Slip ring, as a key junction of connecting rotating component (hub) with static component in wind power generator set, can directly affect overall safety, stability and efficiency as well. Once breaking down, the consequences will be happened, which will be lead to severe effects on current transmission, control systems, operation safety as well as its maintenance costs for the motor.
1. Electric power transmission interruption that can lead to power generating capacity loss
Slip ring functions as transmit the power generated from the motor from rotating hub side to tower cylinder for the purpose of corresponding on-line power. If bad contact for slip ring, the brush will be used with excessive wear and tear, which will lead to the wear of electric ring or ineffective insulation. Worse, the followings will be happened:
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Instable current transmission that will lead to voltage fluctuation or momentary power outage:
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If severe, electric power will be totally output interruption, which will lead to the fact that the motor will be forced shutdown and can directly cause power generating capacity loss;
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In the condition of high loading, contact resistance will be increased, which may lead to local overheating, fire risk and even threating the equipment safety.
2. Control signal interruption that will lead to affect normal operation for pitch system
Modern wind power generator sets depend on precise pitch system to adjust blade angle for the purpose of optimizing wind power capture efficiency and its safety. Slip ring functions as transmit control order and power to the pitch control system inside the hub. If signal path of Slip ring is breakdown, the followings will be happened:
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Pitch order will not be transmitted, which will lead to the fact that the blade cannot feathering or adjust its angle in time.
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If wind speed is suddenly changed or the equipment is shut down emergently, the feathering cannot be safely realized, which will lead to increase its risks for excessive speeding and loss of control and structural damage;
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Out-of-step pitch of the blade that will lead to the fact that wind power generator sets will be sharply vibrated with uneven load distribution, speeding up key components fatigue damage for gearbox and main shaft.
3. Slip ring functions as passing back of its sensor date (including the temperature, vibration, running speed and the angle). Once signal transmission blocking, the followings will be happened:
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Supervision system cannot capture real-time date inside the hub, which will lead to operation system "Blackboxing";
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Ineffective fault pre-warning system that will lead to hardly supervise potential problems in time and to increase sudden fault risks;
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Maintenance staff cannot judge fault causes, which will lead to prolong fault inspection period and to reduce its maintenance efficiency.
4. Electromagnetic interference and signal crosstalk that will lead to malfunction for control system
Inside the slip ring, if bad shield or aged insulation, electromagnetic interference or signal crosstalk may be generated. Further, the followings will be happened:
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Error code for control signal and data Packet loss;
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Control system accepts error order or false alarm, which will lead to malfunctioning machine stoppage or malfunctioning pitch;
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Long-period operation will speed up logical mess for control system, which will lead to affect overall stability of the wind power generator sets.
5. Increasing maintenance costs and safe risks
The breakdown of Slip ring is hardly be supervised within the operation, which will be only inspected after the shutdown. Once breakdown:
- Need to inspect after the shutdown. And, even need to return to repair. Long-period shutdown and heavy loss for generation capacity;
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Need to maintenance with working high above the ground and complex operation, which will increase staff safety risks and its maintenance costs;
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If fault is not be inspected in time, related equipment such as pitch motor, controller and the cable will be affected, which will lead to secondary damage and related large amount of losses.
6. Shorten equipment lifetime and affect motor reliability with its full life circle
Slip ring, as quick-wear component, will speed up aging accelerating for itself and its related components, if frequent breakdown or long-period bad running conditions. Further, the followings will be happened:
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Conductive powder will be generated by abnormal wear between the brush and its conductive ring, which will lead to inner pollution;
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Insulted material will be broken down by over-heating or electric arc, which will lead to reduce overall reliability;
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Component inefficiency, including bearing and sealed parts, will be speeded up with long-period running, which will lead to overall lifetime of the motor.
Therefore, though small structure of slip ring, its fault may lead to multiple consequences from reducing its power generation efficiency to severe safety accidences. Furthermore, it is important for ensuring stable operation of slip ring, which means not only key component for improving economic benefits for wind power plant but also important precondition for ensuring the motor safety, reliability and its normal operation within its lifetime.
