Capacity Allocation of Multi-time Scale Energy Storage Improving Power System Flexibility under High Penetration Renewable Energy

The carbon dioxide emission peak and neutralize policy proposed by the government of China requires an ever- increasing development scale of renewable energy such as wind and photovoltaic units since the traditional fossil fuel is responsible for carbon dioxide emission when generating electricity. The new-type power system was also put forward to reduce the non-fossil energy consumption proportion. With the rapid development of wind and photovoltaic units in the power system, flexibility has gradually become an important issue on account of renewable energy curtailment under high wind and photovoltaic penetration rate. When the wind and photovoltaic penetration is reaching into some level, the short-time flexibility of the power system is no longer adapted, which leads to massive renewable energy curtailment. Multi-time Scale Energy Storage is introduced into the power system to promote flexibility on both short-time and long-time scale with high penetration renewable energy development. The study provides a multi-time scale energy storage capacity allocation method. Firstly, a wind and photovoltaic energy curtailment configuration method in the actual operation conditions is proposed. Secondly, the power system flexibility demand is established considering the renewable energy curtailment simulation result using the configuration method mentioned above. Finally, on account of economic factors, a capacity allocation method of multi-scale energy storage improving power system flexibility is presented and case study is also proposed to prove renewable energy utilization improvement and curtailment decrement.