Real-time congestion management in transmission networks

Abstract

The transmission network serves as the backbone of any power system. The possibility of power transportation from generation to consumption is done with the help of the transmission and distribution networks. Though an important part of the power system, transmission networks are prone to many untoward events ranging from faults, congestion, tripping, lightning strikes, etc. To provide uninterrupted and reliable service to the consumers and the producers in a power grid, an independent system operator (ISO) must be highly considerate of the transmission network security. An ample amount of hardware in the form of a protection scheme is deployed in the grid system, ensuring the health and security of transmission system and the associated equipment. The hardware comprises relays, circuit breakers, lightning arresters, etc.This chapter examines one of the undesirable events in the transmission network known as transmission congestion. Traditionally congestion problem is solved once in every 5-30 min using tertiary dispatch. This forces the operators to operate the transmission lines conservatively much below the thermal limits to avoid congestion in between subsequent tertiary dispatches due to changes in loads, generation, and contingencies. However, real-time synchrophasor measurements of line power flows can be used to detect congestion in the smart grid and take appropriate corrective actions in real time. This will allow the lines to operate closer to the thermal limits as any violation of the limits can be resolved in real time. This chapter explains two different approaches for real-time congestion management, first a market-based scheme to encourage the electric vehicles (EVs) participate in the congestion management and then a centralized controller to resolve congestion in lesser time.