Study On The Influence To Distribution System Protection With The Application Of Power Electronic Equipments

With the development of science and technology, higher and higher quality requirements were needed by the electrical consumers about the power energy in power supplying and distributing. For this objective, many kinds of power electronic equipments are applied in power supply systems and distribution systems in order to improve the system running stability with their rapid response operation characteristics. But at the same time, the power electronic equipments may generate some hidden dangers that can not be overlooked to the system, particularly to the reliability of protection action.Based on what is said above, and taking the practice distribution system in TPCO for an example, it is analyzed in this paper that the influences to this distribution system with the assembling of DVR, STATCOM and SFCL, including the normal action of the current protection in this system, phenomena of harmonics, resonance and magnifying of harmonic current, and the cooperation between current protections and these equipments. Some digital simulations are done to support the theory analysis.At the end of this paper, a scheme about how to distinguish the fault and harmonic current is designed with the prerequisite for analyzing the running characteristic of the system in a faulting state and in a harmonic state. This scheme can be used to design the current checking tache in the current protection to achieve the improvement of protection reliability.The research production in the paper has some definite reference value to the technical personnel in this field about relay and harmonic study.