Hybrid power electronic transformer with unified power quality control function and control method thereof

Abstract

The invention discloses a hybrid power electronic transformer with a unified power quality control function and a control method thereof. The power quality detection and control method is based on a topology when the traditional transformer and the power electronic converter are combined; hardware circuit connection is composed of a multi-winding transformer and the power electronic converter, and the converter comprises a rectifier unit, a discharge / balance circuit unit, an inverter unit and a DC output port; according to a power quality detection unit, Park transformation is carried out on three-phase voltage, inverse transformation is carried out after filtering through a filter, and detection on a voltage harmonic and a distortion component is realized; according to voltage stability control, grid-side voltage is acquired and compared with a given value, PI is adopted to adjust a double-closed loop design, and through filtering of the filter, adjustment voltage inputted to the grid side is finally obtained; and according to reactive power compensation control, through synchronous decoupling of a positive sequence and a negative sequence, two sequences are controlled synchronously, and reactive power compensation is finally obtained.

Description

technical field [0001] The invention designs a hybrid power electronic transformer with unified power quality control and a control method thereof, and belongs to the application technical field of power electronics in power systems. [0002] technical background [0003] Electric energy is the most widely used energy in modern society, and its application degree marks the development level of a country. With the rapid development of my country's science and technology and national economy, people's demand for electric energy has increased significantly, and at the same time, the requirements for electric energy quality have become higher and higher. Power quality is of great significance to the safety of power systems and electrical equipment, economic operation, industrial production and product quality, and maintenance of normal life order. [0004] At present, a series of new features have emerged in the power system: first, large and super-large power systems have begun...

AI Technical Summary

Problems solved by technology

[0004] At present, a series of new features have emerged in the power system: first, large and super-large power systems have begun to appear, and how to ensure the safe and stable operation of large power systems is a prominent issue; The power supply of the system has changed from the traditional power frequency AC form to the coexistence of various forms, such as DC power supply (photovoltaic power generation), AC variable frequency power supply (wind power generation), etc. These renewable energy power generation systems involve a series of large Power, high-efficiency, high-quality energy conversion and control issues; the third is the rapid growth of non-linear loads, resulting in continuous decline in power supply quality, and a large number of sensitive load users have higher requirements for power quality, resulting in increasingly prominent power quality problems

[0005] In the context of these new challenges faced by the power system, the power transformer, which is the most basic power transmission and transformation device in the power system, is too single in function to make it more and more difficult to meet the requirements of the modern power system.

Moreover, conventional power transformers have the following disadvantages, including: large volume and weight, and the transformer insulating oil poses a threat to the environment; high no-load loss, and the output voltage is likely to drop when the load is on; when a fault occurs on the load side, the fault cannot be isolated, As a result, the fault will expand; when there is a nonlinear load, the distorted current will be coupled into the power grid through the transformer, which will cause pollution to the power grid; when the voltage on the power supply side is disturbed, it will be transmitted to the load side, resulting in an impact on the sensitive load; supporting related equipment to protect it; in addition, when the iron core is saturated, harmonics will be generated, which will also cause a large excitation inrush current when it is put into the power grid

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