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Mitigating Downward Reserve Deficiency of Power System via Coordinating EV Demand Response at Valley Period

The high penetration rate of electric vehicles (EVs) will have impacts on the operation of power system in the near future. One of the most significant impacts is the extreme load valley caused by “consistency” in off-grid actions of EVs automatically finishing their charging, which normally occurs at night. The dramatic load reduction at limited period not only leads to security problem of power system due to the deficiency of downward reserve in generation side, but also forces the thermal units to operate in the extremely uneconomical deep peak regulation (DPR) state. To address this issue, a coordinated optimization strategy considering nighttime DPR state of units and uncertain EV demand response (DR) is proposed in this paper. Firstly, unlike traditional studies, a detailed unit commitment (UC) model considering life loss and oil cost is established in this paper. After that, on the basis of elastic pricing method and day-ahead contract, price-based demand response (PDR) and incentive-based demand response (IDR) model are proposed to avoid units operating in the DPR state. The uncertainty of both IDR and PDR progress are considered as a whole in the form of opportunity constrain, and then transformed into deterministic linear constraints for solving by adopting sequence operations. Finally, various cases are simulated in the improved IEEE 30-bus system, the results indicate that the presented coordinated optimization strategy can reduce the units’ operating cost effectively, as well as bring benefits to EV owners.