Abstract

The penetration of distributed generation (DG) in distribution power system would affect the traditional fault current level and characteristics. Consequently, the traditional protection arrangements developed in distribution utilities are difficult in coordination. Also, the reclosing scheme would be affected. With the rapid developments in distribution system automation and communication technology, the protection coordination and reclosing scheme based on information exchange for distribution power system can be realized flexibly. This paper proposes a multi-agent based scheme for fault diagnosis in power distribution networks with distributed generators. The relay agents are located such that the distribution network is divided into several sections. The relay agents measure the bus currents at which they are located such that it can detect and classify the fault, and determine the fault location. The proposed technique uses the entropy of wavelet coefficients of the measured bus currents. The performance of the proposed protection scheme is tested through simulation of two systems. The first system is a benchmark medium voltage (MV) distribution system and the second system is practical 66 kV system of the city of Alexandria.

Highlights

  • The traditional power systems, which are based on large fossil fuel fired power generation plants, long distance transmission lines and hierarchical control centers, are changing

  • The protection schemes based on microprocessors with communication capabilities are utilized, so that the status of the relays and breakers can be obtained from the distribution power system supervisory control and data acquisition system, which can serve as an information exchange platform

  • A simple algorithm based on the information collected by different relay agents is proposed to classify and locate the fault such that the faulted area can be correctly isolated

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Summary

Introduction

The traditional power systems, which are based on large fossil fuel fired power generation plants, long distance transmission lines and hierarchical control centers, are changing. To deal with the problem of protection of distributed networks with the penetration of DGs, distribution utilities impose interconnected regulations These regulations are often based on IEEE Std. 1547, 2003 [4] and recommend the tripping of DGs even for remote faults in order to maintain the protection coordination during fault. Several protection schemes have been proposed in literature [1,2,3,4,5,6,7,8] in order to address the shortcomings in current DG interconnection practices and protection problems associated with DGs. boundaries of the network sections to identify the type of fault if it is a three line to ground (3LG), single line to ground (LG), double line to ground (DLG) or a line to line (LL) fault. The results proved the effectiveness of the proposed protection scheme under different conditions of fault type, fault location and fault resistance

Modal Transformation
Wavelet Transformation and Entropy Calculation
Protection Arrangement Based on Relay Agents
Fault Classification Using Current Transients
Test System 1
Test System 2
Conclusions
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