Security-constrained unit commitment with wind generation and compressed air energy storage

Abstract

Wind power is one of the fastest growing renewable sources of generation in the U.S. and many other countries. As wind-generated electricity continues to grow, electric utilities increasingly grapple with the challenges of connecting that power to the grid although maintaining system security. It is difficult to predict and control the output of wind generation because of wind intermittency and a reserve capacity is required to deal with inherent uncertainty. This study presents an approach for securityconstrained unit commitment (SCUC) with integration of an energy storage system (ESS) and wind generation. Compressed air energy storage (CAES) is considered as an alternative solution to store energy. For economical operation and control purposes, utilities with CAES are interested in the availability and the dispatch of CAES on an hourly basis, given the specific characteristics of CAES. The main contribution of this study is the development of enhanced SCUC formulation and solution techniques with wind power, CAES and multiple constraints including fuel and emission limit. Proposed approach allows simultaneous optimisation of the energy and the ancillary services (AS). Case studies with eight-bus and 118-bus systems are presented to validate the proposed model. This study also contributes by conducting comprehensive studies to analyse the impact of CAES system on locational pricing, economics, peak-load shaving, transmission congestion management, wind curtailment and environmental perspective.

On the management of wind power intermittency

“…WDHS systems are defined as any autonomous electric energy generating units in which WTGs associated with Diesel Generators (DG) are employed together to maximize the contribution by the intermittent wind power production to the total generated power while producing continuous power of high quality [133][134][135]. The main purpose of employing such system is to reduce the operation cost while decreasing the fossil fuels consumption and their negative impacts on the environment.…”

“…In CAES systems, energy is stored in a pressure gradient (the amount of charge in a pressure occurring over a fixed distance at a fixed altitude) between ambient air and an underground carven [143]. One of most significant issues with CAESs is their efficiency which is three times more than a simple gas turbine [133].…”

“…This system is independently used for a wind farm in which the profits obtained through spot and reserve markets are maximized. A security constrained unit commitment method is proposed in [133] using ESSs and wind power generation. CAES has been taken into consideration as an alternative for ESS.…”

Wind-CSP short-term coordination by MILP approach

“…Moreover, wind power variability poses problems for system stability, affecting unit commitment decisions, leading to either overcommitment of unneeded reserves, augmenting costs, or undercommitment, decreasing power grid security. So, wind power is to be curtailed [4] and one of the reasons for curtailment is the congestion situations recurrent stressing the lines [5]. Improvements on the use of the existing lines and mitigation on the costs of integrating wind power into power grid, reducing the uncertainty in the power output, requires a coordination between wind power with other energy sources.…”

“…Several coordination schemes and optimization approaches for short-term scheduling have been investigated, for instances: a wind-thermal coordination scheduling via simulated annealing unveiled an improvement of smoothing the active power fluctuations [6]; a wind-thermal coordination via mixed-integer linear programming (MILP) unveiled a reduction of the uncertainty in wind power output [7]; a coordination of wind power with compressed air energy storage unveiled an improvement due to the synergies between wind power and compressed air energy storage [5]. Also, schemes based on the coordination of wind and hydro power, specially pumped-storage hydro power plants [8,9], unveiled an improvement on minimization of curtailment, energy imbalance and dispatchability.…”