Topological structure of three-phase voltage imbalance treatment circuit

Abstract

The invention provides a topological structure of a three-phase voltage imbalance treatment circuit, which comprises a power supply system, a power transformer, a three-phase full-bridge rectificationcircuit, a three-phase four-bridge-arm inversion circuit and a three-phase unbalanced load containing single-phase photovoltaic, wherein the power supply system, the power transformer, the three-phase full-bridge rectification circuit, the three-phase four-bridge-arm inverter circuit and the three-phase unbalanced load containing single-phase photovoltaic are connected in sequence; the power supply system is connected with the power transformer to form a three-wire system; the power transformer is connected with the input end of the three-phase full-bridge rectification circuit to form an alternating-current three-phase four-wire system; the N line is grounded, the output end of the three-phase full-bridge rectification circuit is connected with the input end of the three-phase four-bridge-arm inverter circuit through a direct-current circuit, and the output end of the three-phase four-bridge-arm inverter circuit is connected with a three-phase unbalanced load containing single-phasephotovoltaic to form an alternating-current three-phase four-wire system. According to the invention, real-time response is achieved, and no delay time exists.

Description

Technical field [0001] The invention belongs to a three-phase voltage unbalance treatment technology for a power distribution network, and is specifically a three-phase voltage unbalance treatment circuit topology structure. Background technique [0002] A lot of research has been done on three-phase imbalance control of power systems at home and abroad. The current measures to control three-phase imbalance mainly include commutation and additional compensation, which mainly include commutation using automatic phase commutation devices and capacitive three-phase unbalance compensation. Among them, the automatic commutation device can automatically switch the user's phase sequence to manage the three-phase imbalance, avoiding the disadvantage of manual commutation operation. The automatic commutation device is mainly composed of the station area control terminal and the intelligent commutation switch. The station area control terminal collects the three-phase current and the neut...

AI Technical Summary

Problems solved by technology

[0004] 1. The commutation time is long, although it is less than about 10ms, it cannot fully guarantee to meet the power requirements of all electrical equipment in the grid

[0005] 2. The maximum adjustment of the three-phase load differential current must be guaranteed through wireless communication. It is difficult to ensure reliable communication to meet the requirements of three-phase unbalanced adjustment.

[0006] 3. The installation is inconvenient, there are many construction points, and the power failure during the construction process has a great impact

[0007] 4. Due to its high cost, troublesome installation, poor reliability, and interference during communication, it will affect the meter reading system

[0009] 1. Capacitor adjustment and compensation, it is difficult to see the effect on the network with high power factor

[0010] 2. This mode only achieves three-phase load balance at the low-voltage outlet of distribution transformers through phase-to-phase power transfer, and cannot fundamentally solve the problem of actual load balance distribution.

[0011] 3. Slow response compensation method, poor continuous controllability

[0012] 4. Over-compensation or under-compensation or overvoltage or undervoltage of the system voltage

[0013] 5. The service life is short, and the capacitor needs to be replaced regularly

[0014] 6. It can only be adjusted step by step, not smooth adjustment

[0015] 7. Capacitors are prone to expansion and explosion due to high operating temperature, poor voltage characteristics, poor short-circuit stability, residual charge after removal, low reactive power compensation accuracy, and easy to affect the compensation effect

Due to the influence of changes in light intensity, the power output of the grid-connected photovoltaic power generation system is random. Therefore, while the photovoltaic grid-connected alleviates the power supply pressure of the distribution network, it also increases the uncertainty of the operation of the distribution network, making the network power flow Random changes have also brought new difficulties to the three-phase imbalance control of the power grid

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