HIGH SPEED CALCULATIONS OF SHORT CIRCUIT FOR POWER SYSTEMS WITH VARIABLE STRUCTURES AND PARAMETERS

This paper presents a new method for digital simulation of equivalent circuit parameters and port currents of the short circuit fault port for each sequence networks in power systems with variable configuration and parameters. If the electric values for single-line-to-ground short ciruit are calculated in detail,the other faults at the same location can be rapidly obtained by using the proportional coefficients of the same sequence port current. In this method,the modifications of Z-bus or Y-bus matrices for each sequence network, and the repeated of calculations of the short circuit calculation have been completly avoided.     

Distributed Power Flow Method Based on Ward Equivalent

With interconnecting and developing of power system, the problem of power flow computation on dispersed data resource need to be solved. A new distributed computation method of power flow based on Ward equivalent is presented. According to master-slaver splitting principle, multi-area interconnected power system is divided into master-slaver areas. Boundary buses in different areas are defined as different bus-types. Neighborhood areas are equivalent by Ward equivalent principle, and the equivalent injection power and equivalent impedance are worked out. Power flows from master area to slaver areas are solved by Newton method, and the equivalent injection power and equivalent impedance on the boundary are modified by their solutions. The process above repeats until to convergence. The proposed distributed power flow method takes full advantage of the information of power, voltage, network configuration in neighborhood areas, so it is better on convergence and quality of solution. The proposed algorithm is testified by IEEE 14-bus system and a practical 181-bus system.     

The Optimization Design for the Parameters of Capacitor Welding

Through the analysis in this paper,the optimum relation of the discharging current peak interval t m ,the discharging loop equivalent inductance L and equivalent resistance R is obtained.This paper analyze the original discharging loop equivalent inductance L ,which provides an effective method for adjustment and selection of inductance L to realize the optimization energy saving design of the welding machine.     

Parameter Design for the Power Train and Simulation of the Dynamic Performance of Elctrical Vehicle

The method and principle of the parameter design for the power train of EV is explored and discussed,then the parametersof EV. based on SC7101 are reasonably selected.The method of calculating the SOC of Lead_acid battery is provided and the relation among the electromotive force,the interior resistance, the polarized resistance and the SOC are analyzed. The capacity is compensated according to the relation between the capacity and the temperature, which is the basis on which the energy management system is designed and improved. The dynamic model which reflects the dynamic characteristics of the power train is established,then the dynamic performance of the EV based on SC7101 is simulated, and the factors that affect the continuous mileage of EV are analyzed,the measures to increase the continuous mileage are provided.The result shows that the analysis of the electric characteristics of battery and the dynamic model are correct,and the dynamic performance perfectly meets the need of the design target.     

Calculation Method for Equivalent Model of Regular Isolated Structure with Bend shear Deformation

Isolation technique was not only applied for middle or low buildings, but also recently it was applied to high rise buildings. For high rise buildings, multi order vibration should be considered for upper structure isolation and bend deformation should be taken into account in gross deformation because of large height to width ratio. On the basis of previous studies, calculation method of equivalent model for regular isolated structure with bend shear deformation characteristic was proposed according to equivalent criteria after the analysis for some model structures. With the proposed model, handwork calculation of earquake response for isolated structure can be simply completed and design efficiency of isolation structure was improved. Based on the case studies, the equivalency of proposed model was approved.     

Optimal Standby Capacity and Its Valuation in Power Pool

The problem of optimal standby capacity and its valuation in Power Pool is very important and complicated. On the basis of researching literatures concerned, this paper constructs an optimal standby capacity model and researches the problem of pricing optimal standby capacity and determining power price on the user-side. The result shows that the optimal standby capacity at some period t is completely determined by the probability distribution density function of power load demand at this period and surplus power loss and insufficient power loss, and the price of optimal standby capacity is determined by real power price of entering power grid and the power price of forecasting load demand, and the expected power price on the user-side consists of the settlement price with grid loss on generation-side and reasonable gains and expected additional loss.     

Calculation of lumped parameter of two-port network forvolume conduction energy transfer

Skin electrode unit is a channel through which energy can be transferred to the implanted device by volume conduction. The unit can be equivalent to lumped circuit, but so far there are no appropriate calculation methods of these circuit parameters, so variable load method based on field-circuit coupled is proposed. A skin electrode unit field circuit coupled model is established to obtain the relationship of the network parameters between voltage and current at electrode port, and the amplitude and phase of the power signal is extracted by the use of all phase FFT spectrum analysis. On this basis, equivalent circuit impedance parameters of the skin electrode unit under various conditions are obtained by the application of variable load method and the validity of the method is verified. As a result, the equivalent circuit impedance parameters obtained in this way can be used for the circuit analysis and optimization of the volume conduction energy transfer system.     

A New Algorithm for Open Conductor Faults in Power Systems with Variable Structures

A new method to calculate electric values of unsymmetrical open conductorfaults in power systems with variable structures and parameters is proposed. All the fault componentsof nodal voltage or branch current and the equivalent parameters of open port for each sequence net-work can be obtained rapidly. The method presented here is much more understandable in contrast tothose available, and meanwhile the amount of calculations is greatly reduced. Its effectiveness hasbeen verified by numerical examples.     

Improvement of Method in BIN Building Energy Consumption Calculation

The proportion of radiation load through glass windows in building energy analysis is comparatively great;it is regarded as linear relation with temperature in BIN method,which is extremely a rough method.It is not only because the relation between such radiation load and temperature is far from linear relationship,but also there is lack of objective standard for the selection of corresponding representative temperature to the load.To solve this problem,calculating the maximum factor D_(J max) firstly,then get the hourly corresponding relation of load and temperature by multiplying the hourly cool load coefficient.The practical relation of load and temperature could be obtained by counting up the average load to each temperature at each direction;the load calculation method is still simple using a series of statistic data.A comparison has been made between this method and the former one.As it is the real reflection of relation between the temperature and load,the precision of load calculation is enhanced.The process using this method to calculate load for south facing window in Chengdu is given in this paper.     

An improved dynamic model of transformer hotspot temperature based on top oil temperature

The winding hot spot temperature of the oil immersed power transformer is an important parameter. It has a great influence on the transformer insulation aging and a close relationship with the transformer top oil temperature. The changes of non linear thermal resistance, open circuit impedance, and oil viscosity and winding losses with temperature are also taken into account. An improved model added on the transformer top oil temperature to calculate transformer winding hot spot temperature by using the viscosity and loss correction factors is proposed. Model parameters are estimated by Levenberg Marquardt method. In the end, by comparing with the measured data tested under different conditions, the model shows good consistency under underload (90%), rated load (100%) and overload (110%) conditions respectively, and describes the temperature variation more accurately in the dynamic loading profiles.     

Improved CMI code in passive induction setting system 〖JP〗

Aiming at the low energy transmission efficiency of the passive induction setting system with the existing codes, an improved CMI code is proposed as baseband code by changing the equivalent average time of high level during a code cycle under 2ASK modulation. The properties are analyzed, such as energy transmission efficiency, power spectrum and the error probability in incoherent demodulation in AWGN channel. The code is successfully applied to passive induction setting system, and the decoding method and measured voltage waveform are given. With the code, the energy transfer efficiency is improved by 60% than that of CMI code. It is not only beneficial to energy transmission, but also has the merit of CMI code that the bit timing information is extracted easily, which is fully utilized in incoherent demodulation to solve the sampling moment error accumulation problem resulted from the instability of internal oscillator.     

竖向荷载下弹性支承直墙拱反弯点理论分析

在工程实践中,直墙拱应用较多。由于拱脚位移的存在,合理假设拱脚约束为转角约束、竖向约束和水平弹性约束,应用力法推导出了在弯矩、剪力和轴力共同作用下直墙拱沿弧长的弯矩公式。研究了竖向均布荷载、竖向三角形荷载和竖向集中力荷载作用下,直墙拱沿弧长的弯矩分布及反弯点形成的规律;发现在3种荷载作用下,使得拱脚弯矩为零时的圆心角依次减小。取弹簧支座刚度为等效的下端固支、上端允许水平位移的直墙的抗推刚度,得出了随着直墙高度增加,圆弧拱拱顶弯矩增大而拱脚弯矩减小的变化规律。在直墙拱的设计中,建议选取合适的直墙高度和使得圆弧拱拱脚弯矩为零的圆心角大小,从而有利于提高结构抗弯承载力及拱脚抗剪承载力。     

Hybrid Power Supply Based on One Cycle Control

A hybrid power supply is composed by both a linear and a switching source connected in parallel and it can improve the dynamic response. But the hybrid power supply cant not effectively reject the perturbations in the power supply. A hybrid power supply based on one cycle control theory is proposed in order to improve the capability and the control precision. A switching source based on one cycle control is adopted in the hybrid power supply. The analysis results indicate that the hybrid power supply can effectively reject the perturbations in the power supply. And the analysis results also show that not only the control precision is improved, but also the control circuit is simple. The simulation resuits given verify the correctness and effectiveness of the proposed method.     

Disscussion in the Rural Power Network Construction in the New Rural Construction

To adapt to the continuous improvement of rural power consumption level in the new rural construction,in particular,with the continuous development of the rural economy,the actual operation of the rural power network has emerged as the high loss of electrical power which leads to a greater cost of the electricity,lower power supply reliability,the supply voltage and frequency do not satisfiy with requirements,etc.Through analysis of a typical rural power network,from the overall planning of the transmission to distribution equipments(such as lines,transformers and reactive-load compensation devices),the author proposes some specific measures such as reducing power loss and improving the voltage quality and reliability methods.Through calculation for lines power loss rate and percent of voltage pass,the results show that the methods proposed by the author are effective.The directions to the development trend of the rural power network is given.     

生物制氢方法综述

氢气由于燃烧过程中不产生CO₂,清洁无污染,因此被称为未来的“能量载体”,被应用于燃料电池发电的过程中。综述了生物制氢的不同途径,包括光解水产氢、光发酵产氢、暗发酵产氢和两步发酵工艺,并比较了各种方法的优缺点,在此基础上探讨了未来生物制氢发展的新方向。     

Control Method of Voltage-reactive Power of Substation Based on the Real Time Adjusting Voltage Calculation

The main means of the voltage-reactive power control of substation are adjusting the taps of load-tap-changing transformer or the reasonable capacity of parallel compensating capacitors according to the operation condition of substation.The "nine-area control strategy" is widely used to adjust voltage in the stated range and reduce the transmission capability of reactive power for power system at present.By analyzing the existent shortages of nine-area control mode for voltage-reactive power,an adjusting voltage calculation method is put forward,input data of which are the real time data of current,voltage and power of the substation.Then operation decision of voltage-reactive power control method of substation is made.By the simulating analysis,predigesting method of upper system is built,based on which an applied real time calculating model and calculating steps is given.     

Application of Combination Grey Model in Power Load Forecasting

Based on the gray forecast theory, this paper studies the principle and deficiency in power load forecasting by the basic grey model and other improved models, and introduces a new method -the combination grey model to forecast the long-medium power load. Based on an example, the basic grey model, other improved models and combination grey model are used to forecast power load and results of all models are analyzed and compared. The calculation results show that forecasting power load by grey theory is credible and simple. For this type of complex problems such as forecasting the long-medium power load, the combination grey model is specially useful because of it's high precision and facility. The method can be used as one of the tools of forecasting the long-medium power load.     

Mode-Superposition Method for Passive Energy Dissipation Structures

The methods of equivalent linearization of different energy dissipation devices are different in analyzing passive energy dissipation structure including different type of energy dissipation device by using of mode-superposition response spectrum method based on equivalent linearization, which results in the differences in computing accuracy and cost in dynamic analysis. For structures separately installed different energy dissipation devices, authors utilize relatively uncoupled mode-superposition method and complex mode-superposition method for contrast analysis, and probe into the suitability of the two methods in the dynamic analysis of passive energy dissipation structure. Numerical results show that complex mode-superposition method could be better for structure with viscous dampers in order to guarantee accuracy, and relatively uncoupled mode-superposition method is recommended for structure with viscoelastic, metallic or frictional ones.     

电源分配网络阻抗分析及去耦电容优化

高速印制板电源分配网络（power delivery networks,PDN）受电电源端口具有瞬时电流大、目标阻抗小的特点。针对任意形状电源板的阻抗问题,提出一种基于解析式与有限差分法的互补模型,并在此基础上结合粒子群算法实现多个受电电源端口的阻抗优化。通过Matlab仿真,发现互补模型的结果与全波有限元法的基本吻合,计算时间则大幅缩短。测量结果表明,优化后实验板的多个受电电源端口阻抗均满足各自的目标值要求。     

Equivalent Duffing System Method of Nonlinear System Dynamic Reliability Analysis

Equivalent linear system method is the main method of nonlinear structural system random response analysis. While it would generate big error when the results of equivalent linear system method are used to analyze the structural dynamic reliability. Through minimum mean square error principle, general nonlinear system was converted to equivalent Duffing nonlinear system, based on which the structural dynamic reliability was analyzed. The accurate steady state analytic solution of Duffing nonlinear system can be worked out by FPK equation, so it is not only convenient but also accurate to analyze structural dynamic reliability by using the equivalent nonlinear system method. It is also shown that the analysis results of equivalent nonlinear system method presented here is reliable and the calculation accuracy is higher than equivalent linear system method apparently through the example analysis.