Research And Application Of Grounding Mode Of 35kV System In Qinghai Photovoltaic Power Plant

With the new national energy strategy to promote,solar,wind and other new energy technology has been hitherto unknown development,construction of western area of Qinghai province centralized PV power station has also made a hitherto unknown achievement,by the end of 2016 PV installed for Haixi area of Qinghai Province,the total installed capacity of 66.1%.This paper combined with the operation experience of photovoltaic power plants for many years and Haixi area of Qinghai Province,photovoltaic power plant existing neutral point grounding mode,the over-voltage and insulation level,power supply reliability,communication interference,personal safety,the possibility of the development of the system,analyses their principle,scope and the advantages and disadvantages so,according to the characteristics of the proposed PV power station grounding mode reasonable low voltage system of PV power station.Determination of neutral grounding mode,combined with the low voltage side connection of many years of work experience and commonly used in Qinghai,on the neutral point through low resistance setting calculation principle of relay grounding transformer,transformer,feeder and other related equipment to protect the photovoltaic power station grounding short-circuit current calculation,analysis,calculation for zero sequence short-circuit current,this paper presents a method to calculate the zero sequence current protection device through respective different short-circuit points,and through the method of zero sequence current grounding resistance calculation is given.At the same time,the short circuit current calculation and analysis are carried out for the complex connection mode,such as the double circuit line connection,multi line connection and so on.Finally,combined with the actual case,further analysis of the short-circuit current calculation and protection setting calculation.Finally,according to the years of photovoltaic power plant accident trip analysis experience,design,construction and operation of photovoltaic power plants and other aspects and puts forward some matters needing attention,for the construction of photovoltaic power plants,the subsequent operation and maintenance to provide reference.