Analysis of Influence of DC Modulation on System Frequency Response

DC modulation mainly includes emergency power control, emergency frequency control, additional power modulation, and other functions. DC modulation is the main control measure to improve the frequency stability of the power grid, which effectively avoids over-frequency generator tripping and under-frequency load shedding. When the system has a large disturbance such as generator tripping in the sending-end power grid, DC blocking or the receiving-end power grid fault, it gives full play to the advantages of wide adjustment range and fast adjustment speed of the DC sending-end and collaborates with the generator primary frequency regulation, stability control and over-frequency generator tripping to quickly suppress the frequency rise and fall. In this paper, a simulation model is built in MATLAB Simulink environment. The influence of DC frequency modulation on system frequency response is analyzed considering renewable energy access. Then, considering the cooperative control of primary frequency regulation of thermal power unit and DC frequency modulation, the effects of DC frequency modulation on the system frequency response characteristics and DC modulation under different parameters are analysed. Finally, based on the simulation result, the suggestions about DC modulation are summarized.