Wind Power Ramp Control With Energy Storage System

The uncertainty and fluctuations of high penetration wind power challenge the power system operation and stability, especially the impact of rapid wind power ramp events on power balance and frequency stability in power systems. A method of wind power ramp control with energy storage system (ESS) is proposed in this paper, including optimization of wind power ramp limitation in power, wind power ramp control with ESS in wind farm and energy management in ESS. Major outcomes of this research work include:1) The impact of wind power integration with different ramp limitations on power system frequency stability is analyzed with a power system frequency simuliation model. Then a dynamic optimization is proposed to optimize the wind power ramp limitation according to the operation condition of power system and wind power. The dynamic wind power limitation make a relation between wind power ramp control and power system operation. The proposed strategy can avoid the off-limit of frequecny and minimize the economic cost of wind farm to meet it.2) According to the technical requirement of wind power ramp control during different ramp event, a ramp event forecast based wind power ramp control strategy with ESS is proposed to minimize the required ESS power and capacity. A linear programming (LP) model is established to optimize the output power of ESS and the wind curtailment to meet a hybrid wind power ramp limit. Three types of wind power ramp scenarios are presented based on wind pwer ramp event forecast and a scenario switching adjustment (SSA) with fuzzy logic systems (FLS) is designed to reduce the capacity demand of ESS and the curtailed wind energy.3) A power allocation control strategy is proposed to optimize the power instructions allocation in multi-unit battery energy storage system (BESS). A mixed-integer quadratic programming (MIQP) model is established to maximize the charge/discharge capability of BESS and avoid overcharging and overdischarging. Two types of charge/discharge switching constraints are presentd to reduce the number of charge/discharge cycles, which can prolong the operational lifetime of the BESS.Firstly, the dynamic wind power ramp limitation is updated and delivered to wind farm according to the analysis of operation condition in power system. Then the power order of whole ESS is optimized based on the wind power ramp event forecast, realtime wind power and ESS energy state in wind farm. Finnaly, the power order of each storage unit is calculated on the basis of the energy state and charge/discharge state of storage units. The energy state of whole ESS is transfer to wind farm ramp controller as a feedback signal. Power system, wind farm and storage system are coordinated to realize optimal wind power ramp control with connection signals as ramp limitation, power order of ESS and energy state of ESS.The IEEE Reliability Test System (IEEE RTS) and real wind power data from National Wind and Solar Energy Storage and Transmission Demonstration Project in China are used to verify the effectiveness of proposed wind power ramp control method.