Compensation of Voltage Sags with Phase-Jumps through DVR with Minimum VA Rating Using PSO based ANFIS Controller

Compensation of Voltage Sags with Phase-Jumps through DVR with Minimum VA Rating Using PSO based ANFIS Controller

Anil Kumar Ramakuru (IIT MADRAS, India), Siva G. Kumar (IIT MADRAS, India), Kalyan B. Kumar (IIT MADRAS, India) and Mahesh K. Mishra (IIT MADRAS, India)
Copyright: © 2012 |Pages: 15
DOI: 10.4018/978-1-4666-1592-2.ch008
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Abstract

Dynamic Voltage Restorer (DVR) restores the distribution system load voltage to a nominal balanced sinusoidal voltage, when the source voltage has distortions, sag/swell and unbalances. DVR has to inject a required amount of Volt-Amperes (VA) into the system to maintain a nominal balanced sinusoidal voltage at the load. Keeping the cost effectiveness of DVR, it is desirable to have a minimum VA rating of the DVR, for a given system without compromising compensation capability. In this regard, a methodology has been proposed in this work to minimize VA rating of DVR. The optimal angle at which DVR voltage has to be injected in series to the line impedance so as to have minimum VA loading on DVR as well as the removal of phase jumps in the three-phases is computed by the Particle Swarm Optimization (PSO) technique. The proposed method is able to compensate voltage sags with phase jumps by keeping the DVR voltage and power ratings minimum, effectively. The proposed PSO methodology together with adaptive neuro–fuzzy inference system used to make the DVR work online with minimum VA loading. The proposed method has been validated through detailed simulation studies.
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Dynamic Voltage Restorer

A DVR is a power electronic device, connected in series to the feeder, to protect the loads from typical voltage problems in distribution system. The schematic diagram of a series compensated distribution system is shown in Figure 1. In Figure 1, the source voltage is represented by vS. The terms LS and RS represent feeder inductance and resistance. The terminal voltage and load voltage are represented by vt and vl, respectively. The DVR is realized by a voltage source inverter with DC capacitor voltage Vdc and power electronic switches S1, S2, S3, S4. The term Lts represents the leakage inductance of the injection transformer and Cf represents the capacitance of the capacitor filter. The operating principle of the DVR is to inject a voltage (vDVR) of required magnitude and phase to compensate sag/swell and distortion in the terminal voltage (vt) and provide a balanced sinusoidal voltage (vl) at the load. The reference DVR voltage to be injected (vDVR) is realized by switching S1, S2, S3, S4 through hysteresis control (Woodley, Morgan, & Sundaram, 1999).

Figure 1.

Per phase representation of series compensated distribution system

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