by adding a voltage signal to the control voltage, which is proportional to the frequency deviation. Then, the existing controller inherently sets the required additional power fluctuation required for the virtual inertia function.

	Wide Frequency Range Medium-Voltage Grid Impedance Analysis by Current Injection of a Multi-MW Power Converter By Frederik HAHN	[View] [Download]
Abstract: More and more energy is fed especially by decentralized converters from renewable energy sources into the grid. Therefore, it is important to know the grid behavior at a wide frequency range from the fundamental frequency up to the kHz-range. This paper presents an advanced impedance mediumvoltage measurement system with a high frequency range for an electrical medium-voltage grid. A sinusoidal current of a predefined frequency is injected into the grid. With this, the grid impedance is calculated from the measured magnitude and phase of the injected current and the resulting voltage. The measurements will be executed at different frequencies to produce approximate continuous impedance versus frequency characteristic of the grid at the measured coupling point. Results of a ready to use, low-voltage impedance measurement system are discussed, and the design considerations the basic concept and first simulation results of the developed medium-voltage system are presented in this paper.