Frequency is an important operating parameter of power system;and nodal dynamic frequency response characteristics get attention increasingly for its advantage compared to static frequency characteristic.A method of analyzing nodal dynamic frequency response characteristics influencing factors based on curved surface fitting is put forward in this article.Moreover,relationship between them is reflected directly and appropriate frequency characteristic coefficient is obtained to adjust the load.Simulation analysis of EPRI-36 system is executed firstly by means of altering P0,△P and S to get different sampling points and corresponding K values.Afterwards,K values are forecasted based on modified curved surface fitting in addition to effect analysis.Errors between simulation values and fitted values are calculated.The results show that the method proposed to obtain K values is effective,so as to provide reference for the scheduling department when frequency deviation is caused by power disturbance.

电力系统运行过程中产生的无线电干扰会影响周边环境和设备运行,进而影响电力行业的进一步发展.因此有必要对线路无线电干扰水平进行计算研究.为此提出了一种以变电站出线端为代表的有限长交流输电线路电晕的无线电干扰计算方法.根据输电线路的空间排列、材料参数,采用激发函数法,得出当三相线路发生均匀电晕时产生的电晕电流.然后利用相模变换和行波在变电站入口处发生反射的原理,建立了体现电晕电流在有限长导线端部反射特性的传播模型,计算出电晕电流在空间任意点产生的电场强度,进而得到无线电干扰值.以变电站出线端的有限长输电线路模型为例,对单回和双回线路的无线电干扰进行了计算,并研究了不同空间位置无线电干扰值的规律.实地测量值验证了计算方法的准确性,对后续研究和工程实践提供了参考和指导.

不确定性分布式电源的接入,给配电网规划带来新的挑战.首先将含分布式电源的配电网规划归纳为求解斯坦纳树问题,提出了一种新的配电网规划建模方法.其次通过DG供电分区的划定,将分区内的负荷节点处理为一个不接DG的负荷节点,消除DG对配电网规划的影响.针对斯坦纳树问题传统解法求解时间会随着斯坦纳点的规模成倍增加的缺陷,采用一种改进的粒子群优化(PSO)算法解决斯坦纳树N-P完全问题.结合54节点算例并与传统方法计算结果比较,验证了该方法的有效性.

Under trend of large number of distributed generations,mainly wind and photovoltaic power,integrated into power grid,research on permitted capacity of distribution generation is of great significance for operation dispatching in power system.Taking voltage fluctuation index and short-circuit capacity limit into account,an optimization model with maximized capacity of distributed power as its objective function is constructed.Through simulation of a real distribution system,effects of different types of distributed power and distribution network capacity limits are analyzed and maximum capacity limiting boundaries considering different combinations of distributed wind turbines and photovoltaics are given.Results show that distributed generations have limited impact on short circuit capacity of distribution system,and it has no substantial effect on traditional power distribution automation system.Voltage deviation and fluctuation are main factors restricting permitted capacity of distributed power.

随着风力发电在配电网中的渗透率不断增加,风机并网造成的电压质量问题不容忽视.本文首先分析了分布式电源接入配电网对供电电压冲击的影响因素.接着结合配电网十三节点算例,基于PSCAD软件对风机并网运行特性以及对配电网电压质量影响的特点进行了仿真分析.最后,针对风机接入对配电网产生的不利影响,给出了改善配电网电压质量的措施,包括合理选择风机装机容量、接入位置与接入方式、进行负荷投切以及投入电容器与动态无功补偿设备.

When forced power oscillation occurs in a power system,location and elimination of disturbance sources is of great significance for the secure and stable operation of the system.The electromechanical disturbance caused by the forced power oscillation travels along the transmission line.According at the time delay characteristics of disturbance waveforms at different locations,a novel method for locating disturbance sources using the least mean square(LMS)time delay estimation method is proposed.In this method,the starting of forced power oscillation is tested by the second-order difference method,and the travelling sequence of the disturbance is obtained by calculating the time delay of the disturbance waveforms at different buses, thus the disturbance source is located according to the sequence.The proposed method only needs the wide area measured data and is capable of on-line application.The validity of the proposed approach is verified by simulation results of a four-machine two-area power system and in the Central China power grid.

Many studies on static frequency characteristics have been done yet nodal dynamic frequency response characteristics gain more attentions for the important role frequency plays in power system stability. Influencing factors such as balance power, power shortage and electrical distance are altered during PSASP simulation of IEEE36 bus system to acquire diverse sampling points and relevant K values. Modified curved surface fitting obtained by the K values can both be used to forecast K values under any circumstances and simultaneously analyze the influencing effect. The method is proved to be feasible by analyzing the errors between simulation values and fitted values and it can offer reference for dispatch department to process the frequency variation caused by the power disturbance.

With the continuous development of the Power market and the power of information technology, communication networks become increasingly complex and the number communication services is rapidly growing, the study of power of information technology become more important, this paper analysis the different communication needs of Power communication and study the characteristics and the requirements in various communication network.

When predicting the noise level of substation, the model of transformers and reactors as noise sources is very important. A new acoustic mode of the transformers and reactors is built in ultra-high voltage substation. Each of the transformers and reactors is equivalent to several point sources based on equivalent source method. And in the process of the equivalent, the measurement and calculation are made easier by using sound power level to represent the equivalent sources intensity. A model of 9 equivalent point sources is chosen to verify the accuracy of the model. This acoustic model of the transformers and reactors is combined with outdoor point sound sources attenuation theory to predict the substation noise value. Simulation of a 1000kV substation has been down which shows that the model is feasible to calculate the noise level anywhere inside the substation.

Due to the intermittent fluctuation of wind, large-scale wind power integrated to the power system poses serious challenge on the safe operation of the grid. A novel security constraint unit commitment optimization method based on scenario analysis considering the uncertainty of wind power is proposed. With the generation and reduction techniques, wind power generation volatility is generated. Security constraint unit combined with mathematics scenario analysis model is introduced. By applying Benders decomposition techniques, the original problem is decomposed into one master problem and sub-problems, the optimal combination unit output results are calculated by iterative calculation between the master and sub-problems. Well-used 6-bus and Modified IEEE 118-bus cases are studied to present the behavior of the proposed method. The simulation results confirm the validity of the proposed method.

A new method based on sample entropy algorithm that can perform real-time detection of sub-synchronous oscillation is proposed. The rotor torque signal is chose to be analyzed. The sample entropy of rotor torque during continuous period is calculated. Sub-synchronous oscillation detection is achieved by analyzing the variation of sample entropy. The method needs less data and has good anti-interference ability. The effectiveness of the proposed method is proven by the result of the IEEE first benchmark system model simulation.

The traditional methods used for distribution network planning are challenged because of the access of the stochastic distributed generation. A new distribution network planning model is proposed by converting the distribution network planning with distributed generation into solving the Steiner tree problem. Moreover, in order to solve the problem that the time of calculation multiplied along with the increase in the amount of Steiner nodes, an improved particle swarm optimization algorithm is proposed to solve the Steiner tree Non-deterministic Polynomial problem. In this algorithm the problem of premature convergence is solved by applying a small disturbance to the global optimum and the searching results are more reliable and accurate by improve the search ability for global optimum. Typical results of the proposed algorithm and the traditional algorithm are further illustrated and compared through an actual 54 nodes system to prove the validity of the methods in this paper.

This paper proposes the MLR (multiple linear regression) algorithm for parameter estimation of power system post-fault configuration based on the PMU real-time measurement and generator dynamic equations. Using real-time data collected by wide-area measurement system, the algorithm can take complicated cascading fault events into consideration without any information about the specific parameter and fault type or structure of the power system. This attractive feature avoids the difficult problem to determine the parameter and the topology state of a transient event in actual projects, making it possible for the complex perturbed trajectories prediction. The proposed algorithm has been tested on various sample power systems with promising and accurate simulation results.