Modelling of a multi-source low-head pico hydropower off-grid network

Pico hydropower, generating under 5kW from water flow, is traditionally utilised in stand-alone systems; a single unit feeding a number of houses. This paper investigates the design and performance of a low-head pico hydro off-grid network where multiple `generator units´ are connected to a remote AC grid to form a more reliable and more powerful system that can be expanded. Each generator unit comprises a Turgo turbine and a power electronic interface. A model of the system is developed, the turbine model is experimentally validated at small scale, and a control system model uses droop control for the parallel inverters. A simulation of two non-communicating generator units feeding a single load is presented showing the response of the model to variable load and to varying turbine head. The simulation shows that the droop-based control of the inverter output is able to react to a range of varying loads and changes in input power, whilst sharing the load and providing loose regulation of the supply.