The Steady-state Control Strategy Of Flexible Multi-state Switch And Its Application Scenario Optimization Method

With the development of renewable energy technology and the innovation of energy structure,the proportion of distributed new energy and multiple types of uncertain loads in the distribution network is increasing day by day,which brings great challenges to the stable operation and energy consumption of the traditional distribution network.At the same time,the existing methods have been difficult to solve the problems of feeder power imbalance and voltage inconsistency caused by the access of distributed new energy and load imbalance,which makes the grid connection of distributed new energy more difficult.Flexible Multi-state Switch in distribution network is a kind of installation to connect two or more feeder new power electronic device,the switch with power continuous adjustable,flexible mode,the characteristics of imbalance for the power and voltage does not match the problems such as to provide reliable solutions,so as to realize flexible interconnection between multiple feeders and network.In this paper,the steady state control and operation optimization method of Flexible Multi-state Switch in distribution network are studied.Firstly,the MMC terminal of the three-terminal Flexible Multi-state Switch is taken as an example.Based on the topology structure and working principle of the MMC,the dynamic mathematical model and control method of the MMC in the synchronous rotation coordinate system are analyzed.The device-level closed-loop control and the valve-level control of the sub-module capacitor voltage balance and circulation suppression are realized by simulation.A three-phase MMC test prototype based on DSP and FPGA is built,and its device level and valve level control are verified experimentally.Secondly,according to the power coupling mechanism of flexible multi-state switch and multi-terminal,the principle and control characteristics of three kinds of multi-terminal cooperative control methods,namely master-slave control,DC voltage slope control and DC voltage deviation control,are introduced.Under different working conditions,the three cooperative control methods were compared and analyzed and verified by simulation,and the multi-terminal power coupling feeder equalization was verified by RTDS hardware-in-the-loop real-time simulation experiment platform.Finally,the Particle Swarm Optimization is adopted in this paper to solve the problem of energy consumption caused by new energy grid-connection.With the voltage level of the safe and stable operation of Flexible Multi-state Switch and the distribution network,the power flow of the system feeder and the line capacity as the constraint conditions,and the minimum deviation of the actual voltage of each node relative to the rated voltage as the objective function,the operation optimization model of the flexible multi-state switch connected to the distribution network is established and solved,which provides a feasible way to solve the voltage fluctuation and energy consumption problems caused by the output uncertainty of distributed new energy.