Xiaodan Gao

Cooperation-Driven Distributed Control Scheme for Large-Scale Wind Farm Active Power Regulation

Being more actively involved in the electricity market and power systems, wind farms are urgently expected to have similar controllable behavior to conventional generations so that demand assigned by the system operator can be met. However, determining the method of dispatching the reference among the widely spread and low-rating wind turbines is difficult. This paper provides a cooperation-driven distributed control scheme for wind farm active power regulation. Instead of competing with neighboring controllers completely, the control strategy evaluates system-wide impacts of local control actions, and aims to achieve coordinated control effect. In addition, the kinetic energy storage potential in a wind turbine is tapped to provide a buffer for power dispatch. Case studies demonstrate that a large wind farm can be effectively controlled to accurately track the demand power through the proposed control scheme.

Coordinated Dispatch of Virtual Energy Storage Systems in LV Grids for Voltage Regulation

The growth in installed solar photovoltaic (PV) capacity and the ever-increasing power demand due to the use of energy-hungry appliances have caused voltage issues. In this paper, a hierarchical dispatch strategy is proposed for coordinating multiple groups of virtual energy storage systems (VESSs), i.e., residential houses with air conditioners, to regulate voltage in low-voltage (LV) grids with high solar PV penetration. Specifically, the two levels of the proposed model are: 1) in the lower level, VESSs within each intelligent residential district are controlled locally by individual aggregator; 2) in the upper level, multiple aggregators are coordinated to achieve voltage regulation through a consensus control strategy. By exchanging information through sparse communication links, each aggregator shares the required active power adjustment among all participating groups, without compromising users’ thermal comfort. Simulation result demonstrates that the proposed control scheme can effectively regulate voltage in LV grids with greater robustness and scalability.

Distributed control of thermostatically controlled loads in distribution network with high penetration of solar PV

High penetration of solar energy can result in voltage rise in midday, while growth in residential air conditioning is the main contributor of overloading and voltage drop issues during peak demand time. This paper provides a hierarchical control scheme to coordinate multiple groups of aggregated thermostatically controlled loads to regulate network loading and voltage in a distribution network. Considering the limited number of messages that can be exchanged in a realistic communication environment, an event-triggered distributed control strategy is proposed in this paper. Through intermittent on and off toggling of air conditioners, the required active power adjustment is shared among participating aggregators to solve the issue. A case study is conducted and simulation results are presented to demonstrate the performance of the proposed control scheme.

Optimal wind turbine and air conditioner loads control in distribution networks through MILP approach

This paper considers two important challenges in the distribution network with high renewable penetrations. One is that during the peak load, generation is normally low or zero and it will cause the voltage drop. Meanwhile, during peak generation period, the generated power will exceed the load and be injected to the grid, which will subsequently cause the voltage rise. This paper proposes a MILP (Mixed Integer Linear Programming) approach to accommodate more wind generation in distribution networks. By coordinating the status of controllable load, battery energy storage system (BESS) and wind power, this paper proposes an optimal scheduling model for the distribution system to minimize the total costs from grid. Rolling optimization and weighting factor were implemented to obtain a good operation strategy under real-time operation. Detailed case studies are conducted to demonstrate the feasibility of the proposed method.

Consensus-driven distributed control of battery energy storage systems for loading management in distribution networks

With the electricity demand growing around the world, overloading is becoming a critical problem needed to be solved in distribution systems. Although renewable-based distributed generation methods are a good option, its intermittency and uncertainty should be addressed. This paper aims to provide an attempt to coordinate battery energy storage systems (BESSs) for loading management in distribution network with solar power energy penetration. Through limited communication, required load shedding is shared among participating BESSs. Communication topology variation is also studied in this research, which proves that communication network is playing a critical role in regulating distributed resources. Simulation results demonstrate the effectiveness of proposed control strategy.

A distributed control for active power curtailment within a wind farm based on ratio consensus algorithms

Power networks with renewable energy always encounter the imbalance between supply and demand. One case is that during the peak load, generation is normally low or zero and other generation plants adjust more to meet with requirement. The other is during peak generation period, the generated power will exceed the load and be injected to the grid, which will cause the voltage rise and extra power curtailment is essential. To solve the latter problem, this paper proposes a ratio consensus based distributed control scheme to dispatch the curtailment power within a wind farm. Detailed distributed control scheme with ratio consensus algorithms is theoretically illustrated. System was developed in MATLAB software. The result of case study on the proposed system demonstrated the effectiveness of the curtailment strategy.