cvt暂态对串补线路距离保护影响及其新算法的研究-电力系统及其自动化专业毕业论文.docx

INVESTIGATION 0F CVT TRANSIENT AND ITS INFLUENCE ON DISTANCE RELAYS APPLIED TO PENSATED LINE PROTECTION
Abstract
Wnh the development of technology on higll voltage instrument transformers,the Capacitive Voltage Transformer(CVT)has been used in High Voltage and Extra High Voltage systems ,they create certain problems for distance relays. During line faults,when the primary voltage collapses and the energy stored in the
stack capacitors and the tuning reactor of a CVT needs to be dissipated,the CVT generates severe transients that affect the performance of protective relays and cause the transient overreach of distance overreaching is influenced by the parameters of the CVT itself,the load and the inception voltage angle when a fault transient error is increased significantly when applies to the
protection of pensated line.
Tms thesis proposes a new algorithm aiming to improve the transient performance of distance analyses of the equivalent circuit of a CVT, examines the contributing factors of CVT transients,and performs transient simulation study on the influence of CVT transients on the performance of digital distance relays when applied to pensated proposed approach takes an bining the outputs from a full—cycle and a half-cycle Fourier transformation to e the transient overreach.
Expensive RTDS(Real Time Digital Simulator)simulation tests indicated that the proposed method is feasible and reliable,and the distance algorithm utilizing the proposed method is able to stay stable when a fault causing severe CVT
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llew algorithm also e强lsures distance relays applied for pensated line protection operate correctly during faults condition witll severe CVT transient.
Key Words:capacitive voltage transformer;pensated lines;distance relay; transient overreach;Fourier algorithm;real time digital simulator
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