中压配电网络低电压补偿调控技术及实现

Implementation of low voltage compensation control in medium voltage distribution network

电压是电能质量考核的一个重要指标。处于系统末端的农村中、低压配电网络在用电高峰期"低电压"现象频繁出现,严重影响了农民正常生产生活用电。该文结合辽宁西丰地区中压配电网络,基于线路调压器调压和无功补偿的基本原理,研究了线路调压器以线路末端远程监测电压为依据和无功补偿以线路首端无功潮流为依据的上位机远程控制的低电压协调控制治理方法。通过远程调控技术实现了在最大潮流下线路的功率因数由补偿前0.97提高到0.99,10 k V线路线损率比协调控制前下降了6%,配电变压器原边电压合格率由原有的22%达到了100%。该文集成应用无线通信技术和自动化综合补偿和调压技术,有效地改善了中、低压配电网络的电压合格率和电能损失率。

Voltage is an important assessment criterion of power quality. The low voltage phenomena(LVP) frequently appeared in the power distribution network especially at the rural areas of China, which had been key technical problem to be solved by the local departments of State Grid Corporation of China(SGCC). However, LVP happened mostly at the end of the rural medium voltage distribution system in the peak season, by which the electric power consumption of farming and farmers were seriously affected, and also lay behind the development of agricultural economy.Insufficient primary voltage of the distribution transformer was the main cause of rural low voltage phenomena. Increasing rural substation sites or the conductor section could also improve the power quality, but the investment cycle was too long and the rate of return lower. It is not suitable for large-scale popularization and application in rural areas. The thesis presented a synthesized optimal dynamic compensation method for low voltage in the whole electric power line, which was adopted practically and led in Xifeng medium voltage distribution network of Liaoning. First, based on the line voltage-regulation theory with voltage regulator and the terminal voltage monitored by feeder terminal unit(FTU), the voltage level of the whole electric power line was up to the national criteria with the power on-load tapping voltage regulator controlled by the remote host computer. In the meantime, at the basis of reactive power flow of the head line, and with the constraint condition of voltage in the nodes of reactive power compensators installed, the reactive compensation commands were sent by the remote host computer. The total reactive power capacity was 440 kvar(kilovolt ampere reactive) in each node of compensators,in which 50 kvar was as static compensation and the other as dynamic separated into 4 groups. According to the output of reactive power tide at the transformer substation, 1 static and 4 set of dynamic capacitor banks were composed of 17 different combinations in every compensation node, which was optimized for grouping parallel capacitor switch by the remote host computer based on the principle of reactive balance. Finally the national supervision standards of reactive power dynamic balance were reached after above computerized dynamic adjusting measures taken in the whole experimental power grid. The experimental results showed that the line power factor increased to 0.99 from 0.97 under the maximum power flow after the synthesized compensation implementation, and 10 KV line active power loss rate decreased by 6 percent compared with before, and distribution transformer primary qualified voltage rate rose to 100% from original 22%. In the paper, several theories and methods of wireless communication and computer control and line-automation were integrated into the practical application example of comprehensive voltage compensation, which effectively improved the voltage level and fluctuating range, the qualified voltage rate and the power loss rate in the rural low and medium voltage distribution network.It has good reference value of engineering. The proposed methods also come up with new solutions for the intelligent development of reactive power compensation of rural substation.