**2. The Proposed Test System**

IEEE-13 node test network is modelled as hybrid grid by incorporating the wind and solar photovoltaic (PV) generators. As specified by IEEE, the capacity of this network is equal to 5*MVA* and operated at frequency of 60 Hz and two voltage levels of 0.48 kV and 4.16 kV [16,17]. Doubly fed induction generator-based wind plant (WG) of capacity 1.5 MW is integrated at node 680 of test system using transformer TRFW. Also, PV plant of capacity 1 MW is integrated to test network at node 680 using a transformer TRFS and an overhead line (5 km length) as described in Figure 1. Positive and zero sequence resistances of this line are 0.1153 and 0.413 Ω/km respectively. Positive and zero sequence inductances of the same line are 1.05*e*−<sup>3</sup> and 3.32*e*−<sup>3</sup> H/km respectively. Positive and zero sequence capacitances of the same line are 11.33*e*−<sup>9</sup> and 5.01*e*−<sup>9</sup> F/km respectively. Since, wind and solar PV plants are integrated at node 680, therefore this node is considered to be a point of common coupling (PCC).

The configurations of overhead (OH) lines and underground (UG) cables are considered same as that provided in the original data as illustrated in Table 1. Impedance matrix (*Z*601) of the OH lines (configuration 601) is provided by the equation (1) where all the impedances are expressed in Ω/km. Impedance matrix (*Z*606) of UG cables (configuration 606) is provided by equation (2) where all impedances are expressed in Ω/km. Positive and zero sequence capacitance magnitudes of 1.57199 nF/km and 1.3398*nF*/*km*, respectively are used for OH lines. Similarly, the parameters for UG cables (configuration 606) are taken as 15.96979 μF/km. All loads are assumed as 3*φ* balanced as detailed in Table 2 [18,19].

$$Z\_{601} = \begin{bmatrix} 0.2153 + j0.6325 & 0.0969 + j0.3117 & 0.0982 + j0.2632 \\ 0.0969 + j0.3117 & 0.2097 + j0.6511 & 0.0954 + j0.2392 \\ 0.0982 + j0.2632 & 0.0954 + j0.2392 & 0.2121 + j0.6430 \end{bmatrix} \tag{1}$$

$$Z\_{606} = \begin{bmatrix} 0.4960 + j0.2773 & 0.1983 + j0.0204 & 0.1770 + j0.0089 \\ 0.1983 + j0.0204 & 0.4903 + j0.2511 & 0.1983 + j0.0204 \\ 0.1770 + j0.0089 & 0.1983 + j0.0204 & 0.4960 + j0.2773 \end{bmatrix} \tag{2}$$

**Figure 1.** Hybrid power system network incorporating wind and solar energy plants.


**Table 1.** Feeder Data of Hybrid Grid.


**Table 2.** Loading Data of Hybrid Grid.

Test network of the hybrid grid with RE penetration is integrated to the network of utility grid using a transformer designated as TRFG. A transformer designated as TRFF is used as interconnecting transformer (ICT) between the nodes 633 and 634 of hybrid grid. Parameters of transformers used in the hybrid grid are provided in Table 3.

**Table 3.** Transformer Parameters of Hybrid Grid with RE Penetration.


Protection schemes PS-1 and PS-2 are installed at nodes 650 and 680 (PCC), respectively of the hybrid grid. These schemes will be used to disconnect the test hybrid grid and RE generators from the network of utility grid during the faulty events. Voltage and currents are continuously processed using the proposed algorithm and tripping signals are given to the respective circuit breaker (CB) if fault is detected. Protection schemes may be installed at any node of the hybrid grid by looking towards the actual requirement of protection. This algorithm will work well for all the locations of hybrid grid using a suitable weight factor for the proposed fault index. Results are discussed in detail for the protection scheme PS-1.

## *2.1. Wind Energy Conversion System*

The wind energy conversion system (WECS) is comprised of a wind turbine, a doubly fed induction generator (DFIG) and a converter system. Kinetic energy of the wind is converted into mechanical energy of wind turbine shaft, which is converted into the electrical energy using the DFIG, coupled mechanically to the shaft of wind turbine. WECS consists of DFIG, with the capacity of 1.5 MW and operating at 60 Hz frequency with output voltage of 575*V* [20]. Rated wind speed equal to 11 m/s is considered and generators have the following data: H (inertia constant)= 0.685 s, *Rs* = 0.023 pu, *Ls* = 0.18 pu, *Rr* = 0.016 pu, *Lr* = 0.016 pu, *Lm* = 2.9 pu. Wind turbine, DFIG and their control systems were modelled using the parameters reported in [21,22].
