IEEE Africon 2017 Proceedings

Development of an Internet Based Prepaid Energy Meter

Nazmat Toyin SURAJUDEEN-BAKINDE Sunday Olufenka AYODELE Timilehin David OLORUNTOBA
Dept. of Electrical & Electronics Engineering Dept of Electrical & Electronics Dept of Electrical & Electronics
University of Ilorin, Nigeria Engineering Engineering
Email: deenmat@unilorin.edu.ng University of Ilorin, Nigeria University of Ilorin, Nigeria
Email: ayodelesunday12@gmail.com Email: t.oloruntoba@yahoo.com

Abdulrahaman Okino OTUOZE Nasir FARUK

Dept of Electrical & Electronics Engineering Dept of Telecommunication Sciences
University of Ilorin, Nigeria University of Ilorin, Nigeria
Email: otuoze.ao@unilorin.edu.ng Email: faruk.n@unilorin.edu.ng

Abstract: Energy fuels the growth and development of any deployment of electricity smart meters. They are energy theft,
country, and as such effective monitoring, measurement, cyber-attacks, mismanagement and erroneous billing etc. [2]
billing and access control is imperative. This paper and thus, various research aspects to curb the challenges have
presents a device that uses the evolving Internet of Things been ongoing. This paper proffers a solution of reducing
(IoT) technology in the design and implementation of an human involvement in energy management for both utility
Internet based prepaid energy meter often referred to as companies as well as consumers. All the monitoring and
smart meters. The energy measurement and billing system control features are provided access via a dedicated web
is automated. The system employs the ATMega328p and portal, anywhere, anytime provided there is Internet
ESP8266 to operate a dual core microprocessor unit with connection.
one core dedicated to energy sensing and measurements,
while the other handles the network connectivity, storage, II. RELATED WORKS
computations and overall system performance. This work Smart meters data are collected, stored and analysed for
uses the HTML5 technology to develop a highly interactive proper planning and billing of consumers [3]. Various designs
mobile and web frontend Graphic User Interface (GUI) have been implemented as presented below from some
application that allows for consumers to have access to selected works. In [4], Omijeh and Ighalo, introduced a tamper
monitor and control their consumption pattern while the detect feature for a GSM solution for prepaid energy meter,
utility companies can monitor and control customers and however this work didn’t provide an interactive interface for
their billing systems. real-monitoring, access control as well as a robust database. A
modelled GSM-based Energy Recharge System for prepaid
Keywords: Internet of Things, Energy Meters, HTML5, metering was presented in [5] with focus on proffering
ESP8266, Microcontroller solution to human error, processing error as well as electro-
mechanical errors while [6] aims at proposing a system that
I. INTRODUCTION will reduce the loss of power and revenue due to power thefts
Energy meters are used to measure the amount of energy and other illegal activities. It uses an AT89S52
consumed by domestic, commercial and sometimes industrial microcontroller which acts as the primary controller. The
users [1]. With the growing population of energy consumers, energy meter reading is compared with the smart card
smart meters are timely innovation which eases the energy information by the microcontroller for effective monitoring
management system. Utility companies can monitor and control of switching depending on the credit status.
consumption, automatically disconnect defaulting consumers, Bluetooth technology was employed in [7] where the meters
update tariff, and have a secured database and consumption were made to communicate with a master PC but all
pattern of a mapped location. The consumers on the other end communications were limited to within the 100-meter range
can also monitor their energy consumption in real-time, for Bluetooth connections. In [8], a digital signal processor
recharge their accounts, monitor tariff rates and hence based meter to measure electricity consumption of users in a
improves the demand response. Unfortunately, the energy residential area was presented exploring Power Line
sector is bedevilled by several challenges resulting from the Communication (PLC) technique. The limitation of this

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 IEEE Africon 2017 Proceedings

system is that it cannot detect tampering by consumers. IoT

technology was explored in [9], where each user was provided
a unique IP (Internet Protocol) address to enable access to the
Consumer Premises Equipment (CPE) which in this case is a
smart meter through a web interface. However, the “inefficient
handling of the IP address” as well as the latency that may
occur in communication between the CPE and the web
interfaces made it inefficient. A simplified design protocol and
robust Automated Meter Reading System (ARMS) was
developed to address the problems of complexity, multiple
incompatible standards and expensive design as presented in
[10].
In this work, a robust and scalable protocol in achieving a
seamless communication between the unique systems and
applications is proposed. A web application messaging
protocol (WAMP) is used to implement persistent and full-
duplex web socket connect, using JSON (JavaScript Object
Notation) data serialization for data exchange between the
embedded firmware and server. It provides an efficient and
cost effective solution by eliminating the need for dedicated IP
addresses for the individual CPE.
Fig. 1 Block diagram of an Internet Based Prepaid Energy Meter
III. SYSTEM ARCHITECTURE (IBPEM)
The main architecture of an Internet Based Prepaid Energy
Meter (IBPEM) can be classified into two main subsystems, B. SOFTWARE CONTROL EQUIPMENT
the hardware and software control interface as depicted in
Figure 1. This subsystem is made up of three key components; the web
server, client application and the embedded software.
A. HARDWARE SUBSYSTEM The web server is the unit responsible for managing, all
The hardware subsystem forms the CPE which provides the activities on the system. It is developed using mainly PHP
necessary interface for the power sensing circuit for programming language. The client application provides a
connecting the mains to the client’s home. This subsystem is means for the user to access the system from a remote location
coordinated by ESP8266 and Atmega328P microcontrollers over the Internet. It provides a Graphical User Interface (GUI)
both running on C/C++ written firmware. This subsystem for client’s operation to facilitate excellent user friendly
contains mainly the power measuring unit (PMU), processing experience. The web application is open-source using the
unit (PU) and the interfacing unit (IU). The PMU consists of HTML5 technology – HTML, PHP, JavaScript, CSS and
current sensing unit, voltage sensing unit and the computing MySQL. The embedded software is written in embedded
unit [11]. This unit computes the energy used over a period C/C++ language. This is to program the Atmega328P and
and sends it to the PU using serial communication link. The ESP8266 microcontrollers to make them function in a
PU is made up of the low power 32-bit CPU based ESP8266 regulated and controllable manner. The system firmware
WIFI module which is a complete system-on-chip (SoC) with flowchart is as presented in Fig 2.
an integrated 10-bit ADC, Integrated PLL, power management
units, Integrated TR switch, balun, LNA, power amplifier and C. COMMUNICATION INTERFACE
matching network and an Integrated TCP/IP protocol stack Communication between the two controllers is done using the
[12]. While the IU is made up of a screen, a relay and a power USART communication protocol while communication
control switch. The screen is an Organic Light Emitting Diode between the CPE and the server is implemented using
(OLED). The OLED is a flat light emitting technology, made Websocket communication protocol. Once a WebSocket
by placing a series of organic thin films between two connection is established, the connection stays open until the
conductors. It consumes low power, has higher image quality, client or server decides to close this connection. With this
simpler design and a better durability [13]. The screen open connection, the client or server can send a message at
displays the current tariff and the prepaid balance for a local any given time [14].
observer.

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D. WEB SERVICE SECURITY protocol which makes it compatible with ESP8266. With just
Traditional internet security techniques were employed in the 4 wire connection required, its Pin requirement is fewer than
applications as well as the communications between them. most other displays. The esp8266 NodeMCU provides
These includes authentication built into web application to activating signal to the relay, controls display and connectivity
ensure that no unauthorized user has access to the system. as stated earlier.
Also, the Websocket server requires an authentication before
communication can proceed between the server and the CPE.
The authentication parameters include a One Time Password
(OTP) which is generated during the connection.

E. DESIGN ANALYSIS
The whole device is designed in a modular structure. It is
made up of different modules or subsystems in order to allow
for good maintainability, and to ensure that the system is
scalable and interchangeable. The device uses a dual
controller unit. The first controller is an Arduino AT328p
micro-controller unit which is used for voltage and current
sensing as well as energy computations while the second
controller is an esp8266 NodeMCU. It serves as the main Fig. 2 Complete Circuit Diagram
controller unit of the system. It handles internet connectivity,
communication peripherals, connection to load, control
process, display system and general system utility and
functionalities. The two MCU’s communicate through a Serial
Peripheral Interface (SPI). The esp8266 is the brain of the
system and it features the following a 32-
bit RISC CPU: Tensilica Xtensa L106 running at 80 MHz, 64
KiB of instruction RAM, 96 KiB of data RAM External QSPI
flash: 512 KiB to 4 MiB* (up to 16 MiB is supported), Wi-Fi
802.11b/g/n, low power MCU, integrated 10 bit ADC,
integrated TCP/IP protocol stack, supports antenna diversity,
Wi-Fi 2.4 GHz, and supports WPA/WPA2, very low power
consumption, has a data transmission rate of about 110-
460800bps[12]. However it has only one analog pin and as
such will not be sufficient by itself to read voltage and current
which are both analog parameters. The Arduino UNO
provides for six (6) analog pins which made it a suitable
choice for voltage and current sensing. The voltage sensing
circuit is made up of a step down transformer, which steps
down the voltage and steps up the current following the
transformer formula. The current transformer on the other
hand is used to step down the line current which is then passed
through a burden resistor to convert it to a voltage level
measurable by the Arduino analog pins. To prevent negative
outputs of these two sensing units, their outputs are biased by
a D.C voltage and it is ensured that the outputs will always be
between 0 V and 5 V for all measurements within the device
Fig. 3 The main Embedded System Firmware Flowchart
specification. The project consists of a rectification circuit
which provides 5 V and up to 2000 mA to drive the relay, this
is used instead of the 5 V from the Arduino board because the
load will draw current up to 1A, which the board cannot IV. IMPLEMENTATION AND RESULTS
support. The display unit is made up of Organic Light The hardware components were mainly modular in nature and
Emitting Diode (OLED). It is a low power display as it does hence, the system was implemented unit by unit. The software
not have backlight. It supports Inter Integrated Circuit (I2C) components were implemented with some frameworks such as

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Laravel PHP framework, Ratchet PHP framework and twitter

bootstrap CSS framework. For the embedded system, open V. CONCLUSION
source repository such as Websocket, EEPROM and many The IBEPM is an improvement over the conventional prepaid
more libraries were used to ensure efficient and more compact meters; it uses the IoT technology in proffering solutions to
codes. The applications and services used are up and running the energy monitoring and management. Unlike the
and can be accessed via [http://meter.djade.net]. The Internet conventional prepaid meters, this solution offers a highly
Based Prepaid Energy Meter (IBEPM) was implemented with interactive GUI interface for both consumers and utility
very reliable individual components to ensure considerable companies. It also automates the energy system, as it relates to
level of redundancy. Use of Websocket and JSON based achieving a smart grid system. The system has been designed
communication will ensure very small data size and a very to resort to a local server and database, upon resumption of
compact message line with very little latency needed for real internet connection, all information are synchronized with the
time communication. Also, the small data size helps in saving web server. However, it is important to point out that for the
cost, bandwidth and memory space both on the cloud and purpose of this work, the billing is handled locally by the web
locally on the device. The constructed IBEPM is shown in Fig server and has not been interfaced with any online payment
3. The graph in Fig 4 shows the power consumed by a 2 watt platform agencies. Also further improvements could be made
LED lamp. The device was put on and off intermittently on the project to include load control on the consumer
which accounts for the spikes on the plot. The result shows platform for a high Demand Side Management (DSM).
that the system is accurate and very responsive to load change.
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Fig. 5 Graph of the Energy Reading from the Meter

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