28th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2013 (original) (raw)
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Wide frequency range active damping of LCL-filtered grid-connected converters
The Journal of Engineering, 2019
It can be challenging to guarantee the stability of grids with many converters with LCL filters connected due to the presence of multiple resonances within the system. This paper presents an active damping technique to mitigate multiple resonance effects and harmonics in power converters connected to weak grids. The proposed technique employs grid current and capacitor voltage feedback to achieve active damping for a wide range of multiple resonance frequencies. The effectiveness of the proposed wide frequency active damping and improved controller stability are demonstrated through frequency domain analysis and experimental results for single and parallel grid connected converters.
An Active Damper for Stabilizing Power-Electronics-Based AC Systems
IEEE Transactions on Power Electronics, 2014
The interactions among the parallel grid-connected converters coupled through the grid impedance tend to result in stability and power quality problems. To address them, this paper proposes an active damper based on a high bandwidth power electronics converter. The general idea behind this proposal is to dynamically reshape the grid impedance profile seen from the point of common coupling of the converters, such that the potential oscillations and resonance propagation in the parallel grid-connected converters can be mitigated. To validate the effectiveness of the active damper, simulations and experimental tests on a threeconverter-based setup are carried out. The results show that the active damper can become a promising way to stabilize the powerelectronics-based ac power systems.
LCL-Filter Design for Robust Active Damping in Grid-Connected Converters
IEEE Transactions on Industrial Informatics, 2014
Grid connected converters employ LCL-filters, instead of simple inductors, because they allow lower inductances while reducing cost and size. Active damping, without dissipative elements, is preferred to passive damping for solving the associated stability problems. However, large variations in the grid inductance may compromise system stability, and this problem is more severe for parallel converters. This situation, typical of rural areas with solar and wind resources, calls for robust LCL-filter design. This paper proposes a design procedure with remarkable results under severe grid inductance variation. The procedure considers active damping using lead-lag network and capacitor current feedback. Passive damping is also discussed. The design flow, with little iteration and no complex algorithms, selects the proper ratios between the switching and resonance frequency, the grid and converter inductance, and the filter capacitance and total inductance. An estimation for the grid current THD is also proposed. Simulation and experiments validate the proposals. Index Terms-grid connected converter, LCL-filter, stability, robust design, active damping, weak grid. References [9], [10] established the basic guidelines for the selection of the LCL-filter parameters using an iterative process. The converter-side inductor is sized based on the current ripple at the switching frequency. The capacitor rating is limited by the fundamental reactive power. The grid side
An Effective Damping Control Approach in Grid-Connected Converters
International Journal of Industrial Electronics, Control and Optimization (IECO), 2023
The primary objective of this paper is to address the adverse effects of active power fluctuations on grid-connected converters. One of the challenges in integrating high levels of solar photovoltaic power into the utility grid is the lack of inertia from converter-based resources. This paper proposes a solution to this challenge by synthesizing additional inertia and damping properties using power electronics converters. They emulate the inertia and damping properties of synchronous generators. The paper discusses different approaches to achieving effective damping control in grid-connected converters. It proposes a genetic algorithm optimization tool to optimize virtual damping and inertia parameters. The goal is to suppress oscillations and ensure stable grid operation. The proposed method is evaluated in both time-domain and frequency-domain analyses. The simulation results demonstrate the validity of the optimization technique and implementation procedure. Using virtual inertia and damping properties ensures stable grid operation and improves the integration of solar photovoltaic power into the utility grid. The paper provides a detailed discussion of the approach, optimization tool, and simulation results, highlighting the effectiveness of the proposed method. I.
LCL-Filter Design for Robust Active Damping in Grid-Connected Converters
IEEE Transactions on Industrial Informatics, 2014
Grid-connected converters employ LCL-filters, instead of simple inductors, because they allow lower inductances while reducing cost and size. Active damping, without dissipative elements, is preferred to passive damping for solving the associated stability problems. However, large variations in the grid inductance may compromise system stability, and this problem is more severe for parallel converters. This situation, typical of rural areas with solar and wind resources, calls for robust LCL-filter design. This paper proposes a design procedure with remarkable results under severe grid inductance variation. The procedure considers active damping using lead-lag network and capacitor current feedback. Passive damping is also discussed. The design flow, with little iteration and no complex algorithms, selects the proper ratios between the switching and resonance frequency, the grid and converter inductance, and the filter capacitance and total inductance. An estimation for the grid current total harmonic distortion (THD) is also proposed. Simulation and experiments validate the proposals.
<italic>LCL</italic>-Filter Design for Robust Active Damping in Grid-Connected Converters
IEEE Transactions on Industrial Informatics, 2014
Grid connected converters employ LCL-filters, instead of simple inductors, because they allow lower inductances while reducing cost and size. Active damping, without dissipative elements, is preferred to passive damping for solving the associated stability problems. However, large variations in the grid inductance may compromise system stability, and this problem is more severe for parallel converters. This situation, typical of rural areas with solar and wind resources, calls for robust LCL-filter design. This paper proposes a design procedure with remarkable results under severe grid inductance variation. The procedure considers active damping using lead-lag network and capacitor current feedback. Passive damping is also discussed. The design flow, with little iteration and no complex algorithms, selects the proper ratios between the switching and resonance frequency, the grid and converter inductance, and the filter capacitance and total inductance. An estimation for the grid current THD is also proposed. Simulation and experiments validate the proposals. Index Terms-grid connected converter, LCL-filter, stability, robust design, active damping, weak grid. References [9], [10] established the basic guidelines for the selection of the LCL-filter parameters using an iterative process. The converter-side inductor is sized based on the current ripple at the switching frequency. The capacitor rating is limited by the fundamental reactive power. The grid side
IEEE Transactions on Power Electronics, 2011
This paper presents a robust interfacing scheme for distributed generation (DG) inverters featuring robust mitigation of converter-grid resonance at parameter variation, gridinduced distortion, and current-control parametric instabilities. The proposed scheme relies on a high-bandwidth current-control loop, which is designed with continuous wideband active damping against converter-grid disturbances and parametric uncertainties by providing adaptive internal-model dynamics. First, a predictive current controller with time-delay compensation is adopted to control the grid-side current with high-bandwidth characteristics to facilitate higher bandwidth disturbance rejection and activedamping control at higher frequencies. Second, to ensure high disturbance rejection of grid distortion, converter resonance at parameter variation, and parametric instabilities, an adaptive internal model for the capacitor voltage and grid-side current dynamics is included within the current-feedback structure. Due to the time-varying and periodic nature of the internal-model dynamics, a neural-network-based estimator is proposed to construct the internal-model dynamics in real time. Theoretical analysis and comparative experimental results are presented to demonstrate the effectiveness of the proposed control scheme.
One of the most important aspects for large scale integration of wind power systems is the fault ride through (FRT) capability with frequency and voltage stabilization. Large voltage sags induce high voltages in the rotor circuit of the DFIG and thus the rotor current rises and could exceed the current capability of the converter switches. Dynamic performances of a grid-side converter (GSC) to grid voltage sags and fault conditions with active damping and without active damping are presented. Under the same control platform, a faster dynamic response is achieved for the DC-link voltage when active damping is considered as against a sluggish and ripple-infested response without active damping. Under fault condition, a 42% decrease in DC-link voltage is realized when active damping is considered. This is against 136% increase in the DC-link voltage that may excite the protective system to disconnect the grid-side converter subsystem from the rest of the network and thus disenable the ...
Ijpres Control and Stabilization of Power Electronic Based Ac Systems with Live Damper Involvement
2015
The interactions among the parallel gridconnected converters coupled through the grid impedance tend to result in stability and power quality problems. To address them, this paper proposes an active damper based on a high bandwidth power electronics converter. The general idea behind this proposal is to dynamically reshape the grid impedance profile seen from the point of common coupling of the converters, such that the potential oscillations and resonance propagation in the parallel grid-connected converters can be mitigated. To validate the effectiveness of the active damper, simulations and experimental tests on a three converter-based setup are carried out. The results show that the active damper can become a promising way to stabilize the power electronics-based ac power systems.
Analysis and Mitigation of Harmonic Resonances in Multi–Parallel Grid–Connected Inverters: A Review
Energies
With the move towards decarbonization of the energy system and increased use of renewable generation, the number of power electronics converter interfaced resources connecting to the grid is growing. These power electronics converters have fast dynamics determined by control algorithms, which leads to significant changes in the dynamics and impedance characteristics of the power system. Based on practical experience, concerns have grown about interactions between converters and between converters and the grid which can give rise to instability in a system with multiple grid–connected inverters operating in parallel. This paper reviews the recent work related to the understanding, modeling and mitigation of such interactions. The basic concepts which underpin the interactions are explained and discussed from an impedance stability perspective. The concepts are illustrated by means of an example case of multiple inverters operating in a low voltage distribution system. In recent years...