Research On The Influence To Power System Protection With Harmonic

Today, the environment and energy issues have become more and more deeply the topic of the development of human civilization. To the guidelines can guarantee good environmental and economic stability continued to grow, but also for the community to supple for the economy, high-quality, safe and reliable energy, this is a double challenge for the entire power industry. But the existing power grid harmonics everywhere, undoubtedly affect the quality of power supply, adding to the running maintenance personnel challenges.This article from the harmonic especially harmful impact on relay protection,fully fimilar with:1.Harmonic generation mechanism and resonance related theories, the main power system relay protection equipment,and harmonic resonance hazard and may cause harmonic amplification.2Harmonic source characteristics on the basis of a concrete analysis of the impact of the harmonics of the line protection, proposed the protective installation location away from the harmonic source nearer, the greater its impact; meanwhile studied in detail to understand the harmonic protection of ironcore element the sequence component elements, and the impact of mutations in the amount of components and impedance relay, quantitative analysis formula specified number of lower harmonics to the protection of the most influential, especially in the third harmonic; summary of harmonics on the Protective Relaying conditions and specific harmonic elimination method.3From the actual grid, basing on a large company for TianJin power grid structure appeared three phase short circuit’s voltage flicker problems we did the system’s equivalent and the faults’simulation. According to the question we proposed a power quality solution (i.e., DVR voltage recovery scheme) to the relay protection having a actual analysis on it. We used the electric power system’s commonly simulation software PSCAD, and the simulation results agree with the theoretical analysis, and got the conclusion:the installation of DVR won’t make the original system’s relay protection misoperation and refused to move. But in order to prevent voltage mutation surge, we should add a action in DVR’s testing link to the fault line’s detection of relay protection, i.e., the interlocking link, with this it can compensate voltage effectively and reasonably.4Analyzed this power quality’s control scheme which may lead to the resonance and harmonic amplification phenomenon, as the final result of the DVR, we known although it have brought a harmonic to the system, it don’t have a severe impact on the system harmonic amplification, and almost can be ignored to the system, then with the system’s several times harmonic frequencies, it also won’t produce resonance.