Direct Voltage Control Method Research Articles

Speed sensorless direct voltage control of brushless doubly-fed machine independent generation system based on improved particle swarm optimization algorithm

The speed information is obtained by sensors in the control strategy of brushless doubly-fed machine (BDFM) independent power generation system. However, the use of sensors increases the hardware cost of the system, reduces the reliability and the sensors are difficult to adapt to the harsh environment such as high temperature and high humidity. In order to solve the above problems, a speed sensorless direct voltage control method for brushless doubly-fed machine independent generation system is proposed. At the same time, in order to improve the control quality, the improved particle swarm optimization algorithm is used to optimize the control parameters of the system. Simulation results show that the BDFM independent power generation system can still maintain excellent performance and can meet the performance requirements in various operating conditions with the control method proposed in this paper.

Improving voltage of remote connection using wind‐solar farms equipped with new voltage control strategy based on virtual impedance monitoring enabled by IEC 61850 communication

This study explores how the voltage control of a remote part of the utility gird can be improved using more sophisticated voltage control on wind-solar farms equipped with fast communication platforms. The idea is to make renewable plant the master voltage controller during large disturbance events in the grid. This is done by proposing an enhanced voltage droop control strategy based on instantaneous reactive power consumption by monitoring the virtual impedance of the point of connection using a new customised data class model of IEC 61850 communication protocol. The conventional centralised voltage droop control strategy and the proposed instantaneous direct voltage control method are both implemented on the White Rock Solar Wind Farm in NSW, Australia and their performances are compared using both MATLAB Simulink simulations under 5% voltage step disturbances, single-phase-to-ground and three-phase-to-ground faults as well as some tests conducted in the field.

Current Sensorless MTPA Operation of Interior PMSM Drives for Vehicular Applications

This paper presents a direct voltage control method for interior permanent magnet synchronous motors (IPMSMs) with a single speed regulator. The method achieves maximum torque per ampere (MTPA) operation by controlling the magnitude and the angle of the voltage vector. For that, the mathematical model for the MTPA trajectory of the IPMSM is derived in the voltage plane. As such, no current sensor is needed, which makes the proposed strategy tolerant to current sensors failure unlike cascaded control loop based methodologies. Although no current sensor is used, the control strategy tracks MTPA trajectory by taking into account both voltage and current limits of the machine. The complete MTPA derivation in the voltage plane is presented in this paper; but, only the final solution is needed for real-time implementation. Henceforth, the simplicity of the control scheme combined with its current sensor dependence free characteristics make it a good candidate for real-time implementation in vehicular applications. The concept is developed and evaluated experimentally on a 10-HP IPMSM.

Current Sensorless MTPA for IPMSM Drives

In this paper, a maximum torque per ampere (MTPA) control strategy is presented for interior permanent magnet synchronous machines (IPMSMs) without current sensing or regulation. The developed control scheme achieves MTPA using a direct voltage control method, which varies the machine's stator voltage amplitude and angle. As such, no explicit current loop regulation is needed, which simplifies the control structure and unlike other control strategies, no parameter knowledge, voltage, or current transducer is required. Experimental comparison against the well-known MTPA vector control highlights the performance of the proposed controller in various conditions. Moreover, quantitative efficiency metrics are provided to better illustrate the MTPA trajectory tracking performance. Furthermore, the simplicity of the control scheme makes it a good candidate for low-cost implementation of real-time IPMSM drives.

Direct Voltage Control of Dual-Stator Brushless Doubly Fed Induction Generator for Stand-Alone Wind Energy Conversion Systems

This paper presents a dual-stator brushless doubly fed induction generator-based stand-alone wind energy conversion system (DSBDFIG-SA-WECS). With the advantages of compact structure, high reliability, and low cost, the DSBDFIG-SA-WECS shows great potential in wind energy applications. Based on the traditional stator-flux-oriented control (SFOC), an improved direct voltage control (DVC) is proposed for stand-alone operation. Performance analysis is carried out to evaluate SFOC and DVC in the aspects of control objects, orientation, feedback, and parameters involved. The DVC method is simple, robust, and cost-effective with the outer stator current sensors eliminated, and there are no extra parameters involved that the control performance can be enhanced. Fair comparisons are made in simulation to demonstrate better performance of the proposed DVC, and the effectiveness of DVC is further validated by experiment under variable speed condition.

A novel voltage and frequency controller for standalone DFIG based Wind Energy Conversion System

This paper presents a new speed-sensorless control strategy for a stand-alone doubly-fed induction generator supplying energy to an isolated load. The method is based on the root mean square (rms) detection scheme. The generated stator voltage is controlled via rotor currents. Amplitude of stator voltage and its frequency are controlled simultaneously. The output signals from the voltage controllers are the reference signals for the rotor current amplitude and frequency of the stator voltage is regulated with the help of frequency control loop. This developed direct voltage control method is applicable for both the balanced and unbalanced load and also for standalone and grid connected mode. The control pulses for the rotor side converter is supplied by the hysteresis controller which is operated on the error signal calculated between actual and reference rotor currents. This paper also provides the brief idea about the voltage and frequency control on modern Autonomous DFIG based Wind Energy Systems via single phase mathematical model of standalone DFIG system. A short state-of-the-art review on mechanical position/speed sensorless control schemes for autonomous DFIG based WESs is presented, which helps the present researcher and students working in this area. These include stator flux oriented control techniques; direct voltage control techniques; MARS observer based techniques for autonomous DFIG-based variable-speed WESs. Simulation results obtained from a 2MVA DFIG system, prototype in MATLab/Simulink, are presented and discussed in this paper.