Voltage regulation and power loss reduction assessment using voltage stability indices in distribution network with static var compensator and distributed generation.

• Main Author: Saleh Taleb Salim Ba-Swaimi
• Format: text::Thesis
• Language: English
• Published: 2023

Voltage stability is necessary in order to maintain the health of the grid system. In recent years, the load demand is increasing from time-to-time which compromised the stability of the system. On that purpose, a common method where power factor correction was fixed by having a compensator connected parallel across the load. In an actual condition, loads may differ from time-to-time and upon its usage in a certain period of time. Having a fixed capacitor is not advisable as the selection may result in an overcompensation of power factor which results in an overvoltage on the load. Moreover, capacitor banks and other switched devices, which are used in traditional voltage regulation and controlling reactive power, are not sufficient to solve the problem of rapid fluctuations of the load accompanying with intermittent nature of distributed generation. Flexible AC Transmission Systems (FACTS) controllers could be a suitable solution in controlling reactive power at the distribution network and regulating the voltage within the operating range. Thus, the deployment of the FACTS device within the distribution network comes into effect in order to maintain the voltage level to be regulated within the index compensating reactive power. Steady-state applications of static var compensator (SVC) to regulate bus voltages within normal acceptable voltage range and minimize both real and reactive losses in active distribution networks are still under study. In a general overview, this study is to propose several power compensation techniques on the base case of the IEEE-33 bus whereby power flow analysis using the Newton-Raphson method in PSS/E software is performed. Subsequently, Distributed Generation (DG) and SVC will be implemented within the distribution network to compensate the voltage instability losses based on the weakest index from the bus system. The comparison of results is performed for four cases which are the base case of the IEEE 33-bus distribution network, the distribution network with SVC only, the distribution network with DG only, and the distribution network with both SVC and DG. The comparison is performed by taking into consideration voltage stability margin (VSM), system voltage deviation, and both real and reactive power losses. The optimal location of SVC and DG are identified using system variable based voltage stability indices. Indices used for the identification of the weakest bus for the placement of SVC and DG are Voltage Stability Index (VS Index), Fast Voltage Stability Index (FVSI), Novel Line Stability Index (NLSI), Line stability factor (LQP), Voltage stability indicator (VS indicator), Voltage Stability Index (Ld), and Line Stability Index (Lmn). The assessment is done on three cases, which are IEEE 33-bus system at base case loading, IEEE 33-bus system with high reactive loading, and IEEE 33-bus system with high real and reactive loading. Fast Voltage Stability Index (FVSI) and Voltage Stability Index (Ld) are found to be the most sensitive indices under all critical loading conditions to locate the best placement for SVC and DG. The integration of SVC and DG in the distribution network demonstrates the effectiveness of this method in regulating the bus voltages within acceptable range besides minimizing the real and reactive power losses.