Thin Film Photovoltaic/Thermal Solar Panels
David JOHNSTON
 (Power and Control Research Group, School of Computing, Engineering and Information Sciences,
University of Northumbria at Newcastle, NE1 8ST, UK)
Abstract: A solar panel is described, in which thin films of semiconductor are deposited onto a metal substrate.  The semiconductor-metal combination forms a thin film photovoltaic cell, and also acts as a reflector-absorber tandem, which acts as a solar selective surface, thus enhancing the solar thermal performance of the collector plate.  The use of thin films reduces the distance heat is required to flow from the absorbing surface to the metal plate and heat exchange conduits. Computer modelling demonstrated that, by suitable choice of materials, photovoltaic efficiency can be maintained, with thermal performance slightly reduced, compared to that for thermal-only panels. By grading the absorber layer – to reduce the band gap in the lower region – the thermal performance can be improved, approaching that for a thermal-only solar panel. 9 Refs. In English.
Key words: solar; thin film; photovoltaic; thermal; panel
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 1—8.

A high efficiency zero-voltage-switching boost voltage doubler with low conduction losses
LIN Wei-ming, WANG Jing-hui, HUANG Jun-lai, ZOU Jian-hua, ZHAN Hua　　　　　　　　　　　　　　　　　　　　　　　　　　　　
(College of Electrical Engineering & Automation, Fuzhou University, Fuzhou 350108, China)
Abstract: A high efficiency zero-voltage-switching three level boost converter for power factor pre-regulator is proposed in this paper. The topology can perform ZVS in the main switches and the passive switches, and zero-current switching in the auxiliary switch. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZVS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices is involved in the circulating current path, and the proposed rectifier is suitable for low line voltage and high power applications. A prototype rated at 600W, operating at 50kHz, with an input ac voltage of 90-132 Vrms and an output voltage of 400 Vdc has been implemented in the laboratory. An efficiency up to 97% and power factor over 0.992 have been measured. 6 Refs. In Chinese.
Key words: ZVS soft-switching; power factor correction; efficiency; three level Boost voltage doubler
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 9—12.

Power system short-term load forecasting based on
 empirical mode decomposition and dynamic neural network
LIU Yao-nian¹，YANG De-you¹，PANG Song-ling²，LIU Dai³
(1. Dept. of Elec. Eng., Northeast Dianli University, Jilin 132012, China;
2. Hainan Power Grid, Haikou 570203, China; 3. Haikou Elec. Power Supply Bureau, Haikou 570001, China)
Abstract: This paper proposed a hybrid model based on Empirical Mode Decomposition (EMD)、dynamic neural network and BP nature network as a short-term load forecasting model. At first, based on EMD the load series is decomposed into different lots of calm series, then according to the features of decomposed components different dynamic neural network model, finally using the BP network to reconstruct the forecasted signals of the components and obtain the ultimate forecasting result. Simulink results show that the proposed forecasting method is accurate. 9 Refs. In Chinese.
Key words: short-term load forecasting; empirical mode decomposition (EMD); dynamic neural network
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 13—17.

Study of fault diagnosis model based on neural network using estimation of distribution algorithm combined with genetic algorithm
ZHANG Zhi-sheng¹,  SHI Xiang²,  LIN Tao²,  SUN Ya-ming³
(1. School of Automation Engineering, Qingdao University, Qingdao 266071, China; 2. Qingdao Elec. Power Company, Qingdao 266002, China; 3. School of Elec. and Automation Eng., Tianjin University, Tianjin 300072, China)
Abstract: A fault diagnosis model using NN (neural network) based on EDA (estimation of distribution algorithm) combined with GA (Genetic Algorithm) is constructed in this paper. The traditional GA is regarded as the simulation of biological evolution from microscopic level, while EDA is from macroscopic level. EDA is a kind of novel evolution mode. The essence of combining EDA with GA is to search the optimal solution from microscopic and macroscopic level, meanwhile to avoid NN to immerse in the local minimal points and improve generalization ability, so fault-tolerance performance of fault diagnosis model can be effectively improved. The presented model is used as the fault diagnosis in high voltage transmission line system, and their fault-tolerance performance is assessed. Through the simulation and test, it shows that the fault-tolerance performance of researched model is superior to that of the diagnosis model corresponding BP-NN and GA-NN. So researched diagnosis model possess theoretical and practical value.
Key words: high voltage transmission line system (HVTLS); fault diagnosis (FD); fault-tolerance performance;　　　　　　　  estimation of distribution algorithm (EDA); genetic algorithm (GA); neural network (NN)
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 18—21.

Parameter optimization for active frequency drift with positive feedback islanding detection strategy
LIU Fang-rui, KANG Yong, ZHANG Yu, DUAN Shan-xu
(College of Elec. and Electronic Engineering, Huazhong University of Science & Technology, Wuhan 430074, China)
Abstract: Islanding detection is a mandatory function for grid-connected converters. Among all the passive and active islanding detection method, the active frequency drift method is pretty attractive. It injects perturbations in the frequency of the converter output current to achieve islanding detection. The operation principle of such strategy is analyzed in this paper. Non-detection zone (NDZ) and the parameters optimization principle are provided as well. The islanding detection performance is evaluated through theoretical analysis and experimental results. 13 Refs. In Chinese.
Key words: PV; grid-connected converter; islanding detection; active phase shift
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 22—25.

Passivity-based efficiency optimization control for induction motor based on minimum magnetic energy
JI Xiao-long, SHEN Chuan-wen, MENG Yong-qing, SU Yan-min
(Department of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, China)
 
Abstract: Following the idea and approach of interconnection and damping assignment passivity-based controller design, and according to the minimum magnetic energy criterion, a new torque tracking and efficiency-optimizing controller is presented. Because the efficiency optimizing and torque tracking is aimed at the electrical subsystem, the optimizing law of the rotor-flux norm is independent of rotor resistance, then the robustness of the control system is enhanced. Furthermore, because the controller needn’t the measurements of rotor variables, its control law is defined globally and has no controller singularities, the dynamic and static performances are guaranteed by the fast tracking of torque and rotor-flux norm. The results of simulation validate that the power factor could be improved effectively, and the system has the satisfactory dynamic and static performance still. 12 Refs. In Chinese.
Key words: interconnection and damping assignment; passivity-based control; induction motor; efficiency optimization control; power factor; magnetic energy
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 26—30.

Study of common mode voltage suppression for induction motor driven by a three-level NPC converter
ZHONG Yu-lin, ZHAO Zheng-ming, BAI Hua
(Dept. of Elec. Eng., the State Key Lab of Power System, Tsinghua University, Beijing 100084, China）
Abstract: Common mode (CM) voltage and its related interference have become prominent in high power converters. This paper aims to reduce the CM voltage of an induction motor driven by a three level (3L) NPC converter using the combination of both algorithm modification and hardware modification. The tripling frequency-eliminating SHEPWM (Selected Harmonics Elimination PWM) technique has been utilized to eliminate the low order 3-times harmonics of the converter. And then the rest of the CM voltage is attenuated by a well-designed CM filter. A detailed analysis of the effect of the differential mode inductance imbalance on CM voltage is given. Both experimental and simulation results show that a very low CM voltage at the motor terminal is obtained, which verify the validity of the scheme proposed in this paper. 9 Refs. In Chinese.
Key words: SHEPWM; common mode voltage; three-level NPC inverter
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 31—34.

Study on high speed operation of sensorless PMSM drive system
LIU Kui, SUN Kai, HUANG Li-pei
(State Key Lab of Power Systems, Dept. of Electrical Engineering, Tsinghua Univ., Beijing 100084, China)
Abstract：Permanent magnet synchronous motor (PMSM) has been applied in more and more industrial drives during recent years, such as air condition compressors. During high speed operation of the PMSM-compressor system, the voltage transfer ratio of inverter is limited by using conventional space vector pulse width modulation (SVPWM) method, which results in the lower output torque of PMSM. Meanwhile, position sensor cannot be mounted in PMSM-compressor system because of the working environment. Based on these considerations, a speed/position identification algorithm based on model reference adaptive system (MRAS) is employed to estimate the rotor position as well as motor speed and a single mode over-modulation method is applied to control inverter. Thus, a sensorless over-modulation PMSM vector control system is realized. Simulation and experimental results demonstrate that, the sensorless PMSM-compressor system works stably at high speed range with enhanced output torque capability by using the employed seosorless control algorithm and over-modulation method. 6 Refs. In Chinese.
Key words: PMSM; air-condition; over-modulation; MRAS
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 35—39.

Computation of interconnects parasitic capacitance in VLSI using finite element derivative method
QU Hui¹, REN Zhuo-xiang², KONG Li¹
(1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
2. Mentor Graphics Corporation, USA)
Abstract: At the present stage of integrate circuit technologies, the critical dimension is far less than light wave length used in lithographic processes, and what we got is not what we designed in interconnects. One of the features is the nominally orthogonal structure becoming rounded. The precision of parasitic extraction faces challenges. This paper uses finite element method to compute the parasitic capacitances of IC interconnects based on the nominal geometry parameters, and uses the first derivative of unknown vectors to compute the capacitance sensitivities with respect to the geometry parameters susceptible to vary. The result of computation indicates that accurate parasitic capacitances of interconnect structure with process variation can be obtained by the method, moreover, the parasitic sensitivities to the process parameters provided by the method have higher precision than by traditional method. This is very useful in design.
Key words: VLSI parasitic extraction; sensitivity analysis; process variation
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 40—43.

Realization of multi-winding synchronous machine model by Matlab/SimPowerSystem
WANG Ning, ZHANG Xue-min, MEI Sheng-wei, WANG Guan-qun
(State Key Lab of Power Systems, Dept. of Elec. Eng., Tsinghua University, Beijing 100084, China)
Abstract: Special type electric machines are widely used in isolated power systems for the particular requirements, caused by such restrictions as weight, volume and harmonics. This fact leads to a large difference between the simulation of isolated power systems and the terrestrial ones appeared. This paper proposes a novel method for realizing the model of multi-winding synchronous generator based on the three-phase generator in MATLAB/ SimPowerSystem. This method utilizes the characteristics of magnetism coupling and can conveniently solve the simulation problem in a class of special type electric machines. Comparing with other realization methods, this method can sufficiently use the existing simulation methods, and makes the simulation work become more efficient and easy-operating.
Key words：multi-winding; magnetic coupling; SimPowerSystem
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 44—48.

Exact prediction of capacitive current for distribution network
ZHAO Jian-wen, HOU Yuan-bin
(Xi’an University of Science and Technology, Xi’an 710054, China)
Abstract: Existing schemes’ characteristics to measure capacitive current are analyzed in order to measure capacitive current of distribution network, and then to adjust arc-suppression coil for extingushing electric arc of single phase to earth. The new exact predication scheme of capacitive current is put forward, which is based on a resistance added single-phase line. Using this new method, single-phase ground fault capacitive current is predicted through examining zero sequence voltage and voltage of grounding resistance in normal running condition of distribution network. The intelligent capacitive current measurement device using this new method and DSP is designed. Validity of this new system is testified by giving a distribution network example. The results show that capacitive current, insulation resistance current, remains current, ect, and key parameters of single phase grounding fault can all be exactly predicted, that compensating state of system can be checked at the same time, using the discussed capacitive current prediction system, when distribution network is running normally. This new device is easier to operate, more accurate, more fast and more safe than other methods.
Key words: capacitive current; exact prediction; DSP; distribution network; single phase to earth; sequence network
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 49—53.

A stator flux weaken method for the induction motor
ZHANG Xing, QU Wen-long, LU Hai-feng, FAN Yang, CHENG Xiao-meng
(State Key Lab of Power Systems, Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: A method of stator flux weakening for the induction motor used in EVs is proposed. The determination of the operation region of the motor is firstly decided depending on the voltage of the DC bus supplied by the inverter and the stator voltage reference. The optimal exciting current can then be obtained which can output the maximum torque. Then the stator flux reference of considering the torque reference can be achieved. It does not need rotor field orientation and is suitable for the schemes in which the stator flux is controlled. This method can output the maximum torque under the voltage and current capacity of the converter and motor. The stator voltage reference is used to compare with the corresponding limited voltage, then different operation regions of the motor can be judged. The calculation is simple and the transition between different regions is smooth. The dynamic given torque limit can make the motor avoid over current in steady state. The effectiveness of the proposed method is verified by the simulation and experimental results. 10 Refs. In Chinese.
Key words: induction motor; indirect self control; stator flux weaken control; maximum torque output
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 54—57.

Fast-scale instabilities in boost PFC converters operating in discontinuous conduction mode
ZHANG Xiao-Tian, ZHANG Hao, MA Xi-Kui
 (School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, China)
Abstract: Asynchronous switching maps are derived to describe entirely the dynamics of Boost PFC converters operating in discontinuous current mode. Numerical simulations reveal that the fast-scale border collisions may occur within a line cycle and describe these nonlinear phenomena in detail in terms of the investigation of the critical phase angles of the circuit system operation mode switch. Furthermore, the influences of the fast-scale instabilities on switches and performance of the system are analyzed, and the stability region diagrams in parameter space are provided with the change of some important circuit parameters. Finally, experimental results verify that the system can exhibit fast-scale instable phenomena, and agree with the simulation results. All these results are very useful to the design of practical circuits. 8 Refs. In Chinese.
Key words: fast-scale instability; asynchronous switching map; boost PFC converter; discontinuous conduction mode (DCM); border collision bifurcation
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 58—62.

Numerical modeling of dielectric-barrier atmospheric pressure glow discharge in helium
LV Bo, WANG Xin-xin, LUO Hai-yun, LIANG Zhuo
(Department of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: Atmospheric pressure glow discharge in a 5-mm helium gap between two plane-parallel electrodes each covered by a 1-mm thick quartz plate was numerically simulated. One-dimensional and self-consistent fluid model of the discharge was established. The model is based on the electron and ion continuity and momentum transfer equations coupled to Poisson’s equation. The values of the physical coefficients involved in the equations as well as the initial conditions and the boundary conditions were carefully determined. Based on finite differential method and Newton iteration method, the equations were numerically solved. The calculated waveforms of the discharge current and the gas voltage agree well with the measured ones, indicating that the established physical model and the numerical methods are correct. The temporal and spatial distributions of the electric field, the electron density and the ion density look quite similar to that obtained in the glow discharge at low pressure, which confirms that the dielectric barrier discharge in helium at atmospheric pressure is really a glow discharge.
Key words: atmospheric pressure glow discharge in helium; dielectric-barrier; numerical modeling
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 63—67.

Analysis and research of switching-condition in Boost PFC circuit based on boundary conduction mode
LIN Guo-qing, CHEN Yun-hui
(Fuzhou University, Fuzhou 350002, China)
Abstract：Based on the analysis of switching characteristic in BCM-BOOST-PFC circuit, a novel method to solve the capacitive turn-on loss of the switch is proposed in the paper. By using the inherent delay time of universal PFC integrated control circuit and rightly selecting the resonant capacitor，the turn-on condition of zero-voltage or the lowest drain-source voltage for the main switch is obtained , which reduces the turn-on and turn-off loss and increases the circuit efficiency. The switching loss in BCM-BOOST-PFC circuit and the turn-on condition of zero-voltage or the lowest voltage under different input voltages are analyzed and the design considerations are given in details. The experiment measurements are used to verify the theoretical prediction and analytical discussion. 8 Refs. In Chinese.
Key words: boundary conduction mode; BOOST converter; PFC; soft-switching
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 68—71.

Influence of static negative sequence current in method of high-frequency signal injection and the strategy to cope with
　　　　  ZHONG Li-ping, WANG Chang-song, ZHOU Xiao-min, QI Xin
(Mechanical Eng. School, University of Science and Technology Beijing, Beijing 100083, China)
Abstract: Making use of the negative sequence component of high frequency current to estimate the rotor position of permanent-magnet-synchronous motor is what the method of high frequency voltage signal injection does. But the negative sequence current component is not only related to saliency-pole, the winding’s asymmetry can also result in negative sequence current component，which has nothing to do with the saliencies and can be called static-negative-sequence-current. Apparently this kind of negative sequence current component will give rise to errors to the estimation of position. This paper analyzed the reason the asymmetry occurred and the effects it made, and a kind of measures to eliminate the static-negative-sequence-current is also presented. The experimental results indicated that all the solutions worked well.
Key words: high-frequency-signal; static-negative-sequence-component; asymmetry
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 72—75.

Study on special power supply for streamer-discharging FGD
　　　　　　　　  SUN Ping-ping, JIANG Xue-dong
(School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China)
Abstract: In order to accelerate the industrial application of streamer discharging FGD, a high reliable AC+DC power supply is designed, which can replace the traditional pulse generator with spark-gap switches. The power supply includes AC-DC-AC converter, full-bridge diode rectifier and series resonant circuit. The principle of series resonant part is analyzed in detail, providing the experiment parameters. The optimal resonant condition can be obtained by changing resonant inductance. A transition from streamer discharge to spark discharge happens to the reactor by increasing its voltage amplitude. The theoretical analysis and the reliability of the power supply are verified according to these experiment waveforms.
Key words: streamer discharge; FGD; AC+DC; series resonance
 // Adv. Tech. of Elec. Eng. & Energy, 2008, 27(3). 76—80.