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The harmonic and reactive current detection and analysis is a prerequisite to achieve the control of power quality, the accurate detection of harmonic and reactive current can provide a good basis for harmonic control. this paper proposes an improved harmonic and reactive-power current detection technique based on the fuzzy controller method combined with particle swarm optimization (PSO) for the...
On the application of a shunt active power filter (SAPF), the detection accuracy of harmonics is a vital factor to judge the performance of the SAPF, which is indeed strongly depended on the veracity of software phase-locked loop (SPLL). However, phase jump, frequency variation and harmonic accompanied with the voltage sags usually impact the dynamic response and accuracy of SPLL. In this paper, a...
Shunt active power filter (APF), as parallel part of unified power quality modulation (UPQC), has been proved as a flexible solution for compensating the harmonic distortion caused by nonlinear loads in power distribution power systems. Digital repetitive control can achieve zero steady-state tracking error of any periodic signal under the sampling points within one repetitive cycle that must be a...
Asymmetric voltage sag occurs in the actual operation of the power grid, and the negative sequence component of the voltage will result in the output power fluctuation and the three-phase current distortion. At the same time, the decrease of voltage amplitude will make the peak value of the output current increased, and then bring the safety hazard to the PV system. A control strategy based on the...
This paper presents an improved direct power control (DPC) strategy based on sliding mode control (SMC) with dual-closed-loop for the Vienna-type rectifiers to improve dynamic response during both start-up and load step change periods and guarantee better performances in steady state. The SMC based DPC methodology can directly regulate the instantaneous active and reactive powers without transforming...
This paper presents an improved nonlinear voltage outer-loop and current inner-loop control scheme for three phase Vienna-type rectifier, which adopted the sliding mode controller (SMC) for the outer dc voltage loop and utilized the predictive current controller (PCC) for the current inner-loop. Compared with the conventional PI, the SMC can highly enhance the dynamic performance and robustness of...
This paper presents a simplified SVM for Vienna-type rectifier which is based on the space vector modular of a three-level converter into a two-level converter, the dwelling time calculation and switching sequence selection are easily done like conventional two-level rectifier, which is discussed in detail in this paper. Meanwhile, based on inherent correlation between carrier-based PWM and SVM for...
In this paper a nonlinear predictive control using optimal control is applied to the current control of a three-phase four-wire shunt active power filter. The control law has closed analytical form and on-line dynamic optimization is avoided, the control law is easy to implement. Three phase currents are sensed and then transformed to synchronous rotating reference frame, positive and negative load...
In this paper, a novel three-phase buck PFC converter based on one-cycle control is presented. With the one-cycle control, compared with the traditional direct current control, no need to detect the input and output voltage of the converter, the voltage sensors and the multiplier in the control loop are eliminated. The control circuit is simple, fast response, high precision and low cost. In addition,...
With the development of electronic technology, multi-output power supplies with different output voltage levels and load capacities are required, and using multi-output DC/DC converters is an effective and economical method. In this paper, the cross regulation of multi-output converters is analyzed in theory, and the coupling relations of different outputs are also deduced, and then a kind of post...
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