A Fast-Acting DC-Link Voltage Controller for Three-Phase DSTATCOM to Compensate AC and DC Loads
Ajith Bharadwaz.1, Ch G. DevadasK.2, Girinath Babu3

1Ajith Bharadwaz, CMRCET, Hyderabad, India
2Ch G.DevadasK., CMRCET, Hyderabad, India
3GirinathBabu, CMRCET, Hyderabad, India
Manuscript received on February 11, 2013. | Revised Manuscript Received on February 12, 2013. | Manuscript published on February 25, 2013. | PP: 25-30 | Volume-1 Issue-4, February 2013. | Retrieval Number: D0177021413/2013©BEIESP
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: The transient response of the distribution static compensator (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 0of 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 dc-link 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 dclink 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. Mathematical equations are given to compute the gains of the conventional controller based on fast-acting dc-link voltage controllers to achieve similar fast transient response. The detailed simulation and experimental studies are carried out to validate the proposed controller.
Keywords: DC-link voltage controller, distribution static compensator (DSTATCOM), fast transient response, harmonics, load compensation, power factor, power quality (PQ), unbalance, voltage-source inverter (VSI).