Load-related low-voltage dynamic reactive power compensation capacitor automatic control method

Abstract

The invention provides a load-related automatic control method of a low-voltage dynamic reactive compensation capacitor, the load level of a current distribution transformer can be judged according to a current duty ratio eta (the ratio of a load current and a distribution transformer rated current) of the distribution transformer, and a corresponding power factor control section is selected accordingly to determining switching of a capacitor, so as to improve the loss reduction effect of a 10kV power distribution system and improve voltage quality, and to improve the utilization rate of reactive compensation equipment. Specific steps of the scheme are as follows: measuring the line current and the line voltage of a mounting point of the capacitor; dividing a measured load current value by a rated current of a secondary side of the transformer, and calculating the current duty ratio eta of a load point; classifying the load level into light load, normal load or heavy load according to eta; setting upper limits and lower limits of three sets of power factor control sections according to the difference of reactive compensation requirements when the load level is different; and selecting a corresponding power factor section according to the condition of loading, and performing switching control of the capacitor based on a voltage priority criterion.

Description

technical field [0001] The invention relates to a dynamic switching control technology for low-voltage capacitors, in particular to a method for dynamically selecting a power factor control interval for capacitors in 10kV power distribution lines according to load changes. Background technique [0002] In the Twelfth Five-Year Plan, my country proposes to reduce energy consumption per unit of GDP and reduce the total discharge of major pollutants. As an important energy source, electric energy, in the production and operation of electric power, especially in the distribution network, promotes and applies energy-saving and loss-reducing measures. Significance and significant effect. [0003] According to relevant data, the loss of my country's low-voltage transmission and distribution network (including lines and distribution transformers) accounts for about 10% of the total power output, resulting in huge loss and waste of electric energy. A considerable part of this loss ...

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Problems solved by technology

[0005] (1) The control method of fixed upper and lower limits of power factor is only suitable for lines and networks with relatively stable reactive loads, and targeted compensation cannot be realized in the case of large load changes;

[0006] (2) When the load is light, switching the capacitor bank will cause a large change in the power factor, and the fixed range of 0.90 to 0.95 is too narrow, which may lead to repeated switching damage to equipment and instability of the power grid;

[0007] (3) When the load is heavy, since the distribution transformer and the line will generate more reactive power loss, and the current method generally does not allow reactive power transfer, this part of the loss still depends on the upper power grid to send it down

Therefore, when the load is heavier, the more reactive power flows on the line, the more serious the network loss, and the worse the voltage quality. Obviously, the upper limit of the power factor of 0.95 is difficult to meet the needs of energy saving and high-quality power supply;

[0008] (4) At present, reactive power compensation devices in most areas are configured according to 20% to 40% of the total capacity of the distribution transformer, but in normal operation, according to the power factor range of 0.90 to 0.95, it is not necessary to invest in all equipment, and the existing The performance of compensation equipment in distribution network area optimization, resulting in idle waste of reactive power compensation equipment

[0010] Obviously, the reactive power compensation capacity required by the line under heavy load and light load is very different, and it is difficult to achieve the most effective energy saving and loss reduction effect by using a unified and fixed power factor control under different load conditions

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