Q2. What is the reliability of the system at the cut level?
In wind turbines, many redundancy designs are adopted to improve the reliability of the weakest components and assemblies so that the system reliability can be maintained at a safe level.
Q3. Why do hydraulic systems have high failure rates?
In reality, due to the complex working environment and variable operating conditions, hydraulic systems have high failure rates [1, 2].
Q4. What is the system failure function for a redundant component?
There are three system success function modes for a system of two load-sharing redundant components: both components function, component A fails while component B functions, and component A functions while component B fails.
Q5. What is the reason why the reliability of redundant components is determined?
according to the failure mechanism of the redundancy systems, once the redundant components fail, the surviving components will take the full load, their failure rates will increase, and their reliability will decrease.
Q6. What is the function of the dynamic fault tree analysis?
Markov-based dynamic fault tree analysis (DFTA) not only has the function of the conventional fault tree analysis (FTA) method but also can model55and evaluate the reliability of the problem with dynamic failure characteristics.
Q7. When the WT is forced to stop for the safety, what is the braking force?
When the WT is forced to stop for the safety,125the reversing valve (14) gains electricity, and unit (16) loses electricity; then it begins to be braked; the WT starts up when unit (16) gains electricity.
Q8. What is the reliability of the load-sharing system of wind turbines?
The components in the load-sharing system of wind turbines, whose failure rates are dependent, can share the total workload.320However, these redundancy systems are often seen as parallel systems, in whichcomponents are independent and can not share the load.
Q9. What is the reliability importance of the type i component?
The reliability importance of the type i component can be derived fromequation (6)∂Rs(t) ∂Ri(t) = m1∑ l1=0 · · · mK∑ lK=0 [ li − miRi(t) Ri(t)[1 − Ri(t)]
Q10. What is the likely failure probability value of state S5?
The results of Fig. 6 show that the failure probability can gain the minimal value 0.4749 and the maximum value 0.5989 at cut level α = 0, and gain the median value 0.5369 at cut level α = 1 that is the most likely failure probability value of state S5.
Q11. What is the optimal solution for the hydraulic pump, the one-way valve and the overflow?
The optimal solution is obtained as [2,2,2] with thehighest reliability (0.8940) and the acceptable cost (38), which means that the hydraulic pump, the one-way valve, and the overflow valve need to be allocated a redundant component to keep them functioning reliably and safely.