Capacitor Only SVC Voltage Control Algorithm

Executive Summary In addition to the research and experimentation need to understand the basic control features of an SVC, much effort was also expended on learning the Matlab simulation software. While the Matlab SimPowerSystems and Simulink libraries contain many easily recognizable built-in control blocks, learning how each block worked required careful study and much experimentation. Even the simple " scope " Simulink block required experimentation to affectively use this tool that was needed to develop our controller. Unfamiliarity with the Matlab simulation software coupled with minimal understanding of SVC control methods resulted in various, and sometimes unnecessarily intricate, versions of our TSC only SVC controller. Our final version surprisingly mimics the published examples of SVC controllers consisting of a voltage control block feeding into a TSC selector block. For our version of an SVC controller, the user selectable parameters were entered at the voltage control block and consisted of a reference voltage, and desired bandwidth. Given the actual bus voltage, the voltage control block outputs a Q required signal which is fed into our " B-selector " block. The B-selector activates or deactivates the individual TSC branches based on the Q required. To test the controller, a basic primary system was designed consisting of a 3-phase voltage source and 3-phase dynamic load. The voltage source and associated parameters were selected to represent a major transmission node with many connected transmission paths and no local generation available for voltage control. The loading of the bus was simulated using a dynamic load model. A dynamic load model was selected to better mimic real world system load. Unlike a static RL load, a dynamic load can be configured to mimic the constant power demands of induction machines. To this basic system was added fixed resistors which were energized using time controlled CB's. The CB's were timed to turn on the associated loads at somewhat variable time increments to study the response of the SVC controller to changes in the bus voltage. In summary, the control system needed to turn on and off the TSC branches are simple but effective. In our testing, two basic system conditions were used, strong and weak, to expose our controller design to varying conditions. Without the SVC, the bus voltage dipped to as low as 82% when exposed to our test conditions but never dipped below 95% or above 103% with the SVC controller active.