Wind energy has drawn worldwide attention. Because of simple structure, high efficiency, stable operation and other inherent advantages, variable speed constant frequency (VSCF) direct-drive wind power generation system using permanent magnetic synchronous generator(PMSG) is the development trend and one of the focuses of wind power generation system, on which this paper researches through its converter's topological. To be the interface between PMSG and the grid, typical converter topology structure of direct-driven wind power system with PMSG are analyzed, including the diode rectifier + DC to DC converter + inverter, and the back to back double PWM converter. The topological characteristics and applications of some high-voltage, high-power converters are introduced in detail, including Diode-clamped multi-level converter, Cascaded H-bridge multilevel converter and Flyingcapacitor multilevel converter. Their implementations, working principles, advantages and disadvantages are discussed and compared. Judging from the current situation, for the advantages of low-cost and simple control strategy, diodeclamped three-level PWM converter is the hot spot of current converting technique study for direct-driven wind power system.

Analysis of converter topological structure for direct-drive wind power system with PMSG

In order to reduce the speed overshoot of the traditional PI speed controller in direct drive permanent magnet synchronous motor(DD-PMSM), a novel speed controller is presented in this paper. In addition, a reduced-order load torque observer is proposed to reduce the effect of load torque changes and other disturbance factors on the system performances. The observed torque is imported to the input of q-axis current regulator, which is used as the signal compensating for the output reference current of the novel speed controller. Simulation and experimental results show that the speed overshoot can be reduced and the speed response could be improved by adopting the designed novel speed controller. It is also demonstrated that the capacity of anti-load torque disturbance can be improved significantly with the feed-forward compensation. Therefore, the validity and effectiveness of the proposed novel speed controller based on reduced order load torque observer are verified.

Design of a novel speed controller for direct-drive permanent magnet synchronous motor based on reduced-order load torque observer

This paper presents a survey of recent approaches which addresses solutions for current harmonic reduction in three phase three wire systems. The analyzed works are the most representative solutions focused in to obtain unity power factor in the mains or to fulfil the regulations that are applied, the main comparison is done between shunt active power filters and PWM rectifiers. The revised solutions are varied and a classification according to their operating principle, input currents and output power is done. The main objective is to identify the areas of application of each solution in particular.

Shunt active power filters and PWM rectifiers in three-phase three wire systems: a survey

In this paper, an enhanced control scheme for a pulse-width-modulated (PWM) voltage source converter (VSC) is proposed for a DC zonal shipboard power system (SPS). First, the main design parameters of VSC such as switching frequency and DC-link capacitance are investigated and optimized for the SPS application. Then, the nonideal operating conditions such as sudden load change, sudden supply voltage change, and unbalanced supply voltage are considered. To address these issues, the VSC control strategy has been enhanced by (i) adopting a different PWM strategy that changes the carrier frequency under nonideal operating conditions, (ii) adding a negative-sequence controller, and (iii) implementing an instantaneous phase locked loop (PLL). The results show that the proposed controller shows indeed a satisfactory performance for this specific application and it can also operate at unity displacement power factor under nonideal conditions.

Enhanced Control of Voltage Source Converters for DC Shipboard Power

This paper discuss about the H∞control strategy for DC converter in the energy recovery from landing aircraft. The energy from landing aircraft can be changed to electrical energy by using several power electronics converters combine with the linear generator. To have this effect the controllers must able to control the mechanical and electrical outputs. The mechanical outputs are such as the force, speed of the linear generator while the electrical outputs are the voltage and current. By using the H∞ control strategy at the specific location especially at the converter side it hopes that all the outputs stated above can be controlled. The goals for this paper are to maintain the dc voltage value at the converter and to have constant deceleration speed and force at the linear generator in order to change the kinetic energy from landing aircraft to electrical energy. All the models and the simulations have been done in MATLAB software package.

The DC converter control for deceleration profile in energy recovery from landing aircraft

In general, power electric device is fed by AC/DC rectifier rather than by direct DC source and the inherent default of the rectifier has more bad influence on the power network. As a result, the PWM-rectifier has been paid more and more attention for unity input power factor, greatly reduced input line current harmonic distortion and bidirectional power flow capability. The paper present the topology of the main circuit, deduce the math model both in a-b-c and a - /spl beta/ reference frame, propose the direct current control scheme, get the current and voltage waveform and analyze the result of simulation which is processed by SIMULINK software on the base of math model.

The investigation of PWM rectifier control method

Active-Disturbance Rejection Controller for Permanent Magnet Motor Drive System Control Based on Load Observer

The traditional hydraulic excavator has some questions, so as energy waste, Environmental pollution. In this paper, The control strategy of Oil-electric hybrid excavator presented swing mechanism brake energy recovery system is investigated. Permanent magnet synchronous motor feedback system moving process was analyzed. The control strategy is verified, the results show that the scheme can effectively recover braking energy excavator and high energy conversion efficiency.

http://ieeexplore.ieee.org/iel7/7140653/7161655/07161942.pdf

Wang Hui

Papers

The investigation of PWM rectifier control method

Active-Disturbance Rejection Controller for Permanent Magnet Motor Drive System Control Based on Load Observer

Research on energy management for the swing system of hybrid excavator