| With the proportion of solar photovoltaic power generation system continue to grow in the power supply and its own characteristics different from conventional power generation making it's become more and more urgent to do research on the the system angle stability,voltage stability and frequency stability and its control technology after the large-scale photovoltaic power plants connected the grid.This paper based on learning from the advanced technology,take full account of the intermittent volatility and other characteristics of PV,relying on the one hundred megawatt grid-connected photovo,ltaic demonstration power plant at the region of Haixi in Qinghai,to carry out the research of the operation control technology on large-scale PV connected-grid power plant and solve key technical problems that PV power plants connected-grid faced when it's operation.The main work and conclusions are as follows:(1)According to the four technical parameters provided by solar cell manufacturers this paper establish a simplified mathematical solar cell model,and taking the relationship between the PV module IV characteristics and the changes of irradiance and temperature into account,established various types(crystalline silicon,amorphous silicon)photovoltaic ?characteristics model when the external environment changes,proposed that divide photovoltaic power plant into dividemade one or more photovoltaic power generation systems according to the inverter type or uneven illumination area,neglected something according to the research focus so as to establish a PV power plant s equivalent model;(2)The impact that Hercynian photovoltaic power plant's connected-grid had on system voltage and reactive power flow:?The total PV Access may cause 330kV bus's voltage drop more than 4kV,likely to cause low steady-state voltage in Hercynian region,and it's not conducive to recovery from malfunction,According to State Grid enterprise standard Q/GDW 617-2011 requirements,each photovoltaic power plants should be installed reactive power compensation device,in order to meet the reactive power compensation capacity of photovoltaic output fluctuations rapid adjustment requirements,each photovoltaic power plants shall be fitted with dynamic reactive power compensation device.? Hercynian 750kV and 330kV grid-related lines at N-1 case,each PV power plant can be fed properly,750kV and 330kV lines can meet the requirements of N-1 check.(3)The impact that Hercynian photovoltaic power plant's connected-grid had on grid system transient stability:?Power grid under the 750/330kV line N-1 fault condition,when the PV power plant does not have the low-voltage ride-through capability,may cause most of Haixi Region even all off-grid PV power plant,but the system is able to maintain stable operation.?After Hercynian 750kV and 330kV grid-related line N-1 fault occurs,the system have no transient angle stability and voltage stability problems.If the PV power plant have low-voltage ride-through capability,it can significantly reduce the risk of system operation.(4)The momentary that PV send line occours three phase short-circuit fault,the short-circuit current that PV power plant provided is inversely proportional to the distance that between the short-circuit point and photovoltaic power plants,the farther the distance is,the smaller the short-circuit current that PV power plant provided is,and the bigger the short-circuit current that grid provided is.It can be seen from the results that the PV power plant grid-connect operation slightly increased the grid near node's short-circuit current,but all were below 0.1%,but it has little effect. |
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