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Power System Stabiliser Capability of Offshore Wind Power Plants Copenhagen , 16th April 2012 José Luis Domínguez-García Oriol Gomis- Bellmunt Fernando Bianchi Andreas Sumper Antoni Sudrià -Andreu. Overview. · Introduction · Power system stability background · Objectives
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Power System Stabiliser Capability of Offshore Wind Power Plants Copenhagen, 16th April 2012 José Luis Domínguez-García Oriol Gomis-Bellmunt Fernando Bianchi Andreas Sumper Antoni Sudrià-Andreu
Overview • · Introduction • · Power system stability background • · Objectives • · Power System Stabiliser for Wind Turbine • · System simulations • · Comparison of different PSS schemes • · Effect of the cable length on the PSS capability • · Conclusions
Power System Stability Power system stability background - Rotor angle stability maintain or restore the equilibrium between the electromagnetic torque and the mechanical torque. - Small Signal stability A power system under a small disturbance is considered in small signal stability. A small disturbance can be, for example, minor changes in load or in generation on the power system. Frequency Stability Rotor Angle Stability Voltage Stability Oscillatory mode Small Signal Stability Transient Stability Non-oscillatory mode - Inter-area modes [0.1 – 0.7] Hz - Local or Intra-area modes [0.7- 2] Hz Problem solved by PSS
Data in GW Objectives Wind Power has rapidly increased its penetration to power systems reducing the global inertia of the system. Data in MW Source: Wind in Power (2012) EWEA Offshore is growing faster in the last years. Source: Wind in Power (2012) EWEA
Objectives • TSO are requiring some support, • Fault Ride Through • Reactive Power regulation • Frequency Support • Damp Power System Oscillations (In a Future) Since Offshore Wind Power Plants are far from the shore and Wind Power are connected far from conventional generation. OWPP can only affect to inter-area oscillation modes
Objectives Wind Power neither engage nor induce oscillation modes to power systems, because of their technologies both FSWT and VSWT. FSWT Can contribute with their inertia. (Limited Regulation) VSWT Can regulate the power delivered by the converter. OWPP Communication required (to any signal non-local) OWPP + PSS controller with using local signals
Power System Stabiliser for Wind Turbine Conventional PSS scheme for Synchronous machines Output Input K BPF Inputs: Any signal affected by the oscillation. - Active Power, - Frequency, - Angle synch. generators - Voltages Outputs: Any signal capable to vary the power flow of the power system - Active Power on the WT - Reactive Power on the WT - Voltage on WT terminal or CCP Lead/Lag Simplifications: WT does not need to fix exactly the phase of the Synch. Generators because it affects the power flows.
Power System Stabiliser for Wind Turbine Input: OWPP terminal voltage Local Signal No WAMS communications required Output: Active Power and/or Reactive Power reference of the OWPP
Power System Stabiliser for Wind Turbine Parameter Design Ƭm= 0.1 [0.1-1.5Hz] Band Pass Filter Ƭwh= 2 Kp= 104 Proportional Controller Designed to obtain good response Kq= -105 Δxmin= -0.15 p.u Limiter For all the controllers Δxmax= 0.15 p.u
System under study OWPP Aggregate model 2 synchronous generation areas 2 large tie-lines connecting areas OWPP connected to 1 tie-line FAULT Three-Phase fault in 1 of the connection tie-lines with the following line disconnection
Case I: Comparison of different PSS schemes Assuming a constant location of the OWPP, different PSS schemes have been compared Active Power flowing among areas Voltage mag. at the OWPP terminal Qwt delivered by the OWPP Pwt delivered by the OWPP
Case II: Effect of the cable length on the PSS capability Assuming a the same PSS scheme on the OWPP (PQ-PSS), under various OWPP cable connection length Active Power flowing among areas Voltage mag. at the Area 1 Bus Pwt delivered by the OWPP Qwt delivered by the OWPP
Conclusions • PSS controllers have shown promising damping properties • PQ – PSS presented the best damping behaviour • The length of the cable reduces the observability of the oscillation • Even in case of long cable, OWPP-PSS provides satisfactory damping capability • PSS schemes without communications can provide good damping to the system, even being far away from the point of interaction
Thank you for your attention! Questions?