Predicting the Voltage Sag Performance of Electricity Distribution Networks

Size: px

Start display at page:

Download "Predicting the Voltage Sag Performance of Electricity Distribution Networks"

Chad Clark
5 years ago
Views:

1 Predicting the Voltage Sag Performance of Electricity Distribution Networks by Dr Robert Barr, Prof. Vic Gosbell, Mr Chris Halliday,

2 Figure - Typical Rectangular Voltage Sag PU Supply Voltage Sag voltage 0.3 PU Sag duration 0.3 seconds Time seconds 2

3 Voltage Sag Patterns - Multiple Sites - Typical Data - Log Time Scale SMPS PU Sag Voltage Protection Curve ITIC Curve Typical Sag Data Time seconds 0 log scale 3

4 Voltage Sag Patterns - Multiple Sites - Typical Data Linear Time Scale SMPS PU Sag Voltage Protection Curve ITIC Curve Typical Sag Data Time seconds 4

5 Typical Distribution Network 66kV High Speed Translay Protection (~0.secs) 66kV High Speed Bus Zone Protection (~0.secs) High Speed Differential Protection (~0.secs) kv F E O/C E/F protection at E & F must grade above A, B, C & D D C B A Low Speed Over Current/Earth Fault Feeder Protection - must grade above distribution Tx fuse protection. (~0.3 to.0sec) Customer see sag voltage from faults on feeders A, B and C feeders plus upstream faults 230/400V Range of possible kv fault locations 5

6 Standard Inverse Protection Voltage Sag Model Source Voltage V s D kv busbar C Customers see a sag voltage from the short circuit fault on feeder A B Network Source Impedance (Z src Per Unit) I A Notes > X/R ratio constant throughout kv feeder > Network at zero load before voltage sag generating fault. > Circuit breaker opening time is 0. seconds. > Overcurrent protection relay has a Standard Inverse characteristic. Standard Inverse overcurrent protection relay O/Coperatingtime= τ Variable fault impedance governed by fault location 0.4 ( I/Ipick up) seconds...() SagVoltage(Vsag) = Vsrc I. Z src τ SagDuration (Tsag) = 0.4 ( I/Ipick up) volts (2) seconds...(3) variable fault location 6

7 Fault Model Single Radial kv Line Source Voltage V s kv busbar D C B A 230/400V kv fault locations Observation point 7

8 LV Phase to Neutral Voltages 8

9 7km line - 0.km steps Voltage Sag Model LV Phase to Neutral Va Vb & Vc - MV 3 Sag Voltage PU ITIC Curve Protection Curve June 2005 Time Seconds 9

10 7km line - 0.km steps. 0.9 Voltage Sag Model LV Phase to Neutral Van LV - MV Ph to Vbn LV - MV Ph to Sag Voltage PU Vcn LV - MV Ph to Va Vb & Vc - MV 3 ITIC Curve June 2005 Time Seconds Protection Curve 0

11 7km line - 0.km steps. Voltage Sag Model LV Phase to Neutral Van LV - MV Ph to Vbn LV - MV Ph to Sag Voltage PU June 2005 Time Seconds Vcn LV - MV Ph to Van LV - MV Ph to E fault Vbn LV - MV Ph to E fault Vcn LV - Ph to E fault Va Vb & Vc - MV 3 ITIC Curve Protection Curve

12 LV Phase to Phase Voltages 2

13 7km line - 0.km steps Voltage Sag Model LV Phase to Phase Vab Vbc & Vca - MV 3 Sag Voltage PU ITIC Curve Protection Curve June 2005 Time Seconds 3

14 7km line - 0.km steps. 0.9 Voltage Sag Model LV Phase to Phase Vab LV - MV Ph to Vbc LV - MV Ph to Sag Voltage PU Vca LV - MV Ph to Vab Vbc & Vca - MV 3 ITIC Curve June 2005 Time Seconds Protection Curve 4

15 7km line - 0.km steps Sag Voltage PU Voltage Sag Model LV Phase to Phase June 2005 Time Seconds Vab LV - MV Ph to Vbc LV - MV Ph to Vca LV - MV Ph to Vab LV - MV Ph to E fault Vbc LV - MV Ph to E fault Vca LV - Ph to E fault Vab Vbc & Vca - MV 3 ITIC Curve Protection Curve 5

16 Comparison of Phase to Neutral & Phase to Phase LV Connections 6

17 Voltage Sag Model - Comparison of kv Ph to Ph Faults 7km line - 0.km steps. Sag Voltage PU Van LV - MV Ph to Vbn LV - MV Ph to Vcn LV - MV Ph to ITIC Curve Protection Curve June 2005 Time Seconds Vab LV - MV Ph to Vbc LV - MV Ph to Vca LV - MV Ph to 7

18 Voltage Sag Model - Comparison of kv Ph to E Faults 7km line - 0.km steps Sag Voltage PU Van LV - MV Ph to E fault Vbn LV - MV Ph to E fault Vcn LV - Ph to E fault ITIC Curve Protection Curve Vab LV - MV Ph to E fault June 2005 Time Seconds Vbc LV - MV Ph to E fault Vca LV - Ph to E fault 8

19 Zone Substation 4 kv Feeders 9

20 Cumulative kv Network Exposure (km) L kv Network Exposure ~ k L 2 20

21 Key kv Feeder Parameters L - km Distance Range from Zone Substation 0 km - 2 km 2 3 km 3 4 km 4 5 km km kv Line Exposure km 3 km 6 km 8 km 0 km % kv Line exposure 4% % 2% 29% 36% Cumulative km kv Line Exposure

22 Model Parameters km of kv kv feeders RMS Average feeder length faults/00km/year faults per year years of history to model 22

23 Model Parameters 3% 4% 4% 4% 6% 6% 6% kv 3 phase Faults kv Ph to Ph Faults A - B kv Ph to Ph Faults B - C kv Ph to Ph Faults C - A kv Ph to E Faults A kv Ph to E Faults B kv Ph to E Faults C Total 00% 23

24 Sag Voltage PU Probabilistic Voltage Sag Model LV Phase to Neutral V LV - MV Ph A to Ph B fault V LV - MV Ph B to Ph C fault V LV - MV Ph C to Ph A fault V LV - MV Ph A to E fault V LV - MV Ph B to E fault V LV - Ph C to E fault V LV - MV ITIC Curve 0. Protection Curve June 2005 Time Seconds 24

25 Sag Voltage PU Probabilistic Voltage Sag Model LV Phase to Phase Vab LV - MV Ph to Vbc LV - MV Ph to Vca LV - MV Ph to Vab LV - MV Ph to E fault Vbc LV - MV Ph to E fault Vca LV - Ph to E fault Vab Vbc & Vca - MV ITIC Curve 0. Protection Curve Time Seconds 25

26 Applications for Industrial Customers In general use 400V Phase to Phase connections for control equipment Choose common phasing for control equipment e.g. 400V Red to Blue phases across the entire plant Assess the benefits of using 3 phase 400V supplies for low power control equipment Understand the likely frequency and severity of voltage sags 26

27 Applications for Distributors Understand and quantify the benefits of minimising Network Exposure Understand the benefits of star point resistor/inductor earthing Understand the critical role of Protection Settings and Protection Arrangements on voltage sag performance Inform customers of expected voltage sag performance levels at various parts of the network 27

28 Applications for New Standards Forcast expected sag activity for specific sites without long duration surveys Allows generation of standardised voltage sag environments for equipment immunity Develop immunity guidelines as alternative to generic CBEMA curve 28

29 Conclusions The Voltage Sag Model Gives distributors a tool to predict the comparative voltage sag performance at key parts of the network Helps explain plant & network options available to improve voltage sag performance for customers Has an application in defining a standardised voltage sag environment for use in assessing the immunity of electrical equipment 29

30 Questions? 7km line - 0.km steps. Voltage Sag Model LV Phase to Neutral Van LV - MV Ph to Vbn LV - MV Ph to Sag Voltage PU June 2005 Time Seconds Vcn LV - MV Ph to Van LV - MV Ph to E fault Vbn LV - MV Ph to E fault Vcn LV - Ph to E fault Va Vb & Vc - MV 3 ITIC Curve Protection Curve 30

Techniques for the Control of Steady State Voltage in MV and LV Networks

Techniques for the Control of Steady State Voltage in MV and LV Networks by Dr Robert Barr, Electric Power Consulting Pty Ltd Prof. Vic Gosbell, University of Wollongong Mr Chis Halliday, Electrical Consulting