Abstract:

The process of reducing the phase difference between current and voltage as much as possible by balancing the reactive power is known as reactive power compensation. With reactive power compensation, over currents and voltage drops in the transmission lines are prevented and higher quality, cheaper, and more efficient energy is provided. Reactive power compensation is done by switching capacitors with proper values. In a reactive power compensation system, capacitors are switched on and off by a controller. The switching behavior of this system can be characterized as a discrete event system (DES) that has discrete states and the state evolution depends on the occurrence of asynchronous events. In this paper, the control mechanism of a reactive power compensation system is considered in the sense of DES. The system is modeled by using automata and supervisory control structures are computed. The supervisors are obtained by using the supervisory control theory (SCT). Supervisors in the form of monolithic, reduced, and modular are synthesized to correct the power factor. The computed supervisors are also integrated with the system and simulated. The total size of supervisors, ie the total number of transitions and states of each, are compared. The computed supervisors in the form of modular ones have the smallest size. According to simulation results, it is demonstrated that the power factor is successfully corrected by all of the computed supervisors. The presented study shows how to calculate controllers for reactive power compensation systems by using the supervisory control theory. Since the supervisory control theory used in the study is a formal controller computation method, the presented approach enables the computation of formal controllers for reactive power compensation systems. The use of formal methods in the synthesis of controllers offers significant benefits in terms of realization and verification.

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