A low-voltage load parallel online automatic phase change device and its operating method

Abstract

The invention provides a parallel online automatic commutation device of a low-voltage load. The commutation device comprises a control circuit, an input module, a commutation switch module and an output module; and the control circuit receives a commutation phase sequence state instruction sent by a distribution and transformation terminal, calculates an operation instruction of the commutation switch module, and realizes online commutation of the low-voltage load. The invention also provides an operation method of the device. The operation method comprises that 1) the three-phase voltage of power grid, a current of the low-voltage load and a phase sequence state when the low-voltage load is connected to the power grid are collected; 2) the commutation phase sequence state instruction is calculated; and 3) the operation instruction of the device is calculated, and online commutation of the low-voltage load is realized. Compared with the prior art, the device and operation method thereof use an intelligent optimized algorithm to optimize and select the phase sequence state combination of the low-voltage load in a power distribution district, and change the low-voltage load randomly among phases A, B and C, and three-phase loads in the power distribution district are balanced.

Description

technical field [0001] The invention relates to a load phase change device, in particular to a low-voltage load parallel on-line automatic phase change device and an operating method thereof. Background technique [0002] The rural area is vast, the power users are numerous and scattered, the low-voltage lines in the rural distribution area are long, and there are a large number of single-phase power loads with unbalanced time-space distribution, resulting in varying degrees of three-phase load imbalance in the low-voltage power grid. balance problem. The unequal currents of the three phases lead to unbalanced currents on the neutral line, resulting in increased losses of distribution transformers and low-voltage lines, reduced actual output of distribution transformers, and easily causing low voltage for users on heavy-duty phases, which cannot meet the needs of rural residents. Normal production and domestic electricity demand. How to control the three-phase load imbalan...

AI Technical Summary

Problems solved by technology

The unequal currents of the three phases lead to unbalanced currents on the neutral line, resulting in increased losses of distribution transformers and low-voltage lines, reduced actual output of distribution transformers, and easily causing low voltage for users on heavy-duty phases, which cannot meet the needs of rural residents. Normal production and domestic electricity demand

[0003] Although the three-phase unbalance management measures can reduce the severity of the three-phase load unbalance in the distribution area to a certain extent, due to the randomness and uncertainty of the power load, the occurrence of the three-phase load unbalance has certain Strong real-time performance, manual adjustments cannot be made frequently online according to the actual load imbalance, and there are safety hazards to a certain extent. Offline adjustments to the load distribution on each phase of the low-voltage line will inevitably affect the reliability of power supply to users sex

In some rural areas, phase-to-phase reactive power compensation on the low-voltage side of the distribution transformer is used to adjust the unbalanced three-phase load. balance

[0004] At present, there are three main solutions to the problem of unbalanced three-phase loads: one is to strengthen load management, and to balance the load on each phase of the low-voltage line by manually adjusting the load phase sequence offline. The severity of the three-phase load imbalance in the station area, but due to the randomness and uncertainty of the power load, it is impossible to make online real-time adjustments according to the actual load imbalance by manual work, which will inevitably affect the reliability of the user's power supply, and in There are potential safety hazards to a certain extent; the second is to adjust the unbalanced three-phase load by phase-to-phase reactive power compensation on the low-voltage side of the distribution transformer. This solution can only improve the distribution transformer itself to a certain extent, but cannot solve the distribution station The three-phase load unbalance of the low-voltage line in the district; the third is to adjust and compensate the asymmetrical load, and transform the unbalanced, linear and ungrounded three-phase load by connecting an ideal compensation network in parallel with the load For a balanced three-phase active load with a unit power factor, the unbalanced three-phase load is compensated at the same time as the reactive power compensation. This scheme needs to add a parallel compensation device, which is expensive, difficult to control, and low in reliability. It is mainly for large-scale applications. Electric load

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