Page 36 - Practical Power System and Protective Relays Commissioning

32 Practical Power System and Protective Relays Commissioning

4.3 RENEWABLE POWER SYSTEMS
There are two types of energy: primary energy and secondary energy.
Primary energy comes directly from the environment, with examples such as
nonrenewable energy (fossil fuels) as coal, crude oil, natural gas, nuclear
fuel. A secondary energy source is one obtained from a primary energy
source through a transformation process, typically with the aim to make it
suitable for a particular energy use.
Renewable energy can be categorized into hydro power, biomass, solar
energy, wind, geothermal and ocean energy and waste. Primary energy can
be converted to secondary energy as petroleum products, electricity, heat,
and biofuels.

4.3.1 Introduction
This type of energy is sustainable and coming from nature sources.

4.3.2 Renewable Energy
These sources of energy can be replaced to produce energy and reused by
nature without any impact on the environment. Renewable energy sources
can produce electricity and now produce up to 20% of the required electric-
ity without any environmental impact. The use of renewable energy has
increased in the past 10 years and continues to grow.

4.3.3 Types of Renewable Energy
There are many types of renewable energy sources, some examples are:
1. Solar
2. Wind
3. Geothermal
4. Biomass
5. Ocean or tidal
6. Hydro-electric

4.3.3.1 Solar Energy
Solar electric systems use photovoltaic (PV) systems which utilize sunlight to
generate electricity. A PV panel consists of many solar cells. The cells, made
from silicon, are grouped into a PV module covered by glass (see Fig. 4.1).
Sunlight is absorbed by the silicon in the PV panel and the PV panel pro-
duces a DC current. The DC current is converted to AC current by an
inverter as shown in Fig. 4.1. The AC power is injected into the power grid.
The solar DC energy can be stored in batteries and these batteries supply
loads when there is no light at night and/or when they are fully charged.