Study And Application Of Closed Loop Operation In10KV Power Distribution Network By Different220KV Powers

With the rapid development of the power grid, users have higher requirement to the reliability of the grid. lOkV distribution network in our country generally adopted "closed loop design, open loop operation":the normal operation with one power supply line, which is called open loop operation;When circuit malfunction or repair, it adopts double power to ensure constant power supply, which is called closed loop operation, then need staff to take the closed loop operation. As the220-500kV power grid gradually improved, involving closed loop operation of10kV distribution also increased rapidly.As a result of closed loop operation in different220kV substations, before the closed loop operating, bus voltage, phase differences are often larger size,it is likely to produce larger closed loop current,activating the10kV feeder protection device, while the impact of excessive current may also damage electrical equipment, and affects The power quality. In order to improve the reliability and security of the power grid, reduce the failure probability of the operation, it is necessary to research on the problem of lOkV closed loop in different220kV substations.In order to solve the problem, closed loop steady-state and dynamic-state process is firstly analyzed, and carries on the theoretical analysis. Established a equivalent model of steady-state trend, and making multi-node branches reducting as a single node branch, greatly reduces the Amount of calculation. According to the ideas of the superposition method, derived the calculation formula of the steady-state current, analyzed the influence of the grid on various parameters. In addition, analyzing the dynamic-state process, respectively, to solve the impact current and overvoltage circuit, circuit model is established,and analyzing the effects of the impact current and overvoltage on the feeder. With the theory of closed loop in the network, combining the actual situation of regional power was analyzed, and through the calculation and statistics, research on the distribution of closed loop current in a variety of typical way (large way in summer and small way in winter). Through the simulation experiments, the paper analyzes the influence factors of closed loop operation such as the voltage of Phase Angle difference and Amplitude difference.Fanally based on the above analysis gives the preliminary rules of closed loop operation.Based on the study of the theory of the lOkV closed loop operation in different220kV substations, designed the software for the calculation of the current of the closed loop network. The software adopts the common "two-stage method" as the core of the software algorithm, namely taking each branch part of the initial trend as the first part of the calculation, and the trend caused by closed loop switch as the second. Through the data collection of all the closed loop points, as well as the single line diagram (collected by SCADA system), historical data of the BPA calculating, and the common parameters of the10kV feeders, etc., complete the application of the software.Through in-depth study of the problem of the closed loop network, make the operation more theoretically, getting rid of the staff simply relying on experience for closed loop operation, improve the quality of power grid and enhance the reliability of the power grid.