The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Current-controlled LCL-filtered inverters are usually paralleled together for interconnecting the renewable energy resources into the grid. When the inverter output impedance is not well designed, the harmonic circulating currents out of the control bandwidth may be easily aroused. To reveal this resonant phenomenon and to enhance the stability of the parallel system, this paper builds the parallel...
A grid-connected inverter is equipped with an LCL filter after its output. This filter has a resonant characteristic and many active damping methods have been researched to suppress the resonant effects. The inverter is often controlled digitally and there is a control time delay which is inevitable due to A/D conversion, computation times, and so on. This delay degrades stabilities and damping effects...
In this paper, a sensorless active damping scheme of LCL-filter is proposed in grid-connected parallel inverters for battery energy storage systems. The proposed damping method is superior to the conventional notch filter and virtual damping methods with respect of robustness on the variation of resonance of the filter and unnecessary additional current sensors. The theoretical analysis of the proposed...
LCL-filter is commonly used as an output-side filter in a grid-connected converter due to its good attenuation capability at the switching harmonic frequencies. LCL-filter creates several resonances in the converter dynamics which shall be damped for ensuring robust performance of the converter. The resonant behavior introduced by the LCL-filter can be attenuated with active damping (AD) instead of...
Digital control system usually introduces a beat of delay, which includes PWM upload delay and zero-order holder delay. The delay not only reduces the system phase margin, but also changes the impedance characteristics of active damping, which influences the system minimum phase property and threatens the stability of the injected current. In this paper, a PWM real-time upload method and the detailed...
Modified LCL (MLCL) filter can be employed in a transformerless PV grid-connected inverter for leakage current reduction without any modifications in the modulation technique and inverter topology. However, MLCL filter requires a damping scheme, either passive or active, to avoid possible instability in the grid connection. The use of passive damping in the MLCL filter causes additional power losses...
PV Grid-connected inverters must fulfill the standards specifications of current harmonics injected to the grid. In order to satisfy these grid requirements, passive filters are connected between the inverter and the grid. This paper compares the response characteristic of the traditional inductive (L) filter with the inductive-capacitive-inductive (LCL) filter. It is shown that the increasing the...
In this paper, a current controller for an inverter connected to the grid through an LCL filter is proposed. Unlike classical active damping schemes, it is proposed to implement the controller by measuring the injected current only. It can be done irrespectively of the filter resonance frequency. In addition, it is possible to place the closed-loop poles of the system in an arbitrary way. The controller...
This paper proposes control of 3-level inverter with small DC-link capacitance and grid filter inductance for high speed motor drive system where regeneration and hold-up time are unnecessary. The controller consists of three simultaneously operating sub-controllers; High speed motor controller for flux weakening and maximum torque per ampere (MTPA) control, neutral voltage controller for DC-link...
This paper illustrates the assessment between the multiloop control strategies that aim to damp the resonance hazard of LCL-filters and expanding the available stability margins. The establishment of the multiloop control is sustained in a sensorless manner with the reconstruction of the state variables using the Kalman observer, thus enhancing the cost measures and reliability of the distributed...
For grid-connected LCL-filtered inverter, the inherent resonance of LCL filter endangers the stability so that the inverter is hard to be controlled. To solve the resonance, the capacitor-current-feedback active damping (AD) is welcomed. However, the digital control delay was not seriously considered in the previous studies. The research on the stability with such control considering the digital control...
The grid-connected LCL-filtered inverter is widely used in distributed power generation systems based on renewable energies. Single inverter-side current feedback control only needs to sample one current to realize both current control and inverter protection. However, with single inverter-side current feedback control, the closed-loop system is under-damped or even unstable due to the digital control...
Compared with LCL filter, an LLCL-filter is characterized with smaller size and lower cost for grid-connected inverters. But this high order filter may also have resonant problem which will affect the system stability. Many methods can be used to alleviate the resonant problem including active damping, passive damping or even without damping if it is designed conservative. In this paper, an overview...
A higher order passive power filter (LLCL-filter) for the grid-tied inverter is becoming attractive for the industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. To avoid the well-known stability problems of the LLCL-filter it is requested to use either passive or active damping methods. This paper analyzes the stability when damping is required...
The penetration of the distributed power generation systems (DPGSs) based on renewable sources (PV, WT) is strongly dependent on the quality of the power injected to the utility grid. However, the grid impedance variation, mainly caused by grid faults somewhere in the electric network, can degrade the power quality and even damage some sensitive loads connected at the point of the common coupling...
A novel control method based on the proportional resonant differential (PRD) control is proposed for the grid-connected current source inverter (CSI) used in the direct drive permanent magnet synchronous wind generation system. By the optimal design of the parameters of the PRD controller in two-phase stationary frame, the CSI system can realize zero steady-state error control and effectively damp...
A grid connected CSI requires a CL filter stage. In this work, the isolation transformer leakage inductance constitutes this filter inductance. This CL filter is lightly damped for efficiency constraints. Hence, it is subject to resonance if excited by inverter current harmonics, pre-existing grid voltage harmonics, or due to step changes in power. Previous work on active damping employed a virtual...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.