1. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Dynamic and Short Circuit Performances of A Radial Flux PM Synchronous Generator For Vertical Axis Standalone Wind Turbines By Using Dynamic Linked External Circuit Method
Durmuş UYGUN, Yücel ÇETİNCEVİZ and Güngör BAL
Presenter: Prof.Dr. Güngör BAL
3rd European Conference on Renewable Energy Systems (ECRES 2015)

2. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Outline
Introduction
Analytical Study and Parameters
Simulation Platform with Dynamic Linked External Circuit Method Through Simplorer and RMxprt
Simulations with Dynamic Study and Faults Scenarios
Results, Discussion and Future Studies
3rd European Conference on Renewable Energy Systems (ECRES 2015)

3. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Introduction
In this study;
Short-circuit fault analysis and transient performance of a designed radial flux permanent magnet synchronous generator (RFPMSG) for a standalone wind turbine was studied,
Dynamic generator model derived in RMxprt environment was linked with the ANSYS Simplorer external circuit simulator,
Co-simulation method was used to analyze dynamic and short-circuit performances of a 600 W RFPMSG feeding an ohmic and inductive load,
Moreover, the performance results of the studied generator were presented.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

4. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Analytical Study and Sizing Equation
Even though the structure is inner or outer, the design of the permanent magnet generators is typically initiated with the sizing equation [J. Gieras, et al. 1997].
where S is the apparent power of the generator, B is the specific magnetic loading, ac is the specific electrical loading, D is the outer diameter of the motor, L is the stack length of the motor, Kw1 is the winding factor and n is the rated speed.
Parameters
Value
Load Resistance (ohm)
80.66
Load Line Voltage (V)
229.68
RMS Phase Voltage (V)
134.91
Specific Electric Loading (A/mm)
25.11
Armature Current Density (A/mm2)
5.58
Iron-Core Loss (W)
7.94
Frictional and Windage Loss (W) 12
Armature Copper Loss (W)
101
Output Power (W)
647
Efficiency (%)
84.25
Power Factor
0.97
3rd European Conference on Renewable Energy Systems (ECRES 2015)

5. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Turbine and Generator Model
Prototype of vertical axis wind turbine with RFPMSG topology
3rd European Conference on Renewable Energy Systems (ECRES 2015)

6. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Simulation Platform
Simulation platform of overall generator and network system
3rd European Conference on Renewable Energy Systems (ECRES 2015)

7. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Operation Steps
PMSG was operated under constant load of 80Ω and 0.001H at variable generator speed related to wind speed regime.
And then, PMSG was operated under variable load at constant rated speed of 750 rpm.
Short circuit performance of the generator was performed using the same model as well.
The three fault scenarios were used for short circuit analysis as follows:
The first scenario is “a short-circuit at generator terminal”
The second scenario is including “open one phase fault of the generator”
And the third scenario is a “short-circuit at load side”.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

8. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Simulation Results from Variable Speed Operation
Generator speed regime in combination with wind speed
OUTCOME: 600W PMSG is able to generate minimum 220 VAC line voltage which is acceptable in variable speed operation. There are some lacks in the simulation results which may be due to sharp drops or increments in speed data.
Generator side measurements
Load side measurements
3rd European Conference on Renewable Energy Systems (ECRES 2015)

9. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Simulation Results from Variable Load Operation
Variable load regime at constant generator speed
OUTCOME: The trend in voltage and current is acceptable. Although these variations lead instability on generator side, the voltage and current variations on load side are quite acceptable which can also be reported for variable load operation.
Generator side measurements
Load side measurements
3rd European Conference on Renewable Energy Systems (ECRES 2015)

10. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Open one phase fault of terminal
A line to line fault switch is included in the circuit to see how the machine behaves during fault condition.
Time-controlled fault activator (operated via a step function at a given time period or moment) activates the fault switch.
Generator side measurements
OPERATION and OUTCOME:
One of the phases of the generator terminal was open at 100ms.
It can be stated that generator line voltage dropped instantly which is an expected case.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

11. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Short circuit fault of terminal
Second scenario is with a case due to a short circuit fault at generator terminal.
The simulation is done by first starting the system under the rated load.
Winding currents in normal operating condition
Terminal currents for a short circuit fault of terminal
OPERATION and OUTCOME:
Phase C is faulted or shorted to phase B at 100ms.
With two stator windings are short-circuited, the motor cannot operate as expected; so the time waveforms correctly illustrate.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

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Short circuit fault of load
In the third scenario, a short circuit fault case of a load is studied.
This is one of the worst cases for generator + load operation where all terminals of the inverter are shorted to each other (but not to the ground).
Generator side measurements
Load side measurements
OPERATION and OUTCOME:
In that case, it is expected that load line voltage and generator terminal voltages drop instantly and go to zero while at that time, load currents critically increase.
As illustrated and expected from simulations; when a fault at inverter terminals is activated at 100ms, generator terminal (line) and load line voltage dropped to zero and load current instantly increased up to 18A which was 10 times greater than rated line current.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

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Conclusion and Future Works
The main goal of this study which was to co-simulate a permanent magnet synchronous generator (PMSG) was attained,
The aim has been well achieved as the simulations show variable speed/load operation and faulty cases indicating the behavior of co-simulation system under fault,
When the analyzed model of the machine is then coupled to control system, it provides better information to the controller to generate reasonable control signals. This suggests that, in order to develop control strategies for complex machines, there is a need of using different designing tools,
Future Studies include;
Testing, verification and advanced analysis,
Focus on eddy current loss minimization in permanent magnets as well as copper loss optimization in stator windings,
Providing correct faults prediction and detection mechanisms of critical inverter/converter operation conditions.
3rd European Conference on Renewable Energy Systems (ECRES 2015)

14. 3rd European Conference on Renewable Energy Systems (ECRES 2015)
Thank You
For Participating and Listening
3rd European Conference on Renewable Energy Systems (ECRES 2015)