Saft and ABB have developed the world's first high voltage Li-ion (lithium-ion) battery system designed to improve the stability of power distribution grids. The new system combines dynamic energy storage provided by Saft's 5.2-kV battery, which will help respond to disruptions in the grid, with ABB's SVC (Static Var Compensation) Light technology for dynamic voltage control. Potential applications include industries with high short term power demands as well as utility grids fed by a high percentage of variable renewable energy sources, especially wind power.
The new SVC Light with dynamic energy storage will further extend ABB's FACTS (Flexible AC Transmission Systems) portfolio covering a number of technologies that enhance the security, capacity and flexibility of power transmission and distribution systems, as well as improving productivity and power quality in industrial applications. While current FACTS technology is focused primarily on stabilizing grid voltage, the addition of energy storage now broadens its scope to covering short term load or supply variations.
"The key aim of this project is to demonstrate the feasibility and added value of incorporating Li-ion energy storage within a FACTS system," said Per Eckermark, Head of ABB's FACTS System Group. "It could play a vital role in ensuring the stability of utility grids as the penetration of wind power increases."
Li-ion battery system
Li-ion battery technology offers a number of important features in this application, such as excellent cycling capability, long calendar life, high energy density, very short response time, high power capability both in charge and discharge, and maintenance-free design. Furthermore, Saft's Li-ion technology provides the system with precise information on the state of charge (SOC), which is a vital function in a dynamically operating energy storage system. The battery system comprises eight individual units based on Saft's Intensium Flex modular, rack-mounted Li-ion modules. The units, rated at 646 V and 41 Ah, are connected in series to achieve a nominal voltage of 5.2 kV and the system can deliver 200 kW for an hour and 600 kW for over 15 minutes.
Saft is also supplying the control and management devices for the battery, as well as a CAN-based optical communication interface with ABB's MACH-2 controller that will monitor the battery continuously and optimize its operation.
ABB's SVC Light is a unique power semiconductor technology based on a high power IGBT (Insulated Gate Bipolar Transistor), a compact switching device, which allows high frequency switching. In combination with dynamic energy storage it will enable simultaneous voltage control and control of active power flow in the grid. The 11-kV pilot system can deliver 600 kVAr reactive power and 600 kW active power.
In addition to the development and supply of the battery system, Saft is partnering with ABB in qualification and field testing of the complete system. The battery system has already completed commissioning and bench testing at ABB's facilities in Sweden, where its performance to specification was confirmed.
The next stage, in 2009, is for an SVC Light with dynamic energy storage to be installed in a field application in order to demonstrate its capability under a variety of network conditions, including operation with nearby wind generation.