摘要
合环转供电已成为中压配电网转移负荷的重要方式,但计划停电进行合环会降低供电可靠性,直接合环又会产生较大的冲击电流,影响电网稳定运行。基于此,该文首先提出了一种改进型移相变压器(IPST),其在传统移相器的基础上增加了调幅绕组,可以灵活改变电压幅值与相位,实现不停电合环;其次针对负荷转供后,IPST内部阻抗引起的负荷侧电压质量下降问题,通过多端口网络理论建立IPST等效模型,将IPST端口阻抗特性转化为等效解析式,并推导调节电压关于调幅挡位T_(m)、调相挡位T_(p)的函数表达式,从而结合电压调节目标预测出IPST的目标挡位,提升电压质量;然后针对IPST退出旁路合闸时产生的冲击电流问题,推导出冲击电流关于IPST挡位的函数关系式,结合电流调节目标及电压质量约束预测出IPST目标挡位,实现在保证电压质量的同时,使得冲击电流下降,安全退出IPST;最后基于PSCAD/EMTDC验证阻抗表达式的正确性和调控策略的有效性。
Due to the existence of important loads,the new distribution network needs to be supplied with power when the equipment of the original distribution network is overhauled.Two closing types exist when accessing the new distribution network:loop and ring-closing.The distribution network is cut off for loop closing,leading to power supply interruption,or the ring of the distribution network is directly closed,producing a large impulse current due to the large voltage difference between the two distribution networks.As a result,the relay protection malfunction occurs,which affects the reliability and stability of the power grid.Two ways are adopted to avoid the above issues.One is to provide the loop closing condition through theoretical calculation,and the voltage of the loop closing point is similar by controlling the whole distribution network.The loop is directly closed after meeting the ring closing conditions.However,the control process is more complex,and the loop closing current is still large.The second is to use the voltage regulating device to change the voltage of one side of the ring closing point and carry out the ring-closing.Although the control effect of the ring-closing device is better,the price and maintenance costs are high.This paper proposes an improved phase shifter(IPST)with an amplitude modulation winding(ETm)based on the amplitude modulation winding(ETp)of the traditional phase shifter.It can flexibly change the voltage amplitude and phase by adjusting the gears of ETp and ETm,thereby changing the voltage at the closing point.The voltage between the two distribution networks is similar,and the loop closure is realized.In addition,the voltage quality on the load side is degraded because of the internal impedance of the IPST after the load transfer.An IPST equivalence model is established based on the multi-port network theory.The impedance characteristics of the IPST port are converted into the equivalent analytical formula.The functional expressions of the regulation voltage on the amplitude modulation gear T_(m) and phase modulation gear T_(p) are derived.Thus,the target gear of the IPST is predicted,and the voltage quality is improved.Thirdly,to address the problem of the inrush current generated when the IPST exits bypass closing,the functional relationship of the inrush current on the IPST gear is derived.The IPST target gear is predicted by combining the current regulation target and the voltage quality constraint.The voltage quality can be ensured,and the impulse current can drop and safely exit the IPST.Finally,the impedance expression’s correctness and the control strategy’s effectiveness are verified through PSCAD/EMTDC.
作者
杨用春
杜翔宇
唐健雄
陈巽同
赵成勇
Yang Yongchun;Du Xiangyu;Tang Jianxiong;Chen Xuntong;Zhao Chengyong(State Key Laboratory of New Energy North China Electric Power University,Baoding 071003 China;State Grid Chongqing Electric Power Company Shinan Power Supply Branch,Chongqing 401336 China)
出处
《电工技术学报》
北大核心
2025年第8期2532-2546,共15页
Transactions of China Electrotechnical Society
基金
国家自然科学基金(51607068)
中央高校基本科研业务费专项资金(2021MS068)资助项目。
关键词
配电网
合环转供
移相变压器
等效阻抗
合环电流
Distribution network
loop closing to supply
phase-shifting transformers
equivalent impedance
closing loop current
