Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

A Versatile Control Scheme for a Dynamic Voltage Restorer for Power-Quality Improvement

189 views

Published on

This paper presents a control system based on a repetitive controller to compensate for key power-quality disturbances, namely voltage sags, harmonic voltages, and voltage imbalances, using a dynamic voltage restorer (DVR). The control scheme deals with all three disturbances simultaneously within a bandwidth. The control structure is quite simple and yet very robust; it contains a feed forward term to improve the transient response and a feedback term to enable zero error in steady state. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modeling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

Published in: Education
  • Be the first to comment

  • Be the first to like this

A Versatile Control Scheme for a Dynamic Voltage Restorer for Power-Quality Improvement

  1. 1. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 A Versatile Control Scheme for a Dynamic Voltage Restorer for Power-Quality Improvement ABSTRACT: This paper presents a control system based on a repetitive controller to compensate for key power-quality disturbances, namely voltage sags, harmonic voltages, and voltage imbalances, using a dynamic voltage restorer (DVR). The control scheme deals with all three disturbances simultaneously within a bandwidth. The control structure is quite simple and yet very robust; it contains a feed forward term to improve the transient response and a feedback term to enable zero error in steady state. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modeling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation. KEYWORDS: 1. Dynamic voltage restorer (DVR) 2. Harmonic distortion 3. Power quality (PQ) 4. Repetitive control 5. Voltage sag. SOFTWARE: MATLAB/SIMULINK
  2. 2. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 BLOCK DIAGRAM: Fig. 1. System configuration with a DVR. EXPECTED SIMULATION RESULTS: Fig. 2. Three-phase rms voltage. (a) Across the sensitive load. (b) At the PCC.
  3. 3. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 Fig. 3. Line-to-line voltage. (a) At the PCC. (b) Across the sensitive load. Corresponding to the interval Fig. 4. Detail of the spectrum of the line-to-line voltage. (a) At the PCC. (b) Across the sensitive load.
  4. 4. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 Fig. 5. Line-to-line voltages at the PCC. Corresponding to the interval Fig. 6. Sensitive-load line-to-line voltages. Corresponding to the interval (s) Fig. 7. Control outputs. Corresponding to the interval
  5. 5. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 CONCLUSION: The use of dynamic voltage restorers in PQ-related applications is increasing. The most popular application has been on voltage sags amelioration but other voltage-quality phenomena may also benefit from its use, provided that more robust control schemes than the basic PI controller become available. A case in point is the so called repetitive controller proposed in this paper, which has a fast transient response and ensures zero error in steady state for any sinusoidal reference input and for any sinusoidal disturbance whose frequencies are an integer multiple of the fundamental frequency. To achieve this, the controller has been provided with a feed forward term and feedback term. The design has been carried out by studying the stability of the closed loop system including possible modeling errors, resulting in a controller which possesses very good transient and steady-state performances for various kinds of disturbances. A key feature of this control scheme is its simplicity; only one controller is required to eliminate three PQ disturbances, namely, voltage sags, harmonic voltages, and voltage imbalances. The controller can be implemented by using either a stationary reference frame or a rotating reference frame. In this paper, the highly developed graphical facilities available in PSCAD/EMTDC have been used very effectively to carry out all aspects of the system implementation. Comprehensive simulation results using a simple but realistic test system show that the repetitive controller and the DVR yield excellent voltage regulation, thus screening a sensitive load point from upstream PQ disturbances.
  6. 6. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 REFERENCES: [1] M. H. J. Bollen, “What is power quality?,” Elect. Power Syst. Res., vol. 66, no. 1, pp. 5–14, July 2003. [2] J. G. Nielsen and F. Blaabjerg, “A detailed comparison of system topologies for dynamic voltage restorers,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1272–1280, Sep./Oct. 2005. [3] V. K. Ramachandaramurthy, A. Arulampalam, C. Fitzer, C. Zhan, M. Barnes, and N. Jenkins, “Supervisory control of dynamic voltage restorers,” Proc. Inst. Elect. Eng., Gen., Transm. Distrib, vol. 151, no. 4, pp. 509–516, Jul. 2004. [4] P. T. Nguyen and T. K. Saha, “Dynamic voltage restorer against balanced and unbalanced voltage sags: Modelling and simulation,” in Proc. IEEE Power Eng. Soc. General Meeting, Jun. 2004, vol. 1, pp. 639–644, IEEE. [5] M. H. J. Bollen, Understanding Power Quality Problems: Voltage Sags and Interruptions.. Piscataway, NJ: IEEE Press, 2000.

×