Computer simulation of hv circuit breaker interruption EnergoBos september 2020

EnergoBos ILJIN d.o.o. Sarajevo
Computer simulation of HV circuit breaker
interruption
>> HV CB Simulation <<
by
Bosnia and Herzegovina
www.energobos.com
Sarajevo, September 2020.

Contents
❑ Introduction
❑ Main application diagram
❑ The Main mask of HV CB Simulation
❑ Modules
❑ Input data
❑ Gas flow - universal model
❑ Automatic calculations
❑ Breakdown withstand voltage calculation
❑ The travel measurement system and control
❑ KEMA oscillogram viewer
❑ Help files
❑ Results & verification
❑ Prediction of thermal breakdown
❑ Conclusion
2

Introduction
❑ Computer simulation is an economic way in research and development of modern SF6 circuit breakers.
❑ Work on computer simulations started on early 80’s – used first available PCs and simple Basic programming
language.
❑ With limited number of short circuit tests and results of those tests, program can help us with:
• prediction of interruptions for other arcing times and other values of short circuit currents,
• prediction of breakdown withstand voltage after capacitive current interruption,
• calculation of interaction between interrupting unit and driving mechanism,
• optimization of an existing interrupting unit and driving mechanism,
• calculate influence of any design changes on circuit breaker performance,
• calculation of state of gas in circuit breaker chambers,
• electric arc influence on gas mass flow,
• pressure build up calculation,
• nozzle ablation,
• contact erosion,
• driving mechanism behavior during interruption of high short circuit currents.
❑ The program can not predict result of interruption in advance, but program results combined with other calculations can
help us in this.
3

Main application diagram
4

The main mask of HV CB Simulation
The program consists the following modules:
❑ Exit-Open-Save module,
❑ Interrupter unit,
❑ Driving mechanism-Travel,
❑ Gas,
❑ Electrical current,
❑ Data analysis,
❑ Calculation-Automatic calculation,
❑ Vbd- Breakdown voltage estimation
❑ EB measurement system control
❑ KEMA oscillogram viewer
❑ Help.
HV CB Simulation Version 4.1.0.
5
Main mask
( )
( )
( ) ( ) ( )
, ,
, 1 a R t n r t n
R
R a a
E t
E t n k k e
n

 −  − 
 
 
= 

 + −
 
( )
1
0
luka
c c
t
c c c
m i k i dt
 

+
=  
+ 

( ) ( ) ( ) ( ) ( )
s o komp tr abs
E t E t E t E t E t
= − − −
cs cs cs cs
m A v t
 
 =    
( ) ( )
el in in out
Q m h u m h u
u
m
 +   − −   −
 =
 
2 2
1 1
h p
h p cs
dp
dh

=
 
( ) ( -1)
m t m t m
= +
( ) ( -1)
u t u t u
= +
( )
( )
( )
m t
t
V t
 =
1
2 ( )
cs cs
v h h
=  −
( )
( )
( )
1
1
2 s
k
red
E t
v t
M h t

=
 
 

Modules
❑ Exit – Open – Save module (close - open - save all input data about circuit breaker)
❑ Interrupter unit (interrupter unit geometry, nozzle ablation, contact erosion, heating of interrupter unit chambers)
❑ Driving mechanism – Travel (coordinates, lengths, angles, masses and moments of inertia of mechanical parts,
kinematic calculations, compression force calculation, data about spring(s), calculation of opening, single or three
phase operated, using experimental travel instead mechanism simulation, model of shock absorber, double speed
model)
❑ Gas (selection of used gas, arc model, iteration accuracy)
❑ Electrical current (analytical presentation of single or three phase short circuit currents, model of synthetic circuit:
serial and parallel with current injection, data from experiment used as input data in calculation)
❑ Data Analysis (graphical representation of program results and experimental results, open & save results, comparison
between calculated i measured results)
❑ Calculation – Automatic calculation
❑ Vbd – (breakdown voltage estimation, visualization of dielectric stresses inside a circuit breaker nozzle)
❑ Measure – Travel measurement system and control is being used to control the measurement process including the
tripping of the test object's opening and closing coils, measurement data acquisition from several linear and rotary
encoders, digital processing, filtering and fitting of raw measurement data, as well as determining of the corresponding
velocity and acceleration curves for every travel record.
❑ KEMA Osc - KEMA Oscillogram viewer allows the user to import experimental data from KEMA type tests.
❑ Help – Help files.
6

Input data – Chamber and Connections
7
Defining interrupter unit chambers and connections between them
V14 V15 V8 V9 V11 V17
❑ Easy scheme drawing for any type of interrupter
❑ Calculation of state of gas (pressure, temperature, density...) in all interrupter chambers
❑ Calculation of gas flow for every interrupter with a known geometry configuration
❑ Simulation of SF6 and other gases
❑ Simulations of O-CO and O-CO-CO operating sequences
Chamber data

Input data – interrupter unit – nozzle and arcing contact geometry
Nozzle geometry - input data
8
Arcing contacts geometry - input data

Graphical representation of Nozzle(s) and contact(s) system geometry
9
Nozzle(s) and contact(s) system geometry
– after test
Nozzle(s) and contact(s) system geometry
– before test

Input data – Chamber and Connections
10
Connection data – Type Constant
Connection data – Type Valve
There are four types of connections that can be chosen:
❑ Valve
❑ Nozzle
❑ Variable
❑ Constant.

Input data – driving mechanism
Spring - input data
Absorber – input data
Mechanism geometry – input data
11
Mechanism – input data

Input data – electrical current
❑ The arc model - simple integral arc model: modified Frost Lieberman’s enthalpy flow arc model, system of equations,
thermodynamic characteristics of plasma, arc voltage and arc diameter, input of data from experiments.
Electrical current
The arc model
12

Automatic calculations
❑ The program module for Automatic
calculation of opening operations
provides multiple calculations where one
input parameter varies in a defined range
with predefined number of steps.
❑ The program module for Test duty
calculation offers the possibility of
automatic calculation of test duty
operations or calculation of sequence of
operation tests during one shift in the
laboratory.
13

HV CB Simulation results combined with other calculations (CFD, Electrical field
calculation...) - Breakdown voltage estimation procedure
Circuit
breaker
design
HV CB Simulation
Electric field
calculation
CFD
HV CB Simulation results
as initial conditions for
CFD (p0, T0, ρ0)
BREAKDOWN
E field calculation results (E) CFD Results (p, T, ρ)
Breakdown voltage
Ubd=f(E, ρ)
Uapplied > U bd
NO
YES
NO
BREAKDOWN
Next project
phase
14

Breakdown withstand voltage estimation procedure
Recovery voltage in time (capacitive current interruption):
Breakdown voltage in time:
 CFD
 E field
15

The travel measurement system and control module implemented in HV CB Simulation
❑ This form is used to prepare, initialize, activate and to control EB’s travel
measurement system and the test object.
❑ Loading, digital post-processing and filtering of raw measurement data is
also implemented. Additionally, information about specific travel-related
parameters are being calculated and displayed for each travel record.
.
16

KEMA oscillogram viewer
❑ The form KEMA Oscillogram viewer allows the user to import experimental data from KEMA type tests in three different
frequency ranges (low, middle and high).
❑ After selecting one of these frequency ranges, available oscillograms in the chosen range are automatically detected in
the folder KEMA and are ready to be imported. This can be done by selecting the name from the Osc. number dropdown
combo box.
❑ The next step is to add channels from the chosen oscillogram that will be displayed on the Analysis form: Mode 4: KEMA
type-testing results.
17

HV CB Simulation – User Manual, Technical Manual and Input Data Description
18

Results
19
List of output diagrams:
013 - Arc voltage [V]
014 - Arc energy [J]
015 - Minimal flow cross-section
in main nozzle [mm2]
056 - Total nozzle ablation mass
in segment 1 [g]
108 - Temperature of SF6 gas in
heating chamber [K]
114 - Pressure of SF6 gas in
heating chamber [Pa]

20
Results for O-CO-CO operating sequence
O
O
O
C
C
1st O 2nd O 3rd O
Time s
room temperature
filling pressure
higher temperature
higher pressure

Results & verification
Comparison (no load) between experimental and
calculated travel and speed (puffer type)
Comparison (on load – three phase – 40 kA)
between experimental and calculated travel and speed
(puffer type)
21

Comparison between experimental and calculated pressure
(peak value) in thermal chamber
Test No:
GCB 245 kV 40 kA, SLF tests
Breaking
current,
rms [kA]
Arc
duration
[ms]
Max
pressure
Experiment
[MPa]
Max
pressure
Calculation
[MPa]
1. 31.9 11.6 - 3.952
2. 31.9 11.6 3.89 3.888
3. 32.3 10.6 3.98 3.694
4. 35.5 10.4 4.06 4.090
Pressure rise in thermal chamber, L90 test No 4,
experiment versus calculation
22
Total mass loss [g]
Mass loss of stationary and
moving contact [g]
Shortening of stationary contact
length [mm]
Calculation
Measured
Calculation
Measured
Calculation
Measured
Comparison between experimental and calculated mass loss of
contacts and decreasing length of stationary contact

Calculated (vertical) and measured (horizontal)
mass loss of main nozzle
Calculated (vertical) and measured (horizontal) increase in main
nozzle throat diameter
Calculated (vertical) and measured (horizontal) increase in
auxiliary nozzle throat diameter
Main nozzle cross section, calculation
and experiment, T100s phase C
23

Program results combined with other calculations
Prediction of thermal breakdown
4. MatLAB simulation
Model verification
1. Computer simulation 2. Calculation of parameters
Characteristic
quantities
Parameters
black box
model
3. Composite black box
model
5. Results of MatLAB simulation
and CZ measurement
P1, t1
P2. t2
P3, t3
P, l, Mg
Source: “Correlation of Black Box and Integral Physical Arc Model Parameters for a Real SF6 Circuit-Breaker”,
Doctoral disertation, Almir Ahmethodžić, Faculty of electrical engeering Sarajevo
24

Prediction of thermal breakdown - puffer
Quantitatively :The accuracy of prediction of success of the interruption
Source: “Correlation of Black Box and Integral Physical Arc Model Parameters for a Real SF6 Circuit-Breaker”,
Doctoral disertation, Almir Ahmethodžić, Faculty of electrical engeering Sarajevo
18
2
90
Correct prediction in 18 out of 20 cases
25

Prediction of thermal breakdown – self blast
No: Pol Test No. Struja [kA] t luka [ms] Ispitivanje/Simulacija
1 A 4021 36.1 13.8 R*
2 A 4022 36 14.9 R/I**
3 A 4029 36.4 16.6 I/I
4 A 4033 35.8 25.3 R/I
1 C 4003 36.2 15.2 I/I
2 C 4004 35.8 14.2 I/I
3 C 4005 36 23.1 I/I
4 C 4006 36 18.6 I/I
5 C 4008 36 18.4 I/I
6 C 4012 36 27.6 I/R
7 C 4013 36 18.2 R/R
8
2
80
26

Conclusion
❑ General lack of knowledge and experts for arc modeling and the simulation of high voltage SF6 circuit breakers is
already evident.
❑ A team for arc modeling and the simulation of high voltage SF6 circuit breakers consisting of some dozen experts is
very expensive for any company in the world.
❑ The idea is to organize a team which will continuously work on arc modeling and the simulation of high voltage SF6
circuit breakers with the support of several companies interested in the project.
❑ The Team will treat fairly all companies and we do commit ourselves to the highest ethical and professional codes.
❑ Our goal is a universal software to provide calculations and simulations of high voltage circuit breaker interruption for
different companies in the world,
and why not even for YOUR COMPANY?
All we need is:
kinematic chain data (coordinates, angles, lengths, masses and moments of inertia),
spring and absorber characteristics,
volumes of interrupter unit chambers and cross sections between them,
nozzle and arcing contact geometry ...
27

Computer simulation of hv circuit breaker interruption EnergoBos september 2020

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