STATCOM Integration in Weak Power Systems

Several factors have led to weaker grids and a greater need for power quality. These include the rapid spread of distributed generation, multi directional power flows, increased electricity consumption and generation capacity, long distance bulk transmission, and fewer synchronous machines connected to the power systems. Modern power systems experience low fault currents, narrow reserve margins and limited inertia contribution. To face these challenges a Static Synchronous Compensator (STATCOM), one of the most wide spread Flexible Alternating Current Transmission Systems (FACTS), can be involved. The main objective of this thesis is to analyze how the integration of a STATCOM enhances the performance of non stiff power systems. The study examines how the behavior of the system changes according to the placement and the control strategies of the STATCOM in continuous operation and different fault and outage scenarios. A steady-state analysis is conducted in PSS®E to find the main differences existing between strong and weak power systems. Then the focus shifts on the performance of weak grids in different scenarios, such as continuous operation, outage of one transmission line, remote fault and short circuit occurring close to the generation buses. A model of a STATCOM is added to a IEEE 14-bus system in PSCAD to find any improvement for power quality and stability. The Grid Forming (GFM) and the Grid Following (GFL) control strategies are tested. Even if the power system is weak, through the integration of a STATCOM, the reserve margins are wider and the voltage stability is higher in all operating conditions leading to an overall stronger power system. In steady-state, the behavior of the GFM and GFL converters is almost the same. Future works may focus on STATCOM’s performance in different operating conditions, the dynamic behavior of GFM and GFL converters and the interaction of more STATCOMs connected to the same power system to test the overall stability.