Power control method for low-voltage flexible distribution network power supply system

Abstract

The invention provides a power control method for a low-voltage flexible distribution network power supply system. The system comprises four distribution transformers T1-T4, four sections of 400V low-voltage AC (alternating current) buses and four flexible DC (direct current) converters, wherein the four sections of 400V low-voltage AC buses are connected through bus coupler switches; a DC bus isfurther connected to an energy storage system and a distributed photovoltaic system. The power control method is used for performing energy storage charge control, emergency power support control andflexible DC converter powerless control in one-way wire inlet operating modes and performing zoned power support control, the emergency power support control and the flexible DC converter powerless control in two-way, three-way and four-way wire inlet operating modes. According to the system, interconnection of multiple lines of the distribution network is realized by the flexible DC converter, power wheeling support between the lines is realized, and after a certain distribution line fails and breaks, the flexible DC converters perform islanded operation with load; meanwhile, interconnectionis realized on the DC link with photovoltaic and energy storage systems, and an optical storage and flexible DC combined hybrid system is formed.

Description

technical field [0001] The invention belongs to the technical field of flexible power transmission, and in particular relates to a power control method for a low-voltage flexible distribution network power supply system. Background technique [0002] Due to its unique technical advantages, flexible DC transmission is introduced into the urban power grid with intensive power consumption, and its rapid controllability is used to solve the problems of power supply difficulties, high costs and difficult power flow control in urban power supply. There are also broad application prospects in power distribution. First, the active power transmitted by flexible DC transmission can be quickly and flexibly controlled, and the power flow between different lines in the distribution network can be effectively and feasiblely allocated; secondly, flexible DC transmission can dynamically compensate the AC bus. The reactive power is conducive to the grid-connection of distributed power source...

AI Technical Summary

Problems solved by technology

The traditional power distribution network has the following problems: 1) The main transformer corresponding to a bus with a light load (for example, during the day on a working day) works in a light-load or no-load state, and the efficiency is low; 2) When two low-voltage buses When the total load exceeds the capacity of a single main transformer, at this time, due to the failure of a certain incoming line or the failure of the main transformer, the bus tie switch is closed, which will easily cause the single main transformer to be overloaded or even tripped due to overcurrent, causing the fault to expand; 3) With the increase in the number of electric vehicles in cities, more charging piles or chargers have been added, and the power is above 50kW. The input of short-term high-power impact loads such as charging piles or chargers may easily cause overloading of distribution transformers.

4) With the development of distributed energy, the access of community buildings or rooftop photovoltaics will bring new challenges to the existing capacity of the distribution network and the power quality of the distribution network

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