Real -Time Hardware-In-The-Loop Simulation of Transmission Capacitor Banks For System Protection Training

As the modern electrical grid experiences increased loading, reactive power devices are becoming more critical to its efficient operation. Capacitor banks play a vital role in this by providing reactive power compensation. Dominion Energy’s shunt capacitor banks regulate voltage, improve the power factor correction, increase power flow capability, and reduce system losses. Capacitor banks provide VARs during periods of high load; so, it is important that when these devices trip, any problems are resolved quickly. To maintain the effectiveness of the capacitor banks, it is essential to monitor their performance. This has become more crucial when considering the historical performance of these devices. Over the past 10 years there have been a significant number of events involving capacitor banks within the Energy Transmission system. These events were due to capacitor can failures, animal contact, and sensing equipment failure. To ensure proper operation and isolate the fault, microprocessor relays conducted voltage-differential protection. The voltage-differential scheme compared the bus voltage with the tap point voltage of the capacitor bank to detect failures. Failures in the grid can lead to significant disruption. Given the frequency and variety of these incidents, a more robust and realistic approach to fault analysis has become essential. Using a real-time system simulator, Dominion Energy has developed a model of a standard transmission capacitor bank for training purposes. This model enables instructors to replicate a wide variety of field scenarios during system protection courses. The training is designed to teach engineers and technicians how to properly commission a capacitor bank. Additionally, it allows students the opportunity to observe, in real-time, how protective relays respond during capacitor failure events. It incorporates two voltage-differential protection relays, multiple amplifiers, and a circuit breaker simulator. During the training, students can adjust the relay settings to balance out the voltage differential. This model also simulates the shorting of a single can unit within the capacitor bank, allowing students to observe its impact on the system voltage. Using hardware-in-the-loop (HIL) simulations, this event was recreated by sending amplified voltage and current signals from the model to the relays. Overall, the development and implementation of these simulations have enhanced the training program. By providing a realistic and controlled environment, technicians and engineers can test different settings and replicate field scenarios, including rare and complex events. As the grid continues to evolve and face increasing demands, innovative training tools will play a crucial role in maintaining system reliability and performance. Exposing students to realistic case scenarios early on will reduce human performance errors in the field.