Since 2010, photovoltaic (PV) was growing rapidly for policy guidance in China. The large-scale PV electricity generation had a great influence on the power grid operation because of the change of the power supply layout. How to analyse the influence is an important matter to power system development. The analysed results will decide the trends of the PV electricity generation in future. Therefore, the Coordination analysis of PV generation growth is crucial to those developments. In this paper, the reasonable plant scale arrangement was discussed based on the difference between peak and valley of power system.

Accurate calculation of power grid investment scale is an important work of power grid management. It is very important to power grid efficient development. Due to the characteristics of short data time series, lots of influencing factors, and large change of power grid investment, it is very difficult to calculate grid investment accurately. Firstly, this paper uses hierarchical clustering analysis method to divide the 23 provinces into four classes with considering fifteen power grid influencing factors, then uses spearman's rank-order correlation to find out five key influencing factors, and then establishes the regression relationship between the growth rate of investment scale and GDP, permanent population, total social electricity consumption, installed power capacity of operation area, maximum power load, and other growth rates by using the multiple linear regression method (MLR), and the estimation error is corrected by using RBF neural network. Finally, the validity of the model is verified by using data related to power grid investment. The calculation error indicates that the model is feasible and effective.

As the clean energy developing rapidly in recent years, the operational mode of power system was adjusted persistently because it was impacted by the randomness of clean energy output. Meanwhile, the efficiency of transmission grid was decreasing in certain level for the same reason. The production simulation model of power system was presented, and the power source which considering the output characteristics of different clean energy was described respectively. In additionally, the analytical method of efficiency assessment was proposed to assess the impact degree of clean energy. Moreover, the efficiency index of power transmission system programming was adopted to choose planning scheme. At last, three planning schemes of a power grid with massive clean energy are analyzed to confirm the production simulation model and assessing method.

According to the 9th power industry reform document,revenue of electric power companies will come from transmission and distribution tariff approved by government in future.Utilization of power grid equipment will determine income of electric power companies to some extent,and will be a major factor in economic evaluation of transmission planning.A new approach of calculating transmission network utilization considering security constraints is proposed for transmission network planning studies.This approach incorporates security constrained generation dispatch into probabilistic load flow algorithm based on Monte Carlo simulation.It calculates utilization indices based on Monte Carlo simulation on variety of operation conditions.The proposed approach is validated with IEEE RTS 24-bus system.Meanwhile,impact of security constrained generation dispatch on transmission network utilization is quantitatively analyzed.Results show that with this approach generation dispatch becomes more reasonable without failure problems such as line overload occurring.Obtained utilization indices can objectively reflect utilization of actual systems.

With the decrease in the total electricity consumption growth rate,how to improve the efficiency of the transmission network without violating the safety constraints has become an important concern in the planning and operation of power grid.For this reason,an evaluation method for transmission grid efficiency considering the accident probability,based on the No.599 order issued by the State Council,is proposed.This method calculates the accident probability using the cascading failure model,which takes the actual power system characteristics into account to guide the planning and operation of power grid.Meanwhile,it has avoided the defect that actual statistical data gathered from grids with different features cannot be used for horizontal comparison directly.A regional power grid in Hubei Province is selected to verify the effectiveness of the evaluation method,and the factors affecting the efficiency increment of the transmission network are discussed.

The reasonable transmission efficiency of power grid was analyzed considering to N-1 and power outrage risk constraint respectively in this paper. The representative index of security and efficiency had been selected to reflect the condition of power grid. In the aspect of security, the N-1 Pass ratio represented the determinacy index and the power outage risks represented a non-determinacy index were used to evaluate the security of grid, the transformer and power line load ratio was used to assess the efficiency of power grid. The relation between security and efficiency of power grid with unchanging framework was studied. The efficiency of considering to N-1 constraint was obtained through the optimal growth load. The variation ratio are defined to seek the rapidly increase point of security relative to efficiency, and the reasonable transmission efficiency of power grid considering to the power risk outrage constraint was found out by the variation ratio.

数据包络分析(Data Envelopment Analysis,简称DEA)模型能有效评价电网投入产出效率.但对具有包含关系的不同对象如何进行综合效率对比与分析的研究尚不清晰,对此,笔者研究了具有包含关系的重叠对象的投入产出效率,并以中国、国网经营区以及国家电网公司三个对象为实例进行了综合效率水平分析与对比.结果表明,包含关系的多个对象的投入产出效率存在不等式映射关系.

The coordinate evaluation of grid is about the matching degree between capacity of power import and export for a level grid, it is important to power network planning. Considering the power transmission direct, the definition of equivalent import capacity and the equivalent export one are proposed, the import one includes generation, DC converter station, tie line, step-up substation and so on, uniformly, the export one includes direct load capacity, step-down substation and so on. The coordinate evaluation criterion is present based on Code about power system. Finally, a provincial power grid is used to demonstrate the calculation of equivalent import capacity and equivalent export one, and the coordinate of the provincial power grid is analyzed based on the evaluation criterion.

“十一五”以来我国电网实现了跨越式发展,规模基本翻番,以特高压交直流输电为代表的电网新技术取得实质性突破,进入全面建设智能电网的新阶段.电网建设步伐进一步加快的同时,如何提高电网发展质量、发展效率及设备能力的发挥越来越受到社会、行业监管部门以及电网企业的关注.国内外针对输电网利用效率的研究多集于评价指标,评价标准方面的研究还不多见.参考文献[1]从电网年最大负荷利用率、主变压器容量利用率、线路容量利用率和土地利用效率四个方面提出了有关电网利用效率的指标.参考文献[2]分析了影响输电网利用效率的主要因素,针对输电线路和变压器建立了包括最大负载率和平均负载率在内的两类评价指标.

随着我国电力需求不断加大,电网规模持续扩大,电网投资大幅度提升,电网投资建设效益是否合理受到我国电网行业的重点关注.文章将电网投资建设视为一个投入产出实体,利用数据包络分析(Data En-velopment Analysis,简称DEA)方法对我国电网行业进行投资建设效益分析,评价我国15年来电网投资建设效益.经过对比各年份效益水平,分析计算过程中松弛与冗余变量,总结电网投资建设效益低下的原因.

With the power requirement increasing dramatically, the power grid scale of China continuous expanding recently. The power grid scale should keep an appropriate adequacy to avoid power supply capacity constrained, at same times it should keep a high efficiency. Therefore, the evaluation of the grid scale becomes an important matter in grid development planning study. Meanwhile, the power grid development unbalance phenomenon exists in operations. For that, the electricity transmission characteristics of power grid are analyzed and the hierarchical structure is proposed in this paper. An evaluation system of transmission line and transformer was established to analyze the adequacy of the power grid based on the hierarchical structure, which used to estimate the adequacy of the whole power grid. And then, the adequacy discrete analysis method for estimating local area and components is proposed to find out the weakness in power grid. Finally, the adequacy index and the discrete analysis method were verified by the actual power grid of 4 provinces respectively, the experimental results shows that the index system is capable to evaluate the adequacy, the discrete analysis method is capable to find out the mainly nonuniformity problem which contributed to guide the power grid planning and developing.

随着我国电网规模持续扩大,供电能力大幅提升,电网投入产出效率已成为我国电网规划研究与建设运作关注的重点问题.将电网视为一个投入产出环节,利用数据包络分析(Data Envelopment Analysis,DEA)方法对电网进行投入产出效率评价,分析15年间电网投入产出综合效率.结果表明,各年份效率水平与电力体制、经济形势显著相关,并结合电网不同分布范围,分析电网企业规划建设运营对电网投入产出效率的影响.

The power system now is a typical complex system, which has inherent characteristics of SOC. Studying on cascading failures are necessary and meaningful to insure the grid's safety, national security and economic development. This paper firstly establishes the indices of power system development diagnosis, which are closely relevant to the trigger of power system evolution. Then a cascading failure model is proposed, considering planning and evolution of the power system. This model is based on OPA model, including both fast dynamics and slow dynamics. The slow dynamic process simulates the evolution of power system, which represents the functions of the planning department, while the fast dynamic process simulates power flow and cascading failures, which takes the effects of dispatch, relay protection and automation into consideration. Moreover, simulations are tested on the case of Kaifeng-Shangqiu power system in Henan Province of China, and evolution results are presented.

In order to evaluate whether the investment of power grid is adequate when the outage risk is considered, a blackout model considering grid evolution and a related evaluation method is proposed in this paper. The model consists of fast and slow dynamic. The former is based on an improved OPA model, adding low frequency load shedding control. The latter upgrades equipment number, other than their capacity, of power plants, transformers and transmission lines, according to load ratio of equipment and N-1 criterions, which makes the method more realistic. Based on the model, the customer outage cost caused by cascading failure and construction cost are used to evaluate the grid evolution from the perspective of economy and security. The power grid of Kaifeng City in Henan Province, of China is used to simulate the evolution. The grid development cost and self-organized criticality are analyzed.

In order to analyze the correlation between security and efficiency of power grid, the representative index had been selected, which contained N-1 pass ratio, the power outage risks and the transformer load ratio. The grid evolution model was proposed to simulate the development of power grid under certain rules in this paper, and the force-dynamic relation between the security and efficiency of electrical power grid based on simulated data during in developing process. The result shows that the relationship between the security and efficiency is increasing exponential function. The reasonable load ratio of transformer is presented for the power grid under a demanded security requirement.

With the power system of China continuous expanding recently, the electric power generation, transmission and supply capacity increased dramatically. In order to improve economic operational efficiency and realize scientific development, the Input-Output efficiency between the input of the power system facilities and the output of the power supply becomes a critical issue that government, business and academia have to face up to. In this paper, we used the DEA (Data Envelopment Analysis) model and tested the Input-Output efficiency of power system development and study the trend of important development segment. The relative efficiency of power system is closely related to the electricity management system and economic situation, the elements of reduce the efficiency were been found out by analyzing the DEA results. And a series of suggestions were proposed to increase the comprehensive efficiency.

In this paper, AC ageing characteristics of high voltage gradient ZnO varistors doped with different Y2O3 concentration were investigated. The voltage gradient of these samples is markedly improved by increasing Y2O3 content, however, the nonlinear coefficient decreases and the leakage current increases at the same time. Y2O3-doped ZnO samples exhibit lower stability under accelerated AC ageing stress of 0.85 V1mA/135 °C/168 h, compared with samples without Y2O3. Double-Schottky barrier(DSB) parameters before and after ageing tests indicate that the decrease of barrier height for traditional sample is less than that for high voltage gradient sample, which should be ascribed to its slight variation in the interface state density.

The statistical AC ageing characteristics of single grain boundaries of ZnO varistor were investigated in this paper using the microcontact measurement method. ZnO varistor sample deposited with micro-electrodes was degraded under the ageing stress of 0.85 V1mA at 135 °C. The electrical properties of 100 grain boundaries were measured after ageing with different time. The results indicate that the distribution of nonlinear coefficients concentrates to the lower region and the leakage current gradually increases in the ageing process. Meanwhile, more grain boundaries with lower breakdown voltage emerge as the ageing time increases, which means that the nonlinearities of these grain boundaries become weak.

The effects of nickel oxide (Ni2O3) additives on electrical characteristics and microstructural phases of ZnO varistors with low residual voltage ratio are studied. The breakdown electrical fields increase remarkably with the amount of the doped nickel oxide increased. The minimum of the residual voltage ratios of the samples reaches 1.39. While the amount of the doped nickel oxide is more than 2 mol %, a new phase of chrombismite Bi16CrO27 is observed from X-ray diffraction (XRD) and scanning electron microscopy (SEM). The delta-Bi2O3 phase decreases and the BiO2-x phase increases correspondingly. In addition, the capacitance versus voltage (C-V) characteristics of the samples are measured and analyzed. (c) 2011 The Ceramic Society of Japan. All rights reserved.

In order to investigate the influence of sintering temperature on the Schottky barrier and bulk electron traps of ZnO varistors,ZnO-Bi2O3 based varistor ceramic samples were sintered at 1000,1100,1200 and 1300°C,respectively.The measured results indicate that the sample sintered at 1300°C possesses the lowest voltage gradient and nonlinear coefficient,compared with other samples.The barrier height of the samples decreased as the sintering temperature increased,which resulted in the deterioration of nonlinearity.Furthermore,two bulk electron traps determined by admittance spectroscopy were generally independent of sintering temperature,which indicated that these two traps might originate from the intrinsic defects in ZnO lattice.