Abstract

With the decentralization of the electricity market and the plea for a carbon-neutral ecosystem, more and more distributed generation (DG) has been incorporated in the power distribution grid, which is then known as active distribution network (ADN). The addition of DGs causes numerous control and protection confronts to the traditional distribution network. For instance, two-way power flow, small fault current, persistent fluctuation of generation and demand, and uncertainty of renewable energy sources (RESs). These problems are more challenging when the distribution network hosts many converter-coupled DGs. Hence, the traditional protection schemes and relaying methods are inadequate to protect ADNs against short-circuit faults and disturbances. We propose a robust communication-assisted fault protection technique for safely operating ADNs with high penetration of converter-coupled DGs. The proposed technique is realizable by employing digital relays available in the recent market and it aims to protect low-voltage (LV) ADNs. It also includes secondary protection that can be enabled when the communication facility or protection equipment fails to operate. In addition, this study provides the detail configuration of the digital relay that enables the devised protection technique. Several enhancements are derived, as alternative technique for the traditional overcurrent protection approach, to detect small fault current and high-impedance fault (HIF). A number of simulations are performed with the complete model of a real ADN, in Shenyang, China, employing the PSCAD software platform. Various cases, fault types and locations are considered for verifying the efficacy of the devised technique and the enabling digital relay. The obtained simulation findings verify the proposed protection technique is effective and reliable in protecting ADNs against various fault types that can occur at different locations.

Highlights

  • Low-voltage active distribution networks (ADNs) comprising distributed generations (DG) such as photovoltaic (PV) solar system, microturbine, wind generation, mini-hydro, and fuel cell have become prominent in the energy sector especially in the existing smart grid setup

  • The devised protection technique uses a digital relay to sense the occurrence of fault and segregate the minimum section of the ADN impacted by the fault

  • To reveal the success of the devised protection technique, the ADN whose schematic framework illustrated in Figure 2 is used

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Summary

Introduction

Low-voltage active distribution networks (ADNs) comprising distributed generations (DG) such as photovoltaic (PV) solar system, microturbine, wind generation, mini-hydro, and fuel cell have become prominent in the energy sector especially in the existing smart grid setup. Network voltage-based fault protection of ADNs and microgrids (MGs) has been proposed by few studies [6,7,12,13]. The scheme delivers speedy and coordinated fault clearance for both ADNs and isolated MGs. the strategy uses under voltage-based method of fault detection that may lead the relays to command false trip signals to circuit breakers (CBs) in case of temporary occurrence of voltage-sags, which all the time present in the power networks because of dynamic variation of load demands and volatility of RESs. the strategy neither guarantees protection for symmetrical HIFs nor delivers techniques for protecting buses. ADNs containing high penetration of converter-interfaced renewable energy resources It uses microprocessor-based digital relay to enable the proposed protection technique.

Configuration of the Devised Relay
Solid Fault Detection
HIF Detection
Directional Decision Forming
Proposed Protection Technique
Results and Discussions
Relays andand their respective responsibility in case the case
Conclusions
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