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Customers may have different power quality requirements, thus, the economic operational strategy can try to provide them with distinctive quality levels as customized service. An optimization based method is proposed in this paper to realize this functionality, offering the possibility that the customers can flexibly set and adjust their requirements. Converter interfaced distributed generators are...
Shunt active power filters (SAPF) generally compensate harmonic current of centralized non-linear loads, which may cause undesired economical burden for networks with distributed harmonic sources. This paper proposed an SAPF predictive control method based on online impedance measurement which can suppress the network-wide harmonics systematically in an optimized way.
Harmonic power sharing and PCC voltage quality are both important issues for the power quality of islanded microgrids. This paper proposes a new control scheme to deal with those two issues based on controlling the equivalent harmonic impedance of DGs. With the proposed control scheme, harmonic power is shared according to remaining power capacities of DGs and PCC voltage harmonics are effectively...
The authors of this paper suggest a mathematical model of a vessel diesel-generator installation meeting in larger extent the specific properties of such system and its application. A distinctive feature of the method under consideration is the use of the synchronous generator itself as a precise multifunctional sensor of the diagnostic information. The paper is also presenting the results of practical...
The problem of input saturation in linear-quadratic-gaussian (LQG) control of a single-phase converter with LCL filter is addressed by design of an anti-windup compensator. Since the full state is not directly observed, a Kalman filter observer has been designed. Performance of the proposed control is illustrated on simulation examples under ideal sinusoidal source and source with additional harmonics.
This paper presents a design and an implementation of inverters with ultra-low total harmonic distortion (THD) under all kinds of loads. In this study, the ultra-low THD objective is achieved by combining the advantages of the repetitive controller, the predictive-PID controller and the reference signal feedforwarding method in a multi-loop structure. The high performance uninterruptible power supply...
In this paper a dual DC/DC/AC inverter with discrete non-stationary state feedback controller is presented. Neural network based control algorithm is proposed to optimal control of PMSM drive. The considered converter topology and designed control structure with discrete state feedback controllers significantly reduces the harmonics content in phase currents.
It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation. The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added...
This paper presents a new modulation concept for three-to-single-phase direct AC/AC modular multi-level converter-based railway interties. The concept minimizes the inherent harmonic coupling between the two grid sides and is therefore particularly suited to operation at very low cell numbers and switching frequencies. Moreover, it facilitates the use of specific modulation methods, such as optimized...
The paper addresses the problem of fault detection in an unbalanced microgrid with distributed generators, using algorithms based on harmonic estimation: Wavelet Transform (WT), Fast Fourier Transform (FFT) and Reduced Fast Fourier Transform (RFFT). Simulations were carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with distributed generation was used. Experimental...
This paper presents the method of current higher harmonics control for grid connected power electronic converter by means of a digital comb filter application. The proposed method provides multiple harmonics compensation and simple implementation. The Proportional-Resonant (PR) control was complemented with appropriately tuned comb filter which resulted in reduced mitigation of output current harmonics...
A strategy for voltage harmonics suppression is proposed to upgrade existing grid-connected inverters. It utilizes the already available measurement of the voltage at the point of common connection and the inverter output current. As a result, on top of conventional power injection, the inverter is equipped with an additional feature for harmonics compensation. Model analysis, simulation and experiments...
A Lyapunov approach based homogeneous higher order SM-Controller (HOSMC) is considered here, for grid connected three phases three wires shunt active filter (SAF) via LCL filter. This nonlinear controller is an alternative solution to overcome phase shift caused by a linear controller and a chattering effect caused by a 1st order sliding mode controller that is supposed to be of relative degree 1...
In this paper, a self-adaptive resonance frequency tracking method is presented. The resonance frequency tracking is used in a LCL-filter-based active power filter to adapt the frequency of the notch filter applied for active resonance damping. By determining the resonance frequency of the LCL-filter and adapting the notch filter frequency, the bandwidth of the notch filter can be decreased, whereby...
The aim of this paper is to investigate the implementation of an adaptive generalized delayed signal cancellation (DSC) method for estimation of phase-sequence components. The proposed approach overcomes the intrinsic problems of the digital implementation of the classical DSC algorithm due to nonideal selection of the sampling frequency and variations in the nominal system frequency. The derived...
In this paper, a drive scheme generating 24-sided polygonal voltage space vector structure using an inverter topology with single DC source is proposed. A 24-sided structure eliminates dominant low order phase voltage harmonics including and up to seventeenth and nineteenth orders throughout the speed range including step operation. The power circuit has a two-level inverter and two low voltage cascaded...
The future of distribution networks tends more and more to include computational power, embedded intelligence and smart metering on the high voltage level as well as the low voltage micro-grids. Several hardware solutions were developed to implement the so-called smart grids with measurement devices delivering data about the state of networks on various levels. This work introduces the use of a specific...
The objective of this project is the performance optimization of an electrical drive system, which consists of a two-level Voltage Source Inverter (VSI) and a Permanent Magnet Synchronous Motor (PMSM) with high magnetic anisotropy. To this end, the concept of Synchronous Optimal Modulation (SOPWM) is employed for inverter control and the optimal inverter switching angles are defined for an isotropic...
The paper examines application of wavelet transform for voltage dips detection in microgrids with distributed generation. IEEE13 test grid with added 1.6 MW distribution generators is used for evaluation. Distribution generators are two 0.8 MW doubly-fed induction generators. Matlab/Simulink environment is used for modelling and evaluation of proposed algorithm for voltage dips detection. Six types...
This paper proposes a new commutation approach for direct converters with bidirectional switches based on UCE-measurement and verifies the applicability with a commutation scheme for V-connection AC choppers. The practicability is proven experimentally and the current and voltage quality of the one-step commutation is compared with the two-step commutation approach.
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