Strategy of Hybrid Energy Storage System for Auxiliary frequency modulation Based on Energy Distribution Management

The safety and stable operation of power systems requires more high-quality power regulation resources to be applied in frequency regulation auxiliary service market. Due to the vacancy of rules on reimbursement for battery energy storage system (BESS) alone in China, the combination of thermal power unit and BESS for the AGC frequency regulation gets commercial promotion. So far, the power plants usually use the Lithium Battery as the power resource to carry on AGC service. However, the batter has the weakness of short life and low power density, which produce high maintenance fees. As an alternative energy source, the super capacitors can solve these problems, but it has the weakness of low energy as well. So that it cannot be used as an independent frequency regulation power resource. Therefore, it is worth to find a Control Strategy to combines the advantages of these two power supply resource. Some related cases are studied in the area of vehicles and trains. Up to now, there are few research applied in the power plants have been taken. So in this regard, a control strategy based on energy distribution management about power plants AGC is proposed. This strategy takes full advantages of the high energy density of lithium batteries and the fast response of super capacitors, and improves the regenerative braking energy utilization rate of the system by suppressing the energy exchange.