Modelling and analysis of CIGRE HVDC offshore …...Modelling and analysis of CIGRE HVDC offshore...
Transcript of Modelling and analysis of CIGRE HVDC offshore …...Modelling and analysis of CIGRE HVDC offshore...
Modelling and analysis of CIGRE HVDC offshore multi-terminal benchmark grid
Trondheim, February 2015
Jordi Pegueroles Queralt, Mike Barnes, Oriol Gomis-Bellmunt, Antony Beddard and Fernando D. Bianchi
INDEX
• Motivation • System Description
• Control of HVDC converters • Power Control
• Droop control • Modelling components
• DC line model • DC grid
• Small signal models • AC and DC dynamics
• Dynamics with DeadBand • MT-HVDC dynamics
• Simulations Results • Conclusions
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Motivation, 4-terminal HVDC benchamrk system by CIGRE
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500 MW
400 MW
100 MW
800 MW
300 MW
AC voltage control
DC Dead Band control
DC Droop control
DC Droop control
The objective is this study is to analyse of the stability and transient performance of the 4-terminal HVDC system
INDEX
• Motivation • System Description
• Control of HVDC converters • Power Control
• Droop control • Modelling components
• DC line model • DC grid
• Small signal models • AC and DC dynamics
• Dynamics with DeadBand • MT-HVDC dynamics
• Simulations Results • Conclusions
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Power control of HVDC converters
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0 dB
ω
|·|
General control scheme for HVC converters and control loop bandwidths
Qualitative bode diagram
Line Modelling: n T sections line model
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4 input / 4 output DC-Grid
HVDC line model
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The dynamics of the line are comparable with the dynamics of the converters
Analysing the physical specifications of the cable, and taking into account the presence of a return line, we have concluded that a slightly modified values from the ones used in the CIGRE model are more accurate for the study.
INDEX
• Motivation • System Description
• Control of HVDC converters • Power Control
• Droop control • Modelling components
• DC line model • DC grid
• Small signal models • AC and DC dynamics
• Dynamics with DeadBand • MT-HVDC dynamics
• Simulations Results • Conclusions
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AC and DC small signal models
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VSCk
G-ACk DC-Grid +
MT-HVDC grid
Sigma plot of the MT-HVDC system
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MT-HVDC grid
Normal operation
Sigma plot of the MT-HVDC system
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MT-HVDC grid
Dead band operation on the offshore wind farm
Pole location of the MT-HVDC system
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MT-HVDC grid
Dominant poles of the closed loop
system
Pole location of the MT-HVDC system
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MT-HVDC grid
Dominant poles of the closed loop
system
INDEX
• Motivation • System Description
• Control of HVDC converters • Power Control
• Droop control • Modelling components
• DC line model • DC grid
• Small signal models • AC and DC dynamics
• Dynamics with DeadBand • MT-HVDC dynamics
• Simulations Results • Conclusions
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Conclusions
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The MT-HVDC system is stable, but the interaction among the droop controllers presents a oscillatory response in the DC voltage variation, as well as on the power output
Conclusions
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The response of the MT-HVDC system without one of the droop converters presents a faster extintion rate than the previous case. This is also produced by the faster response of the DeadBand control of the OWP
INDEX
• Motivation • System Description
• Control of HVDC converters • Power Control
• Droop control • Modelling components
• DC line model • DC grid
• Small signal models • AC and DC dynamics
• Dynamics with DeadBand • MT-HVDC dynamics
• Simulations Results • Conclusions
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Conclusions
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• Careful coordination on the droop control is required, as parallel operation of droop controllers results in oscillatory response.
• The parameters and model of the HVDC cables have to be carefully chosen to match the frequency range of the study.
• The transient performance of the system can be improved with a more sophisticated droop control scheme.
Acknowledgements
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