Simulation And Experimental Study On The Integrating Compensation Method Of Distribution Transformer And STATCOM

As an important member of the Flexible AC transmission system family, StaticSynchronous Compensator has played an important role in the power system. Resently, it iswidely used in dynamic reactive power, harmonic suppression, voltage support and thestability improvement of the system. This article holds that, the intersection of high, lowvoltage grade in the power grid is one of the most important and effective compensationcontrol point. Among them, the widely used distribution transformer is one of the mostideal, flexible and effective power grid energy-saving, reactive power compensation and thehierarchical compensation control point of quality of electric energy. This paper presentsthe distribution transformer with STATCOM device integrated design thought andTechnology (DT-STATCOM Technology), thus realizing the transformer and load powerquality comprehensive control.First of all, research on the DT-STATCOM technology scheme and compensationprinciple. According to the distribution transformer connection group variety structure,designed the corresponding integration form. Elaborated the DT-STATCOM compensationprinciple, focus on the analysis of Yyn coupling transformer and Dyn coupling transformertap injection mode, Analyze the influence of DT-STATCOM integration structure ontransformer winding current distributions, Combined with the transformer economicoperation conditions, select the appropriate voltage level for the transformer tap, and studyin the mode simulation of Dyn coupling transformer tap injection mode. Research resultsshow that, under the transformer economic operation conditions, DT-STATCOM hassatisfactory reactive power compensation capacity.Secondly, study the DT-STATCOM system structure and its control strategy and theDT-STATCOM inverter circuit structure based on two level, three level topology, prove thatthe three level structure has more advantages in lower device voltage level, improving theswitching frequency, reducing the output du/dt and output current harmonics than the twolevel structure through simulation research. Research on DT-STATCOM AC output filterstructure, pointed out that the LCL filter has better filtering effect than the LC filter, and putforward the design method of the parameters of LCL filter, and put forward the parameterdesign method of LCL filter. Research on the mathematical model and control strategy of DT-STATCOM system, put forward two kinds of the DT-STATCOM instruction currentcalculation method (instantaneous) based on power balance principle, Simulation resultsverify the correctness of control method.Third, the strategy of reducing the system loss in DT-STATCOM has been studied. Thetheory and method of synthetically reducing loss is analyzed. The compensating devicecould decrease the current level by choosing a suitable access voltage level, which helps toreduce the power loss of the device. At the same time, the third harmonic could be injectedby the transformer tapping to adjust the magnetic flux, thus, to reduce the transformerno-load loss. And the experiment system of the no-load loss in DT-STATCOM is built, theno-load loss experiment of DT-STATCOM is studied. The result of the experimentconfirmed the function of DT-STATCOM in reducing the system loss.In fourth, construct the DT-STATCOM system test platform, do the DT-STATCOMsystem dynamic model test research. Establish a dynamic simulation test platform withpower supply, line, load and monitoring system, the experiment platform has a variety ofDT-STATCOM integrated wiring method, developed a number of experiments and schemes.do a number of dynamic model tests,such as reactive power compensation, the unbalancedcurrent compensation, harmonic current compensation on the DT-STATCOM system. Theresults show that DT-STATCOM has good compensation performance.Finally, this paper summarizes the research results, suggestions for follow-up researchcontent.