Operation and Control of Renewable Energy Systems

Chapter 4Grid-Scale Energy Storage

4.1 Requirement of Energy Storage

The necessity of energy storage in renewable systems is mainly due to the fact that most of the renewable sources of energy such as solar, wind are intermittent in nature. When the renewable energy exceeds 10–30% of the power supply, additional resources are needed to match the fluctuating supply to the already fluctuating load. The main purpose of energy storage device is to store the energy when production is more than the load and return it back to the grid during shortage in production.

Battery or other form of energy storage systems are used to regulate frequency, act as reserve capacity, improve power quality, support voltage and help to reduce peak load. Energy storage system can also be used as emergency power source in long-duration outages [1]. If the cost of energy storage can be reduced substantially, it can bring revolutionary change in the operation and control of energy systems. Storage can be applied at the power plant, in support of the transmission system, in the distribution system and on the customer side.

4.2 Types of Energy Storage Technologies

Electrical energy can be stored in various forms which is suitable for grid-scale energy use. It can be broadly classified as [1–4] the follows:

1. A. Electromechanical Storage
   • Pumped hydro storage
   • Compressed air energy storage
   • Flywheel storage
2. B. Superconducting Magnetic Energy Storage
3. C. Chemical Storage
4. D. Supercapacitors
   • Batteries
5. E. Thermal ...