Development of smart energy meter using ARM platform
Author: Darijo Topić
Subject: Advanced Programmable Electronic Systems
Mentor: assoc. prof. Matej Rojc, PhD
Degree: 2
Date: 2018
DKUM: DARIJO TOPIĆ
This master thesis describes the development of smart electricity energy meter on the ARM platform. In general, the commercial electrical energy meters are measuring only the total active energy, therefore, users cannot also monitor other important power consumption parameters. The goal of this thesis is to develop a prototype of smart ARM based energy meter, which is capable to measure several power consumption parameters and display them on a webpage in real-time.
This master thesis describes the development of smart electricity energy meter on the ARM platform. In general, the commercial electrical energy meters are measuring only the total active energy, therefore, users cannot also monitor other important power consumption parameters. The goal of this thesis is to develop a prototype of smart ARM based energy meter, which is capable to measure several power consumption parameters and display them on a webpage in real-time. In the thesis the complete design of the ARM based smart energy meter is presented in detail. Further, the development of user interface for displaying measured data on the webpage in real-time is also presented. These results are presented both in textual and graphical form. Additionally, the theory of electric power consumption measurements and some commercial energy meters are presented.
The core of the proposed system is an ARM microcontroller that collects data from a power metering module, which otherwise measures all power consumption parameters. The main task of an ARM microcontroller is to process the parameters and send them via the WIFI module. Additionally, an LCD can be added to the system to display data, while an SD card can be used as memory for the data. Further requirements are that the ARM microcontroller has a low power consumption, a low cost and a powerful enough power to perform all the intended functions. The ARM Cortex microcontroller series is the most popular and best choice for the proposed energy meter. An isolator must be used between the microcontroller and the power meter to create galvanic separation. Namely, if there is an error during the energy measurement, the electricity measurement module must be separated from other electronic components in order to protect the components and the user. In addition, it is easier and cheaper to replace only the damaged component than the entire platform.
The electricity metering module is the module we need to measure the power consumption parameters. This module collects data through a current sensor and a power supply (230 V). The flow sensor is an important part of the energy measurement module as it is indirectly responsible for reading the current value. It is available in several versions, such as. shunt resistor, current transformer or Rogowski coil. The third component we need in the system is the WIFI module, which must send the data to a website for further data analysis. There are many WIFI modules nowadays also due to the rapid development of IoT solutions. The main requirements for choosing a WIFI module are in our case the cost and flexible integration with the selected ARM microcontroller.
A smart power meter was performed on a two-sided PCB circuit using SMD components. The dimensions of the capacitors and resistors are the same as those in the 0805 series. Namely, it is better to solder systematically and gradually and before continuing to check for defects. The one-step soldering approach is not recommended because there is always a risk of damage to all components on the PCB in the event of a fault. During the soldering process, the presence of a short circuit was also checked using a multimeter. Emoncms is an open source web application used for processing, logging and visualizing energy, temperature and other data in the environment and is part of the OpenEnergyMonitor project. It can be configured through a graphical user interface that can include many graphs and rows. Received data is also stored in the database of the website so that all received data can be viewed.
The proposed smart energy meter can monitor the consumption of all electrical household appliances in real time. In the testing phase, we first set up a test environment that actually simulated a home electrical network. The power source was a standard 230 Vl outlet. The voltage was brought to a separate PCB circuit where the voltage was converted to 9 V. This was also the voltage at the ADE7953 input on the main PCB circuit. The current was brought to the current input ADE7953 via a current transformer. The main objective of the testing was to compare the proposed smart energy meter with the aforementioned HIKING DDS238-2 SW meter. If the smart energy meter is properly calibrated, the readings on both meters should also be close enough. We carried out measurements for four different load configurations. We measured the energy consumption of each device and the energy consumption at all loads. The measurements were made for different energy consumption (different electricity consumption and current). The results of the proposed Smart Energy Meter prototype show very small variations. It means that the calibration has been performed properly and that the energy meter is ready for use.
Discussion and results
