A multi-time scale reactive power coordinated control strategy based on continuous and discrete VAR sources

Integration of large-scale wind power had become main mode of wind-power delivery in China, however, as the weakness of grid and diversity of VAR sources, operation voltage fluctuation of power systems integrated with large-scale wind power remains to be solved. Therefore, propose a multi-time scale reactive power coordinated control strategy regarding fast continuous and slow discrete VAR sources, design a two-level coordinated voltage control model based on property of various VAR sources. The primary control level deals with operation of discrete VAR sources such as shunt capacitor and reactor based on wind power forecast to mitigate long-term substantial voltage fluctuation of pilot buses at large time scale; while the secondary control level deals with operation of continuous VAR sources such as wind turbines, SVC and SVG to mitigate small frequent voltage fluctuation of pilot buses at short time scale. Voltage fluctuation of pilot buses is effectively mitigated by two-level coordinated control strategy. The calculation on the voltage of China´s grid accommodating large-scale and centralized wind power validates that the proposed method can effectively solve the problem of voltage fluctuation of pilot buses.