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A WIDE AREA SYSTEM FOR POWER TRANSMISSION SECURITY ENHANCEMENT USING A PROCESS SYSTEMS APPROACH. *Jerry Thambirajah, *Nina F Thornhill & + Bikash C Pal *Centre for Process Systems Engineering, + Department of Electrical and Electronic Engineering Imperial College London, United Kingdom.
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A WIDE AREA SYSTEM FOR POWER TRANSMISSION SECURITY ENHANCEMENT USING A PROCESS SYSTEMS APPROACH *Jerry Thambirajah, *Nina F Thornhill & +Bikash C Pal *Centre for Process Systems Engineering, +Department of Electrical and Electronic Engineering Imperial College London, United Kingdom. WAMS Workshop, 12th-13th April 2010
Contents: • Problem, Motivation & Objectives • Methods • ICA • RD • Case Examples • Result 2
Problem: 0.3 – 0.4 Hz ~0.5 Hz 4
Objectives: • Develop methods and tools that use available data to infer system stability • Detect inter-area modes • Determine damping ratios 6
The Challenge Is... By contrast... • Frequency and damping from ambient data • Some methods: • Independent Component Analysis • Random Decrement 7
METHODS 8
Mode Estimation: Basis Functions • Simple signals to represent complex signals • Different techniques: • Principal Component Analysis • Independent Component Analysis • Empirical Mode Decomposition 9
Independent Component Analysis (ICA): • Independent narrowband oscillatory sources – Independent Components (ICs) • Spectral ICA – uses power spectra • Sources are narrowband features in frequency spectrum • However, also removes phase information 10
START ICA: Flowchart Is NO maximum? YES Store D and C 11 END N frequency channels m process variables
ICA Significance Indices: • Normalised mixing ratio of sources in each signal X D C 12
ICA: Example • Synthetic signals sampled at 10 Hz (inter-sampling time: 0.1 s) for a duration of 300 s with noise added such that the SNRs are 2, 10, 4 and 2.5 respectively: 13
ICA: Example 15
Damping Estimation: Random Decrement (RD) Step input Impulse Random input Linear System 16
RD: Flowchart START Collect signal segments, Sj Determine zi END 17
RD: Process y Threshold t Segment 26 Segment 10 ... ... Take average t Impulse Response t tr10 tr26 18
RD Signature: • Resulting time trace is in the form: A Amplitude Time (s) 19
ICA-RD: • ICA provides mode frequency information • RD provides estimate of damping • Accuracy of estimate depends on location of measurement • Solution – combine methods utilising SIs 20
ICA-RD: Mode Frequencies ICA Data Length of sliding window Filter Update Time Significance Indices Exponential Fit Random Decrement z,w Cycles 21 Threshold
Case 1: ICA • Monitoring System detected 0.07 Hz oscillation • Aim to determine source • Analysis done: • Modes in power flows between substations • Relative comparisons 23
Case 1: ICA H I A J B K C D L E F M G 24
Case 1: ICA • ~0.07 Hz distinct • Most prominent alternately in A-C and L-M transfers L-M A-C 25
Case 1: ICA Spine of oscillation A C L M 26
Case 2: ICA-RD 0.3 – 0.4 Hz Petäjäskoski Keminmaa Olkiluoto Yllikällä Rauma Kymi Espoo 27
RESULT 29
Configurable Map Dynamic Markers 30
Signal View Damping 31 Detected Modes
Signal View Damping 32 Detected Modes
Signal View Damping 33 Detected Modes
A WIDE AREA SYSTEM FOR POWER TRANSMISSION SECURITY ENHANCEMENT USING A PROCESS SYSTEMS APPROACH *Jerry Thambirajah, *Nina F Thornhill & +Bikash C Pal *Centre for Process Systems Engineering, +Department of Electrical and Electronic Engineering Imperial College London, United Kingdom. WAMS Workshop, 12th-13th April 2010