**2. Microgrid system reliability**

The one-line diagram of the case study's microgrid system shown in **Figure 2** consists of a HGU, a WPGS or a wind farm (WF), and two load areas represented as PL1 and PL2. HGU and WPGS are apart from each other by a TL1 (20.12) km transmission line.

Microgrid system reliability (MSR) is a measurement of the system's overall ability to produce and supply electrical power. Such measurement indicates the adequacy of power generation and supply by a microgrid system for a given combination of DG units in the system as well as the subsystems contained in a DG unit. In order to evaluate the reliability of the system shown in **Figure 2**, the combination of DG units and the subsystems contained in a DG unit can be presented by means of a reliability block diagram (RBD) [31] as per **Figure 3**.

Owing to the evaluation of the reliability of the generating power supply by the microgrid system, only DG units are considered. As such, the simplified RBD of the microgrid system is presented in **Figure 4**, wherein all DG units are connected in

**Figure 2.** *The single-line diagram of a microgrid system at Fermeuse, Newfoundland, Canada.*

parallel. However, the RBD of the microgrid system at different operational modes

*Reliability block diagram: (a) grid-connected mode, (b) isolated microgrid with wind power generation system,*

Moreover, in order to estimate the reliability of a DG unit, its various subsystems may equally be represented by the RBD. The latter is shown in **Figure 6**, which consists of WT or WT rotor, gearbox, generator, and power electronics interfacing circuitry. In this chapter, HGU and utility grid are considered as highly reliable sources of power generation. This is because the HGU at the Fermeuse site produces power at its rated value for an entire year. In addition, the utility grid is also available over the period of a year. The reliability assessment of a storage unit (SU) is beyond the scope of this chapter. However, its reliability is considered based on the fact that the storage system is capable of supplying power to the load during the isolated mode of operation of the microgrid system when wind power generation is

Monte Carlo simulation treats the occurrence of failures as a random event, which mimics the wind speed distribution [32]. For example, in a time series wind

is shown in **Figure 5**.

**Figure 4.**

*Microgrid System Reliability*

*DOI: http://dx.doi.org/10.5772/intechopen.86357*

**Figure 5.**

**Figure 6.**

*Simplified reliability block diagram of the microgrid system.*

*and (c) isolated microgrid without wind power generation system.*

*Reliability block diagram of a wind turbine system.*

unavailable (**Figure 5c**).

**3. Reliability modeling**

**173**

**Figure 3.** *Detailed reliability block diagram of the microgrid system.*

#### **Figure 4.**

**2. Microgrid system reliability**

*Reliability and Maintenance - An Overview of Cases*

transmission line.

**Figure 2.**

**Figure 3.**

**172**

*Detailed reliability block diagram of the microgrid system.*

The one-line diagram of the case study's microgrid system shown in **Figure 2** consists of a HGU, a WPGS or a wind farm (WF), and two load areas represented as PL1 and PL2. HGU and WPGS are apart from each other by a TL1 (20.12) km

Microgrid system reliability (MSR) is a measurement of the system's overall ability to produce and supply electrical power. Such measurement indicates the adequacy of power generation and supply by a microgrid system for a given combination of DG units in the system as well as the subsystems contained in a DG unit. In order to evaluate the reliability of the system shown in **Figure 2**, the combination of DG units and the subsystems contained in a DG unit can be presented by means

Owing to the evaluation of the reliability of the generating power supply by the microgrid system, only DG units are considered. As such, the simplified RBD of the microgrid system is presented in **Figure 4**, wherein all DG units are connected in

of a reliability block diagram (RBD) [31] as per **Figure 3**.

*The single-line diagram of a microgrid system at Fermeuse, Newfoundland, Canada.*

*Simplified reliability block diagram of the microgrid system.*

#### **Figure 5.**

*Reliability block diagram: (a) grid-connected mode, (b) isolated microgrid with wind power generation system, and (c) isolated microgrid without wind power generation system.*

#### **Figure 6.**

*Reliability block diagram of a wind turbine system.*

parallel. However, the RBD of the microgrid system at different operational modes is shown in **Figure 5**.

Moreover, in order to estimate the reliability of a DG unit, its various subsystems may equally be represented by the RBD. The latter is shown in **Figure 6**, which consists of WT or WT rotor, gearbox, generator, and power electronics interfacing circuitry. In this chapter, HGU and utility grid are considered as highly reliable sources of power generation. This is because the HGU at the Fermeuse site produces power at its rated value for an entire year. In addition, the utility grid is also available over the period of a year. The reliability assessment of a storage unit (SU) is beyond the scope of this chapter. However, its reliability is considered based on the fact that the storage system is capable of supplying power to the load during the isolated mode of operation of the microgrid system when wind power generation is unavailable (**Figure 5c**).
