Idle current detection and calculation method for power network current

Abstract

The invention provides an idle current detection and calculation method for power network current. Based on the formula iq=A1cos (wt-2m Pi / 3), the method is characterized in that a load side power network current detecting part, an idle current resolving part, an idle current scaling factor calculation part and an idle current content calculation part are comprised. The method adopts an instantaneous power calculation method and can quickly detect out the idle current on the load side power network current; based on the detected idle current, in situ reactive compensation can be performed for the power network so as to improve the stability of the power network voltage and reduce the power network wire damage. The detection method is simple and reliable, effectively shortens the development time and cost of a static var generator based on the method, and is conducive to using the market competitive advantage of the SVG control equipment adopting the technology, to stabilizing power network voltage and reducing wire damage, and further to cleaning the power quality of the power network.

Description

technical field [0001] The invention belongs to the field of power electronics and relates to a reactive current detection and calculation method, in particular to a reactive current detection and calculation method in grid current. Background technique [0002] With the development of industrial technology, non-linear loads such as power electronic equipment are widely used in various fields, causing a large amount of reactive current to flow into the grid, resulting in a decrease in grid voltage and an increase in line loss, which affects other power users on the same line. In severe cases, the line will be burned and the power factor of the power grid will be very low. For this reason, some scholars have proposed a fixed-capacity capacitor bank compensation method. This method is still used in the power grid, and the corresponding equipment is relatively cheap. However, the capacitor bank compensation is easy to cause over-compensation or under-compensation, and it will a...

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Problems solved by technology

[0002] With the development of industrial technology, non-linear loads such as power electronic equipment are widely used in various fields, causing a large amount of reactive current to flow into the grid, resulting in a decrease in grid voltage and an increase in line loss, which affects other power users on the same line. In severe cases, the line will be burned and the power factor of the power grid will be very low. For this reason, some scholars have proposed a fixed-capacity capacitor bank compensation method. This method is still used in the power grid, and the corresponding equipment is relatively cheap. However, the capacitor bank compensation is easy to cause over-compensation or under-compensation, and will amplify the fixed harmonic current of the power grid, causing other impacts on the equipment, and even burning the compensation capacitor

[0003] For this reason, modern technicians have proposed a new compensation method, static var generator (SVG), which can quickly and continuously track the reactive current in the power grid, and achieve good results, but most of them are expensive and the algorithm is complicated , which is not conducive to the popularization and application of equipment, for example, i based on the theory of instantaneous reactive power p -i q The algorithm has good real-time performance and a wide range of practical applications, but it requires multiple coordinate transformations. First, the A-B-C coordinate system is transferred to the α-β coordinate system, then to the p-q coordinate system, and then transferred to the α-β coordinate system, and then transferred back to A-B-C In the coordinate system, especially when the three phases are unbalanced, the amount of calculation increases geometrically, which is not conducive to the realization of the algorithm, or the price of the realized equipment is relatively high

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