Application of generator full digital reactive power controller in power plant

Abstract: This paper introduces the design principle of this research product and its application advantages in medium and small power plants.

Key words: power grid, generator, reactive power, digital potentiometer, generator excitation control.

I. Preface

Due to the large inductive load equipment with electrical equipment, so in addition to providing "power grid", must also provide a certain proportion of "reactive power", to use the electric equipment in normal use and operation. The "reactive power shortage" of power grid is a long existing problem.

The current widespread use of the lack of reactive power grid is capacitive in the power supply side of "reactive power compensation, power plant (power) by the method of reactive power compensation with high cost of equipment, from the technical point of view, the generation side using this solution to compensate for the lack of reactive power is not reasonable. Shenzhen Xuzhen Electric Technology Co., Ltd. is engaged in power system automation products research and development of high-tech enterprises, absorbing domestic and foreign advanced technology, combined with the current common problems of reactive power shortage, small power plant, successfully developed with independent intellectual property rights of the "digital generator reactive power controller, and the successful implementation of the product of.

"Digital generator reactive power controller with intelligent digital control method, using the PIC microcontroller as the core, combined with the use of high precision digital potentiometer and excitation system, automatic tracking and operating parameters of power network, the effective use of the generator itself and potential, by adjusting the excitation current to the generator" issued "enough" reactive power and active power matching.

Two. Basic principles

"Digital generator reactive power controller" in addition to the necessary display part, mainly has the high precision "active", "reactive" detection and high precision digital potentiometer output part, in the case of high voltage power grid can effectively emit "reactive" current, also have two step relay output.

Three, technical key

People who have some knowledge of power generation know that when the generator is connected to the grid, the excitation current of the generator is changed slightly when the voltage of the generator is fixed, so that the reactive current of the generator can be changed. Therefore, in order to realize the precise control of reactive current (power), a "digital potentiometer" with high resolution and high accuracy must be used to control the excitation current of the generator. In the actual operation of the generator, the voltage has been changed, therefore, at any time, accurate measurement of relationship between voltage and current of generator and their (i.e., active and reactive power measurement) is the key to realize automatic control.

High precision "reactive power measurement" is not complicated, the universal application of the capacitive "reactive compensation controller" can solve the problem of high precision, high resolution, "" "" digital potentiometer we have successfully developed and widely used. Therefore, we combine their advantages of scientific research, innovation, the two technology to a combination of high difficulty, and combined into a chip, to solve the technical problems of domestic medium and small enterprises generating reactive power shortage.

The station staff all know, in the wet period due to the power plant full load power, often make the voltage rise, the generator is difficult to send enough power to "reactive current to generate reactive current (voltage higher than the voltage of the generator must be subject to the limitation of technology, motor, voltage raised too high), the only solution is to reduce the voltage. There are two ways: first, a plurality of taps are extracted from the transformer, but this method is difficult to switch dynamically. Two is our innovative "series step-down" program. Following chart.

We assume that with two, a decrease of about 5% about voltage is feasible, each transformer capacity is the capacity of about 5%, we have two step-down device control output, effectively solves the technical problem of high voltage generator reactive power output.

Four, application effect

For power plants, the "reactive power" is meaningless, and "reactive power" will be fined. According to the actual situation of the power grid, the dispatching department of the power grid will direct the power plant to send a certain proportion of reactive power to match the active power, otherwise it will affect the power supply quality of the power grid. Because of the low technical content of the equipment, the small and medium-sized power plants in China are fined every year because of insufficient reactive power. The active current and reactive current phase difference is 90 degrees, and which is not a simple sum, but if the vector and arrangement of active current and reactive current "relations" in no more than the maximum generator current, and energy and price factors for optimal power generation strategy is an innovative technology.

Five. Conclusion

The research and development of "full digital reactive power controller" in our country has attracted wide attention of domestic power industry and large and medium sized power plants. The application of the scientific research results to the power users will play a very important role in promoting the development of China's power industry and improving the level of automation control in China's power industry.