SHORT DURATION VOLTAGE DISTURBANCE IDENTIFICATION USING RMS ALGORITHM IN DISTRIBUTION SYSTEM

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1 International Journal of Electrical Engineering & Technology (IJEET) Volume 7, Issue 3, May June, 2016, pp.01 13, Article ID: IJEET_07_03_001 Available online at ISSN Print: and ISSN Online: Journal Impact Factor (2016): (Calculated by GISI) IAEME Publication SHORT DURATION VOLTAGE DISTURBANCE IDENTIFICATION USING RMS ALGORITHM IN DISTRIBUTION SYSTEM S. Vijaya Laxmi Research Scholar, University College of Engg & Tech, Acharya Nagarjuna University, Andhra Pradesh India Dr. P. V. Ramana Rao Professor & H.O.D/E.E.E, University College of Engg & Tech, Acharya Nagarjuna University, Andhra Pradesh India ABSTRACT Delivering good quality of power is the main agenda for distribution system to the loads. But maintain power quality is not so easy due to the load variations in the system. Sag and swell are the main factors that affect power quality. In this paper, multiple sag conditions and swell conditions were tested by producing the condition in different phases of the system. A simple algorithm called RMS algorithm was developed and tested for the said conditions. Sag and swell were generated on single phase and multiple phases for testing the algorithm. The algorithm and the results were obtained using Matlab. Key words: RMS, Algorithm, Sag, Swell, Power Quality Cite this Article: S. Vijaya laxmi and Dr. P. V. Ramana Rao, Short Duration Voltage Disturbance Identification Using RMS Algorithm in Distribution System. International Journal of Electrical Engineering & Technology, 7(3), 2016, pp INTRODUCTION Power quality determines the quality of electric power to load devices. Maintaining frequency, voltage and power factor within nominal values makes load to function properly without stress on the devices. This maintenance of power quality also reduces the losses in the system increasing the life of the equipment connected. The paper and also the technology on that are mostly driven by the able quality problems. 1 editor@iaeme.com

2 S. Vijaya laxmi and Dr. P. V. Ramana Rao The term power quality [1-4] is very general conception. Broadly, it should be outlined as provision of voltages and system style in order that user electrical power will use electric energy from the distribution system successfully, while not interference on interruption. Power quality is outlined within the IEEE one hundred Authoritative lexicon of IEEE normal terms because the conception of powering and grounding instrumentation in a very manner that's appropriate to the operation of that instrumentality and compatible with the premise wiring system and alternative connected equipment utilities might want to outline power quality as responsible. From the able quality market or trade perspective, it's any product or service that's equipped to users or utilities to live, treat, remedy, educate engineers or forestall Power Quality problems, issues and connected things. This paper critically discusses concerning the able quality of power issues, problems and connected standards, assessment of power quality problems and strategies for its correction [5-8]. Power quality issues like transients, sags, swells and alternative to the curving wave shape of the availability voltage have an effect on the performance of those instrumentality items. Voltage sags and swell in an electrical grid aren't forever attainable to avoid as a result of the finite clearing time of the faults that cause the voltage sags, swells and therefore the propagation of sags and swells from the transmission and distribution systems to the low-tension hundreds [9-10]. Voltage sags and swells are the common reasons for interruption in production plants and for end instrumentality malfunctions generally, specifically, in economical identification will cause disruption and vital prices attributable to loss of production. One solution to the present downside is to create the instrumentality itself additional tolerant to sags, either by intelligent management or by storing energy within the instrumentality. The main objective of the paper is to generate sag and swell in different phases of the system and analyze them. A simple RMS algorithm was generated to analyze the condition of the system, whether the sag/swell exists in the system. If yes, in which phase of the system. This algorithm developed is very simple. 2. POWER QUALITY DISTURBANCES Figure 1 Power Quality Issues 2 editor@iaeme.com

3 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System Figure 2 Power System Network that can Produce Sag/Swell Power quality issues are shown diagrammatically in figure 1 and figure 2 shows the power system network that creates sag/swell for observation and analysis. Power system disturbances can occur as general phenomenon and these disturbances are of two types-long term duration and short duration disturbances. Long duration disturbances are the disturbances that persist for the duration more than 1 minute. If the duration of the fault is less than 1 minute, the fault is termed as short duration fault. Long duration voltage raise is called over voltage and short duration voltage raise is called swell. Similarly, long duration voltage drop is termed as under-voltage and short duration voltage drop is termed as sag. Sag is a general phenomenon that occurs due to energizing heavy loads or starting of large motors. Swell is another kind which might be produced due to energizing capacitor banks or sudden release in loads. Voltage sag might cause poor efficiency and decreases the life time of the device connected. Swell might cause the device to be damaged. This causes the power system to poor power quality. Poor power quality can cause unexpected power supply failures, equipment failure or malfunctioning, equipment overheating and might lead to reduction in lifetime of the device, increased system losses and production of EMI. Long term sustained voltage variation if when the supply voltage is zero for more than 1 minute, the long term voltage disturbance is termed as sustained interruption. This sustained interruption cannot be cleared automatically and needs human intervention. Short term variations can be designated as instantaneous, momentary or temporary. Instantaneous variations in voltage vary from time duration 0-30 cycles, momentary variations vary from 30 cycles to 30 seconds and temporary variations vary from 30 seconds to 1 minute in time. Sag is termed as the variation in voltage from 90% to 10% of its final value for short duration. Swell is raise in voltage value from 110% to 180% if its final value. Interruption occurs when voltage or current falls to 0.1 pu in less than 1 minute. When current commutation occurs in power electronic devices, a periodic voltage disturbance is caused which is called notching. Instantaneous rapid change in voltage is called transient. Depending on the type of transient nature, transients are classified into two types- oscillatory and impulsive. Harmonics are power frequency disturbances having frequency which is integral multiples of power frequency. These power frequency disturbances can be decomposed to sum of fundamental quantity and harmonic content. These are mainly produced due to the presence of non-linear loads in the system. 3 editor@iaeme.com

4 S. Vijaya laxmi and Dr. P. V. Ramana Rao 3. RMS ALGORITHM A simple algorithm called RMS algorithm was developed to detect the sag/swell in the system. Sag or swell can cause unusual operation of the system. Thus the sag and swell should be avoided. But in the power system due to load variations these sag and swell cannot be avoided and these are very general phenomenon as per the power system is concerned. But measures should be taken to reduce the sag/swell. To take any action the first step needed is to identify the parameter. Here the identification of sag/swell is much important to take necessary action against to reduce the quantity of sag/swell and bring the voltage level to nominal value. Also the identification is required in how many phases sag/swell are present in the system. So a simple RMS algorithm was developed for identification. Phase - A Table I RMS Algorithm test cases for identification of sag/swell Voltage Sag Phase - B Phase - C Phase - A Voltage Swell Phase - B Phase C Case Output No sag exists No swell exists Case Sag exists in 1 phase Case Swell exists in 1 phase Case Sag exists in 2 phases Case Swell exists in 2 phases Case Sag exists in 3 phases Case Swell exists in 3 phases Case Sag exists in 1 phase Swell exists in 1 phase Case Sag exists in 1 phase Swell exists in 2 phase Case Sag exists in 1 phase Swell exists in 3 phase Case Sag exists in 2 phase Swell exists in 1 phase Case Sag exists in 2 phase Swell exists in 2 phase Case Sag exists in 2 phase Swell exists in 3 phase Case Sag exists in 3 phase Swell exists in 1 phase Case Sag exists in 3 phase Swell exists in 2 phase Case Sag exists in 3 phase Swell exists in 3 phase The test conditions were considered as 1 for ON and 0 for OFF. As shown in table 1, the sag and swell were generated for different phases of the power system. Fourier analysis provides a set of mathematical tools which can be used to break down a signal into its various magnitude components. 4 editor@iaeme.com

5 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System The identified voltage magnitude from the algorithm will send to the MATLAB file for evaluation of voltage magnitudes for the given reference signal. In Matlab file multiple conditional operators have been included for identification type of fault. In the Matlab file, the identified voltages have been compared to the specified reference voltages with the use of logical operators, if the identified voltage is less the specified voltage given as fault identified as sag, if it is greater it is considered as swell. If the Sag/Swell have been identified in the pre process then it have to identify whether symmetrical fault or asymmetrical fault. Analysis for identification of fault in the phases has taken here.the end of the identification process is displaying the results, these results can further utilized for fault reducing devices a like DVR, SFCL...Etc. 4. MATLAB RESULT ANALYSIS Matlab results were obtained by considering different cases producing sag and swell in different phases of power system. Case 1: analysis when no sag and no swell are present in the system Figure 3 Result showing no sag/swell present in the system Case 2: analysis when only sag exists in 1 phase of the system Figure 4 result showing sag present in 1 phase of the system 5 editor@iaeme.com

6 S. Vijaya laxmi and Dr. P. V. Ramana Rao Case 3: analysis when only swell exists in 1 phase of the system Figure 5 Result showing swell present in 1 phase of the system Case 4: analysis when sag exists in 2 phase of the system Figure 6 result showing sag present in 2 phase of the system Case 5: analysis when swell exists in 2 phase of the system Figure 7 Result showing swell present in 2 phase of the system 6 editor@iaeme.com

7 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System Case 6: analysis when only sag exists in 3 phase of the system Figure 8 Result showing sag present in 3 phase of the system Case 7: analysis when swell exists in 3 phase of the system Figure 9 Result showing swell present in 3 phase of the system Figure 3 shows the result window noting that no sag or no swell is present in the system. Figure 4 shows that sag is present in 1 phase of the system while no swell is present in the system. Figure 5 shows the swell present in 1 phase with no sag in the system. Figure 6 shows sag present in 2 phases with no swell and figure 7 shows the swell in 2 phases with no sag. Figure 8 shows sag present in 3 phases with no swell while figure 9 shows swell in 3 phases of the system with no sag. Case 8: analysis when sag exists in 1 phase and swell in 1 phase of the system 7 editor@iaeme.com

8 S. Vijaya laxmi and Dr. P. V. Ramana Rao Figure 10 Result showing sag present in 1 phase and swell exists in 1 phase of the system Case 9: analysis when sag exists in 1 phase and swell in 2 phases of the system Figure 11 Result showing sag present in 1 phase and swell exists in 2 phases of the system Case 10: analysis when sag exists in 1 phase and swell in 3phases of the system Figure 12 Result showing sag present in 1 phase and swell exists in 3 phase of the system Figure 10 shows the window noting sag is present in 1 phase with swell also in 1 phase of the system. Figure 11 shows sag present in 1 phase with swell in 2 phases of the system. Figure 12 shows the presence of sag in 1 phase with swell in 3 phases of the system. 8 editor@iaeme.com

9 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System Case 11: analysis when sag exists in 2 phases and swells in 1 phase of the system Figure 13 Result showing sag present in 2 phase and swell exists in 1 phase of the system Case 12: analysis when sag exists in 2 phases and swells in 2 phases of the system Figure 14 Result showing sag present in 2 phase and swell exists in 2 phase of the system Case 13: analysis when sag exists in 2 phases and swells in 3 phases of the system 9 editor@iaeme.com

10 S. Vijaya laxmi and Dr. P. V. Ramana Rao Figure 15 Result showing sag present in 2 phase and swell exists in 3 phase of the system Figure 13 shows the window noting sag is present in 2 phases with swell also in 1 phase of the system. Figure 14 shows sag present in 2 phases with swell in 2 phases of the system. Figure 15 shows the presence of sag in 2 phases with swell in 3 phases of the system. Case 14: analysis when only sag exists in 3 phases and swells in 1 phase of the system Figure 16 Result showing sag present in 3 phases and swell exists in 1 phase of the system Case 15: Analysis when only sag exists in 3 phases and swells in 2 phases of the system 10 editor@iaeme.com

11 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System Figure 17 Result showing sag present in 3 phase and swell exists in 2 phase of the system Case 16: analysis when sag exists in 3 phases and swells in 3 phases of the system Figure 18 Result showing sag present in 3 phase and swell exists in 3 phase of the system Figure 16 shows the window noting sag is present in 3 phases with swell also in 1 phase of the system. Figure 17 shows sag present in 3 phases with swell in 2 phases of the system. Figure 18 shows the presence of sag in 3 phases with swell in 3 phases of the system. 5. CONCLUSION A Novel sag/swell detection algorithm has been proposed and compared and implemented by using Matlab algorithms. The simulation study of algorithm has been presented in this paper for extracting voltage component of source voltage under sag/swell conditions. The function of in Matlab is a powerful tool for doing that even with noisy signals. The identification process is very accurate. The simulation results shows that sag/swell have been identified with what phase swell or sag exists. This algorithm explained is very simple and can effectively detect the presence of sag/swell in the system. Different cases have been considered for the production of sag/swell and the results were shown. REFERENCES [1] F. B. Ajaei, S. Afsharnia, A. Kahrobaeian, and S. Farhangi, A Fast and Effective Control Scheme for the Dynamic Voltage Restorer, IEEE Transactions On Power Delivery, 26(4), pp , Oct [2] Ding Ning, Cai Wei, Suo Juan, Wang Jianwei, and Xu Yonghai, Voltage Sag Disturbance Detection Based On RMS Voltage Method, IEEE power and Energy Engineering Conference, pp.1 4, March editor@iaeme.com

12 S. Vijaya laxmi and Dr. P. V. Ramana Rao [3] A. O. Al-Mathnani, M. A. Hannan, M. Al-Dabbagh, M. A. Mohd Ali, and A. Mohamed, Development of New Control Strategy for Voltage Sag Mitigation, 2nd IEEE International Power and Energy Conference, pp , Dec [4] H. K. Al-Hadidi, A. M. Gole, and D. A. Jacobson, Minimum Power Operation of Cascade Inverter-Based Dynamic Voltage Restorer, IEEE Transactions on Power Delivery, 23(2), pp , April 2008 [5] B. Singh, P. Jayaprakash, D. P. Kothari, A. Chandra, and Kamal-Al-Haddad, Indirect Control of Capacitor Supported DVR for Power Quality Improvement in Distribution System, 21 st Century IEEE Power And Energy Society General Meeting- Conversion and Delivery of Electrical Energy, pp. 1 7, July [6] Chi-Seng Lam, Man-Chung Wong, and Ying-Duo Han, Voltage Swell and Overvoltage Compensation with Unidirectional Power Flow Controlled Dynamic Voltage Restorer, IEEE Transactions on Power Delivery, 23(4), pp , Oct [7] M. I. Marei, E. F. El-Saadany, and M. M. A. Salama, A New Approach to Control DVR Based on Symmetrical Components Estimation, IEEE Transactions on Power Delivery, 22(4), pp , Oct [8] J. G. Nielsen, and F. Blaabjerg, A Detailed Comparison of System Topologies for Dynamic Voltage Restorers, IEEE Transactions On Industry Applications, 41(5), pp , Sep./Oct [9] S. U. Ahn, J. A. Jardini, M. Masuda, F.A.T. SiIva, S. Copeliovitch, L. Matakas, W. Komatsu, M. G. F. Ortiz, J. Camargo, and E. R. Zanetti, Mini-DVR - Dynamic Voltage Restorer with Functions of Reactive Compensation and Active Harmonic Filter, IEEE/PES Transmission & Distribution Conference & Exposition: Latin America, pp , Nov [10] Y. H. Chrmg, G. H. Kwon, T. B. Park, and K. Y. Lim, Voltage Sag and Swell Generator for the Evaluation of Custom Power Devices, IEEE Power Engineering Society General meeting, 4, pp , July [11] Suresh Kamble, and Dr. Chandrashekhar Thorat, Characterization of Voltage Sag Due To Balanced and Unbalanced Faults in Distribution Systems. International Journal of Electrical Engineering & Technology, 3(1), 2012, pp [12] Premanand.S, K.Vidya, D.Nivea and T.Geethapriya, Improved Performance of ASD Under Voltage Sag Conditions. International Journal of Electrical Engineering & Technology, 4(2), 2013, pp [13] Nadiya G. Mohammed, HaiderMuhamadHusen, Prof. D.S. Chavan, Fault Ride- Through Control for A Doubly Fed Induction Generator Wind Turbine under Unbalanced Voltage Sags. International Journal of Electrical Engineering & Technology, 3(1), 2012, pp editor@iaeme.com

13 Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution System AUTHORS PROFILE S.VIJAYA LAXMI was born in India in 1975; She received the B. Tech degree in Electrical and Electronics Engineering from V.R.S. Engineering College, Vijayawada, Nagarjuna University in 1997 and M. Tech degree from S.V.U College of Engineering in 2005 S.V.U Tirupati and Andra Pradesh, India. Currently she is pursuing Ph.D in Electrical Engineering, as a Research Scholar in University college of Engineering and Technology, Acharya Nagarjuna University, Andhra Pradesh India. Her areas of Interest are Voltage Quality Identification and Mitigation in Power systems and Application of Intelligent control techniques to Power systems. P.V. RAMANA RAO was born in India in 1946; He received the B. Tech degree in Electrical and Electronics Engineering from IIT Madras, India in 1967 and M. Tech degree from IIT Kharagpur, India in He received Ph. D from R.E.C Warangal in Total teaching experience 41 years at NIT Warangal out of which 12 years as Professor of Electrical Department. Currently Professor of Electrical Department in University college of Engineering and Technology, Acharya Nagarjuna University, Andhra Pradesh, India. His fields of interests are Power system operation and control, Power System Stability, HVDC and FACTS, Power System Protection, Application of DSP techniques and Application of Intelligent control techniques to Power systems editor@iaeme.com