หลักการเบื้องต้นเฟสล็อกลูปสำหรับอินเวอร์เตอร์แบบต่อเข้ากริด

ABSTRACT This paper presents the theory, implementation, and application of a phase-locked loop (PLL) for single-phase and three-phase grid connected inverters. Phase-locked loop theory is described as block diagram to express its operation. The PI loop filter in the PLL system is designed using control system theory and then its simulation is implemented as a discrete-time model in Matlab/Simulink. The PI loop filter parameters are designed in this work using the initial condition parameters:  , hence . The phase-locked loop simulation results illustrate that the designed control system can perform effectively in respect to the performance criteria, i.e. . This paper is the first paper in a series of papers on the phase-locked loop. The two ongoing papers present single-phase and three-phase PLL systems that can be applied to a grid-connected inverter. Keyword: Phase –Locked Loop, PLL, Grid -connected inverterบทคัดย่อ บทความนี้นำเสนอทฤษฏี การสร้างและนำเฟสล็อกลูปมาใช้งานในอินเวอร์เตอร์แบบต่อเข้ากริดในระบบไฟฟ้าหนึ่งเฟสและสามเฟส ทฤษฏีเฟสล็อกลูปจะนำเสนอด้วยบล็อกไดอะแกรมเพื่ออธิบายการทำงาน การออกแบบตัวกรองแบบพีไอในระบบเฟสล็อกลูปด้วยทฤษฏีระบบควบคุม จากนั้นใช้การจำลองการทำงานเฟสล็อกลูปแบบ   ดิสครีตด้วยโปรแกรม Matlab/Simulink เพื่อยืนยันการทำงานของเฟสล็อกลูปด้วยค่าเริ่มต้น  มาออกแบบตัวกรองลูปแบบพีไอได้ค่า  จากผลจำลองการทำงานเฟสล็อกลูปสามารถทำงานได้โดยมีเกณฑ์การประเมินสมรรถนะจากพารามิเตอร์  ตามลำดับ บทความวิชาการนี้เป็นบทความแรกในชุดบทความเกี่ยวกับเฟสล็อกลูปโดยสองบทความที่จะนำเสนอต่อไปคือบทความเฟสล็อกลูปแบบหนึ่งเฟส และบทความเฟสล็อกลูปแบบสามเฟส ซึ่งสามารถนำมาประยุกต์ใช้งานกับอินเวอร์เตอร์แบบต่อเข้ากริดได้ คำสำคัญ: เฟสล็อกลูป PLL อินเวอร์เตอร์แบบต่อเข้ากริ

Phase noise reduction of a semiconductor laser in a composite optical phase-locked loop

The bandwidth and residual phase noise of optical phaselocked loops (OPLLs) using semiconductor lasers are typically constrained by the nonuniform frequency modulation response of the laser, limiting their usefulness in a number of applications. It is shown in this work that additional feedback control using an optical phase modulator improves the coherence between the master and slave lasers in the OPLL by achieving bandwidths determined only by the propagation delay in the loop. A phase noise reduction by more than a factor of two is demonstrated in a proof-of-concept experiment using a commercial distributed feedback semiconductor laser

Smart Power Grid Synchronization With Fault Tolerant Nonlinear Estimation

Effective real-time state estimation is essential for smart grid synchronization, as electricity demand continues to grow, and renewable energy resources increase their penetration into the grid. In order to provide a more reliable state estimation technique to address the problem of bad data in the PMU-based power synchronization, this paper presents a novel nonlinear estimation framework to dynamically track frequency, voltage magnitudes and phase angles. Instead of directly analyzing in abc coordinate frame, symmetrical component transformation is employed to separate the positive, negative, and zero sequence networks. Then, Clarke\u27s transformation is used to transform the sequence networks into the αβ stationary coordinate frame, which leads to system model formulation. A novel fault tolerant extended Kalman filter based real-time estimation framework is proposed for smart grid synchronization with noisy bad data measurements. Computer simulation studies have demonstrated that the proposed fault tolerant extended Kalman filter (FTEKF) provides more accurate voltage synchronization results than the extended Kalman filter (EKF). The proposed approach has been implemented with dSPACE DS1103 and National Instruments CompactRIO hardware platforms. Computer simulation and hardware instrumentation results have shown the potential applications of FTEKF in smart grid synchronization

Hidden attractors in fundamental problems and engineering models

Recently a concept of self-excited and hidden attractors was suggested: an attractor is called a self-excited attractor if its basin of attraction overlaps with neighborhood of an equilibrium, otherwise it is called a hidden attractor. For example, hidden attractors are attractors in systems with no equilibria or with only one stable equilibrium (a special case of multistability and coexistence of attractors). While coexisting self-excited attractors can be found using the standard computational procedure, there is no standard way of predicting the existence or coexistence of hidden attractors in a system. In this plenary survey lecture the concept of self-excited and hidden attractors is discussed, and various corresponding examples of self-excited and hidden attractors are considered

Three-frequency resonances in dynamical systems

We investigate numerically and experimentally dynamical systems having three interacting frequencies: a discrete mapping (a circle map), an exactly solvable model (a system of coupled ordinary differential equations), and an experimental device (an electronic oscillator). We compare the hierarchies of three-frequency resonances we find in each of these systems. All three show similar qualitative behaviour, suggesting the existence of generic features in the parameter-space organization of three-frequency resonances.Comment: See home page http://lec.ugr.es/~julya

A comparison of methods for DPLL loop filter design

Four design methodologies for loop filters for a class of digital phase-locked loops (DPLLs) are presented. The first design maps an optimum analog filter into the digital domain; the second approach designs a filter that minimizes in discrete time weighted combination of the variance of the phase error due to noise and the sum square of the deterministic phase error component; the third method uses Kalman filter estimation theory to design a filter composed of a least squares fading memory estimator and a predictor. The last design relies on classical theory, including rules for the design of compensators. Linear analysis is used throughout the article to compare different designs, and includes stability, steady state performance and transient behavior of the loops. Design methodology is not critical when the loop update rate can be made high relative to loop bandwidth, as the performance approaches that of continuous time. For low update rates, however, the miminization method is significantly superior to the other methods