Weijia Liu

Decentralized Short-Term Voltage Control in Active Power Distribution Systems

With increasing utilizations of distributed energy resources and smart energy apparatuses, power distribution systems are undergoing a transition from passive to active networks, which challenges distribution system operators in many aspects of energy management and system control. In this paper, a short-term control strategy for active power distribution systems is proposed to regulate voltages into statutory ranges. The voltage control strategy is modeled as a convex optimization problem by applying a second-order cone relaxation. After the network decomposition, the alternating direction method of multipliers is employed to solve the established optimization model in a decentralized mode. Finally, the IEEE 33-bus and 123-bus test systems are employed to demonstrate the performance of the proposed voltage control strategy in active power distribution systems.

A bargaining model for electric vehicle aggregators and power system dispatchers

The controllable charging/discharging load of electric vehicles (EVs) is believed to be one of the most promising resources for flexible dispatching in the future smart grid. Power system operation could benefit from the reasonable control of EV charging behaviors. On the other hand, EV aggregators should be given some economic incentives for participating in power system optimal dispatching. In this paper, a bargaining mechanism is proposed to work out the reasonable economic compensation for EV aggregators. First, EV charging behaviors and the model for EV aggregators are presented. Secondly, the day-ahead system dispatch is addressed and the dispatching model considering the willingness and capabilities of EV charging loads presented. The bargaining strategies for both the EV aggregators and the power system dispatchers are next investigated. Finally, the proposed bargaining strategies and procedure are demonstrated through a modified IEEE 30-bus test system.