Recent developments and advances in energy storage technologies are making the application of energy storage technologies a viable solution to power applications. The energy storage system can store energy previously, and then release it in the proper time. Due to their flexibility, it is suitable to apply this technology to deregulated power markets. Therefore, this paper will build the economic analysis model for the energy storage system to apply to a distribution substation in a deregulated power market. The costs including installing energy storage system and operation and maintenance expense, and the revenues containing energy price arbitrage, reducing transmission access cost, and deferring facility investment are considered in this model. All these factors are evaluated by present worth value. Due to complexity of this problem, this paper proposes a method combining the genetic algorithm with linear program (GALP) to determine the optimal capacity and operations of the energy storage system
With the progress of the storing technology, applications of the energy storage system to the power systems become feasible. Many practical examples described in [1], [2] and [3] are shown below. A large 20 MW/15 min storage facility in Puerto Rico kept the entire island grid stable for several years. An even bigger 27 MW/15 min facility was commissioned in Fairbanks, Alaska, in 2003. A 250 kW/8 h Vanadium Redox Batteries (VRBs) facility was put into service on a long distribution line in Utah. In Wisconsin, a system of six 1 MW/1 s Superconducting Magnetic Energy Storage (SMES) devices was effectively used to inject power into a collapse-prone transmission loop. A number of demonstrations in the 100 kW to 1 MW range have been field-tested with the US Department of Energy’s support and in cooperation with major utilities.
Large scale energy storage systems are gradually popular around the world. These technologies are categorized into three kinds-bulk energy storage, distributed generation, and power quality-with significant variations in discharge time and storage capacity. The SANDIA National Laboratories have launched a series of researches [4], [5], [6], [7] and [8] about their applications to the power systems. In [4], the energy storage technology and life-cycle costs analyses have been performed to give a more complete representation of the comparison between technologies. In [5], it characterizes electric energy storage applications and related benefits. It also describes criteria and a framework for estimating market potential and provides maximum market potential estimations. In [6] and [7], these reports outline a wide range of innovative ways in which storage could be advantageously used in all aspects of the electric supply system of the future. It discusses ways to expand the envelope of possible storage applications and suggests creative uses for storage. In [8], the handbook makes the business case for energy storage on the national and corporate levels and also provides a guide for T&D utilities looking at particular energy storage systems for representative applications in grid stabilization, grid operation support, and load shifting.
In addition to SANDIA, many authors also present applications of the energy storage system. In [9], automatic generation control with interconnected two-area multi-unit all-hydro power system and two more test systems as all-thermal and thermal-hydro mixed have been investigated. To stabilize the system for load disturbance, comparative transient performance of two cases as (a) Thyristor Controlled Phase Shifter installed in series with the tie-line in coordination with Superconducting Magnetic Energy Storage (SMES) and (b) SMES located at each terminal of both areas are analyzed. It is observed that the case (b) suppresses the frequency oscillations more effectively.
In [10], design of control strategy for hybrid fuel cell/energy storage distribution power generation system during voltage sag has been presented. The proposed control strategy allows hybrid distributed generation system works properly when a voltage disturbance occurs in distribution system.
In [11], the authors present the applications of the energy storage system to advanced power applications. In [12], the authors present a methodology to evaluate energy storage installations in distribution substations. This work is based on multiple objective optimization. In [13], this paper investigates the robustness of damping control implemented by the energy storage system to the variations of power system operating conditions. A load-leveling application is proposed in [14], and an application of deferring upgrades on distribution is proposed in [15]. In [16] and [17], the authors present the application of the energy storage system to industrial customers.
In [18], the concept of combining photovoltaic power stations and energy storage systems comprises a promising solution for small scaled autonomous electrical networks, increasing the reliability of the local network as well. According to the calculation results obtained, one may clearly state that an optimum sizing combination of a PV generator along with an appropriate energy storage system may significantly contribute on reducing the electricity generation cost.
Due to the flexibility and progress of the energy storage system, it will play an important role on the operations of power systems. Therefore, this paper will build the economic analysis model for the energy storage system to determine its maximum power level (kW), its energy storage capacity (kWh), and its operation to obtain the maximal benefit.
This paper proposes a mathematic model for analyzing the economic effect of the energy storage system applied to a distribution substation. This model considers the arbitrage of energy prices, reducing transmission access costs, deferring the investment of equipments, costs of the energy storage system, and costs of operation and maintenance. In order to solve this problem, this paper proposes a GALP algorithm to determine the capacity and the best operation of the energy storage system to obtain the best net benefit.
