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The precise prediction of changes in load flows, currents and voltage magnitudes due to changes in power is important for forecasting and managing grid congestions, voltage deviations and minimizing grid losses for example. This paper describes three different methods and further variants of those for state prediction and compares their approximations, neglects and quality of prediction. Since PTDFs...
Large-scale wind power centralized integration is the major way of wind energy utilization in China. With the increasing scale of wind power integration, voltage security and active power loss of wind farms can't be ignored, thus it is essential to realize economical operation inside wind farms in security. Considering the typical radial feeder network inside wind farms, this paper introduce the DistFlow...
A ferroresonace circuit consists of a voltage source, a capacitor and a nonlinear inductor connected in series. The initial flux in transformer core plays an important role on the onset of different types of ferroresonance modes. In this paper, the likelihood of the onset of sustained fundamental mode ferroresonance under the influence of the initial flux is investigated. The flux linkage, the voltages...
Set up a model of typical minimum ac/dc system. From the electrical distance and the phase difference of steady state between fault point and converter bus to research the spatial characteristics of HVDC commutation failure. Simulation results show that under the condition of invariable system support strength, the electrical distance between fault point and the converter bus is the main factor affecting...
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...
In this paper, common DC-fault detection methods have been reviewed. Effects of two line-to-line and line-to-ground fault types from various fault locations to operation of the DC system are presented. In addition, operation principle, strong and weak points of four main types of protection devices (including fuses, no-fuse circuit breakers, power-electronic protection devices and protective relays)...
Transmission switching as a powerful tool is utilized to change network topology during operations which, in turn, would lead to higher economic benefits of a power system. However, network reconfiguration includes a chain of time sequencing switching actions which can bring disturbances into systems. This paper proposes a model addresses the process of transmission switching. The objective is to...
This paper proposed an effective method based on Cuckoo Search Algorithm (CSA) to identify the optimal configuration of distribution network with the interconnection of photovoltaic (PV) system. The main objective is to reduce the power loss in the system by using reconfiguration technique. The proposed method is tested on 33 bus system and then verified with Particle Swarm Optimization (PSO). The...
Photovoltaic generation access to distribution network will cause voltage disturbance even beyond limits because of its variability and intermittency. Energy storage can effectively suppress the influence of PV on voltage and improve voltage quality. Voltage quality, the intuitive and practical indicator, is proposed in this paper to analyze the energy storage demand of distribution network with photovoltaic...
The development of smart distribution grid is an important part of the construction of the smart grid. The study of the distribution network evaluation system helps to find out the problems of the development of distribution network and thus plays an important role in distribution network planning. With research of the distribution network of Wuhan, this article considers the characteristics of smart...
Multi-type generators peaking problem has always been difficult to the researchers, since there are different generator models and complex constraints. In this paper, a decoupled multi-generator peaking model is proposed and used for control strategies. Also, the peaking control strategies are acquired through quantitative calculation and qualitative analysis. Quantitative calculation gives the output...
This paper presents a new impedance-based fault distance calculation formulation for power distribution systems. The majority of low- or medium- voltage distribution systems are characterized by having numerous branches, laterals and sub-laterals, highly unbalanced operation, and time varying load profile. All of these and other characteristics make most efficient approaches proposed for fault location...
The power grid in China has a series of problems of aged infrastructure, lack of resources and increased energy demand. The construction of smart grid is an important way to solve the above problems. The energy management and optimal adjustment in distributed power grid is the key for the system function realization, and several issues should be addressed: 1) How to effectively manage the uncertainties...
As an important part of the new energy industry, electric vehicle (EV) is attracting widespread attention all around the world. To make the EV charge-swap stations meet the growing demand for charge-swap service, this paper proposes a multi-objective optimization model, considering the investment of the service providers and the service capacity. Besides, a case study, based on a certain city's real...
Efficient and reliable islanding detection method is essential for the grid-connected photovoltaic systems. In spite of a high detection efficiency, the active frequency drift (AFD) method cannot identify the islanding in the case of power matching and is limited by the amount of total harmonic distortion (THD) injected into the grid. To cope with the above problems, a novel composite islanding detection...
Uncertainty of renewable energy systems, namely Photovoltaic (PV) systems, and limitation of battery power charging and discharging are crucial issues for designing and managing battery storage systems of stand-alone renewable energy systems. The paper proposes the Decentralized Battery Energy Management (DBEM) method by separating string battery groups, for minimizing loss of power supply, cost of...
The negative interaction between AC and DC voltage controls of the static synchronous compensator (STATCOM) has attracted much attention, and new control models and strategies need to be developed. This paper proposes a new solution based on differential game theory to solve the negative interaction problem between AC voltage controller and DC voltage controller in the STATCOM. The types of differential...
This paper proposes an application framework to reinforce the existing process for ontology-based transformer fault diagnosis with formal probabilistic semantics using the Bayesian Network. This framework allows users to quantify a certain fault with Bayesian Network, based on the knowledge embedded in a transformer ontology regarding relationships of faults and their features such as causes, symptoms...
Based upon the analysis of the mechanism of power loss and voltage drop in distribution system, a new automatic control method of reactive compensation, namely, Feeder Power Factor Assessment (FPFA) is proposed in this paper. Promising that the voltage of all nodes is qualified, the proposed method aims at keeping the power factor of feeders between 0.98 and 1.0 in lagging, so that the reactive power...
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