A Fast-Convergent Modulation Integral Observer for Online Detection of the Fundamental and Harmonics in Grid-Connected Power Electronics Systems

Abstract

Abstract-Harmonics detection is a critical element of active power filters. A previous review has shown that the Recursive Discrete Fourier Transform and the Instantaneous p-q Theory are effective solutions to extracting power harmonics in single-phase and three-phase power systems, respectively. This paper presents the operating principle of a new modulation function integral observer algorithm that offers a fast solution for the extraction of the fundamental current and the total harmonic current when compared with existing methods. The proposed method can be applied to both single-and three-phase systems. The observerbased algorithm has an advantageous feature of being able to be tuned offline for a specific application, having fast convergence and producing estimated fundamental component with high circularity. It has been tested with both simulations and practical measurements for extracting the total harmonic current in a highly efficient manner. The results have confirmed that the proposed tool offers a new and highly effective alternative to the smart grid industry.

Online Detection of Fundamental and Interharmonics in AC Mains for Parallel Operation of Multiple Grid-Connected Power Converters

“…For practical applications of grid-connected power inverters, the fundamental frequency is selected as 50 Hz and the interharmonic frequency as 1.94kHz (representing the occurrence of resonance between parallel grid-connected power inverters). Note that the use of the integral observer algorithm for detecting total harmonics has been reported in [23] and is thus not repeated here. The mains voltage signal can be expressed as:…”

“…A novel kind of kernel-based algorithms has been recently proposed for estimating n sinusoidal components with arbitrary frequencies [22]. This class of algorithms has been adopted for fast detection of fundamental and harmonics for grid-connected power electronics equipment [23]. The basic theory is based on a rather complex mathematical framework which is beyond the scope of this paper.…”

Kernel-Based Simultaneous Parameter-State Estimation for Continuous-Time Systems

“…Besides, in [25], parameters and states are estimated through an EM or Rauch-Tung-Striebel process with iterative correction. However, the aforementioned methods can only achieve asymptotic convergence while in many time-critical applications, such as medical diagnosing systems [13] and power systems [14], it is often desirable to obtain accurate and simultaneous state-parameters estimates (gilbertopin@alice.it).…”

Deadbeat Simultaneous Parameter-State Estimation for Linear Continuous-time Systems: a Kernel-based Approach

“…Their effectiveness in numerous applications has been shown in [9], [14], [15] and [16]. On the other hand, due to the internal instability issue, periodic resettings are typically needed in these method as in [17] and [16], whose significance has been stated through a simulation comparison in [18].…”

“…Their effectiveness in numerous applications has been shown in [9], [14], [15] and [16]. On the other hand, due to the internal instability issue, periodic resettings are typically needed in these method as in [17] and [16], whose significance has been stated through a simulation comparison in [18]. To overcome this drawback, a kernel-based deadbeat estimation methodology has been proposed recently in [13] and [19] exploiting Volterra operators that allow to avoid the periodic resetting and high-gain injection showing huge potential in many applications (e.g.…”