Novel multifunctional power electronic current-limiting system and control method thereof

Abstract

The invention discloses a novel multifunctional power electronic current-limiting system and a control method thereof. A PWM voltage stabilizing module is connected to a 10-kilovolt power grid in parallel through a shunt transformer Tb, a three-single-phase DVR module shares the direct current side of the PWM voltage stabilizing module to achieve energy supplying, a thyristor branch is placed between each contravariant unit output point of the three-single-phase DVR module and an output filter reactor and is connected with two output points of each contravariant unit of the DVR module, the output point of the DVR module is connected between the power grid and a load through a series transformers in series, and a small capacitor C filter branch is connected with a secondary side of the series transformer in parallel. According to the novel multifunctional power electronic current-limiting system, voltage fluctuation can be offset, the reliability and the stability of power supplying of a power grid system are improved, load voltage is stabilized, devices on the user side can operate normally, a short-circuit current is limited, the safety of a power grid system and the safety of a power supplying unit are improved, the short-circuit current is limited, the safety of a user device is protected, the time that the power grid bears a large short-circuit current in the process from short-circuit trouble occurrence to relay protective actions is shortened, and the safety of the power grid is improved.

Description

technical field [0001] The invention belongs to the field of electric power technology, and in particular relates to a novel multifunctional power electronic current limiting system and a control method. Background technique [0002] Electricity is the country's main energy and economic lifeline. Safe and high-quality power supply is not only related to the country's economic development and the quality of life of the people, but also maintains social stability and national security. In recent years, with the continuous expansion of the grid scale and the increasingly complex structure, it is bound to cause the continuous increase of the short-circuit current of the power system. When a short-circuit fault occurs, the short-circuit current of tens of thousands of amperes will burn the electrical appliances, causing the conductors to be deformed by mechanical stress, and at the same time cause a voltage drop and a change in power distribution, which seriously threatens the sa...

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Problems solved by technology

[0004] 1. Long-term series connection on the line, the loss is large, resulting in a large amount of resource loss;

[0005] 2. When the system is not faulty, the current-limiting reactance is idle in the power grid for a long time, and the utilization rate is low;

[0006] 3. The design of current-limiting reactance is difficult, and it is necessary to consider both the current-limiting effect and the loss during the non-fault period of the power grid; the large reactance value has a good current-limiting effect, but the required reactive power and active energy are also large (the reactance itself has resistance); the reactance If the value is small, the current limiting effect is difficult to achieve;

[0007] 4. It can only realize the fault current limiting function, and cannot compensate for power quality problems

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