Considering Maintenance Cost in Unit Commitment Problems

Abstract

Electric power systems worldwide are receiving an increasing volume of wind power generation (WPG) because of environmental concerns and cost declines associated with technological innovation. To manage the uncertainty of WPG, a system operator must commit sufficient conventional generators to provide an appropriate reserve. At times, frequent start and stop operations are applied to certain generators, which incurs maintenance costs associated with thermal-mechanical fatigue. In this paper, we suggest a comprehensive approach to unit commitment (UC) that considers maintenance cost: the parameters of equivalent start (ES) and equivalent base load hours (EBHs) are adopted in the UC problem to determine optimal generation scheduling. A new formulation for the maintenance cost that can be readily combined with an existing mixed integer linear programming algorithm is presented. The effectiveness of the proposed UC method is verified through simulations based on an IEEE 118-bus test system. The simulation results show that considering maintenance cost in the UC problem effectively restricts frequent start and stop operation scheduling. Furthermore, the operating cost is reduced, the required reserve level is maintained, and the computational time is comparable with that of the conventional UC method.

Simulated Annealing, Differential Evolution and Directed Search Methods for Generator Maintenance Scheduling

“…Since, after operation (Equation (10)), the repair moments do not belong to a set of natural numbers {x i N}, the resultant elements of the population matrix must be rounded off to the nearest integer values. The idea behind the initialization of the standard deviation value for the presented probability distribution is that the pseudorandom departure of the repair moment for unit i cannot be greater than half of the duration of the maintenance period for this unit (i.e., 1 2 τ i -three standard deviations for a normal probability distribution, Equation ( 10)). This approach to the initialization of repair moment departures, which directly affects the diversity of the initial set of repair plans, can be changed depending upon the user's assessment.…”

“…The concern regarding the controllability of generating equipment underlines, in turn, the significance of generator maintenance scheduling procedures. These measures can be completed using generating adequacy approaches, being responsible for the assessment of the balance between generated and consumed energy [1][2][3]. For instance, the criterion being widely used in order to estimate the generating adequacy of a power system is expected an energy not supplied (EENS) coefficient [4].…”

Stochastic Unit Commitment Problem, Incorporating Wind Power and an Energy Storage System

“…The production levels of committed units must be found in order to meet the predicted load at a minimum total production cost over a planning horizon, varying from one day to one week. In general, most of the operation costs include start-up costs and shut-down costs [10]. The minimization of the operating costs is affected by several operating constraints, which can lead to a limitation of the search space.…”