Assessing the Operational Flexibility in Power Systems with Energy Storage Integration

Abstract

Increased level of flexibility is essential in power systems with high penetration of renewable energy sources in order to maintain the balance between the demand and generation. Actually, the flexibility provided by energy storage systems and flexible conventional resources (i.e., generating units) can play a vital role in the compensation of the renewable energy sources variability. In this paper, the flexibility of the conventional generating units is quantified and incorporated in a unit commitment model in order to evaluate the impact of different system flexibility levels on the optimal generation dispatch and on the operational cost of the power system. An emerging flexible option such as the battery storage is included in the unit commitment formulation, evaluating the flexibility contribution of the storage and its effect on the system operational cost. In this paper, the flexibility of a real power system is assessed while the unit commitment problem is formulated as a mixed-integer linear program. The results show that the integration of a storage unit in the power generation portfolio provides a significant amount of flexibility and reduces the system operational cost due to the peak shaving and valley filling.

Enhancement of Power System Flexibility and Operating Cost Reduction Using a BESS

“…In this work, the unit commitment problem is formulated as a mixed-integer linear program (MILP) along an arbitrary time horizon , with one-hour time intervals [3]. The quadratic cost function of the generating units is approximated by a piece-wise linear function in order to use the MILP technique to solve the problem.…”

“…In such cases, the increasing capacity of RES and the fact that most of the flexibility resources are scheduled to be installed in a long-term planning scheme might lead to a system flexibility shortage. In this sense, an energy storage system (ESS) could be a viable solution for the provision of flexibility since it is easily integrated into a power system and it is a quite flexible power source [3], [4]. Furthermore, the deployment of BESS could reduce GHG emissions and the system's operating cost since it increases the RES penetration (by avoiding the need for curtailments), while it leads to more efficient operation of the thermal units.…”

“…Furthermore, the flexibility provided through the ESSs receives increasing attention lately. The minimum required flexibility is guaranteed by using the CFM as a UC constraint in [3], where a BESS is deployed for 48 hours in the power system of Cyprus. In [6], compressed air energy storage is evaluated as a flexibility resource over a 24-hour horizon on a test system.…”

“…In [1], an economic dispatch (ED) method, taking into account emission tax and utilizing BESS is proposed and evaluated on a simplified power system. The UC problem constrained by the CFM is solved for two days and the economic benefit is evaluated in [3]. The RES penetration and operating cost are considered in [4], where a BESS is employed in a small island's power system.…”

“…In this paper, an optimal operating strategy for a power system with high RES capacity and a BESS is considered. A UC and ED model [3] is employed for planning the optimal set of generators, aiming at reducing the operating cost, while several BESS capacities are considered to evaluate their impact on the cost and CO2 emissions. Further, the system capability to accommodate RES, when a BESS is employed, is evaluated under several RES penetration scenarios.…”