| Ancillary services (AS) can be generically defined as all those services needed by power systems to support their basic energy and transmission services and to maintain reliable and secure operations. They have existed since the beginning of electricity supply and, with the old vertically integrated utility structure, AS used to be incorporated into the normal operation and management of the power system. Only recently, the process of creating a deregulated competitive electricity market has brought along the need to separate the different functions of an electrical supply system and this has given AS a new independent and fundamental role.; One of the major issues related to AS is to understand if and how they are suitable for free market trading. In this thesis the attention is focused on two of these services: load following and voltage control/reactive power management.; A model for the decentralized provision of load following through bilateral contract directly between supplier and customer is proposed and developed. The feasibility of such a bilateral market is demonstrated. This bilateral market can easily coexist with any other form of provision for regulation, load following, and frequency control.; An automatic voltage control to dynamically manage the reactive power available in a specific region is shown to be feasible. Such an automatic voltage control is analogous to the Automatic Generation Control (AGC). Thus, a local market to provide voltage control/reactive power service in a certain geographic region, called Voltage Control Area (VCA), can be developed. Investigations on how a competitive market for this ancillary service might operate and what it might look like are also conducted. |
