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EnAPlug – An Environmental Awareness Plug to Test
Energy Management Solutions for Households
Luis Gomes
1
, Filipe Sousa1, and Zita Vale1
1GECAD – Research Group on Intelligent Engineering and Computing for Advanced Innova-
tion and Development, Institute of Engineering – Polytechnic of Porto (ISEP/IPP),
Rua Dr. António Bernardino de Almeida, 431, 4249-015 Porto, Portugal
{lufog, ffeso, zav}@isep.ipp.pt
Abstract. The present paper presents a new kind of Smart Plug that covers the
needs of power systems R&D centers. EnAPlug, described in this paper, ena-
bles the monitor and control of loads, as a normal Smart Plug. However, it has a
great benefit in comparison with a normal Smart Plug, the EnAPlug allows the
integration of a variety of sensors so the user can understand the load and the
surrounding environment (using a set of sensors that better fit the load). The
sensors are installed in the load itself, and must have a clear fit to the load. The
paper presents a demonstration of an EnAPlug used in a refrigerator for a de-
mand response event participation, using the sensor capability to measure im-
portant values, such as, inside temperature.
Keywords: Demand response participation · Multi-agent system · Smart plug
1 Introduction
The power system paradigm has been changing in the last years and will continue to
change in future years, resulting in the appearance of smart grids [1]. The centraliza-
tion of generation will end, appearing decentralized generation [2]. The end-
consumers will be incentivized to actively participate in smart grids, in a win-win
situation, changing completely their roles in today’s paradigm [3]. One of the aspects
of smart grids is the integration of microgrids.
The proliferation of microgrids started using use cases around the world [4,5], and
now this concept can be seen and analyzed in real scenarios. The transaction from
scientific concepts towards real implementations, such as [6], is a positive step ena-
The present work has been developed under the EUREKA - ITEA2 Project M2MGrids
(ITEA-13011), Project SIMOCE (ANI|P2020 17690), and has received funding from FEDER
Funds through COMPETE program and from National Funds through FCT under the project
UID/EEA/00760/2013 and SFRH/BD/109248/2015.
bling the validation of theoretical methodologies in real and uncontrollable environ-
ments.
Other important aspect for smart grid successful implementations is the application
of Demand Response (DR) programs to give an active role to the small and medium
players (usually households or small offices) [7]. The use of DR programs brings clear
advantages to smart grids and microgrids [8]. Some use of DR can be found in [9].
Nevertheless, to increase DR dissemination and to promote the appearance of new
programs, automatic and intelligent responses must be implemented in the consumer
side, specially the small and medium players.
The application of Smart Homes such as in [10] and [11], brings advantages for en-
ergy management inside the households, but must important, can increase the DR
programs participation using intelligent response methodologies. The development
and application of autonomous and intelligent methodologies, for DR users’ response,
must consider the users impact (particularly the negative impact provoked).
2 Background of the Proposal
To implement a Smart Home, monitoring and controlling units are needed, such as,
Smart Plugs. At this moment is possible to find a significant number of Smart Plugs
available on the market. However, must of them had limitations, such as: not having
monitoring; or just monitors the current; or having a closed system without any API.
The use of Smart Plugs in R&D centers can be done using software like Home As-
sistant
1
. This is an open source software that aggregates various Internet of Things
(IoT) devices into a unique system, while provides a RESTFul interface to monitor
and control devices. However, if the R&D center intention is to study intelligent
methodologies in the energy management of the household (for instance, to participate
in DR programs), more data and new types of intelligent load control are needed. And
for this situation, there is not a suitable Smart Plug in the market.
This paper presents the Environmental Awareness Plug (EnAPlug), a Smart Plug
that can be easily developed in R&D centers fulfilling the center needs and proposes.
EnAPlug combines actuators to control the load, and sensors, to monitor not only the
load status and energy but also the environment that surrounds the load.
3 Environmental Awareness Plug
EnAPlug was idealized and developed for R&D centers that have a need to test energy
management solutions in households. The development of EnAPlug enables R&D
centers to overcome the limitations of the Smart Plugs available on the market, with a
costume made solution with context awareness capabilities. EnAPlug can also be used
outside R&D centers for load monitoring and control, enabling a context awareness
monitoring of a specific energy resource, for instance, our home kitchen oven.
1
https://home-assistant.io/
The premises of EnAPlug was to build a modular plug that can work with several
actuators and sensors while being open for other systems. For this reason, the control
and monitor of EnAPlug is open and can be accessible with GET and POST requests.
Fig. 1 shows EnAPlug overall architecture. The light blue block that identifies the
microcontroller was implemented using an Arduino Mega 2560 R3, nonetheless other
microcontrollers can be used. The microcontroller is the processing unit of EnAPlug
and has the following requirements: a serial communication port; at least 1 digital
output for the load control; the capability to have TCP/IP connection (using a compat-
ible module); and some digital and analog inputs for sensors (it can also provide
communication protocols, such as, I2C).
The yellow blocks are connected to the 230 V/AC. The Energy Analyzer must be
compatible with Modbus/RTU protocol. This requirement will enable the microcon-
troller to communicate with the energy analyzer using a simple MAX485 component
that converts serial communications into RS-485 communications, and vice-versa. The
Controller block can be a relay, providing on/off control, or other kind of control,
such as, a dimmer. For this paper, it will be used a relay with a 5V/DC coil. The or-
ange block represents the load that we want to monitor and control.
The green and red blocks are external blocks of EnAPlug and are connected using
the TCP/IP connection available in EnAPlug. The Control Signal is made using a
socket connection to the microcontroller IP on port 80. The Server block is an external
server that receives JSON messages and save them in a SQL Server database. The
period of storages is defined by EnAPlug.
The sensors blocks are the sensors connected to the Microcontroller that are suita-
ble for the measured load. The idea of the sensors is to give a better knowledge about
the measuring Load. For instance, if the intention is to monitor and control a lamp, it
is recommended to use a movement sensor and a clarity sensor. The sensors placed
must increase the knowledge regarding the load and its context. If we know the load
context is possible to perform an intelligent control.
Fig. 1. EnAPlug overall architecture
EnAPlug is a device that understand their environment, enabling an intelligent and
a more efficient control. However, the environment awareness capability is only pos-
sible with the right sensors. For instance, if the goal is to measure a television, a tem-
perature sensor is not adequate. Therefore, to understand a television more appropriat-
ed sensors should be chosen, such as, presence, clarity and noise sensors.
4 Demonstration
For this demonstration, EnAPlug was integrated in the Multi-Agent Smart Grid Plat-
form (MASGriP) [12]. MASGriP has the capability to represent small and medium
players in a microgrid scenario. For this scenario MASGriP will be used as a connect-
ed microgrid with three players, representing our R&D buildings (Fig. 2). This repre-
sentation of MASGriP can be seen in works, such as, [6,13,14,15]. In our R&D cen-
ter, namely building N, two EnAPlugs were installed and connected to its representa-
tive agent:
• EnAPlug for refrigerator (Fig. 3) – for this EnAPlug is used on/off control of the
entire refrigerator (including the inside lamp), an energy analyzer to monitor pow-
er, reactive power, voltage and current and four sensors: inside temperature and
humidity sensor; an outside temperature sensor; and a door opener detector using a
clarity sensor;
• EnAPlug for water heater – for this EnAPlug is used a temperature sensor to moni-
tor the water temperature, an on/off controller. The stored energy readings are
power, reactive power, voltage and current.
Fig. 2. GECAD MASGriP configuration
EnAPlug readings, from the energy analyzer and from the sensors, are stored in a
database each five seconds. A MASGriP agent, that represents building N, uses that
data for energy management and gives direct control signals to the EnAPlug.
Fig. 3. EnAPlug installed in the refrigerator: a) inside sensors, b) EnAPlug, c) User interface
An external DR event was trigger in MASGriP from 05:00 p.m. to 06:00 p.m.. The
event demands to turn off of the refrigerators within this hour. In Fig. 4 is shown the
results of the refrigerator connected to EnAPlug, where is visible the DR event and the
turn off the refrigerator.
During the day is possible to see, in Fig. 4, the refrigerator light turning on (peaks
in blue line of consumptions) when the door is open (red line below). During the event
EnAPlug detects an open door but there is no increase of consumption, meaning that
the light was off. The inside temperature (purple line) was stable and did not increase
beyond the refrigerator limit. The DR event was a success as we can see using the
consumption line and the inside temperature line. The EnAPlug can detect dangerous
situations, such as, the increase of inside temperature and turn the refrigerator back on
in an emergency. In this case, the situation was controlled and no damage was made.
The results show that after DR event, when the refrigerator was turned on again, the
motor started immediately to decrease the inside temperature.
Fig. 4. Refrigerator readings between 00:00 a.m. and 23:59 p.m.
In Fig. 5 is shown the water heater during 24 hours. The temperature sensor is
placed outside the water heater (for security reasons), glued in the water pipe. The
consumption and the temperature increases when the water heater turned on (06:45).
The temperature also increases when a person uses hot water (08:30).
Fig. 5. Water Heater readings between 00:00 a.m. and 23:59 p.m.
5 Conclusions
The use of smart plugs can be included in demand side management systems. Howev-
er, the information provided by the smart plugs, available on the market, are limited
because they don’t understand the load context, making it difficult to execute intelli-
gent energy management algorithms.
The use of EnAPlug brings advantages for R&D centers regarding load study and
analysis. For power systems, EnAPlug has the advantage of environmental and con-
textual awareness that can be used for intelligent algorithms. EnAPlug is dynamic and
easy to use in a R&D center, enabling the sensing, monitoring and control of energy
loads. It is a possibility, demonstrated in the present paper, to use EnAPlugs in a mul-
ti-agent system for power system simulation.
The main contribution of this paper is the demonstration of a truly smart plug with
environment awareness capabilities for energy management.
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