In this paper a novel control method based on Synchronous Reference Frame Theory (SRFT) is proposed to compensate power quality problems through a three- phase Unified Power Quality Conditioner (UPQC) under unbalanced and distorted load conditions. The performance of the proposed system has been verified using MATLAB-SIMULINK and are discussed in detail in this paper.
Table of Contents
I. INTRODUCTION
II. UPQC
III. SRF TECHNIQUE
IV. UPQC CONTROL ALGORITHM
A. Reference Voltage Signal Generation for Series APF
B. Reference Current Signal Generation for Shunt APF
V. SIMULATION RESULTS
VI. CONCLUSION
Research Objectives and Topics
This paper aims to develop and validate a novel control strategy for a Unified Power Quality Conditioner (UPQC) based on the Synchronous Reference Frame (SRF) theory to mitigate power quality issues, such as voltage sags, swells, and current harmonics, under unbalanced and distorted load conditions.
- Application of Synchronous Reference Frame (SRF) theory for harmonic extraction.
- Reduction of system measurement requirements for shunt and series active power filters.
- Compensation of reactive power and power factor correction.
- Performance evaluation using MATLAB/SIMULINK software.
Excerpt from the Book
III. SRF TECHNIQUE
The synchronous reference frame (SRF) method can be used to extract the harmonics contained in supply voltages or currents. For the current harmonic compensation the three phase distorted currents are first converted into two phase stationary coordinated using α-β transformation same as the p-q theory. After that, the stationary frame quantities are transferred into synchronous rotating frame using cosine and sine functions obtained from PLL. The PLL provides the synchronization with supply voltage and current. The harmonics and fundamental components are separated easily by passing the signal from a Low Pass Filter (LPF).
After that, the fundamental components transferred back to a-b-c frame using inverse park transformation. The a-b-c to d-q-o transformation is known as park transformation.
Summary of Chapters
I. INTRODUCTION: Discusses the rise of power quality problems due to non-linear loads and introduces the UPQC as a solution for compensating voltage and current harmonics.
II. UPQC: Describes the structural configuration of a three-phase UPQC consisting of two back-to-back voltage source inverters connected via a common DC link.
III. SRF TECHNIQUE: Explains the mathematical process of using the Synchronous Reference Frame method to extract harmonics and synchronize signals via PLL.
IV. UPQC CONTROL ALGORITHM: Details the specific control logic used to generate reference signals for both the series and shunt active power filters.
V. SIMULATION RESULTS: Presents the evaluation of the proposed control strategy in MATLAB/SIMULINK, confirming its ability to improve power factor and mitigate distortion.
VI. CONCLUSION: Summarizes that the new SRF-based strategy effectively improves system performance by reducing measurement needs while successfully isolating load and source voltages.
Keywords
Phase Locked loop, PLL, Power Quality, PQ, Synchronous reference frame, SRF, Unified Power Quality Conditioner, UPQC, voltage harmonics, current harmonics, mitigation, MATLAB, SIMULINK, control algorithm, power electronics.
Frequently Asked Questions
What is the primary objective of this paper?
The primary objective is to present a novel SRF-based control method for a UPQC to compensate for power quality problems like voltage sags, swells, and current harmonics under distorted load conditions.
Which central topics are addressed in the research?
The central topics include harmonic compensation, the application of SRF theory, DC-link voltage regulation, and the use of shunt and series active filters for power quality improvement.
What scientific methodology is utilized?
The paper utilizes the Synchronous Reference Frame (SRF) theory combined with MATLAB/SIMULINK simulation to evaluate the proposed control algorithm.
What are the main components of the UPQC discussed?
The UPQC consists of two voltage source inverters (VSI) connected back-to-back through a common DC link, with one VSI in series and the other in shunt with the AC line.
How is the performance of the system verified?
The performance is verified through rigorous testing in a MATLAB/SIMULINK environment, measuring the THD (Total Harmonic Distortion) of load and source currents.
Which key performance metrics are highlighted?
Key metrics include the reduction of load current THD, improvement in source voltage THD, and achieving a near-unity power factor.
How does the proposed control algorithm differ from traditional ones?
The proposed algorithm improves system performance by determining mains voltage and filter voltage for the series APF, effectively reducing the number of necessary measurements.
What is the role of the Low Pass Filter (LPF) in the SRF technique?
The LPF is used to separate harmonic and fundamental components from the supply signal by filtering out the oscillating components.
Why is the DC-link voltage regulated in the UPQC?
DC-link voltage regulation is crucial to compensate for active power losses within the UPQC circuit, ensuring the system remains operational and efficient.
What is the significance of the PLL in this control system?
The Phase Locked Loop (PLL) is essential for providing synchronization with the supply voltage and current, which is fundamental for the coordinate transformations in the SRF method.
- Quote paper
- Akshay Kumar (Author), 2014, Harmonic Compensation of Voltage and Current Using UPQC, Munich, GRIN Verlag, https://www.grin.com/document/278319
