Intigrating Dstatcom with Photovoltaic Energy Storage System for Power Transient Stability

Abstract

Recently, with the growth of industry manufacturers and population, electric power quality becomes more and more important. The growing amount of power electronics-based equipment has had a profound impact on the quality of electric power supply. Now a day, consumers require high quality power supply for their sensitive loads. Voltage flicker has therefore been an important power quality concern for supply utilities, regulatory agencies and customers. Erratic variation in reactive power demands lead to a fluctuating voltage drops across the impedance of a distribution system which results in voltage fluctuation at the point of common coupling (PCC). Voltage sags are one of the most dominating power quality problem, which has drawn the attention of many researchers as the demand for sensitivity of loads are increasing due to extensive usage of power electronic devices. Fault at distribution level, sudden increase of loads, motor starting are some of the causes of the voltage sags. Such sudden variations of voltage are undesirable for sensitive loads. Traditionally, for mainly inductive supply system, power quality can be improved by using reactive power control methods. These undesirable power quality problems can be mitigated by connecting controlled devices either in series or shunt to the load. A few of such devices are dynamic voltage restorer (DVR) and Distribution Static Compensator (DSTATCOM). Both these devices require voltage source converters to satisfactory operation. Many topologies have been proposed in recent past for voltage source converters in many published literatures. A DSTATCOM is a fast response, solid-state power controller that provides flexible voltage control at the point of coupling (PCC) to the utility distribution feeder for mitigations of power quality improvement. If it is coupled with energy storage system (ESS), it can exchange both active and reactive power with the distribution system by varying the amplitude and phase angle of the converter voltage with respect to the system voltage. The result is a controlled current flow through the interfacing inductance between DSTATCOM and the distribution system. The DSTATCOM can instantaneously compensate voltage sags by regulating the load voltage using the injected current from the converter and the voltage across equivalent inductance. In this work, DSTATCOM has been modeledwithPhotovoltaic Energy Storage System and simulated in MATLAB/SIMULINK environment for improving the power quality of distribution systems with linear loads and static non-linear loads and the results are discussed.