Autonomous Wind - Photovoltaic Hybrid Power System

1. Abstract

In this project, an isolated wind-photovoltaic hybrid power system with battery storage will be presented that can supply electricity to residential application with a capacity of 10Kw peak electrical power.

A hybrid power generation system consists of a 200W 32V 24 pieces mono crystal solar panel and 10kW permanent magnet synchronized generator (PMSG) wind power generation system, rotating 3600 according to direction of wind, was installed. Besides, to store the consumption excessive electric energy or in case of lack of generation, to ensure energy continuity via renewable power system, a battery bank gel jeep cycle accumulator groups were installed on the wind-solar hybrid power generation system.

In the hybrid power generation system, the data record in 10 second intervals (as kWh) was realized separately from each generation system. Monthly totals of obtained data were arranged separately in tables and graphics. As a result of the comparisons made, it was determined that the generation power of battery storage hybrid power generation system was above its consumption power and at the same time, consumption excessive electric energy was stored in proportional to its battery capacity.

2. Introduction

Renewable energy sources, such as wind energy and photovoltaic (PV) energy, are used by stand-alone systems supplying remote houses. These sources are of intermittent nature and, therefore, the stand-alone systems should include storage battery banks.

The storage battery banks improve the reliability of these systems because the excess energy is stored in the battery bank, and this energy is delivered to the load when the available energy is not sufficient. Wind energy and photovoltaic energy have complementary characteristics.

Combining wind energy and photovoltaic in one system (hybrid system) increases the reliability of this system and reduces the storage batteries. The general configuration of stand-alone hybrid wind-PV system with battery storage is shown in Fig. 1, where the generator used by the wind subsystem is a permanent-magnet

synchronous generator (PMSG).

Compared to induction generator, PMSG is sensitive to heat and of high cost. However, stand-alone hybrid wind-PV system with battery storage using induction generator is not investigated in this project. This controlled generator is used in collaboration with the PV unit to build the stand-alone hybrid system.

Fig. I.1: Stand-alone hybrid system

It is commonly known that there is a maximum voltage limit of the battery bank to protect the battery bank against overcharging. Therefore, it is required to capture the maximum power from the renewable energy source provided that the maximum voltage limit is not exceeded. The voltage constraint will be followed in this project to determine the load sharing of the PV and wind energy subsystem.

3. Wind Energy Conversion Systems (WECS)

WECS convert wind energy into electrical energy: Wind energy ->mechanical rotational energy -> electrical energy. The principal component of the WECS is the wind turbine (WT). WT rotor is coupled to the generator throught a multiple-ratio gearbox or, gearless in small power applications. Usualy induction generators, (squirrel-cage (SCIG) or doubly-fed (DFIG)), or permanent magnet synchrounous generators (PMSG) are used in WECS.

3.1. WT main components

A wind turbine has three major components: the tower, the rotor and nacelle. Generally, the rotor may have two or three blades.