Dynamic State Estimation Based Protection: Laboratory Validation Paul Myrda - EPRI & A.P. Meliopoulos and G. J. Cokkinides - Georgia Tech October 21, 2014, Houston, TX
Contents Background and Motivation Long Term Objectives & Vision Present Relaying Technology The Setting-less Protection Approach Implementation / Examples Applications Other Benefits Substation Based State Estimation Conclusions 2
Background and Motivation Protective Relay Setting has become Very Complex New Power Electronic Resource Interfaces Exhibit Fault Currents Comparable to Load Currents Detection and Locating of Some Faults is Difficult leading to Gaps in Protection. No Substation Level view of Protection Modeling Errors Play a Major Role in many Control Failures Wide Area Blackouts Asset Management is Painful NERC: #1 Root Cause of System Disturbances is Protective Relaying 3
Long Term Objectives / Vision Objective Vision Reduce Complexity Minimize the Coordination Role of the engineer Develop New Dynamic State Estimation Protection Method Establish a GateKeeper Device Transmits the Validated Model Upstream (other substations, control center, enterprise, etc.) Develop a fully automated protection, control and operation infrastructure 4
Present Relaying Technology Key Features Process Bus / Station Bus / Point to Point Mimic E/M Relays More Functions Increased Complexity Protection Dependability? Protection Security? Protection Gaps? NOTE: Protection Functions and Algorithms Mimic E/M Relays. New Technology Capabilities are Grossly Underutilized 5
The Setting-Less Protection Method In Search of Secure Protection: Setting-less Protection can be viewed as Generalized Differential protection Analytics: Dynamic State Estimation (systematic way to determine observance of physical laws) 6
Setting-less Protection Approach 1. Measure/Monitor as Many Quantities as Possible and Use Dynamic State Estimation to Continuously Monitor the State (Condition, Health) of the Zone (Component) Under Protection. Identify bad data, model changes, etc. 2. Act on the Basis of the Zone (Component) State (Condition, Component Health). 3. Advantage: No need to know what is happening in the rest of the system no coordination needed. 7
Implementation Overview The Component is represented with a set of Differential Equations (DE) The Dynamic State Estimator fits the Streaming Data to the Dynamic Model (DE) of the Component Object Oriented Implementation 8
Implementation Calculation Time Typical Sampling Rates t s = 0.1 ms to 0.5 ms Challenges 1. Perform the Analytics at time less than (2t s ) 2. Robust Operation of DSE requires accurate zone model 3. GPS Synchronized Measurements simplify Dynamic State Estimation (for linear zones it becomes a direct method) Example: Data Acquisition is performed 4 ks/s Dynamic State Estimation is performed 2,000 times per sec. 9
Capacitor Bank JCLINE3 LOAD04 Protection Zone 115 kv, 48 MVAr capacitor bank GUNIT2 G G 1 2 1 2 XFMR2L XFMR2H YJLINE1 SOURCE1 SOURCE1-T LINETEE GEN YJLINE2 CAP1 LINE CAPBNK TXFMRHIGH 1 2 External Fault Capacitor Bank Internal Fault TXFMRLOW Event A single phase to ground fault at 2.2 seconds and duration 0.5 seconds at the location designated External Fault. An internal fault in the capacitor bank occurs at 3.0 secs (fault shorted cap cans of phase C, see figure). Fault changes the net capacitance of phase C from 4.8 μf to 2.4 μf. Relay Inputs (Measurements): Voltage of phase A-G Voltage of phase B-G Voltage of phase C-G Voltage at neutral point Current of phase A Current of phase B Current of phase C 10
Capacitor Bank External Fault Internal Fault 125.8 kv -164.9 kv Actual_Measurement_Voltage_CAPBANK_A (V) Actual_Measurement_Voltage_CAPBANK_B (V) Actual_Measurement_Voltage_CAPBANK_C (V) Estimated_Actual_Measurement_Voltage_CAPBANK_A 3Φ Voltage (V) Estimated_Actual_Measurement_Voltage_CAPBANK_B (V) Estimated_Actual_Measurement_Voltage_CAPBANK_C (V) 722.9 A -934.0 A Actual_Measurement_Current_CAPBANK_A (A) Actual_Measurement_Current_CAPBANK_B (A) Actual_Measurement_Current_CAPBANK_C (A) Estimated_Actual_Measurement_Current_CAPBANK_A 3Φ Current (A) Estimated_Actual_Measurement_Current_CAPBANK_B (A) Estimated_Actual_Measurement_Current_CAPBANK_C (A) 100.00 Confidence-Level Confidence Similar Characteristics 0.000 1.000 Trip Trip Signal No Trip Trip 0.000 2.933 us Execution_time_average (s) Calculation Time 1.512 us March 11, 2014-10:46:04.710584 March 11, 2014-10:46:06.145781 11
Protection of multi-section Lines Internal Fault External Fault Protection Zone 500 kv Transmission Line (indicated as Monitored Line ) Event A phase A-C fault at 0.5 secs with duration of 0.5 secs at the location indicated as External Fault. A high impedance (2 kohms) phase A-G fault at 1.3 secs, at the location indicated as Internal Fault. Relay Inputs (Measurements) Three-phase voltages at both terminals Three-phase currents at both terminals 12
Protection of multi-section Lines External Fault Internal Fault 10.11 ka -10.90 ka 418.8 kv -432.8 kv 100.00 Actual_Measurement_Current_TABL_A (A) Actual_Measurement_Current_TABL_B (A) Actual_Measurement_Current_TABL_C (A) Estimated_Actual_Measurement_Current_TABL_A (A) Estimated_Actual_Measurement_Current_TABL_B (A) Estimated_Actual_Measurement_Current_TABL_C (A) Actual_Measurement_Voltage_TABL_A (V) Actual_Measurement_Voltage_TABL_B (V) Actual_Measurement_Voltage_TABL_C (V) Estimated_Actual_Measurement_Voltage_TABL_A (V) Estimated_Actual_Measurement_Voltage_TABL_B (V) Estimated_Actual_Measurement_Voltage_TABL_C (V) Confidence-Level 0.000 1.000 Trip No Trip Trip 0.000 41.15 us Execution (s) 29.83 us January 25, 2014-20:08:30.127224 January 25, 2014-20:08:31.349990 13
Protection of Saturable Core Transformers FAULT Protection Zone G 1 2 SOURCE LINE XFMRH XFMRL 1-Ph LOAD 14.4/2.2kV, 1000 kva single-phase saturable-core transformer Event Inrush Current A 800kW load is connected at 0.72 secs to the transformer (generates inrush currents). A coil to ground fault at 1.52 secs. The fault location is 5% from neutral. Internal Turn-Ground Fault Relay Inputs (Measurements) Voltages at both sides Currents at both sides Temperature measurements at selected points 14
Protection of Saturable Core Transformers Inrush Current Internal Fault 20.22 kv Actual_Measurement_Voltage_XFMRH_A (V) Estimated_Actual_Measurement_Voltage_XFMRH_A (V) -20.21 kv 129.3 A Actual_Measurement_Current_XFMRH_A (A) Estimated_Actual_Measurement_Current_XFMRH_A (A) -82.12 A 100.00 Confidence-Level 4.474 p 1.000 Trip or Not Trip Setting-Less Protection - No Trip Setting-Less Protection - Trip 0.000 107.0 % Differential_Operation_Index (%) Differential Protection No Trip 46.19 m% Differential Protection - Trip July 14, 2014-22:36:58.315318 July 14, 2014-22:36:59.789669 15
Setting-less Protection Applications The following application have been successfully simulated in the lab environment: Capacitor Bank Protection Transmission Line Protection Transformer Protection Doubly Fed Induction Machine Protection Saturable Core Reactor Protection Distribution Line Protection 16
Laboratory Implementation Experimental Setup Block Diagram Experimental Setup PC with D/A Hardware Amplifiers (3) Hardfiber (2) PCIe Cards (2) Protection PC (1) 17
Laboratory Results Example 18
Other Benefits Protection is Ubiquitous Makes Economic Sense to Use Relays for Distributed Model Data Base Capability of Perpetual Model Validation A Ubiquitous System for Perpetual Model Validation 19
Vision: Substation Based State Estimation Control Center State Estimation Time Phasor Domain Transition Advantages Detection of Hidden Failures Overall Model Flow Substation Automation Centralized Substation Protection Automated Protection Coordination 20
Summary Setting-less Protection has been proven in a lab environment in six application areas Prototype installation at NYPA under a NYSERDA grant Multiple secondary benefits Model Validation Detection of Hidden Failures Distributed State Estimation Applications 21
Thank You! Together... Shaping the Future of Electricity