According to the method based on linear sinusoid tracer of adaptive theory for active power filter, there was contradiction between detecting accuracy and dynamic response. And the error in the algorithm was affected by the high order-harmonics, so this system couldn't detect harmonic current accurately. Based on the analysis above, a method based on improved sinusoid tracer of adaptive theory was presented, h the introduction of the low-pass filter to solve the problem. Fist we discussed the stability of improved system. Then theoretical analysis and simulation test show that the algorithm was provided with characteristic of narrow-band. Therefore the improved system can get rid of the contradiction between detecting accuracy and dynamic response.

为了提高电源的精度和稳定性,设计了一种以DSP为核心的智能化精密稳流电源。介绍了精密稳流电源的构成及其控制方式,采用DSP实现稳流控制,使输出电流稳定、精度高,且兼备过流、过压保护功能,改善了电源的性能。通过仿真及实验验证了系统电路简单、调整方便、控制精度高、稳定性好、纹波系数小等优点,特别适用于各种有较高精度要求的场合。

An adaptive notch filter is presented to estimate the fundamental frequency and measure both harmonics and interharmonics of an almost periodic signal with unknown time-variant fundamental frequency, which has the robustness that the convergence speed is determined by neither amplitude nor frequency of fundamental component. The algorithm forms a one-dimensional slow adaptive integral manifold whose existence and stability are proved by averaging method and Lyapunov stability theorem. The local exponential stability and the ultimate boundedness of fundamental frequency estimation are proved. The local exponential stability makes sure that the fundamental frequency, the harmonic and interharmonic components can be all fast tracked. The principle for adjusting the parameters with their influences on transient and steady-state performance is investigated and decreasing parameters can improve noise characteristic. The validity is verified by simulation results.

The poloidal field (PF) converter belongs to the critical systems of ITER, thus its reliability and availability should maintain a high state through the two decades operation life of ITER. This paper is aiming at improving these two abilities with the RAMI (Reliability, Availability, Maintainability and Inspectability) analysis method. The system functional breakdown is performed at first, then the reliability model is established based on it. The initial reliability and availability of the PF converter is obtained by analysing this model. Finally, by improving the reliability and availability of subsystems, the scheme of the PF converter satisfied the requirements of ITER.

A novel scheme based on multipulse technology was proposed for PV system with high voltage and large capacity. The power conversion of PV system is divided into two stages, i.e. DC/DC power conversion and DC/AC power conversion. In DC/DC stage, many power units are connected in parallel, each one of which includes a PV array and an interleaved boost converter that controlled by multipulse technology of carrier phase-phifting. The DC/AC power conversion is equivalent to a voltage source in series with a current source. Square wave inverters together with transformers are employed for the voltage source, which is controlled by multipulse technology of square wave superposition. PWM inverters are employed for the current source. The simulated results show excellent performance of a high-voltage large-capacity PV system that adopts the proposed scheme.

The efficiency, power quality, and reliability of renewable energy power conversion systems are key factors for future industrial applications. This paper presents a novel scheme to improve the performances of high-voltage large-capacity photovoltaic (PV) power stations. The power conversion of the PV system is divided into two stages, i.e., dc/dc power conversion and dc/ac power conversion. In the dc/dc stage, many power units are connected in parallel, each one of which includes a PV array and a nonisolated dc/dc converter. The dc/ac power conversion is equivalent to a voltage source in series with a current source. Square wave converters, together with transformers, are employed for the voltage source, which is based on the multipulse technology of square wave superposition. Pulsewidth-modulated converters are employed for the current source. Simulated waveforms with a whole 10-MVA/10-kV PV system are shown, and experimental results with a 100-kVA/1-kV dc/ac prototype are displayed.

高校特色专业建设工作是教育部、财政部实施"高等学校本科教学质量与教学改革工程"的重要组成部分。电气工程及其自动化专业是合肥工业大学的国家级特色专业,为进一步提升本专业的教学质量,增加毕业生的就业竞争力,本专业依照教育部"质量工程"的要求,明确建设方案,通过近两年来专业全体教师的团队合作和努力工作,电气工程及其自动化特色专业建设已取得了一些进步。

A nonlinear system being composed of multiadaptive notch filters in parallel is introduced to track the sinusoidal components of an almost periodic signal and estimate their frequencies and amplitudes. An almost periodic nonlinear dynamic system for estimation of frequencies is achieved after the existence of a slow integral manifold is proved and results in a nonlinear autonomous system with averaging method employed. Three types of local stability of the autonomous system, the exponential stability in isolated equilibrium point and the semistability on center manifold and the ultimate boundedness under unknown periodic disturbance, are respectively investigated. The transient performance is affected by frequency adaptive gain independent of bandwidth parameter. The validity of the proposed algorithm is verified by simulation results.

This paper put forward a novel grid connection method of three-phased PV inverter by analyzing the principle and vector composition of voltage space vector based on the model of asynchronous machine, in which the synthetically control scheme of grid voltage controller and current PI controller addicted with flexible unit under two phase synchronous rotating frame is proposed, a compacted hardware and software phase locking method is developed. The flexible unit can make amplitudes of currents increasing softly to achieve soft starting. Finally, experimental results obtained from a 6kVA inverter prototype are presented to verify the viability and effectiveness of the proposed method.

The high negative voltage power supply for the ECRH (Electron Cyclotron Resonance Heating) is a key component of the cyclotron. This system is the nonlinear system with the high requirements on static and dynamic performance. It is difficult to control well using traditional PID controller, so a new intelligent method is adopted to turn PID parameters base on RBF Network. Simulation results show that the system has good dynamic and static performance. The steady-state accuracy is less than 0.3%, adjustment time is less than 200μs. And the system has strong robustness and adaptive capacity based on RBF.

The negative high-voltage pulse power supply for the electron cyclotron resonance heating (ECRH) is a key support to the cyclotron’s functioning and good performance is highly required.The principle of operation was analyzed and the model was given.According to the nonlinear characteristics of tetrode and the supply’s control requirements,fuzzy control theory based on integral-separate was adopted,which combined intelligent control with power technology.Simulation results show that this system has good overshot-restrained,self-adaptive and auto-negotiating abilities using this method in comparison with PID method.This is a good new control and will be benefit to digital control intelligently.

Neutral-point (NP) voltage drift is the main technical drawback of NP-clamped (NPC) three-level inverters. Traditional space vector pulsewidth modulation (SVPWM) is incapable of controlling the NP voltage for high modulation indexes and low power factors. Virtual SVPWM (VSVPWM) is capable of controlling the NP voltage under full modulation indexes and full power factors. However, this modulation strategy is more complex than SVPWM, increases the switching frequency, and deteriorates the output waveforms of the inverter. A novel PWM concept that includes NP voltage-balancing conditions is proposed. Based on this concept, a hybrid modulation scheme that uses both SVPWM and VSVPWM is presented for complete control of the NP voltage in NPC three-level inverters. The performance of this new modulation approach and its benefits over SVPWM and VSVPWM are verified by simulation and experiments.

A novel modulating method of two-stage matrix converter, which is based on dual space vector and dual carrier modulation, is proposed in this paper. The harmonics of input current and output voltage impacted by the carrier of rectifier and inverter is discussed. The relation of THD of input current and output voltage and carrier frequency of rectifier and inverter is given, which makes known that if the carrier frequency of inverter is equal to the carrier frequency of rectifier or the multiple of the carrier frequency of rectifier, the THD of input current and output voltage will be maximal. It is indicated that if carrier frequency of rectifier and carrier frequency of inverter are selected properly, the harmonics of input current and output voltage will be least.

This paper presents a constant-current power supply for HB-LED(High Brightness LED). The proposed power supply is designed and implemented by adopting a flyback converter with primary side control and without galvanic isolation. Based on discontinuous conduction mode (DCM), the flyback converter has constant average output current when the peak current on the transformer primary side and the ratio of t'off to TS are constant. A laboratory prototype based on UC3843 PWM controller has been built and tested. Laboratory experimental results from a 12.6W prototype are given to verify the validity and effectiveness. The converter meets the performance requirements of HB-LED driver with ±3% current accuracy in the wide output voltage range.

电气工程及其自动化专业是传统的电工学科,具有显著的工程技术特色。实践教学作为该专业教学体系的重要组成部分,对于培养本专业大学生的实践能力和创新精神、提高其综合素质具有至关重要的影响。为不断提升本专业实践教学质量,本专业一直致力于实践教学改革,以教师队伍的科研成果促进实验室实验教学设备的改进,大力培养实践教学队伍,并按电气工程及其自动化专业的特点构建了课程实验和综合实验、课程设计、毕业实习和毕业设计四个层次的实践教学架构,并取得了良好的效果。

This paper develops mathematics model of SVPWM-based current controller for three-phased grid-connected in-verter and a novel current scheme under two phase synchronous rotating frame is presented,which is combination of grid feed forward controller and PI controller.A kind of software phase-locked and dual-timer sampling scheme which decreases the control delay is proposed.Finally,a laboratory prototype is designed to verify the discussion and analysis.The experi-mental results show that the proposed scheme has very good dynamic and static properties,meanwhile,highly accurate steady output and less harmonic disturbance is gained.

A normalized frequency adaptive comb filter composed of a number of normalized frequency estimators in parallel is proposed to track unknown frequency and unknown amplitude of each component of an almost periodic signal. The filter consists of two coupled nonlinear differential equations respectively for updating frequencies and estimating state variables. A nonlinear autonomous equation for frequency estimation is deduced after average method is applied to the almost periodic dynamic system resulting from system decoupling by slow integral manifold. Three kinds of local stability of the autonomous system:the exponential stability of isolated equilibrium point,the semistability on center manifold,and the robustness under unknown periodic disturbance are proved. The convergence and the boundedness of amplitude estimation and signal tracking as well as the effect of parameters on the transient and steady-state performance of frequency and amplitude are investigated. Each sinusoidal component and its amplitude are accurately tracked on the condition of given intervals instead of the values of frequencies. The response speed is independent of the component amplitude. Simulation results reveal the validity of the proposed algorithm.

Transmission loadability is decided by thermal and protective constraints. In stressed states, such as voltage depression, the relay loadability may replace the thermal loadability, leading to undesirable relay operation and cascading events. In this paper, the operation margins of overload, overcurrent, and underimpedance constraints are quantified. The sensitivity model of the transmission loadability to the bus voltages and the field currents is newly proposed. Numerical results show that: 1) both overexcitation and reinforced excitation control may contribute to undesirable relay operation; 2) overload and underimpedance constraints may over- or underestimate the thermal loadability under voltage depression; and 3) relay loadability is dependent on the protection schemes and the relay settings.

As the extensive multi-level inverter's application, the loss problem of electrical semiconductor has been regarded more and more. The research on loss of switch semiconductor is not only the precondition of heighten efficiency, it also is chief condition of running safety. Three-level inverter has many switches, and the conduction and switch mode is complex, so loss analysis is more difficult than that in two-level inverter. Basic on analyzing conduction and switch mode of three-level inverter, using loss characteristic parameter of semiconductor, this paper calculats the conduction loss and switch loss of the inverter under SPWM modulation strategy and presents the loss surface for modulation index and power angle of the modulation strategy, and makes loss analysis on other modulation strategies, testifies the validity of this loss calculated method by experiment at last. Loss modes and conclusion given by this paper establish foundation for further research on reducing loss.

The traditional rectifiers have very low power factor and pollute the grid seriously due to the use of nonlinear components and effect of output filter capacitance.With the concern on grid pollution increasing,more and more researches focus on power factor correction.Among the three-phase power-factor correction circuits,the full decoupling circuit is especially suitable for high power fields because of its high input power and good electrical performance.This paper analyses PWM Boost rectifier which is the typical circuit of decoupling circuits,and introduces the math model of it.A novel control algorithm for vector calculating is proposed.The new control algorithm doesn't need sine table and occupies less system resource.So it can improve the accuracy of switching vector and reduce the calculating time.And the new control algorithm is verified experimentally on a 1 kW 10 kHz three-phase Boost rectifier.