Impact of Improved Measurements
on Performance of a Smart
Thermal Energy System
Huibert Verra, Jacob Henderson, John Dyer, and John N. Jiang
D
ecentralized electrical energy systems will play an
essential role in the future smart grid. In this paper,
we introduce a new industrial scale electric ther-
mal energy system using a high-voltage electrode boiler, of
which the level of electricity consumption can be adjusted as
desired. It is also shown that, with appropriate instrumenta-
tion and measurement algorithms, the energy consumption
can be adjusted quickly and accurately. This feature makes
such a thermal energy system an ideal candidate to deal with
the variability of renewable energy, to respond to the prices in
the electric power markets and support the frequency stability
of the power grid.
Recent specific applications for the boiler demand new
methods of measurement for critical variables, which are
needed to offer a fail-safe or fault-tolerant class in addition to
more reliable measurements in general. Implementation of
specific instrumentation, many of which require a redundant
setup, and control software is necessary to provide this criti-
cal level of operation. Using the instrumentation to measure
variables such as temperature, pressure, conductivity, etc., a
control algorithm was implemented to improve the overall
performance of the boiler system. The new control method sig-
nificantly improves the performance of this electric thermal
energy system, reducing the mean power errors to 0 ± 0.5%.
The smart electric thermal energy system presented in
this paper provides a fundamental building block toward
expanded use of high-voltage electrode boilers for load-fre-
quency control, with the added benefit of thermal energy as
a by-product for use by various consumers. The enhanced
control algorithm is particularly relevant in electrical power
applications with increased volatility from energy production
by wind turbines.
Decentralized Electrical Power
Generation
Historically, the generation of electrical energy has been ac-
complished in large centralized facilities, often by means of
natural gas, coal and nuclear or hydropower plants. Large
facilities offer great advantages economically, but long
transmission lines are needed, which can have a negative
effect on the environment. As centralized power produc-
tion increased, the distribution grid became so large that the
power companies could not guarantee cheap and reliable
electricity to more remote consumers. Increasing the central
generation was no longer enough to achieve better efficiency;
however, better efficiency might be achieved by implement-
ing smaller generating units collocated with the consumers.
A much-used decentralized generation method is cogene-
ration, which is the use of an engine to generate both electricity
and heat used for heating applications. Fig. 1 shows a typical
layout of a co-generation grid.
Another method of decentralized generation is to generate
power with wind turbines. It was a method used for thousands
of years but became obsolete after the Industrial Revolu-
tion. In the early 1970s, during the first oil price shock, wind
power generation made a comeback as a reliable and consis-
tent power source by using other sources as back up [1]. The
only pollution associated with wind power generation is dur-
ing manufacturing and maintenance.
Wind energy is experiencing the most substantial growth
of all sources of power generation. A status report from the
global Renewable Energy Council (REN) [2] shows that wind
power has had an annual growth rate of more than 20%. In
many areas, wind power is supplying as much as 20% of the
total energy demand [3]. By the end of the year 2012, the to-
tal installed wind power capacity worldwide was more than
282 GW, and 21% of this was generated in the United States
(60 GW) [4]. Not only is the number of installations rapidly in-
creasing, but also the capacity per installation has increased
immensely [5]. In the 1980s, 300 kW turbines were state of the
art; by the time of this writing in 2014, the Danish company Ves-
tas has deployed an 8-MW turbine [6]. However, wind electric
power generation systems, in particular those with variable-
speed wind turbines, are very different from conventional
thermal power generation, because they are not synchro-
nous to the electrical frequency of the power distribution grid
(mains frequency or grid frequency are synonyms for the fre-
quency of electrical generation). Due to the design of modern
February 2015 IEEE Instrumentation & Measurement Magazine 25
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