Research On Operation Optimization Of Distribution Network Based On Soft Open Point

With the maturity of distributed generation(DG)technology,the permeability of distributed power sources in distribution network has been continuously improved,and the trend of high proportion of renewable energy in China's power system has emerged.However,the intermittentity and randomness of DG also have a certain impact on the voltage regulation of power system.The existing primary equipment is lack of regulation ability,and it is difficult to meet the requirements of high-precision real-time operation optimization when new energy and load fluctuate frequently.Soft open point(SOP)is a new type of flexible primary distribution equipment,which can replace traditional contact switch or sectional switch on several key nodes of distribution network.The introduction of SOP can change the power supply mode of closed-loop design and open-loop operation of traditional distribution network.Compared with the switch operation,its power control is more flexible,which can realize the normalized soft connection between feeders and greatly improve the flexibility and stability of the distribution network.For this reason,this paper focuses on the operation and optimization method of distribution network based on SOP.The main research contents are as follows:(1)Based on the back-to-back voltage source converter for SOP implementation object,this paper analyzes the mathematical model of B2 B VSC in d-q rotating coordinate system,and its double closed-loop control strategy and sequential operation optimization model are given.(2)A sequential operation optimization model of distribution network jointly connected with SOP and energy storage device is established.The combination of “SOP+ energy storage” is used as the controllable source and load node of the distribution network,making it a highly integrated intelligent distribution device.At the same time,a multi-time scale operation optimization control strategy is proposed to solve the problem of SOP and energy storage integrated control.In the long time scale,a sequential optimization model is established with the objective of loss reduction.The converters on both sides of the SOP control the DC side voltage level and the active power transmitted between the feeders.The energy storage device is responsible for supplementing the power shortage or absorbing the excess power.In the short time scale,the average voltage deviation of the feeder is taken as the observation to correct the deviation of the global optimization on the basis of the ultra-short-term prediction data.(3)A multi-method complementary voltage control method considering the coexistence of SOP and traditional reactive power compensation device is proposed,and a two-layer ptimization model considering both the operation economy and the system voltage level is constructed.Then a hybrid solution strategy based on genetic algorithm and interior point method is proposed for the model.The pre-action table method is used to determine the action time of the discrete device,and the pre-action timetable is dynamically adjusted according to the power reserve of the SOP.Finally,in the improved IEEE33 node system,the proposed operation optimization model is verified and analyzed.The simulation results show that the combination of SOP and reactive power compensation device can effectively deal with the voltage fluctuation caused by the uncertainty of source and load,and significantly improve the stable operation level and energy transmission capacity of the power grid.