Initialisation and Load Flow with EMTP RV for Multiterminal DC grids P. RAULT (PhD Student) Supervisors: F. Colas (L2EP) X. Guillaud (L2EP) S. Nguefeu (RTE)
2 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initialization
5) Initialize the overall system
6) Conclusion & Improvement
3 Pierre RAULT / EMTP-rv user group / June 20th 2011
Context
EWEAβs 20 year offshore network development plan
Source: EWEA 2009
Currently operating offshore cable Under construction or planned offshore cable Under study by TSO Under study by TSO/EWEA recommendation Proposed by EWEA in the 2020 timeframe Proposed by EWEA in the 2030 timeframe Proposed offshore node Concession and development zones
4 Pierre RAULT / EMTP-rv user group / June 20th 2011
The TWENTIES wind energy project Secure large-scale integration of wind power into the European electricity grid ⒠Demonstration project ⒠Lunched by EU ⒠62 M⬠(32M⬠Directly provided by EU) ⒠26 Electrical companies & Research institutions ⒠10 Member states are represented ⒠Coordinated by Red Eléctrica de España
RTE task: Improving safety and security for offshore wind generation β’ Control & protection to roll out HVDC grid
Further information β’ http://www.twenties-project.eu
5 Pierre RAULT / EMTP-rv user group / June 20th 2011
Context: My work
Multiterminal HVDC network
How can we control this mesh HVDC grid?
6 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initialization
5) Initialize the overall system
6) Conclusion & Improvements
7 Pierre RAULT / EMTP-rv user group / June 20th 2011
Example of 4 terminals
πΌπ·πΆ2 πΌπ·πΆ1
πΌπ·πΆ4
ππ·πΆ1 ππ·πΆ2
ππ·πΆ4
π 12
π 2
4
πΌπ·πΆ3
ππ·πΆ3
π 2
3
π 34
π =
π 11 π 12 π 13 π 14
π 21 π 22 π 23 π 24
π 31 π 32 π 33 π 34
π 41 π 42 π 43 π 44
Resistor matrix
8 Pierre RAULT / EMTP-rv user group / June 20th 2011
Steady state equations
Voltage controlled
Current controlled
πΌ12 = (ππ·πΆ1βππ·πΆ2
)/ π 12
πΌ13 = (ππ·πΆ1βπDC3
)/ π 13
πΌ14 = (πDC1βππ·πΆ4
)/ π 14
πΌ23 = (πDC2βπDC3
)/ π 23
πΌ24 = (ππ·πΆ2βπDC4
)/ π 24
πΌ34 = (πDC3βππ·πΆ4
)/ π 34
πΌπ·πΆ1= πΌ12 + πΌ13 + πΌ14 + πDC1
/π 11
πDC2= πΌ12 β πΌ23 β πΌ24 + πΌDC2
. π 22
πDC3= πΌ13 + πΌ23 β πΌ34 + πΌπ·πΆ3
. π 33
πDC4= πΌ14 + πΌ24 + πΌ34 + πΌDC4
. π 44
&
9 Pierre RAULT / EMTP-rv user group / June 20th 2011
Find steady state solution = solve matrix equation
Voltage controlled
Current controlled
πΌπ·πΆ1
ππ·πΆ2
ππ·πΆ3
ππ·πΆ4
πΌ12
πΌ13
πΌ14
πΌ23
πΌ24
πΌ34
=
0 0 0 0 1 1 1 0 0 00 0 0 0 π 22 0 0 βπ 22 βπ 22 00 0 0 0 0 π 33 0 π 33 0 βπ 33
0 0 0 0 0 0 π 44 0 π 44 π 44
0 β1/π 12 0 0 0 0 0 0 0 00 0 β1/π 13 0 0 0 0 0 0 00 0 0 β1/π 14 0 0 0 0 0 00 1/π 23 β1/π 23 0 0 0 0 0 0 00 1/π 24 0 β1/π 24 0 0 0 0 0 00 0 1/π 34 β1/π 34 0 0 0 0 0 0
πΌπ·πΆ1
ππ·πΆ2
ππ·πΆ3
ππ·πΆ4
πΌ12
πΌ13
πΌ14
πΌ23
πΌ24
πΌ34
+
1/π 11 0 0 00 π 22 0 00 0 π 33 00 0 0 π 44
1/π 12 0 0 01/π 13 0 0 01/π 14 0 0 0
0 0 0 00 0 0 00 0 0 0
ππ·πΆ1
πΌπ·πΆ2
πΌπ·πΆ3
πΌπ·πΆ4
Input vector
10 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initialization
5) Initializing the overall system
6) Conclusion & Improvements
11 Pierre RAULT / EMTP-rv user group / June 20th 2011
Strategy to start DC simulation from steady state
1
β’ Input vector
β’ Resistor matrix
2
β’ Build the steady state matrix
β’ Run DC steady state solution
2 β’ Transmit SS solution to DC initializing bloc
3
β’ Find Steady-state solution and start from steady-state
4 β’ Display results
12 Pierre RAULT / EMTP-rv user group / June 20th 2011
Build a Marix / LF DC
1) Develop method in JavaScript for matrix
operation
2) Program a java script application for DC load flow
1) Usable with any input data
1 & 2
13 Pierre RAULT / EMTP-rv user group / June 20th 2011
Changing global data 2 3
1) Create new structure named βStationβ AC voltage Active power Reactive power DC voltage
2) Get global data object var cct = currentCircuit();
var attr=cct.getAttribute('GlobalDataTag');
oGlobalData=getGlobalValue(attr);
3) Save globale data oGlobalData.station=station;//save new global data object
oGlobalData.confirm_device_updates=true;
cct.setAttribute('GlobalDataTag',attr);
4) update global data in all the circuit parseScriptFile('update_variables_in_black_boxes.dwjβ)
14 Pierre RAULT / EMTP-rv user group / June 20th 2011
Using a table of global data in Β« Black box device Β»
Data for station nΒ°1
Initialization For each converter
2 3
15 Pierre RAULT / EMTP-rv user group / June 20th 2011
Initialization establishing DC voltage (Β« Ξ Β»)
16 Pierre RAULT / EMTP-rv user group / June 20th 2011
1) Currents are well initialized 2) There is no transient
Current Voltage
1249,7 π΄ (πΏπΉ = 1250)
β625,32 π΄ (πΏπΉ = β625)
β937,8 π΄ (πΏπΉ = β937,5)
313,46 π΄ (πΏπΉ = 313.77)
Initialization establishing DC voltage (Β« Ξ Β»)
17 Pierre RAULT / EMTP-rv user group / June 20th 2011
1278 π΄ (πΏπΉ = 1250)
β596 π΄ (πΏπΉ = β625)
β908 π΄ (πΏπΉ = β937,5)
342.6 π΄ (πΏπΉ = 313.77)
Initialization establishing DC voltage (Β« FDQ Β»)
1) There is no transient 2) Small current error (<1,24%)
Current Voltage
18 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initialization
5) Initialize the overall system
6) Conclusion & Improvements
19 Pierre RAULT / EMTP-rv user group / June 20th 2011
How start a time-domain solution using converter AC/DC?
1
β’ Put AC load flow bus
β’ Fill it with DC results
2 β’ Start the EMTP-rvβs AC load flow
3
β’ Start Steady-state solution from Load-Flow solution
4
β’ Step between steady-state solution and time simulation
20 Pierre RAULT / EMTP-rv user group / June 20th 2011
AC Load Flow for initializing the AC part of each converter
Converter disconnected
PQ ππ, ππ
SB ππ, πΏπ
No participation to the load flow calculation
Using short circuit
impedance
Data from DC steady state calculations
?
21 Pierre RAULT / EMTP-rv user group / June 20th 2011
Starting simulation (Power part)
+
Initialization DC voltage
Converter unplugged
PQ ππ, ππ
SB ππ, πΏπ
Generator & impedance initialized
by the SB node Generator initialized
by the PQ node
Voltage capacitor no initialized
22 Pierre RAULT / EMTP-rv user group / June 20th 2011
Initialization of the control part
Current Controller
V
Voltage Controller
+ -
ππ πππ
π’π πππ Power
Controller +
- ππ πππ
ππ πππ
π‘π5% = 100ππ π‘π5% = 100ππ
π‘π5% = 10ππ
Control choice
1 2
PWM
Controllers have to be initialized
23 Pierre RAULT / EMTP-rv user group / June 20th 2011
How initialize a controller from EMTP steady state solution?
Park
ππ π(0) ππ π(0) ππ π(0)
πΏπ(0)
ππ π(0) ππ π(0)
Park
π£ππ(0) π£ππ(0) π£ππ(0)
πΏπ(0)
π£ππ(0) π£ππ(0)
PI + -
+ +
init
πΏπ
ππ π πππ = ππ π(0)
ππ π(0)
ππ π(0)
π£ππ(0) 0 +
+
π£ππ(0)
ππππ‘ = π£ππ 0 β π£ππ 0 β πΏπππ π(0)
Example : Cuurent controller
Measures & transformations
24 Pierre RAULT / EMTP-rv user group / June 20th 2011
Initializing example: Current controller
PI + -
+ +
init
πΏπ
ππ π πππ
ππ π
ππ π
π£ππ +
+
π£ππ
ππππ‘ = π£ππ 0 β π£ππ 0 β πΏπππ π(0)
Current controller
Initialization block diagram
init
π£ππ Hold t0
Hold t0 π£ππ
ππ π Hold t0
- +
πΏπ
- +
25 Pierre RAULT / EMTP-rv user group / June 20th 2011
Transition initialization/simulation
Converter unplugged
t=0 (steady state solution)
+
t>0
β’ Ideal switches are used between 2 configurations
β’ Change before the first calculation step
Converter plugged
26 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initializing
5) Initialize the overall system
6) Conclusion & Improvements
27 Pierre RAULT / EMTP-rv user group / June 20th 2011
Time-domain simulation with MTDC and AC grids
1
β’ Start DC steady state solution
β’ Put results in global data
2
β’ Fill PQ node with corresponding global data
β’ Start AC load flow
3 β’ Start Steady-state solution from Load-Flow
solution
Procedure to follow
28 Pierre RAULT / EMTP-rv user group / June 20th 2011
Outline
1) Context
2) Find DC steady state solution
3) Initialize the DC network
4) Converter initializing
5) Initializing the overall system
6) Conclusion & Improvements
29 Pierre RAULT / EMTP-rv user group / June 20th 2011
Conclusion
1) Calculation of a DC steady state in JavaScript (Matrix operations)
2) Creation of global data in a JavaScript file
3) Use of these data to initialize a AC load flow
4) Initialization of controllers from AC load flow results
5) Startup of time-domain simulation AC/DC from steady state
30 Pierre RAULT / EMTP-rv user group / June 20th 2011
Improvement & further work
1) Initialize measure filters
2) Initialize a detailed converter
3) Use a file to initialize simulation data
4) Use EMTP-rv features to initialize DC
Thank you for your attention!
32 Pierre RAULT / EMTP-rv user group / June 20th 2011
APPENDIXES
33 Pierre RAULT / EMTP-rv user group / June 20th 2011
Structure Β« Station Β»
34 Pierre RAULT / EMTP-rv user group / June 20th 2011
Put LF results in table of structure
Each station is represented by a structure of index i