Srinu Babu . Matta Research Scholar

1. Technical Paper : D2-1-33 Out-of-step Detection using Wide Area Measurements Under the supervision of Dr. Seethalekshmi K.Professor SrinuBabu. MattaResearch Scholar Babu Banarasi Das University, Lucknow, Uttar Pradesh, India

2. Out-of-detection (OOS) using WAMS Contents • Power System – Snap shot & Challenges • Smart Grid – An emerging Technology • Protection schemes – Distance Protection • Out-of-step detection techniques • Proposed OOS- detection methods • Case studies & Results • Concluding Observations • Future scope • References

3. Power System - A Snap-shot Indian Power Scenario The power system – Structure Generation – Transmission - Distribution The power demand in 1947 was 1670 MW and today it is 224,907 MW. (Source: GOI site,CEA, Studygalaxy.com ) Highest monthly power generation recorded, so far is 91.7Million Units in April’13. (Source:Power Line, June’13) Generation

4. Power System - Challenges Indian Power System Perspective

5. Power System - Challenges Peculiarities of Regional Grids in India

6. Smart Grid - An Emerging Technology • Opportunity for existing  AGING systems to leapfrog by envisioning a futuristic power grid • Smart Grid Characteristics • Emerging technology • Integrates new technologies to enable re-look at design & • operation of power system • Detect & address emerging problems before they impact service • Respond to local & system-wide inputs • Incorporate measurements & Feedback controls that quickly return to stable system operation after disturbances • Automatically adapt protective systems to accommodate changing system conditions • Re-route power flows, improve voltage profiles, change load patterns etc. during contingencies • Enable loads & Distributed generation to participate in operations • Self-healing & adaptive • “ Smart Grid”, means different things to different people

7. Wide Area Measurement Systems (WAMS) Synchrophasors

8. Wide Area Measurement Systems (WAMS) Phasor Monitoring Unit (PMU) • ‘PMU’, are devices which usesynchronization signals from the global positioning system (GPS) satellites and provide the Phasor voltages and currents measured at a given substation. • PMU • Hardware • Block Diagram

9. Wide Area Measurement Systems (WAMS) Synchrophasor :: Applications & Benefits • Synchrophasor technology enables cost-effective solutions to substantially improve transmission system planning, operation, maintenance and energy trading. • Real-Time Monitoring & Control • State Estimation. • Real Time Congestion Management • Post-Disturbance Analysis. • Benchmarking & System Model Variation • Power System Restoration • Adaptive Protection

10. Protection system – Need & Schemes Various Schemes Classification of Transmission lines on the basis of Source-to-line impedance ratio (SIR). Typical Protection scheme followed wrt the type of transmission line.

11. Protection system – Need & Schemes Distance Protection - A snap shot • Description: Distance relays are double actuating quantity relays with one coil energized by voltage and the other coil by current. The system impedance is seen by the relay for judging the fault condition. • Rationale: Distance protection is non unit type protection and very simple to apply. The Power swing block signal protects the system from stable power swings by extending a block operation on Distance relay and allowing the trip signal incase of unstable power swing. • Benefits: These relays are used as primary and back-up protection. They can be used in carrier/communication/pilot aided distance schemes in Auto-reclosing schemes. Distance protection is widely used in protection of transmission lines.

12. Out-of-step detection techniques OOS protection – A snap shot • Description: To avoid tripping of any power system element during stable swings. Protect the power system during unstable or out-of-step conditions • Rationale: Protective relays prone to respond to stable or unstable power swings and cause unwanted trippings of transmission lines or other power system elements include OC, UV, distance, directional OC, Out-of-step relay protects the power system from stable power swings by generating a out-of-step block signal (OSB) • Benefits: A controlled tripping of certain power system elements during the OOS condition is necessary in order to prevent equipment damage, and wide spread power outages, and minimize the effects of the disturbance.

13. Out-of-step detection techniques Classification

14. Out-of-step detection techniques Comparison of various techniques • Concentric Distance Relay Characteristics. Merits: +Simple +The power swing condition is checked before one of the impedance tripping zones is entered allowing the tripping elements to be blocked : Demerits : - limited to a single delta impedance setting and a timer setting - Load encroachment or limit the reach of thehigher impedance zones. • Blinders scheme Merits: + Used for power swing detection applications is that it can be used independent of the distance zone characteristics. + Single blinder can be used to restrict tripping of the distance relay for loads outside of the blinders.+ It can be used for load encroachment applications. Demerits : -To find the correct settings for the blinders is not always simple and requires a sophisticated grid analysis. - The single-blinder scheme cannot distinguish between a fault and an OOS condition until the fault has passed through the second blinder within a given time. Two blinder scheme.

15. Out-of-step detection techniques Comparison of various techniques

16. Proposed Out-of-step detection techniques Resistance based scheme The system consists of two 400KV buses M and N connected to two generators EM and EN respectively and two parallel lines connecting the buses. The relay is placed at bus M. Phasor Measurement Units (PMU) are placed at the buses M and N. PMU’s placed at the buses calculate voltage and current of the three phases of the line at a sampling rate of 20 – 60 samples / cycle. A fault occurs on one of the lines and the line is tripped. As a result of which there is an imbalance of power in the other line and thus it experiences power swing. The data collected by the PMUs is then used in the Data Concentrator to calculate the positive sequence voltage and current phasor at fundamental frequency using Discrete Fourier Transform algorithm. . PMU based schemes for SMIB system Flowchart for the resistance based scheme

17. Proposed Out-of-step detection techniques Resistance based scheme Swing Detection Element This element acts as checking criteria to ascertain the out of step condition during stable or unstable power swings. The algorithm comprises of four types of sub-elements as shown here, namely “Magnitude of change detection element “, “Rate of change detection element”, “differential magnitude of change detection element” and “Differential rate of change detection element”. All the parameters like T1 to T4, K1 to K4, R1set, R2set, Tmax and T areprecisely set after conducting thorough study of the system configuration & its transient analysis. If either of the “Magnitude of change detection element “and “Rate of change detection element” sets along with either of the “differential magnitude of change detection element” and “Differential rate of change detection element”, then only the Swing Detection Element gives a positive output, this signal can be used for controlled tripping or for any power shedding application etc. Algorithm of Swing Detection Element

18. Proposed Out-of-step detection techniques Impedance based scheme The system consists of two 400KV buses M and N connected to two generators EM and EN respectively and two parallel lines connecting the buses. The relay is placed at bus M. Phasor Measurement Units (PMU) are placed at the buses M and N. PMU’s placed at the buses calculate voltage and current of the three phases of the line at a sampling rate of 20 – 60 samples / cycle. A fault occurs on one of the lines and the line is tripped. As a result of which there is an imbalance of power in the other line and thus it experiences power swing. The data collected by the PMUs is then used in the Data Concentrator to calculate the positive sequence voltage and current phasor at fundamental frequency using Discrete Fourier Transform algorithm. . PMU based schemes for SMIB system Flowchart for the impedance based scheme

19. Proposed Out-of-step detection techniques Impedance based scheme Swing Detection Element This element acts as checking criteria to ascertain the out of step condition during stable or unstable power swings. The algorithm comprises of four types of sub-elements as shown here, namely “Magnitude of change detection element “, “Rate of change detection element”, “differential magnitude of change detection element” and “Differential rate of change detection element”. All the parameters like T1 to T4, K1 to K4, R1set, R2set, Tmax and T areprecisely set after conducting thorough study of the system configuration & its transient analysis. If either of the “Magnitude of change detection element “and “Rate of change detection element” sets along with either of the “differential magnitude of change detection element” and “Differential rate of change detection element”, then only the Swing Detection Element gives a positive output, this signal can be used for controlled tripping or for any power shedding application etc. Algorithm of Swing Detection Element

20. Case studies & Results Case studies The Power Stability studies for both the proposed schemes have been carried for testing on a single machine infinite bus system (SMIB) [13] and the WSCC 9-bus system [14]. The single line diagram of the systems are shown in Fig.6 and Fig.7 respectively. Simulations are carried out on PSCAD & MATLAB. A disturbance was created on one transmission line, where the performance of the distance relay to be studied, is connected. The disturbance was created by connecting load on same line for some duration. The load location and amount of loading on the line is varied to study the performance of the distance relay on stable and unstable swings. In these schemes, the system frequency is considered to be constant. For stable swings, the accuracy of the relay to classify a power swing as a stable swing is monitored. During unstable swing, the relays have been observed for speed of detection of OOS condition. Loading of the line has been limited near the margins of stability and unstability of the system depending upon the case of study. Single line diagram of SMIB. Single line WSCC 9-bus system.

21. Case studies & Results Results – Resistance based scheme Magnitude change detection element Magnitude change detection element Differential magnitude change detection element Differential magnitude change detection element Differential rate of change detection element Differential rate of change detection element Voltage Signal Voltage Signal Swing Detection Element – Out put signal Swing Detection Element – Out put signal Trip signal No Trip signal

22. Case studies & Results Results – Impedance based scheme Magnitude change detection element Magnitude change detection element Differential magnitude change detection element Differential magnitude change detection element Differential rate of change detection element Differential rate of change detection element Voltage Signal Voltage Signal Swing Detection Element – Out put signal Trip signal No Trip signal Swing Detection Element – Out put signal

23. Out of step detection using WAMS Concluding Observations • Power swing detection schemes based on WAMS - synchronised time measurement is proposed in this paper. Schemes work on the swing detection algorithm for resistance or impedance, where in the resistance, rate of change of resistance and differential measurements made from two sides of the transmission line detects the OOS condition. • These methods use PMU data available at both ends of the transmission line. • It is observed that as the disturbance severity increases, operating time of both the schemes reduces and this technique can operate for faults during steady state as well. • Simulation results in SMIB case and WSCC 9 bus system case reveals that both the proposed schemes can detect and classify the power swing very precisely.

24. Out of step detection using WAMS Future scope • Using Classifiers like SVM to detect the Out of step condition. • Extending the same approach for using stable islanding application. • Application of the same approach for higher bus configured system.

25. Out of step detection using WAMS [1] P.Kundur, “Power System Stability,” McGraw Hill. [2] Stanley H. Horowitz, Arun G. Phadke, “Power System Relaying,” John Wiley & Sons Ltd, Third edition, 2008. [3] Dr. Jürgen Holbach, Siemens AG, Raleigh, NC, USA: “New Out Of Step Blocking Algorithm for Detecting Fast Power Swing Frequencies,” 30thAnnual Western Protective Relay Conference, Washington StateUniversity, Spokane , Washington, October 21-23, 2003 [4] Y. Liu, “Aspects on power system islanding for preventing widespread blackout,” in Proc. IEEE Int. Conf. Networking, Sensing and Control, 2006 [5] A. Mechraoui, “A new principle for high resistance earth fault detection during fast power swings for distance protection,” IEEE Trans. Power Delivery, 1997. [6] D. Tziouvaras and D. Hou, “Out-of-step protection fundamentals and advancements,” IEEE, presented at the 30th Annual. Western Protective Relay Conf., Spokane, 2003. [7] V. Centeno, “An adaptive out-of-step relay [for power system protection],” IEEE Trans. Power Delivery, 1997. [8] R. Padiyar and S. Krishna, “Online detection of loss of synchronism using energy function criterion,” IEEE Trans. Power Delivery, 2006. References

26. Out of step detection using WAMS [9] S. Chakrabarti, E. Kyriakides, T. Bi, D. Cai and V. Terzija, "Measurements Get Together," IEEE Power & Energy Magazine, 2009. [10] Yan Li, Xiaoxin Zhou, and Jingyang Zhou, “A new algorithm for distributed power system state estimation based on PMUs,” IEEE, International Conference on Power System Technology,. 2006. [11] J. Mooney, P.E and N. Fisher, "Application guidelines for power swing detection on transmission systems," Schweitzer Eng. Lab. Inc,59th Annual Coriference for Protective Relay Engineers, 2006. [12] Pratim Kundu, J. Ganeswara Rao, P. K. Nayak, A. K. Pradhan, “Wide Area Measurement based Out-of-Step Detection Technique,” IEEE Trans. Power Delivery, 2011. [13] S.M.Brahma, “Distance Relay with Out-of-step Blocking Function using Wavelet Transform”, IEEE transactions on power delivery, vol. 22, no. 3, July 2007. [14] Seethalekshmi K., S. N. Singh, and S. C. Srivastava, “SVM Based Power Swing Identification Scheme for Distance Relays” IEEE PES,GM, July2010. References