Wireless sensor network (WSN) is recognized a potential monitoring, controlling and communication tool for future power grid, the smart grid. Particularly for wind-based power generation application, the multifunctional wireless sensor nodes are positioned at the possible locations of the wind mill for monitoring. Each wind turbine is said to be a sub-network, where the sensor nodes are deployed at the potential data points to accomplish coverage. Connectivity is then a critical issue because the adjacent wind turbines are very far from each other. Hence, the sensor nodes between adjacent turbines will not be within the communication range. Relay nodes are employed between the turbines to bring up connectivity. We propose a Deterministic Relay node deployment algorithm based on Fermat point and Convex hull (DRFC) to find optimal number of relay nodes. DRFC finds the convex hull and Fermat points recursively until it reaches the centre of target region. The relay nodes are deployed in the Fermat points and also between the Fermat points and the segments to establish connectivity. The DRFC algorithm is analysed mathematically with respect to optimum number of relay node and connectivity. © Springer Nature Singapore Pte Ltd. 2018.