《电力电子学》（双语版） Research in New Renewable Energy

Research in New Renewable Energy Wow and Renewable Energy ukiengineenng Dr Li Ran

Research in New & Renewable Energy Dr. Li Ran

Wind power

Wind Power

Recent studies in Wind Power Grid Doubly Fed Induction Generator Gearbox Filter Wind turbine 4Q Converter DFIG Grid Fault Ride Through

Recent Studies in Wind Power Gearbox Wind Turbine Doubly Fed Induction Generator 4Q Converter Filter Grid DFIG Grid Fault Ride Through

Renewable Energy Networks Grid code sets out requirements for grid interconnection Most current renewable generation systems are treated as negative load Future systems MUsT contribute to system frequency and voltage control Grid interconnection usually makes or breaks project Development of many (ALL?) renewable energy converter systems have concentrated on the device itself without detailed thought of how to convert the power for grid interconnection Future developments MUST consider the system

Renewable Energy Networks ▪ Grid code sets out requirements for grid interconnection. ▪ Most current renewable generation systems are treated as “negative” load. ▪ Future systems MUST contribute to system frequency and voltage control. ▪ Grid interconnection usually “makes or breaks” a project. ▪ Development of many (ALL?) renewable energy converter systems have concentrated on the device itself without detailed thought of how to convert the power for grid interconnection. ▪ Future developments MUST consider the system as a whole – REQUIRES INTEGRATED SYSTEM

Grid Code-Example o The value of grid-fault ride-through is increasingly appreciated. Grid code, e. g. Scottish Hydro-Electric Guidance Note A wind farm must remain connected under the following conditions depending on fault voltage reduction and registered capacity of wind farm wind farm registered capacity voltage during fault =30MW 0% July 2005 January 2004 15% January 2004 before January 2004 The voltage refers to that on the transmission system(275 or 132 KM Transformer impedance and fault infeed from the wind farm are likely to result in a higher voltage at generator terminal Fault is cleared in 140 ms for 132 kV and 100 ms for 275 kV system Backup clearance time can extend to 300 ms

Grid Code - Example ● The value of grid-fault ride-through is increasingly appreciated. ● Grid code, e.g. Scottish Hydro-Electric Guidance Note A wind farm must remain connected under the following conditions depending on fault voltage reduction and registered capacity of wind farm. wind farm registered capacity voltage during fault =30 MW 0% July 2005 January 2004 15% January 2004 before January 2004 ● The voltage refers to that on the transmission system (275 or 132 kV). Transformer impedance and fault infeed from the wind farm are likely to result in a higher voltage at generator terminal. ● Fault is cleared in 140 ms for 132 kV and 100 ms for 275 kV system. Backup clearance time can extend to 300 ms

Initiall Control ldea-why V can't it work otor voltage stator voltage control fault

Initial Control Idea – why can’t it work? stator voltage rotor voltage control i r fault

Recent studies in Wind Power Grid Doubly Fed Induction Generator Gearbox Filter Wind turbine 4Q Converter DFIG Grid Fault Ride Through

Recent Studies in Wind Power Gearbox Wind Turbine Doubly Fed Induction Generator 4Q Converter Filter Grid DFIG Grid Fault Ride Through

Feasibility Region with Proposed Control Riding-through operation range 0.2 riding-through operation fange a0.15 0.1 0.05 super-synchronous sub-synchroneus -0.1 0.1 0.2 0.3 Pre-fault silp: so (pu) This plot says that the dF iG can successfully ride through a grid fault which brings terminal voltage down to 0.3 pu, even it initially operates at full speed

-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0 0.05 0.1 0.15 0.2 0.25 Pre-fault silp: s0 (pu) Fault voltage level: Us (pu) Riding-through operation range riding-through operation range Feasibility Region with Proposed Control { super-synchronous sub-synchronous This plot says that the DFIG can successfully ride through a grid fault which brings terminal voltage down to 0.3 pu, even it initially operates at full speed

Durha 30 kW DFG Test Rig Grid Ⅹ PC-Targetbox4 Q conV VARIAC real time system i Filter DFIG prime drive with programmable direct torque control

Durham 30 kW DFIG Test Rig prime drive with programmable direct torque control DFIG XPC Targetbox real time system Filter Grid 4Q conv VARIAC

Laboratory verification Rotor current constrained by control Simulation Experiment 1.5 30.5 -0.5 -0.5 1.5 1.5 10 10.05 Time(s Time(s)

Laboratory verification 9.95 10 10.05 10.1 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 ir-abc (pu) Time (s) 9.95 10 10.05 10.1 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 ir-abc (pu) Time (s) Rotor current constrained by control Simulation Experiment