混合双馈入高压直流系统最大传输功率控制方法

Control Method of Maximum Transmission Power for Hybrid Dual-infeed HVDC System

常规高压直流(LCC-HVDC)与柔性高压直流(VSC-HVDC)落点之间存在电气通路时就构成了混合双馈入高压直流系统。VSC-HVDC系统具有有功、无功功率独立可调的特点,通过调节VSC-HVDC系统输出的有功、无功功率,可以提高在同等受端电网强度下LCC-HVDC系统的功率输送能力。在建立混合双馈入高压直流系统的数学模型和仿真模型的基础上,通过给出求解混合双馈入高压直流系统临界稳定状态的数值解法,分析了混合双馈入高压直流系统在不同受端电网强度下的功率输送能力,总结出调节VSC-HVDC系统输出的有功、无功功率对LCC-HVDC系统功率输送能力的作用规律,并在此基础上根据系统状态参数随受端电网强度的变化规律提出了混合双馈入高压直流系统基于定虚拟点电压控制的最大传输功率控制方法,该控制模式能针对受端电网强度的变化自动调节系统的功率参考值,使得混合双馈入高压直流系统能始终运行在输送最大有功功率的工作状态。

A hybrid dual-infeed high voltage direct current(HVDC)system contains line commutated converter based HVDC(LCC-HVDC)and voltage source converter based HVDC(VSC-HVDC)which has electrical coupling between terminal locations. VSC-HVDC system has the characteristics of independently adjustable active and reactive power. The power transmission capability of LCC-HVDC can be improved by adjusting active and reactive power output of VSC-HVDC system at the same receiving end. Based on the mathematical and simulation model of hybrid dual-infeed HVDC system, the power transmission capability of hybrid HVDC system with different strength of the receiving end grid is analyzed by proposing a numerical solution to find the critical point of system stability. According to the analysis result of the impact of adjusting active and reactive power output of VSC-HVDC system on the transmission capacity of LCC-HVDC system, a maximum transmission power control method based on fixed virtual point voltage control is proposed, which can automatically adjust the power parameters so as to control the transmission power of hybrid HVDC system to the upper limit when the strength of the receiving end grid changes.