Development of a hybrid reactive power compensation system with synchronous motor

Reactive power is a type of power that have to be drawn by some loads in alternative current circuits but cannot be converted to any work or energy. This power causes voltage drops, power losses and voltage instabilities in generation and transmission systems. It is also an undesirable power due to its limiting effect on power transmission capability of transmission and distribution systems. Therefore, reactive power compensation is done to prevent this power drawn by loads connected power grid. Conventionally, switched capacitors are used for reactive power compensation. In addition, static compensators (STATCOM, SSSC and active power filters), SVC and synchronous machines can also be used. Since the frequently used switched capacitors compensate gradually, it is almost impossible to make full compensation. Therefore, in this thesis, it is aimed to design a hybrid reactive power compensation system with synchronous motor to solve this problem. In the designed hybrid system, the main part of the reactive power required by the load is met by switched capacitors, while the reactive power requirement between the stages is met by a synchronous motor. In the system proposed in this thesis, coils with variable value are connected to the phase windings in order to provide different amounts of reactive power for each phase of the synchronous motor. Thus, it is aimed that the system can operate under unbalanced loads. The proposed reactive power compensation system has been tested with simulations in MATLAB environment and experimental works carried out in laboratory. The obtained results showed that the performance of the proposed system is better than the conventional capacitor switched compensation systems and the power coefficient gets closer to 1.