Title: A Voltage Controller for Three-Phase DSTATCOM to Compensate AC and DC Loads for Quick Response.
Author: M Lakshminarayana, Kurivindala Ravi, Medi Murali Krishna & Chilaka Udaya Kumar
In this paper, DSTATCOM topology for compensating ac loads in the three-phase, four-wire systems as well as supplying dc loads from its dc link and the transient responses of the distribution static compensator (DSTATCOM) for different types of controllers are studied. This transient response of DSTATCOM is very important while compensating rapidly varying unbalanced and nonlinear loads. Any change in the load affects the dc-link voltage directly. The sudden removal of load would result in an increase in the dclink voltage above the reference value, whereas a sudden increase in load would reduce the dc-link voltage below its reference value. The proper operation of DSTATCOM requires variation of the dclink voltage within the prescribed limits. Conventionally, a proportional-integral (PI) controller is used to maintain the dc-link voltage to the reference value. It uses deviation of the capacitor voltage from its reference value as its input. However, the transient response of the conventional PI dc-link voltage controller is slow.
In this paper, a fast-acting dc-link voltage controller based on the energy of a dc-link capacitor is proposed. This paper reveals that the fast-acting dc-link voltage controller can regulate the capacitor voltage within a half cycle period. Owing to its good transient performance, for quick response, it is preferred over the conventional dc link voltage controller. Mathematical equations are given to compute the gains of the conventional controller based on fast-acting dclink voltage controllers to achieve similar fast transient response. The detailed simulation and experimental studies are carried out to validate the proposed controller.
DC-link voltage controller, distribution static compensator (DSTATCOM), fast transient response, harmonics, load compensation, power factor, power quality (PQ), unbalance, voltage-source inverter (VSI).
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