Dr. Pang Hui

CEPRI of State Grid Corp. of China

Aug 31, 2011

Real-time Simulation Technology forModular Multilevel Converter Based

HVDC Transmission

VSC-HVDC based on two-level or triple-

level converters

VSC-HVDC based on multi-level modular converters (MMC)

VSC-HVDC in Brief

Simulation Technology for HVDC

Electro-mechanical simulation based

commercial software

Electro-magnetic simulation based

commercial software

Real time digital simulation system

vconv

Pconv Iconv

Uconv UL

DC cable

converter valveA BDC cable

converter valve

Large nodes in the modular multilevel

converter

Small nodes in the two level or triple level

converter

Difficult in simulation of MMC-HVDC

Structure of simulation system

Composite of simulation platform

Digital accessorial

Electronic device

Valve controller

Control and protect system

Prospect of simulation platform

Picture of MMC-HVDC real time simulation platform

Function of simulation platform

Control procedure of MMC-HVDC, such as charging process on system stirring

Modulation control method of converter

Operating performance under steady state and transient state

Balance control to voltage and current of converter

Response to power-step-order

AC and DC network faults

Summary of Nanhui VSC-HVDC Project

Rated DC voltage of ±30kV

Rated DC current of 300A

Converter of 18MW with 49-level MMC

The transmission line is about 8km cables

Summary of simulation system

Capacity of 300VA;

transformer voltage on valve side of 142V,

short-circuit impedance ratio of 0.08;

converter leg reactor of 0.15p.u.;

DC voltage of ± 140V.

Study with simulation software

0.980 1.000 1.020 1.040 1.060 1.080 1.100 1.120 1.140 1.160 1.180 1.200

-5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

(p ) (p ) (p )

DC line fault analysis and simulation in PSCAD/EMTDC

0.98 1 1.02 1.04 1.06 1.08 1.1 1.12 1.14-6

-4

-2

0

2

4

t/s

Ia(p

.u)

real-time simulation platform with over-current-protect

PSCAD simulation without protect strategy

A phase current after fault

Apply of dynamic simulation system

Apply of dynamic simulation system

Udc rapidly reduced to about zero after short-circuit fault

1 1.05 1.1

-0.10

0.2

0.4

0.6

t/s

Udc

(p.u

)

real-time simulation platformPSCAD simulation

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62-100

0

100

AC

T_P

WR

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62-50

0

50

UA

C_A

LFA

UA

C_B

ETA

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62-2000

0

2000

IV_L

1IV

_L2

IV_L

3

File: TFR FH_S2P1PCPA1 TR1 20110112 19;32;47_171000.CFG

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.620

50

100

UD

C

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62-50

0

50

RE

AC

T_P

WR

0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62

DEBL_SEQVBC_TRIP

PERM_BAC_TRIP

Time [s]

Wave record for protection after short fault in project

Wave record in the project

Conclusion

The dynamic simulation platform has a good equivalent and high accuracy in real time simulation for the valve base and station controllers which used in the project.

It fully consistent with the design and adjustment features testing for the demand of project.

Develop the digital simulation subsystem in order to achieve more application fields of AC network.

Increase the capability of converter in HVDC subsystem to meet the need of larger scale MMC-HVDC project.

16

Dr. Pang Hui

panghui@epri.sgcc.com.cn

Thanks for your attention!

CEPRI of SGCChttp://www.epri.sgcc.com.cn