Real-Time Simulation of Large HVDC-AC

Grids

Reza Iravani

University of Toronto

iravani@ecf.utoronto.ca

CIGRE Session 44 - Paris

Workshop on DC Grid Modeling

August 28, 2012

Presentation Layout:

- Objectives

- Test Systems

- Component and Subsystem Models

- Wind Power Plant Model

- AC Network Equivalent Model

- VSC-HVDC Converter Station Model

- Control Hardware-in-the-loop (CHIL) Structure

- Conclusions

Objectives:

Analysis and performance evaluation of control and

protection strategies/algorithms in large HVDC-AC

systems.

Analysis of electromagnetic transients (emts)

Tasks:

Development of HVDC-AC grid component models:

- off-line simulation of emts (0-50kHz)

- real-time simulation of emts (0-10kHz)

Development of Control-HIL real-time simulation structure

for the analysis of emts of large HVDC-AC emts (0-10

kHz)

Test Systems:

- CIGRE VSC-HVDC Grid Test System

- LCC-HVDC Segmented Grid

CIGRE VSC-HVDC Grid Test System

A1

B4

F1

E1

C2

C1

DC Grid Test System version 2012, March 5

B1

B2

B3

B5

B6

A0

B0

D1

LCC-HVDC Segmented Grid

Component/Subsystem Models:

- Wind Power Plant (WPP) wide frequency-band (0-

50kHz) equivalent model

- Type-3 based WPP

- Type-4 based WPP

- Frequency-dependent AC-network equivalent model

- Single-port (3-phase) equivalent

- Multi-port (3-phase) equivalent

- VSC-HVDC converter station model

- MMC-HVDC converter station

- 2-level/3-level VSC-based monopolar and

bipolar converter station (with/without

transformers)

WPP

Power System

PCC

WPP

PCC

FDNE Model

DLFE Model

(a)

(b)

Proposed Wind Power Plant (WPP) Dynamic Equivalent

• FDNE: Frequency-Dependent Network Equivalent of

all passive components within the WPP (for example

in the frequency range of 0-50 kHz)

- Two-Layer Network Equivalent Model

- Modified Two-Layer Network Equivalent model

- Frequency Scan and Vector Fitting

• LFDE: Low-Frequency Dynamic Equivalent of the

aggregated wind units and local controls of wind units

and the WPP supervisory control

- Generic Models (WSCC models)

- Vendor Specific Models

- User Defined Models

Structure of the Dynamic Low-Frequency Equivalent (DLFE) Model of a Type-4 WTGs-based WPP

Reactive

Power

Control

Current Limits

Vref

Real

Power

Control

VPCC

Pref

Pmultiplier

IQmax

IQmin

IPmax

0

IPcmd

IQcmd

Real

Current

Limiter

Reactive

Current

Limiter

Qref

QPCC

IQmax IPmaxIQmin

PPCC

Qmax

Qmin

VRT

ControlIQ_VRT

IQ

IP

VRT_Flag

The Supervisory Control Block Structure of the WPP Dynamic Low-Frequency Equivalent Model

Schematic Diagram of the Modified Version of Lake Erie WPP as the Test System

PCC Voltage: L-L-L-G Fault, Fault Clearing, Unsuccessful Reclosure, Fault Clearing

4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Time (s)

V(p.u.)

PCC Voltage- Phase b

Detailed Model

Equivalent Model

4.834 4.836 4.838 4.84 4.842 4.844-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Time (s)

V(p.u.)

PCC Voltage- Phase a

Detailed Model

Equivalent Model

4.583 4.584 4.585 4.586 4.587 4.588 4.589 4.59 4.591 4.592

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

V (

p.u

.)V

(p

.u.)

Time (s)

PCC Voltage- Phase b

Detailed Model

Equivalent Model

Detailed Model

Equivalent Model

PCC Voltage – VRT

4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4

0

0.5

1

Time (s)

V(p

.u.)

Detailed Model

Equivalent Model

Grid Code

Implementation of WPP model in RTDS

0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96 0.98

-1.5

-1

-0.5

0

0.5

1

1.5

Time (s)

V (p

.u.)

PCC Voltage

0.955 0.96 0.965 0.97 0.975 0.98 0.985

-1.5

-1

-0.5

0

0.5

1

1.5

Frequency Dependent Network Equivalent

Example of Single-port AC-network equivalent model

AC-network equivalent model - Verification

PSCAD/EMTDC

Real-time Simulation

HVDC Converter Station Configurations:

- MMC based HVDC station

- 2-level/3-level VSC-based monopolar/bipolar stations

with/without transformer

- (DC/DC converter station?)

HVDC Converter Station Models:

- Fundamental-frequency model

- Dynamic averaged-model (switching function based)

- PMW model (detailed switched model)

RTDS-based Control-HIL Real-Time Simulation of

CIGRE HVDC Grid Benchmark

RTDS

(1)

Stratix IV

FPGA

Board

(1)

NI-cRIO

(2)

Stratix IV

FPGA

Board

(2)

NI-cRIO

(n)

Stratix IV

FPGA

Board

(n)

NI-cRIO

- AC & DC Lines

- Transformers

- T-G Units

- AC CBs

- WPP ?

Fast Processor

Power Management System

External

Info & Command

cRIO (PXI)

MMC controllerDQ-transforms

ControlsDetermine number of

modules to be switched

RTDS

Electrical system real-time simulations

Stratix IV FPGA Board

Module SimulationsVoltage Sorting

Module Switching Selections

Fiber optics connection

Fiber optics connection

Red: May be removed if fiber optics RIO module is used

Green: May be added if fiber optics RIO module is used

RTDS-Based Control-HIL Structure

Conclusions

• Type-4 and Type-3 WPP s are efficiently and accurately

modeled by a reduce-order equivalent for EMT studies.

• The frequency-dependent network-equivalent concept is

used for single- and multi-port AC system reduction in

large AC-DC systems.

• An RTDS-based augmented structure for Control-HIL of

large AC-DC systems is being evaluated.

Future Work

• Development of Type-3 based WPP

equivalent model

• Integration of WPP equivalent model in real-

time simulation environment

Admittance Magnitudes of the Fitted Equivalent and the Detailed Modeled Passive Network - (a) self admittance, (b) mutual admittance

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 104

10-6

10-4

10-2

100

Frequency (Hz)

Mag

nitu

de (p

.u.)

Detailed Model

FDNE

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 104

10-4

10-3

10-2

10-1

100

Frequency (Hz)

Mag

nitu

de (p

.u.)

Detailed Model

FDNE

PCC Voltage, L-G Fault

4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66 4.68

-1

-0.5

0

0.5

1

Time (s)

V(p

.u.)

PCC Voltage- Phase a

Detailed Model

Equivalent Model

4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66 4.68

-1

-0.5

0

0.5

1

Time (s)

V(p

.u.)

PCC Voltage- Phase c

4.654 4.655 4.656 4.657 4.658 4.659-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

4.654 4.655 4.656 4.657 4.658 4.659 4.66

-1.1

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1PCC Voltage- Phase c

PCC Voltages: L-L-L-G Fault

4.48 4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66 4.68

-1

-0.5

0

0.5

1

Time (sec)

V(p.

u)

PCC Voltage- Phase a

Detailed System

Proposed Equivalent

4.65 4.652 4.654 4.656 4.658 4.66 4.662 4.664 4.666

-1

-0.5

0

0.5

1

V (

p.u

.)

4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66

-1

-0.5

0

0.5

1

Time (sec)

V(p.

u)

PCC Voltage- Phase b

Detailed System

Proposed Equivalent

Detailed Model

Equivalent Model

Detailed Model

Equivalent Model

V (

p.u

.)

Time (s)

PCC Voltage- Phase c

PCC Voltage- Phase a

4.5 4.501 4.502 4.503 4.504 4.505 4.506 4.507-1

-0.5

0

0.5

PCC Phase-c Voltage, L-L-L-G Fault

4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66 4.68-1.5

-1

-0.5

0

0.5

1

Time (s)

V(p

.u.)

PCC Voltage- Phase c

Detailed Model

FDNE Model

4.65 4.651 4.652 4.653 4.654 4.655 4.656 4.657 4.658

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

4.5 4.52 4.54 4.56 4.58 4.6 4.62 4.64 4.66 4.68

-1.5

-1

-0.5

0

0.5

1

Time (s)

V(p

.u.)

PCC Voltage- Phase c

Detailed Model

DLFE Model

4.65 4.652 4.654 4.656 4.658 4.66

-1.5

-1

-0.5

0

0.5

PCC Phase-c Voltage, L-L-L-G Fault

HVDC Converter Station Models:

- Fundamental-frequency model

- Dynamic averaged-model (switching function based)

- PMW model (detailed switched model)

RTDS-based Control-HIL Real-Time Simulation of CIGRE

HVDC Grid Benchmark

RTDS

(1)

Stratix IV

FPGA

Board

(1) (2)

Stratix IV

FPGA

Board

(2) (n)

Stratix IV

FPGA

Board

(n)

- AC & DC Lines

- Transformers

- T-G Units

- AC CBs

- WPP ?

Fast Processor

Power Management System

External

Info & Command

Model Verification:

Stratix IV

FPGA

Board

Control

AC-1 DC AC-2

MMC-based

HVDC Station

Model

Fundamental

Frequency

Model

RTDS

Stratix IV

FPGA

Board

AC-1 DC AC-2

NI-cRIO

RTDS