power system frequency support of wind turbines with
TRANSCRIPT
Power System Frequency Support of Wind Turbineswith Virtual Synchronous Machine Control
Liang LuPhD student
Centrale Nantes, Nantes, France29-10-2019
Power System Frequency Stability
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Three-phase Alternating Current (AC) Power System
Synchronous Generator
Power System Frequency Stability
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WT
Three-phase Alternating Current (AC) Power System
Synchronous Generator
Power System Frequency Stability
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ππππ
ππππ
ππ
ππ
ππππ β ππππ = π½π½ππππππππππ
Type-4 wind turbine
Power System Frequency StabilityVirtual Synchronous Machine (VSM) Control
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β’ A control scheme for a converter to enable renewable power sources to behave as a synchronous machine (SM) by adding the model and control of an SM within the control scheme;
ππππ
ππππ
ππ
ππ
ππππ β ππππ = π½π½ππππππππππ
Type-4 wind turbine
Prabha Kundur, Neal J. Balu and Mark G. Lauby. Power system stability and control. Vol. 7. New York: McGraw-Hill, 1994.
Synchronous Generator (SG) Model and Control
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βοΏ½ΜοΏ½πβοΏ½ΜοΏ½πΏβΞ¨ΜππππβΞ¨Μ1ππβΞ¨Μ1ππβΞ¨Μ2ππ
=
ππ11ππ21
0000
ππ120ππ32ππ42ππ52ππ62
ππ130ππ33ππ43ππ53ππ63
ππ140ππ34ππ44ππ54ππ64
ππ150ππ35ππ45ππ55ππ65
ππ160ππ36ππ46ππ56ππ66
βππβπΏπΏβΞ¨ππππβΞ¨1ππβΞ¨1ππβΞ¨2ππ
+
ππ1100000
00ππ32000
βππππβπΈπΈππππ
Motivation 1
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Qualified simplicity
WT application
Frequency controlSG Model
Swing equation
Governor
ExciterStator windings
Field circuit
Yong Chen et al. Comparison of methods for implementing virtual synchronous machine on inverters. International conference on renewable energies and power quality. 2012.
Salvatore DβArco et al. Small-signal modeling and parametric sensitivity of a virtual synchronous machine. Power Systems Computation Conference. IEEE, 2014.
More Complex VSM Control
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Modelling & Simulation
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25%, 50%, 75%, 100%
10 ππππ
1 ππ,ππ,ππ, ππ
2 Simulation time
Grid-side converter
Conclusions 1
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β’ A simpler but qualified VSM control scheme is proposed for frequency control;
β’ The proposed VSM control scheme is adapted for WT application;
β’ To achieve VSM control for frequency control capability of WTs, to emulate the swing equation and governor is enough;
β’ Including the modeling of exciter and stator windings does not improve much, while increasing dynamics of voltage;
β’ Including the modeling of field circuit will make things more complex, not necessary;
β’ The proposed VSM control scheme works better in voltage control;
Motivation 2
/ 2214https://orbit.dtu.dk/en/activities/a-virtual-synchronous-machine-control-scheme-for-wind-turbines(4cdc26fd-1829-4c00-af62-5775529c73f3).html
The VSM Control Scheme for WTs Power Angle Small Signal Stability
β’ Focusing on the power loop while idealizing inner voltage and current loops;
β’ State space representation and block diagram of an inverter connected to an infinite bus;
β’ Influence of parameters on the stability by analyzing eigenvalue trajectories;
Power Angle Small Signal Stability (PAS) Model
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1 12 2 2 2
0 0 01 1 00
s
n m
dr dr
g r g
KDH H H Hd T
dtT T
T D T
Ο ΟΞ΄ Ο Ξ΄
β β β β β β = β + β β β β
0cosbs
E EKX
Ξ΄β²
=
Verification
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Grid-side converter Voltage source
β’ ππ = 1π π , ππππ is dropped by 0.5 pu, or ππππis dropped by 5 ππππ
Parameter Design β Inertia Constant π―π―
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β’ 0.1 ~ 0.5;
β’ Little influence on ππ3;
β’ Stability margin reduced by increasing π»π»;
β’ A larger π»π» is better for inertia response;
β’ A compromise;
β’ Exact value also depends on grid code requirements and converter rating;
ππ1
ππ2
ππ3
Parameter Design β Damping Coefficient π«π«
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β’ 10~53: stable, 54~100: unstable;
β’ Little influence on ππ3;
β’ Stability margin improved by increasing π·π·in the stable range;
β’ Positive effects of a smaller π·π·;
β’ A trade-off;
ππ1
ππ2ππ3
Parameter Design β Droop π«π«ππ
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β’ 1% ~ 100%;
β’ Much influence on ππ3;
β’ Stability improved by increasing π·π·ππ;
β’ Constraint and most likely determined by grid code requirements, converter rating and capacity of energy storage;
ππ1
ππ2
ππ3
Parameter Design β Response Time π»π»ππ
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β’ 0.01 ~ 10;
β’ Much influence on ππ3;
β’ Stability is worse when increasing ππππ;
ππ3ππ1
ππ2
Conclusions 2 & Future Work
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β’ Power angle small signal stability (PAS) is proposed as a simpler way of analyzing the small signal stability of VSM-controlled grid-forming inverters;
β’ Helpful for analyzing the rotor angle small signal stability of a big power system with large share of converter-interfaced renewable power sources;
β’ A larger inertia constant π»π» or damping coefficient π·π· reduces the stability margin, but enhances the inertial response and frequency control capability;
β’ A larger droop π·π·ππ or a smaller response time ππππ helps improving the stability;
Overall and systematic design of all parameters simultaneously considering practical constraints;
What is the optimal or acceptable power response from a non-synchronous power source for fast frequency regulation?
Thank you !
Liang [email protected]
This work has received funding from the European Unionβs Horizon 2020 research and innovation program under grant agreement No. 727680 (TotalControl).
This work has also received funding from project PowerKey (EUDP Project No. 12558).