A Wave Shape Based Algorithm for Fast CT Saturation Detection

Slides:



Advertisements
Similar presentations
Introduction to Alternating Current and Voltage
Advertisements

Introduction to Phasor Measurements Units (PMUs)
EXPERIMENTAL STUDY AND COMPARATIVE ANALYSIS OF TRANSFORMER HARMONIC BEHAVIOUR UNDER LINEAR AND NONLINEAR LOAD CONDITIONS.
Pontifical Catholic University of the Rio Grande do Sul Brazil Applying Artificial Neural Networks to Energy Quality Measurement Fernando Soares dos Reis.
Pontifical Catholic University of the Rio Grande do Sul Brazil Applying Artificial Neural Networks to Energy Quality Measurement Fernando Soares dos Reis.
Fourier Analysis D. Gordon E. Robertson, PhD, FCSB School of Human Kinetics University of Ottawa.
SUBJECT : DC Machine & Transformer
in the Age of the Photovoltaic
Chapter 8 Inverters AC Power • Inverters • Power Conditioning Units • Inverter Features and Specifications.
Classification of Electrocardiogram (ECG) Waveforms for the Detection of Cardiac Problems By Enda Moloney.
CLASS B AMPLIFIER 1. 2 In class B, the transistor is biased just off. The AC signal turns the transistor on. The transistor only conducts when it is turned.
Chapter 25 Nonsinusoidal Waveforms. 2 Waveforms Used in electronics except for sinusoidal Any periodic waveform may be expressed as –Sum of a series of.
Power Distribution Harmonics Case Study of 285-3F Chiller Plant Michael W. Harmon Principle Engineer Savannah River Nuclear Solutions, LLC Savannah River.
ET3380 Principles and Methods of Electric Power Conversion David Morrisson MS,MBA Week 1.
Alternating Current Circuits
Fundamentals of Power Electronics and Power System with MATLAB
I. Background The increasing use of Renewable Energy Sources (RES) such as Solar Cell and Wind Turbine Power convertion from DC to AC The using of non.
Alternating Current Electricity Lesson 11. Learning Objectives To know what is meant by alternating current. To know how to calculate the rms value of.
Section 2 AC Circuits. Chapter 12 Alternating Current.
Electricity and Magnetism 29 Alternating Currents and Power Transmission Chapter 29 Alternating Currents and Power Transmission.
EE2010 Fundamentals of Electric Circuits Lecture 13 Sinusoidal sources and the concept of phasor in circuit analysis.
AC Electricity. What is Alternating Current??? 1.Alternating current (AC) electricity is the type of electricity commonly used in homes and businesses.
Unit-3 RECTIFIERS, FILTERS AND REGULATORS :Half wave rectifier, ripple factor, full wave rectifier, Harmonic components in a rectifier circuit, Inductor.
Admin: Assignment 6 is posted. Due Monday. Thevenin hint – the current source appears to be shared between meshes…. Until you remove the load... Assignments.
Protection of Microgrids Using Differential Relays
Applied Circuit Analysis Chapter 11 AC Voltage and Current Copyright © 2013 The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Physical Layer PART II.
Alternating Current Circuits Chapter 33 (continued)
Z bigniew Leonowicz, Wroclaw University of Technology Z bigniew Leonowicz, Wroclaw University of Technology, Poland XXIX  IC-SPETO.
1 AGBell – EECT by Andrew G. Bell (260) Lecture 11.
A common 400 Hz AC Power Supply Distribution System for CMS FEE. Authors C. Rivetta– Fermilab. F. Arteche, F. Szoncso, - CERN.
Least Squares Estimate Algorithm Bei Zhang
Background 2 Outline 3 Scopus publications 4 Goal and a signal model 5Harmonic signal parameters estimation.
1 Challenge the future The Impact of Multi-terminal HVDC Grids on The Transient Behavior in Transmission Systems - Modelling And Analysis Lian Liu PhD.
SIGNAL GENERATORS.
TECHNICAL PAPER ON SIMULTANEOUS AC-DC POWER TRANSMISSION
1 AC Circuit Theory. 2 Sinusoidal AC Voltage Waveform: The path traced by a quantity, such as voltage, plotted as a function of some variable such as.
Chapter 3 – Diode Circuits – Part 3
1 Chapter 3 AC Power Analysis. 2 AC Power Analysis Chapter 3 3.1Instantaneous and Average Power 3.2Maximum Average Power Transfer 3.3Effective or RMS.
Part Three – Relay Input Sources
Vinayan.S Roll no:22 EEE7  Introduction  Saturation in conventional current transformers  Saturated & Non-saturated CT outputs  Problem in Coventional.
Chapter 8 Introduction to Alternating Current and Voltage.
EET307 POWER ELECTRONIC I AC VOLTAGE CONTROLLER
Protection of Power Systems
RECTIFIERS, FILTERS AND REGULATORS :Half wave rectifier, ripple factor, full wave rectifier, Harmonic components in a rectifier circuit, Inductor filter,
Characteristic curve auto-generation in saber
Introduction to Alternating Current and Voltage
A Novel Simulation Approach for Measuring of DC Voltage Offset Influence on Magnetizing Current Even Harmonics in the Power Transformer by Using Dither.
What is MPPT and why it is needed? (Maximum power point tracking)
Inverters Dr John Fletcher.
Sinusoidal Signal Described using three parameters Equation
Chapter 11.
COMPERE Project Meeting Dr Dawei Xiang 18/07/2008
Sinusoidal Waveform Phasor Method.
Inverters Dr John Fletcher.
HNC/D Engineering Science
Electric Circuits Fundamentals
Protective Relaying Conference
Fundamental Electrical Power Concepts
SHUNT ACTIVE FILTER It is a voltage-source converter connected in shunt with the same ac line and acts as a current source to cancel current distortions,
RECTIFIERS, FILTERS AND REGULATORS :Half wave rectifier, ripple factor, full wave rectifier, Harmonic components in a rectifier circuit, Inductor filter,
Electronics Fundamentals
10.6 Fourier Transform Mass Spectrometry
Uses of filters To remove unwanted components in a signal
Diode rectifiers (uncontrolled rectifiers)
Alternating Current Circuits
Physics 312: Electronics (1) Lecture 7 AC Current I Fundamentals of Electronics Circuits (with CD-ROH) By: Charles Alexander, Hathew Sadika, McGraw Hill.
Oscillators. Introduction to Oscillator There are basically types of Oscillators. 1. Sinusoidal Oscillators - These are known as Harmonic Oscillators.
Complex Waveforms HNC/D Engineering.
Presentation transcript:

A Wave Shape Based Algorithm for Fast CT Saturation Detection   CIGRE US National Committee http : //www.cigre.org 2015 Grid of the Future Symposium October 13, 2015 | Chicago , I L Powering a new dawn in solar energy Over 2 gigawatts of solar installed around the world A Wave Shape Based Algorithm for Fast CT Saturation Detection Abouzar Rahmati, PhD, PE, SMIEEE Senior Scientist Manager

Main objectives Discuss background and motivation Common CT saturation detection algorithms Proposed algorithm

Current transformer saturation Current transformers usually suffer from magnetic core saturation due to the large AC current amplitude and the existing decaying DC component in the fault current. CT saturation issues: - Distortion of secondary currents - Inaccurate phasor measurement - Miss-operation of the protective relays

CT Saturation Detection and Compensation Waveform analysis based methods Current signal harmonics Current reconstruction using unsaturated samples Artificial neural networks Wavelet transform

Proposed Algorithm SEO wave-shape Subtraction of the even and odd set samples (SEO) of the fault current is used for CT saturation detection. Why Even and Odd set samples? Saturation effect in the SEO wave-shape is much severe than the original signal. Saturation in the SEO begins with high values and quickly decreases to zero. Therefore, the CT saturation detection through the SEO signal is much more effective than the original fault current signal

Purely Sinusoidal Fault Current 𝑖 𝑡 = 𝐴 1 cos 2𝜋𝑓𝑡+ 𝜑 1 𝑖 𝑛 = 𝑖 𝑒 𝑛 + 𝑖 𝑜 𝑛 𝑖 𝑒 𝑛 = 𝐴 1 cos 2𝜋 𝑁 (2𝑛)+ 𝜑 1 𝑖 𝑜 𝑛 = 𝐴 1 cos 2𝜋 𝑁 (2𝑛+1)+ 𝜑 1 𝑖 𝑒𝑜 𝑛 = 2𝐴 1 sin 𝜋 𝑁 cos 2𝜋 𝑁 2𝑛 + 𝜑 1 − 𝜋 𝑁 + 𝜋 2 𝐼 𝑛 = 𝐼 𝑒𝑜 𝑛 2sin ( 𝜋 𝑁 )

Decaying DC Component 𝑖 𝑛 = 𝑖 𝑎𝑐 𝑛∆𝑡 + 𝑖 𝑑𝑐 𝑛∆𝑡 Removal Algorithm 𝑖 𝑛 = 𝑖 𝑎𝑐 𝑛∆𝑡 + 𝑖 𝑑𝑐 𝑛∆𝑡 𝑖 𝑎𝑐 𝑛 = ℎ=1 𝐻 𝐴 ℎ cos 2𝜋 𝑓 ℎ 𝑛∆𝑡+ 𝜑 ℎ , 𝑖 𝑑𝑐 𝑛 = 𝐴 𝑑𝑐 𝑒 − 𝑛∆𝑡 𝜏 𝑖 𝑜 𝑛 − cos 𝜋 𝑁 𝑖 𝑒𝑜 𝑛 − cos 2𝜋 𝑁 𝑖 𝑒 𝑛 = 𝐴 𝑜 1+ cos 𝜋 𝑁 𝑒 − ∆𝑇 𝜏 − cos 𝜋 𝑁 + cos 2𝜋 𝑁 𝑒 − ∆𝑇 𝜏 2𝑛 𝑑 𝑛 = 1+ cos 𝜋 𝑁 𝑖 𝑜 𝑛 − cos 𝜋 𝑁 + cos 2 𝜋 𝑁 𝑖 𝑒 𝑛 𝑑(𝑛+1) 𝑑(𝑛) = 𝑒 − 2∆𝑇 𝜏

Decaying DC offset parameters 𝜏= −2∆𝑇 𝐿𝑛 𝑑 𝑛+1 𝑑 𝑛 𝐴 𝑜 = 1+ cos 𝜋 𝑁 𝑒 − ∆𝑇 𝜏 − cos 𝜋 𝑁 + cos 2𝜋 𝑁 𝑒 − ∆𝑇 𝜏 2𝑛 −1 𝑑 𝑛 𝑖 𝑑𝑐 𝑛 = 𝐴 𝑜 𝑒 − ∆𝑇 𝜏 𝑛 SEO signal extraction: 𝑖 𝑑𝑐 𝑒𝑜 𝑛 = 𝐴 𝑜 1− 𝑒 − ∆𝑇 𝜏 𝑒 − ∆𝑇 𝜏 2𝑛 𝑖 𝑎𝑐 𝑛 =𝑖 𝑛 − 𝑖 𝑑𝑐 𝑛 𝑖 𝑎𝑐 𝑒𝑜 𝑛 = 𝑖 𝑒𝑜 𝑛 − 𝑖 𝑑𝑐 𝑒𝑜 𝑛

Example 𝑖 𝑛 =𝑖 𝑎𝑐 𝑛 + 𝑖 𝑑𝑐 𝑛 =1.5 𝑒 − 𝑛∆𝑇 0.02 + cos 2𝜋 𝑁 𝑛 𝐸 𝑛 = 𝑖 𝑑𝑐 𝑛 − 𝑖 𝑑𝑐 𝑒𝑠𝑡 𝑛 𝑖 𝑑𝑐 𝑛 ×100%

CT Saturation Detection The secondary current contains two saturated and unsaturated distinguished portions. Non-saturated period: At least 1/6 cycle ( 𝑇 𝑢1 ) before the first saturated portion ( 𝑇 𝑆1 ), and about 1/4 cycle between any two successive saturated portions ( 𝑇 𝑢2 ). Saturated period: 𝑇 𝑆1 The saturated portion ( 𝑇 𝑆 ), begins with a high slope at the end of any 𝑇 𝑢𝑖 and then decreases to a low value.

Comparison of the original and SEO signals Original signal includes 100% of the decaying DC initial amplitude: 𝐴 𝑜 The decaying DC portion in the SEO signal is: 𝐴 𝑜 (1− 𝑒 − ∆𝑇 𝜏 ) 𝑖 𝑑𝑐 𝑒𝑠𝑡 𝑛 𝑖 𝑑𝑐 𝑛 =1− 𝑒 − ∆𝑇 𝜏

Results of Simulation ATP/EMTP 230 kV, 50Hz power system model - Transmission line, JMarti - Circuit breaker - Saturable CTs

Results of Simulation Slight CT Saturation Slight Saturation, CT burden =0.5 Ω Fault current in phase B due to a three phase fault at 𝑡=0.02𝑠. The SEO signal

Results of Simulation Deep CT Saturation Deep Saturation with CT burden =1 Ω SEO: The saturated portions ( 𝑇 𝑆 ) start with a sharp and high amplitude pulse SEO: Is a sinusoidal signal without decaying DC offset, including some pulses in saturation conditions All pulses are located at the beginning of CT saturation area during each cycle.   Therefore, using these pulses existing in the SEO signal, any CT saturation can be detected.

Results of Simulation Deep CT Saturation Expanded view of the SEO signal in deep CT saturation case

Conclusion An efficient method for CT saturation detection was proposed. The method is based on the subtracting the even and odd set samples (SEO). The decaying DC offset is completely removed from the SEO signal. Easy saturation area detection: Saturation areas start with high amplitude pulses, which are easily detected. This method is not affected by fault conditions, such as fault type, and decaying DC characteristics. Is able to detect both deep and slight CT saturations.

Questions? ? Abouzar Rahmati SunEdison Inc. arahmati@sunedison.com