Grid Frequency Composite Support Strategy for Voltage Source Converter-Synchronous Generator Paralleled System

For strengthening the frequency stability of a power system dominated by new energy, a grid frequency composite support strategy for a converter-synchronous generator paralleled system is proposed. The traditional droop control with a low-pass filter can provide inertia for the power grid, but the power output must be along with the power droop curve, which weakens the high dynamic performance of the inverter. Therefore, in this paper, the equivalent load disturbance component is introduced into the droop control loop, and the reference frequency generated from the active-frequency loop is corrected to enhance the short-term support capability of the active power. In the paralleled system of inverter and conventional synchronous generator, the power grid composite support of short-term and long-term provided by inverter and synchronous generator is achieved by the proposed method, respectively. The 2-norm and infinite norm are used as the evaluation indexes for the proposed controller parameters, which are optimized by the particle swarm optimization algorithm, and the optimal frequency composite support is achieved for the converter-synchronous generator paralleled system.