Developing the fault ride through capacity of doubly fed induction generators used in wind turbines with intelligent control methods

Fossil fuels, which meet a large part of the energy need all over the world, are shortening their lifespan, their costs and the extent of the damage they cause to the environment are increasing day by day. The problems created by global warming have had a noticeable effect in recent years. In every part of the world, natural events are encountered with a frequency never seen before. In addition, the increase in the world population and the increase in industrialization in parallel increase the need for energy continuously. All these reasons have forced countries to turn to new sources where they can meet their energy supply. Since renewable energy sources are the most efficient and environmentally friendly alternative, the interest in renewable energy is increasing exponentially all over the world. In this context, wind energy is mostly used in our country, as in the rest of the world. Although wind power plants have positive aspects such as being sensitive to the environment, not having carbon emissions, and not causing great destruction in nature due to low land occupation, they also have some disadvantages. The fact that the wind cannot be predicted clearly and changes according to environmental and natural conditions reduces the continuity and reliability in energy. In addition, the increase in these power plants has also caused concerns about the performance of the power plants in case of changes in the voltage and failure situations. For this reasons, countries have added renewable energy plants to their grid codes. In the grid code, many topics such as faulth ride through capacity (FRT), active power control, reactive power capacity, frequency response are covered. The issue of reconnection capacity after failure is grouped under three headings. These are; solution strategies based on reactive power generation, protection circuits and software. In this thesis, the FRT capability of a power plant with doubly fed induction generator (DFIG) wind turbines has been tried to be developed. In this context, a static synchronous compensator (Statcom) operating on the basis of reactive power generation is used. In the power system created in Matlab/Simulink, single phase-to-ground short circuit, phase-to-phase short circuit and 3 phase-to-ground short circuit faults are simulated. The voltage drops occurring in the system at the time of the fault were examined with reference to two separate measurement points. In the control of Statcom, the developed proportional-integral (PI) control method and the adaptive neural fuzzy inference system (Anfis) among the smart control methods were preferred. In this study, the effect of Statcom, which has different control methods, on the FRT capability of DFIG; Three different cases were studied: without Statcom, with PI-controlled Statcom and with Anfis-controlled Statcom. When the post-fault conditions are examined, it is seen that the system with Statcom with Anfis controller gives the best performance in terms of maximum overshoot and settling time. With the developed smart method, a different approach has been developed to improve the FRT capability of wind turbines, and a new method with a much shorter response time, stable and safe to be used in practice has been proposed by avoiding the system-challenging effects such as sudden voltage spikes that may be encountered in practice.