Research on a Novel Inverter of VSC

In order to improve waveform performance of light HVDC system, a lot of switches which operate in high frequency are used, which causes large switching losses and results high cost. A new Buck type voltage source converter(BVSC) is proposed. The new BVSC comprises a dual-buck converter and a three-phase inverter operating in grid frequency. Only two high frequency switches are used, which results good output waveform performance. In order to reduce the high frequency switching losses, a novel improved double-frequency Buck type voltage source converter(DBVSC) is also proposed. An additional dual-Buck converter is added to the BVSC, the added dual-Buck converter deals with the fundamental power that operates in low frequency, and BVSC only deals with harmonic power that operates in high frequency. The output waveform is enhanced and the switching losses are reduced in DBVSC, and the power rating is also increased. The DBVSC is very suitable for large power rating application. The one cycle control theory is adopted to control the proposed DBVSC with analog circuit, which is very simple. The proposed DBVSC and control method are verified by simulation.     

Intelligent Extracting Method for Feature Mode of Electric Days Load

Generally there have a number of bad data in the electric load data and it affects the precision of load forecasting,so it is necessary for extracting the feature mode of days load data,then cleaning the load data before it is used to forecasting electric load or performing power system analysis.Inspired by soft clustering thought,a intelligent feature mode of days load data extracting method is proposed based on the mutual offset of fuzzy c-means clustering arithmetic and Kohonen self organization feature map neural network.With the merits of not only high extracting precision and convergent speed but also dynamic calculation capability,the method proposed can supply load forecasting or system analysis procedure with due data.Test results using actual data of Chengqu power supply bureau in Chongqing demonstrate the effectivity and feasibility of the method.     

The power-supply of X-ray machine adopting PID control and high-frequency inverter technology

To solve the problem of low control accuracy and low stability of current X-ray machines, a kind of digital power supply for X-ray machine is introduced. In the digital power supply, some key technologies are used to improve the output stability of the high frequency inverter, including improved BUCK circuit for voltage regulating circuit, high frequency inverter and soft switching technology for the high-voltage generator. The PWM control technology is used to control the switch transistor of voltage regulating circuit and inverter circuit, which makes the drive waveform output stable and easy to control. In order to improve the control accuracy, reduce the volume and change high voltage consecutively, the software PID of the microcomputer is used to control the feedback circuit. The high-accuracy power chip is used for the filament power supply to make the filament electric current stable. Through the analysis of the circuit, the parameters of the circuit are calculated and the circuit is simulated by PSPICE software. The results show that the theoretical analysis is consistent with the practical simulation results. The design can meet the requirement of the technology indices of the power supply of the X-ray machines.     

A charge balance control algorithm of dual-transistors forward converter

An algorithm is proposed for dual-transistors forward converter (DTFC) by using the principle of charge balance control during a transient process to improve their dynamic performance. Combined with response curve,the theoretical analysis and some key equations are presented to improve the dynamic performance of the DTFC by minimizing the over/under shoot and the recovery time. In order to avoid the magnetic saturation of the transformer,an approximate method is introduced in the calculation of the optimal switching time,which can also be applied to other isolated converters when the maximum duty cycle is limited. Finally,the simulation results and the experimental results of the prototype show that,compared with the traditional voltage mode control,the proposed algorithm can significantly improve the dynamic performance of DTFCs.     

Hierarchical control method of low voltage looped microgrid

The low voltage (LV) looped microgrid has high reliability of power supply and good accessibility of the DG. The medium voltage distribution network with single loop network and multi sectioned & multi linked is studied to analyze the wiring mode of the LV looped microgrid. A research on the two hierarchical control scheme of the looped microgrid is conducted, and the sub microgrid, which meets island operation requirements, is divided according to their segments. Then the incidence matrix is formed based on the connection relation of different segments and components, and the plan for switching the microgrid operation status is concluded from the reform of incidence matrix on the basis of the judgment of island and reconnection segments. A resynchronization strategy using microgrid central controller is proposed. The MATLAB/SIMULINK simulation software is used to analyze the dynamic characteristics of different operation status switching and synchronizing, and the results verify the effectiveness and correctness of the proposed control method.     

改进粒子群算法的自动阻抗匹配技术

由于无线电能传输距离的改变或谐振线圈之间发生偏移、负载改变等多方面的影响使系统的输入阻抗发生变化,导致输入阻抗与射频源内阻不匹配,使传输效率大幅下降。在射频源和发射线圈之间加入阻抗匹配网络可以提高无线电能的传输效率。为了提高阻抗匹配的精度和速度,提出了一种改进的粒子群算法。重点将改进算法和传统算法进行仿真实验比较,证明了改进算法在匹配精度和速度方面的优越性。最后将该算法嵌入到自动阻抗匹配系统中,提高了无线电能的传输效率,同时证明了所提算法的有效性。     

Simulation of The Torque Control System of Motor for Hybrid Vehicle

A strategy for induction motor control based on the grade of errors is developed to improve the performance of hybrid vehicle drive system. The stator flux error, electric magnetic torque error and flux position angle are used as control variables, and rules for the switching states are chosen according to the errors and the principle of the Direct Torquc Control. This strategy improves efficiently the electric magnetic torque response of the system. The result of simulation shows that this strategy is an ideal control strategy of hybrid vehicle, which can make the motor generate the electric magnetic torque efficiently, steadily and quickly.     

Single-end Flyback High-frequency High-voltage Switching Power Supplies

Based on the research of a practical project of high frequency high voltage switching power supplies,the system design and experimental investigation of a single end flyback high frequency high voltage switching power supply are presented. In order to solve the problem of durable voltage of power MOSFETs that are used in the single end flyback high voltage switching power supply,an effective approach that adopts dual MOSFETs in series connected is proposed.The procedure of the designing and the parameter of each device is given in detail.A prototype of 220 Volt input and 2000V/3mA output is developed, and the validity of the scheme is demonstrated by the experiment.     

A Control Algorithm to Regulate the Active and Reactive Power and Simulation Research of Dual-frequency Dual-Buck Inverter

This paper deduceS the control algorithm ,which can both regulate the active and reactive power of the novel dual-frequency dual-Buck inverter, and the control function. The control function based on one cycle control can control the AC-side active and reactive power by simple circuit. The simulation is given and the results prove the validity of the theory analysis. This inverter is valuable for the research of grid-connected inverters.     

A preventive control model for static voltage stability considering the power constraints of weak branches

The voltage instability of power system often occurs when the active power on one or more weak branches exceeds its transfer capability. A preventive control model for static voltage stability is proposed using the active power transfer capability of weak branches as static voltage stability constraints. A local line based voltage stability index is used to determine the critical contingencies, weak branches and transfer capability of each weak branch. A static security analysis method, which is based on DC power flow equations, is used to establish the non linear active power flow expressions on weak branches following each critical contingency. The active power constraints on weak branches can be obtained from the active power flow expressions and transfer capabilities of weak branches. A quadratic optimal model for preventive control including the proposed active power constraints on weak branches is presented. The simulation results for IEEEE14 bus system and IEEE118 bus system demonstrate the correctness and effectiveness of the proposed preventive control model.     

Multi-objective control strategy for parallel HEV using fuzzy logic

A fuzzy multi-objective control strategy is proposed for parallel hybrid electric vehicles (PHEV). By the concept of motor equivalent fuel consumption, the overall vehicle fuel economy and the corresponding emissions can be treated as the optimization objectives. Then a minimum average weighted deviation method is designed to find the Pareto optimal solution with considering the variations of objective preference in different district. The simulation on ADVISOR reveals that, compared with the rule based control strategy (RBCS), with the premise that there is no loss to power performance, the proposed fuzzy multi-objective control strategy (FMCS) not only improves fuel economy and emission level but also maintains battery SOC within its operation range more effectively.     

Research on the Realization of Remote Controlling for Multi-output Power Supply of Communication Equipment Based on Ethernet

According to the requirements of communication power supply, such as high reliability, wide application and high availability, the authors raise a new remote control design for a multi-output power supply for communication equipment based on TCPIP protocol and embedded technology. Then the hardware design is given for the system is discussed based on Ethernet professional chip PRTL8019AS and related circuits. The firmware software design for the salve-computer based TCPIP technology, and the soft design of communieation and control for the master-computer are proposed based on Winsoek and MFC technology in detail A test machine is built to do the testing, the test results prove that the test machine works stably and well, satisfies the design rules and also provides a feasible method for the remote supervise in communication power supplier whose requirement includes remote supervise, no-people on duty and so on.     

Dual mode AC DC AC converter for contactless power transfer system

A new type AC DC AC converter which can work in Buck or Boost mode is proposed in order to overcome the deficiencies of the primary circuit of the traditional contactless power transfer system. Through switching this two modes and turning the duty cycles of the switches, not only the resonant current amplitude of the primary resonant current can be controlled to be constant against a wide range variation of input voltage, but also the problems, such as surge current, high cost, complex control etc., caused by the DC filter and DC/DC converter in a traditional CPT system are effectively eliminated. The topology and operation principle of the proposed converter have been analyzed. The corresponding control strategy has been presented and verified by simulation results.     

光储微电网混合储能系统的控制策略及开关优化

传统光储微电网混合储能系统控制策略将蓄电池视为容量无限大的理想元件,而实际上蓄电池容量有限,当蓄电池剩余电量达到阈值无法正常工作时传统控制策略将不适用。在二阶低通滤波法的基础上提出一种光储微电网混合储能系统的新型控制策略,同时考虑超级电容与蓄电池的剩余电量,根据储能元件的荷电状态调整储能元件输出电流参考值,维持储能元件剩余电量,但在极端天气情况下,仍需与储能元件保护开关相配合。由于采用传统储能元件保护开关的储能系统需独立的充放电电路,存在成本较高、充放电不连续等问题,因此,对储能元件的保护开关进行了改进,利用开关与二极管并联使其具有4种工作状态,在储能元件剩余电量达到阈值时,可自动恢复电量,降低了成本,提高了并网输出电能质量。最后结合新型控制策略与改进的保护开关,提出整体的混合储能系统控制方案,并用Matlab/Simulink对其进行仿真验证,结果证明了所提方法的正确性与可行性。     

Research on the improvement of the convergencespeed for CDMA system power control

Optimal power control with game-theory has been a hot research topic in code division multiple access (CDMA) system. However, the convergence speed of the power control algorithm based on traditional static game-theory is not fast enough and the power fluctuation is large during the iterative process. In order to solve this problem, dynamic game-theory is introduced into CDMA system power control algorithm. The simulation results show that the proposed algorithm, compared with the distributed power control algorithm based on the traditional static game theory, can improve the convergence speed obviously with the same power spending.     

A coordinated state transition control strategy for microgrid with multi-energy generation systems

A coordinated control strategy is proposed based on state transition for a microgrid containing continuous or intermittent DG, energy storage device and sensitive loads. According to the available operation states, a scheme of operation state transition is established through setting the current operation state and trigger event as inputs of MGCC and regarding the control modes of components as outputs. By considering the no deviation control for frequency and the capacity limitation of energy storage device under all operation states, control modes of components and trigger events of state transition under all defined states are designed respectively for a reliable power supply of sensitive load. The PSCAD/EMTDC simulation software is used for analysis of the three typical transition processes of operation states. The results show that the proposed coordinated control strategy is effective for a safe and reliable power supply to the sensitive loads and ensures a smoothing transition between operation states of microgrid as well as the no deviation control of system frequency.     

The efficiency of a Ni MH battery used in hybrid vehicles

The efficiency of the 60QNY6.5 battery is studied by testing and theoretical analysis in order to improve the control precision of hybrid electric vehicles (HEVs) and the battery useful life. A rig for testing the Ni MH batteries of HEVs is established. The data from experiments performed on the Ni MH battery are analyzed. Based on the experimental results and the temperature of the batteries, internal resistance and electromotance models of Ni MH batteries are proposed by function fitting methods. The theoretic formula for battery efficiency is deduced by the operational principle of the battery and motor, which provides theoretical basis for dynamic optimizing technology of HEV system controlling strategy.     

The study on EMI principle and suppression method of vehicle ignition system

Vehicle ignition system is the main electromagnetic interference source. Electromagnetic radiation produced by ignition system will produce the interference to electromagnetic environment around. It is necessary to study the electromagnetic interference (EMI) principle, noise paths and suppression method. We analyze the electromagnetic interference principle of ignition system, and harness trouble-shooting related to electromagnetic interference is also tested. Results show that the spark discharge between spark plug electrodes is the main interference source in ignition system. Then, the paths of conducted interference and the reason of radiated emission are discussed in detail. Finally, two kinds of power supply cord EMI filters are designed and implemented on the basis of analysis results. Experimental results indicate that the filter can reduce the noise of power-wire in broadband range. Simultaneously, the radiation emission performance from power wire is also reduced observably. The proposed mixing filter has been demonstrated in this paper to perform satisfactorily with excellent effectiveness in suppression of conducted EMI from 10 MHz to 110 MHz, and the object car can also pass the EMC standard tests.     

simulation of a brushless direct current motor based on finite state machine theory

A novel method simulating a brushless direct current(DC) motor was presented, based on principles of hybrid system modeling and finite state machine theory. Brushless DC motor control mainly focuses on controlling the on/off condition and power switch duration. Modes of control therefore can be defined by corresponding states, and the states can be combined as a finite state machine. This approach uses the popular Simulink/Stateflow simulation method to control brushless DC motor loops. A three phase brushless DC motor was analyzed to illustrate the process of model building with Simulink/Stateflow. The analysis demonstrates the feasibility and validity of the proposed method.     

Sustainable Development of Chongqing Energy Industry

The idea of the sustainable development is proposed by analyzing the present Chongqing energy industry. Enumerated some energy technologyies and energy forms, which not only save energy but also reduce enviromental pollution. Some suggestion on the development of Chongqing energy industry is given. The main content is the following:Electricity should be developed first when developing energy industry. The government should exploit and apply the technology of the clean coal, develop equipments generating electricity with gasvapor cycle, and improve actively advanced technology of thermal power joint production and thermal power cooling joint supply. It is also necessary to make full use of natural gas in favour of developing sustainable energy industry and take advantage of three gorges area. Some useful suggestions are given at last.