Output circuit of three-phase power voltage regulator

Abstract

The invention discloses an output circuit of a three-phase power voltage regulator, and aims at providing the output circuit of the three-phase power voltage regulator, which can protect the normal work of an electric device when the electric device has a single-phase impact load with larger power. The output circuit comprises a three-phase voltage regulation circuit and an output control circuit, wherein the output control circuit comprises a step-down transformer TB (1) and a single-phase output wire connecting terminal (2), the primary of the step-down transformer TB (1) is 380V, the secondary is 220V, the primary of the single-phase step-down transformer TB (1) is connected with any two phases of the output end of the three-phase voltage regulation circuit, the three-phase electric device is connected with the output end of the three-phase voltage regulation circuit, and the single-phase impact load is connected with the single-phase output wire connecting terminal (2). The outputcircuit can be widely applied in the field of power voltage regulators and is particularly applicable to electric places which contain the single-phase high-power impact loads in the electric devices.

Description

technical field [0001] The invention relates to the field of electric voltage stabilizers, in particular to an electric place where single-phase high-power impact loads are included in the post-stage electrical equipment of a three-phase four-wire input three-phase electric voltage stabilizer. Background technique [0002] The voltage stabilizer commonly used in the power system is a three-phase power voltage stabilizer. Its input and output usually adopt a three-phase four-wire system. The electrical equipment can be three-phase (3Φ380V) or single-phase (single-phase 220V) , Try to use the basic balance of the three-phase power of electrical equipment in design and construction. Due to the difference in power load and power supply environment, there may be situations that affect the normal operation of the voltage stabilizer due to failure of the voltage stabilizer. For example: 1. The power consumption site is far away from the distribution transformer, and the impedance o...

AI Technical Summary

Problems solved by technology

Due to the difference in power load and power supply environment, there may be situations that affect the normal operation of the voltage stabilizer due to failure of the voltage stabilizer. For example: 1. The power consumption site is far away from the distribution transformer, and the impedance of the power supply line is relatively large; 2. The wire cross section of the transmission line is selected to be too small, and the neutral line (zero line N) is designed to be half of the phase line, resulting in a further increase in the impedance of the zero line; 3. There are single-phase high-power impact loads in the electrical equipment , such as single-phase motors, single-phase air conditioners and other electrical equipment

[0003] The starting current of the motor load is 6 to 8 times the rated operating current. In the above-mentioned power consumption environment, the large starting current of the single-phase electrical equipment causes the three-phase load to be seriously unbalanced, and the excessive single-phase load current passes through the phase of the power supply line. Line to the electrical equipment and then back to the neutral point of the power supply transformer through the neutral line (N), the instantaneous large current will produce a large impedance drop on one of the phases and the neutral line of the three-phase power supply line, and the single-phase large current will cause Severe neutral point shift causes the voltage of one of the phases to drop instantly while the voltage of the other two phases rises instantly, and the voltage of one phase with a large load drops instantly and exceeds the undervoltage protection value, so that the voltage stabilizer performs "undervoltage protection" ;The two-phase voltage with a small load rises instantaneously and exceeds the overvoltage protection value, and the voltage regulator implements "overvoltage protection", while "undervoltage protection" and "overvoltage protection" will both cause the circuit to cut off the power output

After the voltage stabilizer cuts off the output, the load current drops to zero, the input voltage of the voltage stabilizer returns to the normal value, and the electrical equipment restarts the voltage stabilizer to perform "undervoltage protection" and "overvoltage protection" again and again to form oscillations, causing The device is not malfunctioning and cannot operate normally

[0004] To sum up, the output circuit of the three-phase power regulator in the prior art has problems when there is a large power single-phase impact load in the electrical equipment and the impedance of the power supply line is large, especially the impedance of the neutral line is large. When the voltage stabilizer cannot operate normally, it will affect the normal operation of the electrical equipment.

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