Flexibility and their role in capacity and congestion management

Abstract

The energy market transition from a regulated power market to a deregulated power market ensures a more liberalized approach toward energy trade as it allows small and medium independent power trading entities to share the market. This provides a competitive environment in the energy market, and market forces also come into action to ensure the balance of the market. With all these advantages, deregulating the market also increases the power system complexity, as new participants are less concerned about the power system planning and more biased towards their profit maximization. One of the major problems faced by power systems in a deregulated model is congestion during power flow. Multiple participants of the market commit to supply energy to the consumers, but the flow of this energy needs transmission capacity. In the case of a power transmission system working near its capacity, it will have less room for newer electricity flow commitment, thus leading to a violation of thermal and voltage constraints in case of increased power flow. This kind of situation means that transmission is suffering from congestion and it is not flexible enough to handle the increased power flow to quench further electricity demand.

By upgrading the system transmission capacity, the system can become more flexible in terms of increased power flow but the investment cost for this is very high, and it is economically not feasible. Traditionally used load shedding technique is also not a solution as it brings down power system reliability. In this study, various ways to mitigate congestion are discussed. This study aims to manage the deregulated power market while prioritizing system reliability and security. The thesis suggests the inclusion of Renewable Energy Sources (RES) in congested systems to fulfill the locational demand causing transmission congestion. The reactive power needed by the system, such as in industrial zones, due to penetration of reactive components, the reactive power supply is ensured via local Flexible Alternating Current Transmission Systems (FACTs) devices. The sizing and placement of these devices are discussed. The study also discusses a backup system where consumers can take part by selling their backup energy in the market during congestion mitigation operation. These techniques are implemented on IEEE standard bus systems to observe congestion management and to increase the flexibility of the power system.