Two case-study reports are presented here. The first describes metal oxide varistor (MOV) arresters used by electric utilities to protect transmission and distribution equipment against transient overvoltages in power systems with rated voltages through 345 kV [22]. The second describes the presently installed capacity of wind generation in North America and the impacts of wind generation on operations. Some Independent System Operators (ISOs) have developed wind-forecasting tools for real-time and day-ahead forecasts to help in determining the impact of variable wind-generation resources on dispatch requirements and in establishing market prices for reliable and economic system operation. As the amount of wind generation installed in power grids increases, the occurrence of large and rapid changes in wind-power production is becoming a significant grid management issue [23].
CASE STUDY QUEST IONS
A. Why are circuit breakers and fuses ineffective in protecting against transient overvoltages due to lightning and switching surges?
B. Where are surge arresters located in power systems?
C. How does one select a surge arrester to protect specific equipment?
D. Which states in the U.S. have more than 1,000 MW of installed wind generation?
E. What are the positive impacts of wind generation on the reliability of power system grids? What are the negative impacts?