Operation and Control of an HVDC Circuit Breaker

with Current Flow Control Capability

ESR3: Wei Liu

Supervisors：Jun Liang & Carlos Ugalde Loo

Cardiff University, UK @ October 2020

This project has received funding from the European Union's Horizon 2020 research and innovationprogramme under the Marie Sklodowska-Curie grant agreement no. 765585. This presentation reflects onlythe author’s view. The Research Executive Agency and European Commission are not responsible for anyuse that may be made of the information it contains.

Outline

1. Motivations

2. Proposed device

3. Simulation results

4. Conclusion

1

1. Motivations

2

Multi-terminal DC systems

3

Multi-terminal HVDC systems

Improve system’s flexibility Improve system’s reliability Integrate different types of renewable energy

‘Zhangbei’ ± 500 kV HVDC system for Beijing Olympic Games 2022

[1] G. Tang, H. Pang, Z. He and X. Wei, "Research on Key Technology and Equipment for Zhangbei 500kV DC Grid," in Proc. 2018 International Power Electronics Conference Niigata, 2018, pp. 2343-2351.

CBCFC

T1 T2

T3T4

L12

L23

L34

L14

CBCFC

Parallel paths

MTDC networks

DC fault and Current flow control

4

Challenges of MTDC grids: dc fault

No zero crossings (dc current) High rising rate of current (di/dt) Low capability of overcurrent (IGBTs)

Examples of dc fault for VSC

Challenges of MTDC grids: Current flow control

Dominated by the resistance of the transmission lines Overloading of transmission lines Limit capacity of power transmission

CBCFC

T1 T2

T3T4

L12L

23

L34

L14

CBCFC

Parallel paths

Four-terminal system

Challenges

5

500 kV HCB developed for Zhangbei project

Challenges for DCCB and CFC

Cost Reliability

M. Callavik, A. Blomberg, J. Hafner, and B. Jacobson, “The hybrid HVDC breaker: an innovation breakthrough enabling reliable HVDC grids”, ABB Grid Systems, Technical Paper, Nov. 2012.

‘Zhangbei’ ± 500 kV HVDC system for Beijing Olympic Games 2022

Solutions

6

M. Callavik, A. Blomberg, J. Hafner, and B. Jacobson, “The hybrid HVDC breaker: an innovation breakthrough enabling reliable HVDC grids”, ABB Grid Systems, Technical Paper, Nov. 2012.

CFC

L12

L13

L1

CB

CB

CB

MMC

(a)

CB/

CFC

(b)

L12

L13

L1

CB

MMC

Targets

Integrate several CBs and CFC into one device Reduce semiconductors and costs Maintain same function

Separate HCBs and CFC. Integrated device.

2. Proposed device

7

Proposed device

8

Topologies

Two CBs and one CFC integrated

MO

V1 U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L2 L3

MO

Vn

Main breaker branch Low-loss branches Capacitor branch

Uc

Sc

Proposed device (CB/CFC)

CB/

CFC

I1 I12

I13

I23

I2

I3

Node 2

Node 3

Node 1

MMC1

Circuit BreakerCurrent limit inductor Transmission Line

MMC2

MMC3

L12

L13

L23

System configuration with the CB/CFC

Proposed device

9

DC fault isolating

Four steps

(a) (b)

(c) (d)

MO

V1U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L12 L13

MO

Vn

Uc

Sc

Vc

MO

V1U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L12 L13

MO

Vn

Uc

Sc

Vc

MO

V1U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L12 L13

MO

Vn

Uc

Sc

Vc

MO

V1U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L12 L13

MO

Vn

Uc

Sc

Vc

Fault isolation process. (a) Pre-fault. (b) Current commutation. (c) Fault current interruption. (d) Post fault.

Proposed device

10

MO

V1 U1p

U1n U2n U3n

U2p U3p

S1p

S1n

S2p

S2n

S3p

S3n

MBL1 L2 L3

MO

Vn

Main breaker branch Low-loss branches Capacitor branch

Uc

Sc

Current flow control

Vc

S1p

S1n

S2p

S2n

S3p

S3n

L1

L12

L13

Simplified equivalent circuit as a CFCTopology of CB/CFC

Proposed device

11

Bypass mode

Vc

S1p

S1n

S2p

S2n S3n

S3p I12

I13=0

Vc I13=0

I12I1

Current nulling mode

Vc

S1p

S1n

S2p

S2n S3n

S3pI1

I13

I12I1 Vc=0

I13

I12

Vc

S1p

S1n

S2p

S2n S3n

S3pI1

PWM

DVc

(1-D)Vc

I13

I12I1

I13

I12

Vc

S1p

S1n

S2p

S2n S3n

S3pI1

PWM

(1-D)Vc

DVc

I13

I12I1

12 1I I D=12 1 /I I D=1 12 13I I I= + 12 1 13, 0I I I= =

Current sharing mode

Proposed device

12

Control and modulations

0

-1

1

2

-2Iref

vcref>0

Carrier (500Hz)

(a)

vcref<0

PWM_12

PWM_1p

PWM_1n

PWM_13

Gate SignalsComparators

Signvcref

Vc

S1p

S1n

S2p

S2n

S3p

S3n

L12

L13

I1

MMC1

PIPI

vc

i12

×

vcref

Sign

Modulation

S1pS1n

S2p

S2n

S3p

S3n

Dual-loop control for the CFC

C1

C2

C3

C4

(b)Modulation

Sharing

Reverse

Reverse

Level-shift modulation Dual-loop control loop

3. Simulation results

13

Proposed device

14

System parameters

CB/

CFC

I1 I12

I13

I23

I2

I3

Node 2

Node 3

Node 1

MMC1

Circuit BreakerCurrent limit inductor Transmission Line

MMC2

MMC3

L12

L13

L23

Proposed device

15

Simulation results of dc fault isolation

CB/

CFC L12

L13

L1CB

MMC

CB/

CFC L12

L13

L1CB

MMC

Protection of dc faults at transmission lines. (a) Fault current. (b) Currents of MB and MOV. (c) Voltage of MB. (d) Energy absorbed by the CB/CFC.

Protection of dc faults at transmission lines. (a) Fault current. (b) Currents of MB and MOV. (c) Voltage of MB. (d) Energy absorbed by the CB/CFC.

Proposed device

16

Simulation results of current flow control

Current reversal mode for CFC operation. (a) Active power ofconverters. (b) DC currents of converters. (c) Currents oftransmission lines. (d) Modulation and carrier signals.

Current reversal mode for CFC operation. (a) Active power ofconverters. (b) DC currents of converters. (c) Currents oftransmission lines. (d) Modulation and carrier signals.

Proposed device

17

Comparisons

(a)

(b)

(c)

CFCHCB1HCB2

HCB3

HCB1

HCB1

CFC

CB/CFC

HCB2&3

U1

U2

U1

U2

U1

U4

U7

U6

U3

U2

U5

MB(n)

MB(n) MB(n)

MB(n)

MB (n)

L12L13

L12L13

L1

L1

MMC1

MMC1

MMC1

L12L13

U0

U0

U0

MB

L1

MB

MB

MB (n)

MB (n) MB (n)

Integrated schemes of CFC with HCB. (a) Scheme I: Sharing LCSs.(b)Scheme II: Sharing LCSs and MBs. (c) Scheme III: CB/CFC.

4. Conclusion

18

Conclusion

19

1. DC protection and current flow control were analysed for MTDC applications

2. The proposed device was described.

3. Simulation results were given to verify the function of the proposed device.

[1] Wei Liu, Jun Liang, Carlos Ugalde Loo, Chuanyue Li, Gen Li, Peng Yang. “Level-shift Modulation and Control of a Dual H-bridge Current Flow Controller in Meshed HVDC systems”. ECCE.2019.

[2] Wei Liu, Carlos Ugalde Loo, Jun Liang, Chuanyue Li, Frederic. “Modeling and Frequency Analysis of a Dual H-bridge Current Flow Controller in Meshed HVDC Systems”. EPE.2019.

[3] W. Liu, C. Li, C. E. Ugalde-Loo, S. Wang, G. Li and J. Liang, “Operation and Control of an HVDC Circuit Breaker with Current Flow Control Capability," IEEE Journal of Emerging and Selected Topics in Power Electronics (Early access).

[4] S. Wang, W. Ming, W. Liu, C. Li, C. E. Ugalde Loo and J. Liang, "A Multi-Function Integrated Circuit Breaker for DC Grid Applications," IEEE Transactions on Power Delivery (Early access).

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