Journal ArticleDOI
Impedance-Phased Dynamic Control Method for Grid-Connected Inverters in a Weak Grid
TLDR
In this paper, a study of the stability of grid-connected inverters with high grid impedance based on impedance analysis is presented, where the effects of the PLL loop and the digital control delays on the output impedance characteristics have been taken into account.Abstract:
A power distribution grid exhibits the characteristics of a weak grid owing to the existence of scattered high-power distributed power-generation devices. The grid impedance affects the robust stability of grid-connected inverters, leading to harmonic resonance, or even instability in the system. Therefore, a study of the stability of grid-connected inverters with high grid impedance based on impedance analysis is presented in this paper. The output impedance modeling of an LCL -type single-phase grid-connected inverter is derived, where the effects of the PLL loop and the digital control delays on the output impedance characteristics have been taken into account. To enhance the stability of grid-connected inverters with different grid impedance, a novel impedance-phased compensation control strategy is proposed by increasing the phase margin of the grid-connected inverters. Specifically, a detailed implementation and parameter design of the impedance-phased compensation control method is depicted. Finally, an impedance-phased dynamic control scheme combined with online grid impedance measurement is introduced and also verified by the experiment results.read more
Citations
More filters
Journal ArticleDOI
An Improved Feedforward Control Method Considering PLL Dynamics to Improve Weak Grid Stability of Grid-Connected Inverters
TL;DR: It can be demonstrated that the proposed method can enhance the stability of grid-connected inverters under weak grid conditions and reduce the impact of PLL perturbations on grid-connecting current and low-order harmonics of the network current can be suppressed effectively.
Journal ArticleDOI
An Improved Design of Current Controller for LCL -Type Grid-Connected Converter to Reduce Negative Effect of PLL in Weak Grid
TL;DR: An improved design of current controller, i.e., proportional–integral controller and capacitor-current-feedback active damping, is proposed to reduce the negative effect of PLL on current control and has a strong robustness against wide-range variation of grid impedance.
Journal ArticleDOI
Improved Design of PLL Controller for LCL -Type Grid-Connected Converter in Weak Grid
TL;DR: An improved design of PLL controller parameters is proposed to mitigate the negative effect of P LL on the current control in weak grid, and not only the dynamic and static response performance of Pll independent system can be maintained, but also the negative influence of Poll dynamic on theCurrent control can be effectively reduced inWeak grid.
Journal ArticleDOI
Line Impedance Cooperative Stability Region Identification Method for Grid-Tied Inverters Under Weak Grids
TL;DR: The proposed line impedance cooperative stability region identification method is more effective and less conservative than the norm-based stability criteria and can provide guidance for system planning and stabilization method researches with simplified computational process.
Journal ArticleDOI
An Adaptive Active Damper for Improving the Stability of Grid-Connected Inverters Under Weak Grid
TL;DR: An adaptive tuning method of the virtual resistor is proposed, which can automatically regulate thevirtual resistor to the critical value to stabilize the system, and thus reduce the power loss.
References
More filters
Journal ArticleDOI
Impedance-Based Stability Criterion for Grid-Connected Inverters
TL;DR: In this paper, a new method to determine inverter-grid system stability using only the inverter output impedance and the grid impedance is developed, which can be applied to all current-source systems.
Journal ArticleDOI
Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values
TL;DR: In this paper, the authors analyze the stability problems of grid connected inverters used in distributed generation and demonstrate that the use of active damping helps to stabilise the system in respect to many different kinds of resonances.
Journal ArticleDOI
Impedance Modeling and Analysis of Grid-Connected Voltage-Source Converters
Mauricio Cespedes,Jian Sun +1 more
TL;DR: In this paper, a small-signal impedance modeling of grid-connected three-phase converters for wind and solar system stability analysis is presented, where a converter is modeled by a positive-sequence and a negative-sequence impedance directly in the phase domain.
Journal ArticleDOI
Capacitor-Current-Feedback Active Damping With Reduced Computation Delay for Improving Robustness of LCL-Type Grid-Connected Inverter
TL;DR: In this article, a capacitor-current-feedback active damping with reduced computation delay is proposed, which is achieved by shifting the capacitor current sampling instant towards the PWM reference update instant.
Journal ArticleDOI
Small-Signal Methods for AC Distributed Power Systems–A Review
TL;DR: In this article, a review of small-signal analysis for AC distributed power systems can be found in several new and emerging applications, and the compatibility of each type of models with state-space and impedance-based system analysis approaches is discussed.