*Article* **Study and Simulation of a Wind Hydro Isolated Microgrid**

#### **Rafael Sebastián and Antonio Nevado \***

Departamento de Ingeniería Eléctrica, Electrónica y de Control, ETSII UNED, 28040 Madrid, Spain; rsebastian@ieec.uned.es

**\*** Correspondence: anevado@ieec.uned.es

Received: 6 October 2020 ; Accepted: 11 November 2020; Published: 13 November 2020

**Abstract:** Isolated microgrids are microgrids which operate autonomously. This paper presents an isolated microgrid which combines a Hydraulic Turbine Generator (HTG) with a Wind Turbine Generator (WTG) to supply consumers forming a Wind Hydro Isolated Microgrid (WHIM). The WHIM includes a Dump Load (DL) to dissipate the active power excess. The WHIM has been modeled and its operation has been simulated in two modes: Wind-Hydro (WH), where both HTG and WTG supply power, and Wind-Only (WO) mode, where the WTG is the active power supplier and the HTG keeps connected to the grid with null power to generate the grid voltage. In WO, a fast frequency regulation is achieved by means of a controller which commands the DL to consume the WTG power excess. Additionally, the simulation of the mode transition from WO to WH, which is triggered by a system active power deficit in WO mode, is shown. A kick starting system designed to speed up the HTG power production improves the transient from WO to WH mode change. Finally, the simulations in WH mode show the interaction between the HTG and WTG. The two controls proposed have been proved effective and the simulations show a good WHIM dynamic performance.

**Keywords:** hydro turbine generator; wind turbine generator; dump load; isolated microgrids; power systems simulation; power systems control
