Author : Sujin P. R, T. Ruban Deva Prakash, L. Padma Suresh

Electric power quality broadly refers to maintaining a near sinusoidal bus voltage at rated magnitude and frequency. Due to the advancement and proliferation of information technology and the widespread use of power electronic devices in recent years, utilities’ customers in various industrial fields are suffering economic losses from short interruptions and voltage flickers. The FACTS devices like SVC’s, STATCOM, UPFC and DVR have been able to solve the voltage flicker problems by rapidly controlling the reactive power. In the case of two different sensitive loads in an industrial park fed from two different feeders with different voltage levels, protection from voltage flicker can be done by two DVRs having common dc link called IDVR. But in case when the lines are connected with same grid substation and feeding two different sensitive loads in an industrial park, voltage flicker in one line affects the voltage profile of other lines. Under the above circumstances, voltage flicker cannot be mitigated by IDVR due to insufficient energy storage in dc-link. This paper proposes a voltage flicker compensator based on generalized unified power flow controller (GUPFC), which comprises of three voltage-sourced converter modules sharing a common dc link. Two voltage-sourced converter modules connected in series with the lines, compensate voltage flicker and a third shunt converter module maintains bus voltage and replenishes the common dc-link energy storage. The control strategy for power flow control of shunt converter and flicker compensation control of series converters are derived. This work evaluates the performance of the above compensating device with the proposed algorithm called two neuron control algorithm for simultaneous flicker compensation and replenishing dc bus energy. This algorithm uses the simplest pre-sag supply voltage boosting technique. Besides, a self-charging technique is used which maintains the dc capacitor voltage at the desired level. Since the controls do not include any parameter which is dependent on network condition, the performance of such controller is robust with respect to network structure, flicker location and system loading. The control structure is decentralized and does not need any coordination with other compensating devices. The structure of proposed algorithm is easy to understand, easy to implement and attractive from a view-point of engineering. The model is simulated in MATLAB/SIMULINK platform and GUPFC controller’s performance is evaluated. Numerical simulation proved the effectiveness of the GUPFC with two neuron model in compensating voltage flicker.

Keywords: Voltage flicker, power quality, Two neuron control algorithm, generalized unified power flow controller (GUPFC), self-charging technique.

Article published in International Journal of Current  Engineering  and Technology, Vol.2,No.2 (June 2012)