Analysing the integration of different types of energy and reserve providers in a competitive electricity supply market
Toh, Guen Keng
Date of Issue2013
School of Electrical and Electronic Engineering
Deregulation of the electric power industry has unbundled a single electric power entity into separate business entities in the past two decades in many developed countries. The introduction of competition in the electricity market allows generation plants of different types, inclusive of renewable energy, and demand side management (DSM) to offer their energy and reserve. The main objectives of this new electric power industry are to reduce the cost that the consumers have to pay for electricity and to alleviate damage on the environment from electric power production. The choice of fundamental energy resources for generation has become an important factor in energy planning, since their availabilities and cost of extraction have a direct effect on the selection of generation types for electricity generation to achieve the objectives of the new electric power industry. The operating characteristic of these generation types is another factor that will influence the overall operating efficiency of the electric power system. In this thesis, a 10-mintue operating reserve requirement (ORR) scheduling which integrates the probabilistic approach into the Unit Commitment (UC) function via a deterministic reserve criterion is presented to determine the reserve. The UC problem is modelled by Mixed Integer Programming (MIP) which is coded using General Algebraic Modelling System (GAMS) and is solved by the solver CPEX 10.2. The impact of demand side participation for reserve offering in the electricity market is analysed. The issues, on how the interruptible loads (ILs) may influence and affect the electricity market, and power system economic and reliability, are addressed. A penalty cost is imposed on IL service providers who are responsible for the maintenance of under-frequency relays and circuit breakers connected to ILs. This thesis also presents how the incorporation of ILs will affect the system EENS. Improving in technology and manufacturing process of turbine construction has caused an investment switch from conventional large thermal units to small gas turbine units. These gas turbines, such as open cycle gas turbines (OCGTs), a type of rapid-start units, have a short start up time and a high ramp rate. They are called upon to serve during plant outages and system contingencies. However, these OCGTs have poor starting reliability, which is undesirable in energy scheduling and reserve allocation. In this thesis, a joint probability distribution approach is proposed to incorporate the starting reliability into the operating reliability of the rapid-start units. A methodology for modelling the rapid-start units and for considering the start up time needed for non-spinning reserve contribution is presented. The expected energy not served (EENS) terms computed from different energy and reserve providers are then pictorially presented. The EENS diagram provides a better understanding on the un-served energy caused by different providers. A penalty calculation scheme which penalises rapid-start units which fail to start up for reserve contribution is proposed. The importance of modelling the rapid-start units with starting reliability in the UC problem is illustrated. Hydro units, a type of rapid-start generator, are examined. In this study, constraints such as cascaded plants, reservoir contents and spillage, etc, which are environmentally dependent are modelled in the UC problem. In addition, conventional thermal units are incorporated in the study to examine the combined effect of the hydro and thermal generating system on reliability and economics, as well as the reserve procured at a specific reliability level. A methodology is then proposed to integrate the forecast errors of the uncertain wind energy production due to sporadic wind flow, and the fluctuation of system demand in the formulation of EENS. The system reserve is then determined via the UC problem to optimise the system total energy, reserve and EENS costs. The availability of the wind turbine is modelled in the thesis. Variations of wind energy penetration for different load levels are performed in order to delve into the reserve requirement study for the wind turbine system. Finally, generation mix is considered to investigate the electric power system reliability and economics with different source providers. The proposed methodologies and results obtained in this thesis can be used by generation companies (Gencos) for effective resources planning through understanding on how to maximise their profits. At the same time, the developed software can serve as a useful tool for independent system operator (ISOs) to deploy energy/reserve providers more efficiently in the electric power system. The operating characteristic of each energy/reserve provider will influence the energy scheduling and reserve allocation shares in the electricity market.
DRNTU::Engineering::Electrical and electronic engineering::Electric power::Production, transmission and distribution