Page 52 - Modern Control Systems

Chapter 1 Introduction to Control Systems

are key technology areas that enable the smart grids [87]. Green engineering appli-
cations can be classified into one of five categories [88]:

1. Environmental Monitoring
2. Energy Storage Systems
3. Power Quality Monitoring
4. Solar Energy
5. Wind Energy

As the field of green engineering matures, it is almost certain that more applications
will evolve, especially as we apply the eighth principle (listed above) of green engi-
neering to create engineering solutions beyond current or dominant technologies
and improve, innovate, and invent technologies. In the subsequent chapters, we pre-
sent examples from each of these areas.
There is a global effort underway to reduce greenhouse gases from all sources.
To accomplish this, it is necessary to improve both the quality and quantity of our
environmental monitoring systems. An example is using wireless measurements on
a cabled robotic controlled mobile sensing platform moving along the forest under-
story to measure key environmental parameters in a rain forest.
Energy storage systems are critical technologies for green engineering. There
are many types of energy storage systems. The energy storage system we are most
familiar with is the battery. Batteries are used to power most of the electronic de-
vices in use today; some batteries are rechargeable and some are single-use throw-
aways. To adhere to green engineering principles, we would favor energy storage
systems that are renewable. A very important energy storage device for green engi-
neering systems is the fuel cell.
The problems associated with power quality monitoring are varied and can in-
clude leading and lagging power, voltage variations, and waveform harmonics. Many
of the green engineering systems and components require careful monitoring of
current and voltages. An interesting example would be the modeling of current
transformers that are used in various capacities for measuring and monitoring with-
in the power grid network of interconnected systems used to deliver electricity.
Efficiently converting solar energy into electricity is an engineering challenge.
Two technologies for generation of electricity using sunshine are solar photovoltaic
and solar thermal. With photovoltaic systems the sunlight is converted directly to
electricity, and with solar thermal the sun heats water to create steam that is used to
power steam engines. Designing and deploying solar photovoltaic systems for solar
power generation is one approach employing green engineering principles to utilize
the sun's energy to power our homes, offices, and businesses.
Power derived from wind is an important source of renewable energy around
the world. Wind energy conversion to electric power is achieved by wind energy tur-
bines connected to electric generators. The intermittency characteristic of wind en-
ergy makes the smart grid development (see Example 1.4) essential to bring the
energy to the power grid when it is available and to provide energy from other
sources when the wind dies down or is disrupted. The irregular character of wind
direction and power also results in the need for reliable, steady electric energy by
using control systems on the wind turbines themselves. The goal of these control