The Reactive Power Compensation Of The Static Var Generator In Wind Power Generation System

Since the 1980s of last century, large wind farms based on the asynchronous generator has become the most important focus in modern people’s eyes. However, in order to create field excitation and send electric energy to the grid, the asynchronous generator has to absorb reactive power from the power system. What’s more, the load connected to the grid is not purely resistive. So it also needs reactive power from the grid. If all the reactive power is provided by the grid, it is not practical. More importantly,the reactive power needed by the asynchronous generator is changed as the wind changes. With the advantages of small size, low cost, flexible control, as a reactive compensator the Static Var Generator (SVG) gradually become more and more important in the field of reactive power compensation. As a result, it is playing an increasingly important role all over the world.On the basis of reading a large number of foreign and domestic literatures, the paper analyzes the operation principle of the SVG and the characteristic is the wind farms. First it introduces the design of the main circuit parameter of SVG. Then based on the ip-iq detection method, it simplifies and improves the traditional reactive current detection method. The new method can avoid the poor effect from current tracking error caused by the traditional reactive current detection. And then it presents the control method whose improvement and innovation are reflected in two parts: First it for the first time employs the triangular modulating control to control the SVG; Second it takes the advantage of BP neural network to train three sets of data: the reactive current i q detected by ip-iq detection method, the current i q1 needed by Cpq-1 part when generating modulated wave and the triangular amplitude control signal K. The purpose is to simulate the optimal approximate function among i q, i q1 and K and generate the best duty cycle between the modulated wave and the triangle wave. At last the simulation proves with the control method the SVG can compensate reactive power rapidly and precisely.The system model is established on wind farms. The SVG is proved to be in practice have good performance in compensating reactive power.