Proportionalresonant controllers and filters for gridconnected voltagesource converters
01 Jan 2006-Vol. 153, Iss: 5, pp 750-762
About: The article was published on 2006-01-01 and is currently open access. It has received 583 citations till now. The article focuses on the topics: Converters.
Citations
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TL;DR: A new multiresonant frequency-adaptive synchronization method for grid-connected power converters that allows estimating not only the positive- and negative-sequence components of the power signal at the fundamental frequency but also other sequence components at other harmonic frequencies is presented.
Abstract: This paper presents a new multiresonant frequency-adaptive synchronization method for grid-connected power converters that allows estimating not only the positive- and negative-sequence components of the power signal at the fundamental frequency but also other sequence components at other harmonic frequencies. The proposed system is called MSOGI-FLL since it is based on both a harmonic decoupling network consisting of multiple second-order generalized integrators (MSOGIs) and a frequency-locked loop (FLL), which makes the system frequency adaptive. In this paper, the MSOGI-FLL is analyzed for single- and three-phase applications, deducing some key expressions regarding its stability and tuning. Moreover, the performance of the MSOGI-FLL is evaluated by both simulations and experiments to show its capability for detecting different harmonic components in a highly polluted grid scenario.
950 citations
TL;DR: A new grid synchronization method for three-phase three-wire networks, namely dual second-order generalized integrator (SOGI) frequency-locked loop, based on two adaptive filters, is presented, able to perform an excellent estimation of the instantaneous symmetrical components of the grid voltage under unbalanced and distorted grid conditions.
Abstract: Grid synchronization algorithms are of great importance in the control of grid-connected power converters, as fast and accurate detection of the grid voltage parameters is crucial in order to implement stable control strategies under generic grid conditions. This paper presents a new grid synchronization method for three-phase three-wire networks, namely dual second-order generalized integrator (SOGI) frequency-locked loop. The method is based on two adaptive filters, implemented by using a SOGI on the stationary αβ reference frame, and it is able to perform an excellent estimation of the instantaneous symmetrical components of the grid voltage under unbalanced and distorted grid conditions. This paper analyzes the performance of the proposed synchronization method including different design issues. Moreover, the behavior of the method for synchronizing with highly unbalanced grid is proven by means of simulation and experimental results, demonstrating its excellent performance.
620 citations
Cites background from "Proportionalresonant controllers an..."
...The GI is the base of proportional-resonant controllers [32]– [35], and it can be applied both to AF and PLL implementations...
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TL;DR: The modeling, control design, and stability analysis of parallel-connected three-phase VSIs are derived and a hierarchical control scheme for the paralleled VSI system control architecture is developed.
Abstract: Power-electronics-based microgrids (MGs) consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel-connected three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs are based on the stationary reference frame. A hierarchical control scheme for the paralleled VSI system is developed comprising two levels. The primary control includes the droop method and the virtual impedance loops, in order to share active and reactive powers. The secondary control restores the frequency and amplitude deviations produced by the primary control. Also, a synchronization algorithm is presented in order to connect the MG to the grid. Experimental results are provided to validate the performance and robustness of the parallel VSI system control architecture.
610 citations
Cites background or methods from "Proportionalresonant controllers an..."
...Based on the abc/coordinate transformation principle, a three-phase system can be modeled in two independent single-phase systems [4]....
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...Voltage source inverters (VSIs) are often used as a power electronics interface; hence, the control of parallel VSIs forming a MG has been investigated in recent years [1-9]....
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...This LCL filter may exhibit a critically unstable response when trying to control the output current with the inverter voltage, as can be deduced from its transfer function [4]....
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TL;DR: This paper concentrates on the design, control, and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate for harmonic currents produced by nonlinear loads in a three-phase three-wire power system.
Abstract: This paper concentrates on the design, control, and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate for harmonic currents produced by nonlinear loads in a three-phase three-wire power system. With an LCL filter added at its output, the proposed SAPF offers superior switching harmonic suppression using much reduced passive filtering elements. Its output currents thus have high slew rate for tracking the targeted reference closely. Smaller inductance of the LCL filter also means smaller harmonic voltage drop across the passive output filter, which in turn minimizes the possibility of overmodulation, particularly for cases where high modulation index is desired. These advantages, together with overall system stability, are guaranteed only through proper consideration of critical design and control issues, like the selection of LCL parameters, interactions between resonance damping and harmonic compensation, bandwidth design of the closed-loop system, and active damping implementation with fewer current sensors. These described design concerns, together with their generalized design procedure, are applied to an analytical example, and eventually verified by both simulation and experimental results.
509 citations
Cites background from "Proportionalresonant controllers an..."
...This is explained in [27], where it is shown that a resonant controller in the synchronous frame is more effective, since it represents two equivalent resonant terms in the stationary frame for compensating two harmonics....
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...Other details on the discretization and optimization of the resonant controllers can be found in [27], [28], and are therefore not explicitly elaborated here....
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TL;DR: An exhaustive study about different discrete-time implementations of resonant controllers, extending to the discretization of the schemes with delay compensation, which is proved to be of great importance in relation with their performance.
Abstract: Resonant controllers have gained significant importance in recent years in multiple applications. Because of their high selectivity, their performance is very dependent on the accuracy of the resonant frequency. An exhaustive study about different discrete-time implementations is contributed in this paper. Some methods, such as the popular ones based on two integrators, cause that the resonant peaks differ from expected. Such inaccuracies result in significant loss of performance, especially for tracking high-frequency signals, since infinite gain at the expected frequency is not achieved, and therefore, zero steady-state error is not assured. Other discretization techniques are demonstrated to be more reliable. The effect on zeros is also analyzed, establishing the influence of each method on the stability. Finally, the study is extended to the discretization of the schemes with delay compensation, which is also proved to be of great importance in relation with their performance. A single-phase active power filter laboratory prototype has been implemented and tested. Experimental results provide a real-time comparison among discretization strategies, which validate the theoretical analysis. The optimum discrete-time implementation alternatives are assessed and summarized.
487 citations
Cites background from "Proportionalresonant controllers an..."
...It should be remarked that the resonant peak at the fundamental component provides total disturbance (fundamental component of Vsrc) rejection, so a feedforward compensation is not needed [13], [24]....
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...Indeed, it is a common practice to tune PR controllers with identical gains KIk for all harmonics [14], [24], [39]....
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...proposals for frequency adaptation of resonant controllers rely on discretizing two separated integrators (defined as group D in Section II-C) [8], [24], [25]....
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...implement this scheme due to the simplicity it permits when frequency adaptation is required [13], [15], [24], [25]....
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