云南电网中发电量的自动控制模式对电网频率影响特性分析

Influencing Characteristic Analysis of AUTO Control Mode of AGC upon Power Frequency in Yunnan Power Grid

随着南方电网“八交八直”的输电格局的形成,交直流并联运行、强直弱交、远距离大容量输电、多回直流集中馈入的主网架结构特征使得电网安全稳定问题异常复杂,大容量直流闭锁、多回直流换相失败等问题近年来一直困扰着南方电网的安全稳定运行。2016年南方电网实施云南电网与南方电网主网异步联网运行方式,使得南方电网的安全稳定水平得到了极大的提高,异步运行前云南送出直流故障后的暂态稳定问题在异步运行后转化为了云南电网的频率稳定问题。但异步运行后,云南电网先后多次出现了由AGC超调引起的电网频率波动现象,直接威胁设备与电网安全。本文通过云南电网5.19振荡以及6.26振荡分析,发现AGC调节功率超出系统需求功率和AUTO模型机组响应滞后是引起功率振荡的主要原因,为解决这一问题,利用现有的数模仿真实验室或开发数值仿真软件对事故现象进行仿真,在RSS仿真系统模拟云南电网实际运行工况,再现功率振荡过程,最后分析出大型水电机组对云南电网频率稳定影响以及由AGC超调引起电网频率振荡的机理。

With the formation of the transmission pattern of the“Eight Crossing and Eight Straight”of China Southern Power Grid,the main grid structure characteristics of AC/DC parallel operation,strong and weak weak cross,long-distance large-capacity transmission and multi-turn DC centralized feeding make the grid security and stability problem extremely complicated.In 2016,the asynchronous network operation mode of Yunnan Power Grid and China Southern Power Grid main network was implemented,which greatly improved the security and stability level of China Southern Power Grid.The transient stability problem after Yunnan DC fault was sent before asynchronous operation was converted into asynchronous operation.However,after asynchronous operation,Yunnan Power Grid has repeatedly experienced grid frequency fluctuations caused by AGC overshoot,directly threatening equipment and grid security.In this paper,through the 5.19 oscillation and 6.26 oscillation analysis of Yunnan Power Grid,it is found that the AGC regulation power exceeds the system demand power and the AUTO model unit response lag is the main cause of power oscillation.To solve this problem,the existing digital-analog simulation laboratory or development is utilized.The numerical simulation software simulates the accident phenomenon,simulates the actual operating conditions of Yunnan power grid in the RSS simulation system,reproduces the power oscillation process,and finally analyzes the influence of the large hydropower unit on the frequency stability of the Yunnan power grid and overshoots by the AGC.The mechanism that causes the grid frequency to oscillate.