Low voltage load online phase modulation device and phase modulation method thereof

Abstract

The invention relates to a low voltage load online phase modulation device and a phase modulation method thereof. According to the invention, optimization selection is performed to phase sequence state combination of electric load of users in a power distribution area, and then the electric load of the users is switched freely among phases A, B and C via a controllable switch, so that loads of the three phases of the power distribution area can be balanced. The low voltage load online phase modulation device fully integrates advantages of a mechanical switch and an electronic switch, so that the function of zero passage seamless switching of voltage and current can be realized, the impacts on a low voltage power grid and the electric load of the users are avoided, and the reliability of power supply and the voltage quality are guaranteed. The low voltage load online phase modulation device ensures that the load of the three phases of the power distribution area realizes minimum unbalance degree, the switching times of the switch is minimum, and the service life of the low voltage load online phase modulation device is improved. The low voltage load online phase modulation device has the function of three-phase load adjustment, and moreover, has functions of fault protection for over-current and over-voltage and leakage protection.

Description

technical field [0001] The invention relates to the field of unbalanced control of three-phase loads in a low-voltage distribution network, in particular to an online phase modulation device for low-voltage loads and a phase modulation 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 elec...

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 unbalanced management measures can reduce the severity of the unbalanced three-phase load in the distribution area to a certain extent, due to the randomness and uncertainty of the power load, the unbalanced three-phase load occurs It has strong real-time performance, and it cannot be adjusted frequently online according to the actual load imbalance by manual work, and there are safety hazards to a certain extent. Offline adjustment of the load distribution on each phase of the low-voltage line will inevitably affect the power supply to users reliability

At present, some rural areas adopt the method of phase-to-phase reactive power compensation on the low-voltage side of the distribution transformer to adjust the unbalanced three-phase load, but this method can only adjust the problem of the distribution transformer itself to a certain extent, but cannot solve the three-phase load of the low-voltage line unbalanced situation

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