Design of LCL filter for grid-interfaced PV system based on cost minimization
01 Dec 2016-pp 1-6
TL;DR: In this paper, a cost-based minimization approach on a cost per joule basis for each of the filter elements is explored to obtain the optimal filter design for grid interfaced PV system.
Abstract: This paper proposes a novel approach to design the LCL filter for grid interfaced PV system. A cost based minimization approach on a cost per joule basis for each of the filter elements is explored to obtain the optimal filter design. Simulation results for a 10 KVA grid connected inverter with LCL filter are presented in order to verify the behavior of the proposed design. The impact of designed filter parameters on the ripple current is also discussed in the paper. The total inductance of the LCL filter is varied and filter parameter values which give lowest cost is identified while meeting harmonic standard requirements and the fundamental voltage drop across the filter.
Citations
More filters
TL;DR: A comprehensive review on the modeling and stability analysis of the LCL -type grid-connected inverters is conducted, with the emphasis on different modeling methods of inverter output impedance and online impedance measurement techniques.
Abstract: Due to the advantages of superior harmonics attenuation ability and reduced size, the LCL filter has been widely adopted to interface between the inverter and the grid for improving the quality of injected grid currents. However, the high-order characteristics and various constraints of the LCL filter complicate the filter design. Moreover, the stability of the internal current control loop of the individual inverter is susceptible to the inherent LCL -filter resonance peak. Meanwhile, the overall system stability would be aggravated by the external interactions between the inverter and the weak grid as well as among the paralleled inverters. Both the LCL -filter resonance peak and two types of interaction would cause severely distorted grid currents. Motivated by the existing problems, a comprehensive review on the modeling and stability analysis of the LCL -type grid-connected inverters is conducted in this paper. Concretely, the generalized parameter constraints of the LCL filter are outlined to facilitate the passive components selection, and the magnetic integration techniques of filter inductors are also introduced to reduce the weight and size of filter for increasing the power density of the system. Then, the various damping methods for enhancing the individual internal stability and the relevant application issues are also discussed. Furthermore, the impedance-based method for evaluating the system-level interactive stability is subsequently reviewed, with the emphasis on different modeling methods of inverter output impedance and online impedance measurement techniques. Finally, the future research trends on the modeling and stability analysis of LCL -type grid-connected inverters are also presented.
78 citations
Cites background from "Design of LCL filter for grid-inter..."
...Recently, several literatures have been published to discuss the LCL-filter parameters design [18]–[23]....
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TL;DR: Experimental results from real-time simulations and from a real prototype with commercial powder core inductors show that the proposed procedure can provide superior results than conventional controllers designed not taking into account the soft-saturation.
Abstract: This article provides as contribution a systematic design procedure for robust current control of grid-tied inverters with LCL filters affected by inductor magnetic soft-saturation and also by uncertain grid impedances. The proposed design is based on the following: first, a polytopic time-varying model to describe the effect of the inductances variations; second, a set of linear matrix inequalities to design fixed (robust) state feedback gains, ensuring bounded settling times for the closed-loop transient responses. A less conservative set of linear matrix inequalities is used to certify the procedure. Experimental results from real-time simulations and from a real prototype with commercial powder core inductors show that the proposed procedure can provide superior results than conventional controllers designed not taking into account the soft-saturation. The results with the proposed controller comply with the IEEE 1547 Standard, leading to grid currents with low harmonic content, respecting limits prescribed by this standard even under distorted grid voltages.
32 citations
Cites background from "Design of LCL filter for grid-inter..."
...2938474 suitable passive filters are necessary to meet such requirements, being the LCL type widely used due to its good high-frequency attenuation [3]....
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TL;DR: The proposal contributes to improve the effective use of metaheuristics for automated control tuning in GCCs, avoiding time-consuming human–machine interaction in the design stage and ensuring a good tradeoff between performance and robustness against uncertain grid parameters.
Abstract: This article proposes a design procedure for $\mathcal {H}_{\infty }$ current controllers suitable for application in grid-connected converters (GCCs) subject to disturbances and uncertain parameters. Linear matrix inequalities provide robust state feedback controllers from a set of design parameters automatically tuned with the help of a genetic algorithm, oriented by a suitable objective function. Such strategy allows to overcome the problem of $\mathcal {H}_{\infty }$ high control gains, ensuring a good tradeoff between performance and robustness against uncertain grid parameters. The proposal contributes to improve the effective use of metaheuristics for automated control tuning in GCCs, avoiding time-consuming human–machine interaction in the design stage. A case study with experimental results is presented, demonstrating the viability and the superior performance of the proposed controllers with respect to similar techniques, and also the compliance with the IEEE 1547 Std for grid currents.
20 citations
TL;DR: An approach to estimate the state variables is proposed in this paper, which cuts down the number of sensors and cost of implementation and results are validated in a hardware setup, under dynamic and steady-state conditions, thereby showing that this is a promising approach.
Abstract: Grid-tied inverters and associated control techniques have gained importance in the domain of distributed generation. Different methods of control have been compared in the literature depending upon the ability to meet total harmonic distortion limits, damping offered to resonant oscillations, and stable operation. Multiple-loop methods compared to their single-loop counterparts have proved to be highly effective for meeting the grid regulations. In the literature, while single-loop and two-loop control systems for LCL filter have been assessed, not much study on three-loop control (TLC) has been done, possibly due to the hardware complexity and cost imparted by the increase in the number of sensors. In this paper, a TLC structure for grid connected inverters is analyzed for stability and parametric variations. Robustness of TLC is compared with single-loop grid current feedback control and a two-loop control structure. An approach to estimate the state variables is proposed in this paper, which cuts down the number of sensors and cost of implementation. The performance of the system is analyzed through simulations and results are validated in a hardware setup, under dynamic and steady-state conditions, thereby showing that this is a promising approach.
19 citations
Cites methods from "Design of LCL filter for grid-inter..."
...The design of an LCL filter was carried out along the lines of [21]....
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TL;DR: A cost-based minimization approach on a cost per joule basis for each of the filter elements is explored to obtain the optimal filter design in a grid-interfaced PV system.
Abstract: Many research works report the use of LCL filters for grid-interfaced PV systems. Indiscreet selection of passive LCL filter parameters may result in poor filtering and increased power losses. LCL filter parameter selection is critical to get a good performance and at the same time ensure that losses and costs stay low. This paper proposes a novel approach to design the LCL filter for a grid-interfaced PV system. A cost-based minimization approach on a cost per joule basis for each of the filter elements is explored to obtain the optimal filter design. Simulation results for a 10-kVA grid-connected inverter with an LCL filter are presented in order to verify the efficacy of the proposed design. The impact of designed filter parameters on the ripple current is also discussed in this paper. The total inductance of the LCL filter is varied and filter parameter values which give lowest cost is identified while meeting harmonic standard requirements and the fundamental voltage drop across the filter. Finally, the proposed design is also experimentally validated via a hardware prototype. Results validate the design method in terms of the harmonic attenuation and total harmonic distortion.
19 citations
Cites background from "Design of LCL filter for grid-inter..."
...This can be reduced to a simpler form involving ratios of costs [28], [29] as...
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References
More filters
30 Sep 2001
TL;DR: In this article, a step-by-step procedure for designing the LCL filter of a front-end three-phase active rectifier is proposed to reduce the switching frequency ripple at a reasonable cost, while at the same time achieving a high-performance front end rectifier.
Abstract: This paper proposes a step-by-step procedure for designing the LCL filter of a front-end three-phase active rectifier. The primary goal is to reduce the switching frequency ripple at a reasonable cost, while at the same time achieving a high-performance front-end rectifier (as characterized by a rapid dynamic response and good stability margin). An example LCL filter design is reported and a filter has been built and tested using the values obtained from this design. The experimental results demonstrate the performance of the design procedure both for the LCL filter and for the rectifier controller. The system is stable and the grid current harmonic content is low both in the lowand high-frequency ranges. Moreover, the good agreement that was obtained between simulation and experimental results validates the proposed approach. Hence, the design procedure and the simulation model provide a powerful tool to design an LCL-filter-based active rectifier while avoiding trial-and-error procedures that can result in having to build several filter prototypes.
2,147 citations
"Design of LCL filter for grid-inter..." refers background in this paper
...The authors in [4]– [6] present the design constraints on the selection of filter parameters and propose a step by step design of the LCL filter, but for a three phase rectifier application....
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...In several works, the inductors are fixed based on the voltage drop at the fundamental frequency [4]....
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...Studies [4], [10], [12] indicate that in order to have good filter attenuation with minimum filter cost, the two inductances are to be equal in value....
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TL;DR: In this article, a design methodology of an LCL filter for grid-interconnected inverters along with a comprehensive study of how to mitigate harmonics is presented for small-scale renewable energy conversion systems and may be also retrofitted for medium and large-scale grid-connected systems.
Abstract: The use of power converters is very important in maximizing the power transfer from renewable energy sources such as wind, solar, or even a hydrogen-based fuel cell to the utility grid An LCL filter is often used to interconnect an inverter to the utility grid in order to filter the harmonics produced by the inverter Although there is an extensive amount of literature available describing LCL filters, there has been a gap in providing a systematic design methodology Furthermore, there has been a lack of a state-space mathematical modeling approach that considers practical cases of delta- and wye-connected capacitors showing their effects on possible grounding alternatives This paper describes a design methodology of an LCL filter for grid-interconnected inverters along with a comprehensive study of how to mitigate harmonics The procedures and techniques described in this paper may be used in small-scale renewable energy conversion systems and may be also retrofitted for medium- and large-scale grid-connected systems
601 citations
TL;DR: This paper introduces a new iterative design procedure of L and LCL filters for low-voltage active-front-end PWM two-level voltage source converters using the analytical expression of the converter harmonic voltages by Bessel functions.
Abstract: This paper introduces a new iterative design procedure of L and LCL filters for low-voltage active-front-end PWM two-level voltage source converters. The analytical expression of the converter harmonic voltages by Bessel functions is applied to design the filter parameters for defined maximum grid current harmonics. Different filter designs are derived for various resonance frequencies and inductance split factors of LCL filter. The minimum amount of stored energy of passive components is used to select a final filter design. A voltage-oriented control scheme, including active damping, is applied in the (400 V and 50 kVA) experimental setup. Both simulation and experimental investigations are presented to verify the accuracy of the filter design procedure. Finally, the steady state and transient performance of the active front end with different LCL filters are depicted.
409 citations
"Design of LCL filter for grid-inter..." refers background in this paper
...In [7], the authors discuss another iterative approach for selecting LCL component values, again for an active rectifier....
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TL;DR: This paper demonstrates a frequency-domain-model-based approach to determine the optimum filter parameters that provide the necessary performance under all operating conditions given the necessary design constraints.
Abstract: This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral-point clamped converter to be adopted for a multimegawatt (multi-MW) wind turbine. The unique filter design challenges in this application are driven by a combination of the medium-voltage converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design procedures of grid filters for lower power and higher switching frequency converters are not valid for a multi-MW filter connecting a medium-voltage converter switching at low frequency to the electric grid. This paper demonstrates a frequency-domain-model-based approach to determine the optimum filter parameters that provide the necessary performance under all operating conditions given the necessary design constraints. To achieve this goal, new concepts, such as virtual-harmonic content and virtual filter losses are introduced. Moreover, a new passive-damping technique that provides the necessary damping with low losses and very little degradation of the high-frequency attenuation is proposed.
383 citations
"Design of LCL filter for grid-inter..." refers methods in this paper
...In [14], the final filter design has been chosen as a trade-off between the inverter losses and filter volume....
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15 Jun 2003
TL;DR: In this article, the design considerations of the output filter for the grid-interconnected inverter were comprehensively discussed and different passive damping filter solutions were compared and the optimized design guidelines were also proposed.
Abstract: Traditionally, LC filter is used for an inverter power supply. A grid-interconnected inverter, however, has some unique requirements that an LC filter may not be sufficient. This paper comprehensively discusses the design considerations of the output filter for the grid-interconnected inverter. Different passive damping filter solutions are compared and the optimized design guidelines are also proposed. Simulation results are provided to validate the design.
360 citations
"Design of LCL filter for grid-inter..." refers background in this paper
...The authors in [9]–[12] propose LCL filter design guidelines based on the inverter current ripple, fundamental reactive power and current ripple attenuation for the grid interfaced inverter applications....
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