Table 1 Control methods used for the FRT capability improvement
From: Fault ride-through capability improvement in a DFIG-based wind turbine using modified ADRC
Type of technique | Technique used | Control methods/protection circuits | References | Advantages | Disadvantages |
|---|---|---|---|---|---|
Hardware | Protection circuits and storage-based approaches | Crowbar | [22] | Activation during faults and protection of RSC against rotor overcurrent | Lack of control of active and reactive powers by RSC during the faults |
Crowbar with series R-L | [23] | Remaining the RSC in the circuit during the faults Control of active and reactive powers during the faults | Damage to RSC due to inrush current of the rotor in the case of small series impedance and high resistance of crowbar | ||
Crowbar with SBR | [24] | No frequent use of a crowbar Keeping the RSC in the circuit during the fault Suppression of the fluctuations of torque | Dependence of voltage quality on SDBR switching pattern | ||
Crowbar with DC-link chopper | [24] | Suppression of fluctuations in the DC-link voltage Control of active and reactive powers during the faults Increasing the duration of normal operation in DFIG | Increasing the required time for disengagement and restoration of RSC compared to the time of using the crowbar | ||
ESS | [26] | Improvement in the transient stability of DFIG Adjusting the steady-state active power in DFIG | Requiring battery maintenance Discharging the battery if not in use | ||
SGSC | [27] | Suppression of the oscillations of stator flux and direct handling of the stator flux | Negative effect on DC-link power balance | ||
FCL, SFCL | Limiting the fault currents More controllability of RSC Better support of reactive power Not adding any impedance to the network under normal operating conditions | High price of SFCL | |||
Device-based reactive power injection methods | SVC (shunt compensator) | [30] | Simple configuration for reactive power compensation Reactive current support, voltage stability improvement, continuous voltage control | Voltage-dependent performance | |
STATCOM (shunt compensator) | Better transient border with the ability to run overload capability for a short time in a severe voltage sag Faster performance compared to SVC Acceptable performance against disturbances Compensation of negative sequence parameters (current and voltage) | Higher price Inability to provide active power Restriction of injecting power | |||
DVR (series compensator) | [32] | Ability to eliminate transient current and transient power of generator during a network fault Reduction of stator power reference Fast voltage recovery Reactive power control | Requiring additional active power produced by DFIG during fault to adjust its DC-link voltage at the desired value Requiring enough energy storage to suppress voltage sag | ||
MERS (series compensator) | [33] | Removing the blocking switch Useful for large-scale network Low losses of switching | Mechanical bypass switching Undesirable robust control | ||
UPQC (hybrid compensator) | [34] | Control of active and reactive powers Fast compensation of reactive power | Absorption of active power Requiring a large capacitor in DC-link | ||
Software | Traditional control methods | Blade pitch orientation control | [36] | Adjusting the rotor velocity | Low response speed due to mechanical control |
Modified vector control | [37] | Consideration of stator flux dynamics Better transient and steady-state response during fault conditions than traditional vector control | Ignoring the dynamic variations of stator magnetizing current and degradation of the DFIG performance during faults | ||
Hysteresis control | Simple configuration Intrinsic characteristic for limiting the peak current Helping power converters to stay connected to the network during faults Avoiding reactive power consumption in the event of faults and contributing to network stability | Long-term operation is not favorable because of variable switching frequency and current distortions with low-order harmonics Difficult implementation | |||
TCCFFC | [40] | Improving the control of transient current Suppression of the pulsations of torque due to negative sequence current | Complex control Cabling and maintenance due to the use of sensors to sense the input voltage | ||
Advanced control methods | SMC | [41] | Robustness to external disturbances No further stress on the drive train of the wind turbine | Oscillations caused by chattering event Overestimation of the control coefficient Complicated model Saturation of control commands | |
FLC | Less overshoot compared with SMC | High cost Complicated structure | |||
MPC | Fast response Taking into account nonlinear factors and system constraints | Complicated implementation High cost of implementation Requiring experimental verification | |||
ADRC | No dependence on the exact mathematical model of the controlled design High accuracy in control Strong immunity against noise Explicit configuration and simple implementation | Complexity of manually adjusting the numerous parameters in a nonlinear ADRC and consequently limitations for practical usage Increasing the order of the system equations because of the addition of extended state |