Research on Coordinated Frequency Control Strategy of Multi-DC Transmission Power Grid with Different Types of New Energy Units

With the development of new energy power generation and HVDC transmission technology, the AC grid may have certain high-frequency/low-frequency operation risks under the serious fault mode of the system. In this paper, a coordinated frequency control strategy of AC/DC hybrid power grid involving generator units, load and DC emergency power modulation control is proposed, and an electromagnetic transient digital-analog hybrid simulation model of AC/DC hybrid power grid containing new energy such as photovoltaics generation, wind turbines and three DC transmission systems is built based on HYPERSIM software and super parallel computer, and the actual frequency control device is connected through the interface device. The simulation results show that in view of the high-frequency/low-frequency changes of faults in the sending power grid, the DC transmission power can be urgently adjusted by the frequency control strategy and the corresponding generator or load will be cut off from the grid when necessary. In this way, the goal of system frequency stability and improving the transient stability characteristics of the power grid can be achieved under the premise that the grid network loss is as small as possible.