Neutral point installation electronic type rapid harmonic-vibration eliminating device

Abstract

The invention discloses a protection device eliminating electric system non-linear harmonic vibration. The neutral point installation electronic type rapid harmonic-vibration eliminating device comprises a switch device DK, an electronic control device KZQ and a signal collection device CG. The switch device DK is used for cutting off a zero-sequence current, and therefore restrains development of harmonic vibration. The electronic control device KZQ is used for collecting and judging the operation state of a system, and when the system has harmonic vibration, the electronic control device KZQ instantly sends an action command to the switch device, enables the switch device to be switched off for a short time, and eliminates harmonic-vibration faults; meanwhile, fault information is recorded, and the action state is sent to a supervisor. The signal collection device CG sends collected zero-sequence current signals to the electronic control device so that the electronic control device can judge the operation state. The neutral point installation electronic type rapid harmonic-vibration eliminating device is wide in application range, harmonic vibration caused by various reasons can be instantly, rapidly and reliably eliminated, the system is without any harmful effect, and a voltage mutual inductor can be effectively protected. The neutral point installation electronic type rapid harmonic-vibration eliminating device has the advantage of being simple in structure, convenient to work, high in reliability and low in cost.

Description

technical field [0001] The invention relates to a protection device for eliminating nonlinear resonance of a power system, specifically a switch-type harmonic elimination device installed at the primary neutral point of a voltage transformer, which can quickly eliminate various nonlinear resonances of the power system Fault, but also protect the voltage transformer. Background technique [0002] Most of the medium-voltage power systems in my country adopt the neutral point non-effective grounding method. This system has high power supply reliability, but the overvoltage is relatively serious, especially the nonlinear resonance caused by the saturation of the voltage transformer, which is even more common. It not only has a high amplitude, but also has a lot of energy, and can spread throughout the entire power grid, which is very destructive. Once an overvoltage occurs, it often causes damage to electrical equipment and large-scale power outages. The records and accident an...

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Problems solved by technology

[0003]Nonlinear resonance is mainly due to external excitation, which saturates the electromagnetic voltage transformer, resulting in zero-sequence loop oscillation, resulting in high resonance overvoltage, and zero-sequence The loop also generates a large zero-sequence current, which forms a loop with the grid through the neutral point of the voltage transformer. Because the capacity of the voltage transformer is small, the large zero-sequence current will burn the voltage transformer, and due to the resonance overvoltage The action time is long, and there are many reasons for the resonance phenomenon, so it is very difficult to choose protection measures.

[0004]At present, the most commonly used methods to eliminate resonance are the following two: one is short-term short-circuiting the secondary open winding of the voltage transformer, and the resonance intensity is reduced by consuming resonance energy. Gradually attenuate and disappear. Although this method is simple, the reliability is poor. If the resonance of the system is low-frequency resonance, it is difficult to eliminate the resonance. At the same time, it cannot protect the voltage transformer. When the resonance is eliminated, the voltage transformer is burned. In particular, this type of resonance elimination device all uses zero-sequence voltage as the criterion, it is difficult to distinguish the difference between resonance and grounding, and misjudgment often occurs, which brings a lot of trouble to the site operation; A resistor (linear or non-linear resistor) is connected in series between the neutral point and the ground. The purpose is to increase the reactance of the zero-sequence return and damp the zero-sequence current. Although this method can protect the voltage transformer, the measurement of the voltage transformer In addition, when a single-phase ground fault occurs in the system, the resonance eliminator often burns out due to its limited capacity, especially when the resonant current generated by the system is large, the resonance eliminator will generate a high voltage, which poses a threat to the insulation of the neutral point of the voltage transformer

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