Yang Fu

Optimal DG penetration rate planning based on S-OPF in active distribution network

Active distribution network (ADN) is an indispensable content of smart distribution network under smart grid framework. On the basis of integration modes study, an economy optimal model of DG integration from a DSO perspective is proposed and three DG integration indexes are defined, respectively, integration ratio, GC ratio and adjustable power factor. The hourly sequential model is adopted to simulate load and DG uncertainties and a method of DG optimal integration based on stochastic optimal power flow (S-OPF) is presented. According to different integration modes, the principle of initialization and conversion of DG bus type in optimal power flow calculation is discussed. Monte Carlo Simulation aiming to get expected value and variance of network parameter precisely is used in stochastic power flow. Combining actual connection mode of Shanghai distribution network, a Shanghai 48 bus test system is built for ADN research. The influence of integration indexes on economy in two scenarios is analyzed and some useful conclusions are achieved.

Optimal Capacity-Load-Ratio Research of the Multi-Voltage Distribution Network

The optimal capacity-load-ratio has great significance to the distribution network’s planning. It’s an important technical indicator of Transforming Capacity Adequacy. In this paper, optimal capacity-load-ratio of multi-voltage distribution network is researched. The cost of construction and operation of distribution network is set as the optimization objective and the reserve life of substation is considered as an optimization variable. The impacts of distributed load factor, the safety operation index, the average power factor of transformer and reserve coefficient of load development are all analyzed. In optimization objective, the construction costs, maintenance cost, energy consumption cost, resource consumption cost and residual value are considered respectively. Finally, a local distribution network in the area of East China is taken as the simulation example and the optimal capacity-load-ratio of this distribution network is calculated. The simulation result verifies the effectiveness of the model established in the paper for distribution network planning.

Spatial Load Forecasting of Distribution Network Based on Intuitionistic Fuzzy Entropy and Fuzzy Clustering

Load density index method is one of widely used spatial load forecasting techniques in distribution planning. The determination of load density is a key task for this method. In order to overcome the drawback of traditional method which adopts analogy method to obtain load density and is hard to meet the demand of precision, a new approach based on intuitionistic fuzzy entropy and fuzzy clustering is proposed. The fuzzy clustering analysis is adopted to classify the set of load density and impacting factors into several grades. Then the intuitionistic fuzzy theory is utilized to describe the uncertainty that would appear in the load density selection. According to the intuitionistic fuzzy entropy the grade of load density can be selected, and the load density interval is available by the fuzzy clustering from the grade selected. An example is used to demonstrate the validity of the proposed method.

Study on Offshore Wind Farm Maintenance Strategies Optimization

With the harsh maritime environment, the accessibility of the site leads to the high cost directly. The cost on Operation & Maintenance for offshore wind farm is about twice of equivalent onshore wind farms. Consequently the study on the maintenance strategies is necessary. The objective of this work is to optimize the offshore wind farm maintenance strategies by network planning method, to minimize the total cost, by considing the effect of several factors, such as weather, boat availability, the location of the wind farm and ect.

Wind Power Short-Term Prediction Method Based on Multivariable Mutual Information and Phase Space Reconstruction

Wind power is influenced by multivariable, which usually shows complex nonlinear dynamics. Therefore the wind power is hardly described and traced by single variable prediction model; the precision of which decreases while it contains uncorrelated or redundant variables. The approach is proposed to reconstruct the phase space of multivariable time series and then predicate wind power. First, the delay time of single variable time series is selected by mutual information entropy, and then the embedding dimension of phase space is extended by the false nearest neighborhood method, which can eliminate the redundancy of reconstructed phase space from low space to high space. Then, the vector is utilized as input to predicate the wind power using the radial basis function neural network. Simulation of wind predication of Shanghai wind farms, show that the proposed method can describe the nonlinear system by less variables, and improve the precision and sensitivity of prediction.

Optimal DG Integration in Active Distribution Network Based on S-OPF

Active distribution network (ADN) is an indispensable content of smart distribution network under smart grid framework. On the basis of integration modes study, an economy optimal model of DG integration from a DSO perspective is proposed and two DG integration indexes are defined, respectively, integration ratio and GC ratio. The hourly sequential model is adopted to simulate load and DG uncertainties and a method of DG optimal integration based on stochastic optimal power flow(S-OPF) is presented. Monte Carlo Simulation aiming to get expected value and variance of network parameter precisely is used in stochastic power flow. The influence of integration indexes on economy in two scenarios is analyzed and some useful conclusions are achieved.

Study on Stability Improvement of Wind Farm Integrated to Weak Grid by VSC-HVDC

Reactive and active power variation of large scale wind farms always lead to the instability of voltage and frequency. To solve this problem, this paper proposed a method of joining with frequency and voltage control loop of Voltage Source Converter HVDC (VSC-HVDC). Control loop of VSC-HVDC converter WFVSC (Wind Farm Side VSC) and GSVSC (Grid Side VSC) were detailed designed. By the frequency loop of WFSVSC, transient stability is greatly improved. Finally, based on the DIgSILENT/Power Factory simulation, the results show its validity and effectiveness.

Effect of Wind Farm on Transient and Small-Signal Stability Based on BPA

Large scale wind farm output variation always deteriorates the system stability. To study this problem, this paper builds the model of power system with the integration of large-scale wind farm based on BPA. The simulation results show that large oscillations of voltage and rotor angle of system will happen, when three-phase short circuit fault occurs on the main line for transmitting wind power. With wind farm output decreasing, the transient stability and small-signal stability of power system will be improved.

Predictive Condition Monitoring and Fault Diagnosis Techniques for Offshore Wind Turbines

Wind energy conversion is the fastest-growing source of new electric generation in the world. The unforeseen damages of a component in a wind turbine have significant impact on the wind turbines, especially offshore ones. There has been a trend towards adoption of various forms of condition monitoring and fault diagnosis to know the deteriorating condition for both mechanical and electrial components, well in advance of a breakdown. This paper review the most recent advances in these areas with a special focus on offshore wind turbines. Different type of faults on offshore wind turbines are reviewed, including gearbox and bearing failures, generators failures, rotor failures and electrical failures. And then two widely-used methods(vibration analysis and oil monitoring) for predictive condition monitoring and fault diagnosis in offshore wind turbines are reviewed.

Impact of Large Wind Farms with DFIG on Power System Transient Stability

It’s a new challenge to power system stability with large wind farm’s integration. Taking the wind farm which consist of GE1.5MW double fed induction generators that has been modeled in the software PSS/E as the research object, The difference between the impact of wind farm and conventional generators integrated to grid in power system transient progress is analyzed. Besides, the impact on transient progress of increasing wind farm penetration and differnet interconnection with wind farm to power system is investigated.