新能源高占比的特高压电网频率控制模式及性能评价

Frequency Control Mode and Performance Assessment in UHV Grid With High Proportion of Renewable Energy Resources

在新能源广域消纳和特高压交直流混联的电网新特征下,频率控制模式及其控制性能评价方式应该发生改变。基于协同控制理念,提出了省网采用新的协同频率偏差控制模式(cooperationfrequencybias control,CFBC);针对交直流混联增强区域网间相互影响的情况,论述了交流互联采用联络线功率频率偏差控制模式、直流互联采用定频率控制模式的合理性;综合分析国内外电网评价标准,提出新的通用评价方法,包括长期的频差均方根值约束和短期的频率持续越限时间约束;建立针对网调和省调的两层级评价结构,并设置了新的频率偏差系数和控制偏差。仿真表明,省调采用CFBC模式有利于充分利用全网调节资源,实现频率快速恢复;网调采用联络线功率频率偏差控制模式益于实现交流互联区域网的自治管理以及责任的划分;该文评价方法既能满足电网长期和短期的运行要求,又能减少机组调节次数。

Renewable energy large-scale accommodation and hybrid UHVAC/DC become new features of modern power grid. Frequency control mode and performance assessment method should be changed with the new features. With the idea of cooperation control, a new frequency control mode, called cooperation frequency bias control(CFBC), is proposed for provincial grids in this paper. Considering that hybrid UHVAC/DC enhances interaction between regional grids, it is proved that tie-line bias frequency control(TBC) mode fits the regional grids with UHVAC interconnection and flat frequency control(FFC) mode is suitable for the regional grids with UHVDC interconnection. A new common assessment method is proposed through analysis of some assessment standards in China and abroad. The method includes root mean square(RMS) index for frequency deviation and duration index for over-limit frequency. A two-layer assessment structure with regional grids and provincial grids assessed independently and respectively is established. In this structure, new types of frequency response coefficient and area control error are defined. Test results show that the case of provincial grids with CFBC mode is beneficial for full use of regulation resources in whole regional grid. When the regional grids with UHVAC interconnection use TBC mode, their autonomous management and responsibility assignment are easy to complete. The proposed assessment method can meet requirements of short-and long-term operation security and decrease times of unit regulation.