Research on Transient Voltage Instability Mechanism of Receiving-end Power Grid with High Renewable Energy and Direct Current Proportion

With the intensive infeed of multiple DCs and the increasing penetration rate of renewable energy in the load center, conventional units in the receiving-end power grid have been extensively replaced, and the issue of transient voltage stability is becoming increasingly prominent. This paper theoretically analyzes the effects of DC and renewable energy on the transient reactive voltage characteristics of the receiving-end power grid separately, derives the calculation formula for the transient voltage amplitude of the load node in the receiving-end power grid, and explains the mechanism of weakening the transient voltage stability of the receiving-end power grid by the coupling of renewable energy and DC. Finally, based on the PSCAD/EMTDC electromagnetic transient simulation platform, the mechanism of the influence on the transient voltage stability of the receiving-end system by the coupling of renewable energy and DC is simulated and verified. The research results indicate that during the short-circuit fault period of the receiving-end power grid, the coupling of renewable energy and DC reactive voltage will weaken the transient voltage stability of the receiving-end power grid, and severe faults will lead to the transient voltage instability of the receiving-end power grid.