Advanced Materials Research Vols. 986-987

Abstract: In order to investigate the impacts of large scale PV power plants on the stability of power system, dynamic PV models are of particular interest to the industry for simulating large-scale power systems. The transient model of large scale grid-connected PV generation system was given based on the model of each component of PV generation system. Response of the model was simulated respectively when the illumination changes. The methods proposed could be applied to the power grid with photovoltaic generation integration.

Abstract: This paper discusses using the battery energy storage system (BESS) to mitigate intermittency and sustain stability of distribution system integrating high penetration level of renewable energy resources (RER). The goal of the control is to have the BESS provide as much smoothing as possible, so that the RER power can be dispatchable in some kind and reliable. The effectiveness of model predictive control (MPC) based approach proposed in this paper have been tested by detail case study, also compared with the day ahead control strategy, load following strategy , and normal situation without energy storage which are usually used before. The result shows that the proposed MPC based approach is more practical, and more robust.

Abstract: Heuristic methods by first order sensitivity analysis are often used to determine location of capacitors of distribution power system. The selected nodes by first order sensitivity analysis often have virtual high by first order sensitivities, which could not obtain the optimal results. This paper presents an effective method to optimally determine the location and capacities of capacitors of distribution systems, based on an innovative approach by the second order sensitivity analysis and hierarchical clustering. The approach determines the location by the second order sensitivity analysis. Comparing with the traditional method, the new method considers the nonlinear factor of power flow equation and the impact of the latter selected compensation nodes on the previously selected compensation location. This method is tested on a 28-bus distribution system. Digital simulation results show that the reactive power optimization plan with the proposed method is more economic while maintaining the same level of effectiveness.

Abstract: Considering different kind of external grid failures, this paper gives analysis of voltage fluctuation and flicker of large petrochemical enterprise grid. Trajectory-based time-domain dynamic simulation method is used to analyze problems of transient voltage security. A strategy for the application of STATCOM is proposed in order to improving electric power quality. The total loss of motor load of the whole system is counted and buses are sorted according to sensitivity analysis to ascertain installing sites of STATCOM. Then the optimal capacity of STATCOM can be gained by the way of solving linear programming model,which is suitable for transient voltage security under multi-faults. Test simulations show very encouraging result.

Abstract: Virtual Power Plant (VPP) technology can take advantage of interactive communication and energy management system to optimize and coordinate the control of distributed generation, controllable load, energy storage device, so as to integrate them and participate in the energy exchange of the grid and the quote trading of power market. This paper is devoted to study the energy management system in virtual power plant. Under the day-ahead market ,this project puts forward the maximum profit model, analyzes the operation condition of various elements in virtual power plant, and set restrictions for its operation and energy storage; According to the randomness of the energy resources such as wind and light in actual operation as well as the price in power market, the change of power grid load and electricity demand, and the fluctuations in the retail price of electricity, this paper adopts the proposed model of optimal allocation to coordinate and optimize the configuration of the elements in virtual power plant.

Abstract: Along with the increasing use of cables in power grid and the increasing ration of distributed power sources’ synchronization, such as small hydropower’s synchronization, increasing the reactive power transmission on the line, make it difficult to achieve the balance of reactive hierarchical partition. Take a certain region’s power grid for actual examples, after the installation of magnetic control reactor (MCR), using immune genetic algorithm (IGA) to coordinate the capacity of magnetic control reactor and the existing reactive power resources, the results show that the magnetic control reactor does much good to absorb the system’s excessive reactive power and limit the voltage’s increasing.

Abstract: First, behavior models of the station operator and consumer are established considering all the main factors. Second, an optimized EV charging pricing method using Game Theory is introduced based on benefit-cost analysis. The calculation of government subsidies is also proposed in order to reach an equilibrium charging price. Finally, actual data of Hebei is used and results are shown to give supports to local government and charging station operator’s decision making.

Abstract: Through the summary of typical accident, the problem between the over speed protection device of thermal power unit steam turbine and over frequency generator tripping measure is analyzed in island operation of sending ends of regional grid. The optimizing allocation principle between over frequency generator tripping measure and over speed protection equipment is put forward. By a variety of program analysis and comparison, the optimizing scheme is given. Finally, the typical models of thermal power unit steam turbine over speed protection are established in software. Based on a practical power system as an example, the whole process of islanding is simulated. Checking the coordination with existing over frequency generator tripping measure and the relay setting related to power network in the islanding operation, the validity and practicability of the optimal scheme and principle are analyzed. With the method, the regional grid will remain safe and stable.

Abstract: In China, some remote areas with rich small hydropower stations suffer from a tradeoff between water surplus and off-limit voltage in the grid during wet seasons. The microgrid of new energy sources provides a new way of solving this problem. Under the background of the microgrid proposed in somewhere of Jiangxi Province, this paper firstly carries out simplified model on the actual system. Output models of PV and small hydropower stations are established. Then with Minimizing transmission losses of microgrid system and the amount of all small hydropower abandoned waters as the optimization objective, and considering the output constraints of each micro power source, power balance constraints and voltage constraints. A micro-power output optimization model is established and then solved by improved particle swarm optimization algorithm. By comparing the micro-power output and system line loss before and after the optimization, it verifies that the proposed power control method can prevent the off-limit voltage effectively and reduce transmission losses of the system.

Abstract: The plan for power supply and distribution system in the Chemical Industry Park is complex. The evaluation method must be easy and truly show the site conditions in order to maintain the proper function of the system. Thus the fuzzy comprehensive evaluation method was chosen and applied in this paper. As for the weight calculation, Analytic hierarchy process (AHP) was used to compute the subjective weight; on the purpose of avoiding strong effect of subjective factors, the standard deviation for each index was calculated, and then the subjective weight was integrated to build the subjective and objective comprehensive weight model. Lastly fuzzy comprehensive evaluation method was applied into the model for assessing the power supply and distribution system in the Chemical Industry Park.