Yonghong Kuang

A Time-Scale Adaptive Dispatch Method for Renewable Energy Power Supply Systems on Islands

A salient feature of a renewable energy power supply system (REPSS) on islands is the high level of uncertainties caused by high penetration of volatile power sources, such as wind and solar photovoltaic farms. This creates large forecast errors under some conditions and makes the fixed time-scale dispatch impotent in maintaining system reliability. To tackle this challenge, a time-scale adaptive dispatch method is developed in this paper. The time-scale for dispatch REPSS on islands is adjusted online according to the confidence interval of forecast error predicted by neural network. Extensive tests have validated the effectiveness of the presented method in offsetting the uncertainties in the system and improving the system reliability.

Asynchronous Method for Frequency Regulation by Dispersed Plug-in Electric Vehicles

Abstract: Plug-in electrical vehicles (PEVs) can participate in frequency regulation (FR) in electric power systems under the framework of vehicle-to-grid (V2G) technology. With a growing number of electrical vehicles (EVs), a greater number of distributed electrical vehicle (EV) chargers may change charge or discharge power simultaneously to participate in FR, resulting in over response. In this paper, considering the over-response and equality issues, an asynchronous method for dispersed PEVs participation in FR is proposed. PEVs participate in FR with the same set of parameters. Over-response can be avoided during the process of FR. Equality enables the dispersed PEVs to participate in FR with the same probability. The presented method empowers PEVs to actively participate in FR without a control centre or a communication network. Simulation results demonstrate the validity of the presented method in different operational scenarios.

Influences of EVs on Power System by Improving the Microclimate

The influence of EVs on power system is diverse. A lot of literatures have studied the influence of EVs on power system in the following aspects.

The Asynchronous Response of Small-Scale Charging Facilities to Grid Frequency

The increasing penetration of renewable energy sources, such as wind and solar energy, gives rise to new challenges for the operation and dispatch of power systems [1, 2, 3]. Demand response is an effective ancillary service for power systems [4, 5, 6, 7]. And EV loads can take part in demand response. V2G technology achieves bidirectional power flow between EVs and power systems. Using V2G, the charging EVs can be regarded as not only controllable load, but also distributed energy storage units [8]. FR provided by charging EVs has gained increasing attention [9, 10, 11, 12].

The Response of Large-Scale EV Charging Loads to Frequency

Power system stability is a requirement for the security and economic operation of power system. Many major blackouts are caused by power system instability, which proves the importance of power system stability [1].

The Response of EV Charging Loads to TOU Price

One of the bottlenecks that restrict the rapid growth of EVs is the lack of the EV charging facilities [1, 2, 3, 4, 5]. The model of fuel cell charger is established and a corresponding control strategy is proposed in [3]. A new concept of mobile charger and its optimal scheduling methods are presented in [4]. With incremental development in EV charging facilities, EV loads are expected to increase phenomenally in the near future, which will bring negative impacts on the stability of power grids [6]. EV loads are seldom taken into account in current practice of power system planning, which results in risks in system operations and management [7].

The Response of EV Charging Load to the Grid Voltage

Modern power system is a complicated, nonlinear and dynamic system with large scale. Improving power system stability has always been a hot topic. The problem of power system stability can be classified from different perspectives. In view of the causes of instability, it can generally be divided into angle stability and voltage stability (Vournas et al. in Electr Power Energy Syst 18(8):493–500, 1996 [1]; Ouassima et al. in IEEE Trans Power Syst 14(2): 620–628, 1999 [2]).

Analysis on Typical Schemes of the Integration of EV Charging Facilities into the Grid

EVs can benefit the climate and play an important role in power system. The EV charging facility which provides power supply for EVs running is a necessary and important supporting facility for the development of EVs. Therefore, rational planning and distribution of EV charging facilities is a crucial precondition for large-scale application of EVs [1, 2]. Currently, EV charging facilities mainly include EVCSs and electric vehicle charging piles (EVCPs) [3–5].

EV Charging Facility Planning

EV charging facility provides power supply for EVs running and it is a necessary and important supporting facility for the development of EVs. Therefore, the EV charging facility planning has been studied in many literatures. The basic principles of EV charging mode and EV charging facility are explored in Kang et al. (Power Demand Side Manag 11(5):64–66, 2009 [1]; Xu et al. East China Electric Power 37(10):1678–1682, 2009 [2]).