柔性直流输电系统阻抗稳定性分析

采用基于ESAC(energy system analysis consortium)标准的阻抗分析方法分析了柔性直流输电系统(voltage source converter based HVDC,VSC-HVDC)的阻抗特性和稳定性。首先建立了柔性直流输电系统的等效电路,进而通过其复频域等效电路分析了VSC-HVDC柔直系统的阻抗特性,并由ESAC标准的阻抗分析法提出了判断VSC-HVDC柔直系统稳定性的实用判据。然后在复频域中得到了柔直换流站在不同PI控制参数下的Nyquist曲线以确定柔直系统的稳定性。最后在PSCAD/EMTDC仿真软件中进行了时域电磁暂态仿真,其稳定性结果与在复频域中的计算结果一致,进一步验证了所提出的稳定判据的正确性。

Analysis of Impedance Stability of VSC HVDC Systems

Based on ESAC (energy system analysis consortium) standard of the impedance analysis method, the impedance characteristics and stability for the voltage source converter based HVDC (VSC HVDC) are analyzed. Firstly, an equivalent circuit of the VSC HVDC system is established. The impedance characteristics of the VSC HVDC system are analyzed by using a complex frequency domain equivalent circuit. A practical stability criterion, based on ESAC standard to determine the stability of VSC HVDC system, is proposed. Secondly, the Nyquist curves of the VSC HVDC system under different PI control parameters are calculated and obtained in the complex frequency domain. The stabilities of the VSC HVDC system are verified through the Nyquist curves. Finally, the time domain electromagnetic transient simulation results of the VSC HVDC system performed in PSCAD/EMTDC show that the stabilities of the VSC HVDC system are similar to that produced in the complex frequency domain, which further proofs that the presented stability criterion is suitable for stability analysis of the VSC HVDC system to select the optimal control parameters.