System Impacts Analysis Of Voltage Stability In Regional Power Grid With Large-scale Wind Farm Connection

With the development of wind power generation technology,the permeability of wind power becomes increasingly higher and the wind power integration has increasingly larger influence on the stability of wind power system.The regions with extensive wind power resources are usually at the weaker end of the grid and are far away from the main grid.In addition,different types of wind power generators all have the reactive power characteristics and the voltage of the system is closely related to this kind of characteristics.Four-component model for the wind speed,mathematical model for the cage asynchronous generator,mathematical model for double-fed asynchronous generator and mathematical model for direct drive synchronous generator are established in this paper;Ningxia Zhongwei regional power grid model is built on the PSASP simulation platform to simulate and calculate the steady-state voltage distribution of the main bus before and after centralized wind power connection to the regional power grid in Zhongwei.The steady-state voltage stability of the regional power grid before and after wind power connection is analyzed in combination with PV curve and steady-state voltage stability indexes.The steady-state voltage stability of the regional power grid with or without the reactive compensation is compared respectively through parallel capacitors and reactive compensation of SVC reactive compensation device;transient stability indexes obtained from time-domain simulation method are utilized to analyze the transient voltage stability of different types of wind power generators connected to the power grid,and finally simulation calculation is conducted for voltage inducing interlock fault after centralized wind power connection by setting the constraints(fault type,fault place,capacity of the wind power unit type,capacity of reactive power compensation type,etc.)The simulation results show that the power allowance of the main bus in the regional power grid,steady-state stability indexes and limit transmission power of the cross section of regional power grid are all increased after centralized wind power connection,so the centralized wind power connection can improve effectively the steady-state voltage stability of the regional power grid.The static reactive compensator can better improve the power allowance of the bus and limit transmission power of the cross section while the parallel capacitors can better improve the voltage of bus in the regional power grid.Comparatively speaking,the static reactive compensator is able to better enhance the steady-state voltage stability of the system;the transient stability calculation suggests that the transient voltage stability of the double-fed asynchronous wind power generator and direct drive synchronous generator connected to the regional power grid is better than cage asynchronous wind power generator.Finally,simulation calculation is conducted for voltage inducing fault interlock after centralized wind power connection and off-network paths which have interlock fault under different constraint conditions in the Jiucai wind power farms are obtained.