Saturday, 23 August 2014
The sky-rocketing cost of energy production has necessitated a more efficient energy consumption process. This has brought revolution in electrical equipment manufacturing and energy metering infrastructure. Home area network (HAN) is an advanced electrical ecosystem in which a smart utility meter and HAN devices communicate with each other to control the energy consumption profile. Armed with the latest technological advancements in the field of energy utilization, HANs are ready to supplant the traditional electrical ecosystems at home.
|Fig. 1: Application diagram of HAN device|
A basic HAN device has a two-way communication link with a utility meter and optionally with other devices in a HAN ecosystem, sharing energy consumption data of the equipment it is connected to and also receiving commands to turn off or hibernate the equipment when unused.
This low-cost device can be hooked in the existing electrical infrastructure without the need to replace, renovate, alter or rework the infrastructure. The power consumption is very low (in micro amperes) when it’s not in use. The following sections describe certain enhancements to the basic HAN device architecture which extend its capability and feature-set.
The HAN device can be considered as an intelligent power socket, which at one end connects to the normal power socket and on the other end offers pluggable connection interface for home appliances, e.g., microwave and air-conditioner. It can be controlled directly by the utility meter over wireless interfaces like radio frequency (RF) or wired interfaces like power line communication (home plug, etc). Additionally, its firmware can be upgraded over the RF/programmable logic controller (PLC) interface by the utility meter. Various energy parameters of the device can be displayed on the LCD. It also supports battery backup option for maintaining the time and date.
Fig. 1 shows the application diagram of the HAN device. The device consists of a microcontroller, 230V-3.3V converter, relay, signal conditioning circuitry, infrared (IR) interface (supporting both transmitter and receiver), LCD panel and RF/power-line communication physical layer.
Its main operational features are:
- Very low current consumption (10 μA) when it’s not functional
- Very low run current (10 mA); 40 mA at full load
- Fully controlled by the energy meter
- High-voltage cut-off to save the appliances
- Wireless communication over 2.4GHz Zigbee
- Month-wise information storage of the power consumed
- Fully-functional system starting from 90V AC to 300V AC
- Easy to hook on to the network
- Compact in size
Role of various components
Fig. 2 shows the block diagram of the device components. The role of these components is described below:
Microcontroller. The microcontroller or system-on-a-chip (SoC) plays a pivotal role in the device operation. In addition to controlling other components, it stores the application firmware in its internal Flash memory. For supporting various functionalities of the HAN device, the microcontroller should be equipped with the following features:
- Low-power processing core with the capability to perform complex arithmetic operations required for energy calculation
- Suitable physical-layer communication interface for RF or power-line communication, if used
- On-chip Flash memory and static random-access memory for storing application firmware and faster operation
- LCD driver for LCD display
- Interfaces like universal asynchronous receiver/transmitter, which can support infrared communication
- High-resolution analogue-to-digital converters (ADCs) with programmable gain amplifier for voltage and current measurements
- Input/output (I/O) ports for driving relays
- Real-time counter for time keepingThe microcontroller senses the voltage and current through the signal conditioning circuit along with the ADC and programmable gain amplifier to calculate root mean square (RMS) voltage and current values, instantaneous energy consumed and total energy consumed over a period of time (one month or longer). It then sends this data to the utility meter through RF or power line communication and also displays it on the LCD. When a command to turn off the device is received, it drives suitable logic on its I/O ports to operate the relay.
The microcontroller gets its power supply from the power line through a 230V-3.3V converter. The converter can be suitably configured according to the operating voltage of the microcontroller. The on-chip Flash firmware can be updated over the RF or PLC interface by the utility meter. The protocol and exact details of firmware updation depend on specific implementations.
|Fig: 2: Block diagram of HAN device|
Signal conditioning. The signal conditioning unit consists of an analogue front-end for voltage and current measurement. The line voltage is measured by first down-size in it with a resistor ladder, thereafter direct-current (DC) filtering and DC biasing.
Compared to voltage measurement, current measurement is less involved. First, the line current is downsized using a current transformer and then passed through a small value of high-precision shunt resistor. The voltage drop across this shunt resistor gives a measure of the line current. As this voltage drop is very small, it is suitably amplified before being fed to the ADC.
The amplifier consists of programmable gain stages for amplification of only the alternating-current (AC) components, thus preventing the amplifier output from saturation.
Infrared interface. The infrared interface can be configured suitably according to the range and power consumption. It provides remote configuration support for the HAN device, enabling the user to remotely turn on/off the home appliance connected to the HAN device. The protocol and exact details of operation can be flexibly chosen for particular implementations.
LCD panel. The LCD panel displays the instantaneous energy consumed, total energy consumed last/current month, date and time of the day, RMS voltage and RMS current. It inherits some of the utility meter display, thus acting as a low-accuracy but smart AC energy meter.
In a nutshell, the above architecture conceptualizes a cost-effective and extremely versatile HAN device, which is replete with all the essential HAN device features along with the support for advanced features like firmware upgrade and full control of appliances over RF/PLC interface. It also doubles as a low-cost smart AC energy meter, providing round-the-clock energy consumption details of the home appliance.
Though the device is depicted here as a standalone intelligent power socket, it can also be implemented inside home appliances.
Dept. of EEE
Rajeev Gandhi Memorial College of Engineering and Technology, Nandyal
|Rajeev Gandhi Memorial College of Engineering and Technology, Nandyal|
Today, banks have realized that their next huge customer base is not in the urban setting but in the often-neglected rural areas. However, reaching this customer base is not so easy, primarily because the rural areas are not as infrastructure-rich as their urban counterparts. Simple tasks like going to the ATM and withdrawing money make people miss their working hours and, as a result, lose a significant part of their income as well.
To counter this problem, YES Bank has come up with an innovative technology called YES Sahaj micro ATM, worked upon by the team of Ajay C. Desai, Vaibhav Peshney, Sushanta Tripathy, Rupesh Kumar and Amulya Bisht—all working with the Development Banking section of YES Bank.
What is the need for a micro-ATM?
YES Sahaj micro ATM is a doorstep mobile banking solution-cum-mobile ATM device for the under-banked and unbanked population base. As other similar point-of-sale (POS)-based services are also available, what sets the YES Sahaj solution apart? Sushanta, vice-president, YES Bank, explains, “YES Sahaj is a mobile banking facility for the needy customers. As you have mentioned, there are other formats like biometric POS devices which provide similar services and are easily available in the market. What differentiates YES Sahaj in the sector is that its total life-cycle cost is significantly lower than the other products in the market which are very costly due to their high capex and opex costs.”
When asked about what prompted them to think about such a solution, Ajay Desai, president, YES Bank, shares, “YES Sahaj micro ATM was developed as a response to some ‘felt need’ of internal and external stake-holders. The next billion customer base, which is the target segment, can’t leave their business premises for banking transactions. YES Sahaj provides them with the convenience of the ‘doorstep banking’ services both within and beyond the normal banking hours. For customers, it provides the bare necessity of the doorstep banking, saving their wage loss to the tune of Rs 150 to 200 per bank branch visit. Cumulatively, this results in savings of around Rs 30 million to the customers.”
The technology behind YES Sahaj is a combination of two very simple devices, viz, a low-power bluetooth printer and a low-cost mobile communication device, that have been interfaced to develop a full-blown ATM. The system consists of a specially programmed mobile handset connected to the central server using GPRS connectivity, and a hand-held thermal printer that automatically prints receipts as and when triggered by the server.
Since the device is targeted at rural areas where lack of adequate infrastructure is a prime issue, the ability to work with low power is of prime importance. A thermal printer is used here because it is much more suitable for portable applications than ink-based printers.
Thermal printers work by heating a thermochromic paper that makes the heated areas on the paper turn black. Thermochromic paper, as the name suggests, is sensitive to temperature changes and shows the effect by visual blackening of the affected areas. Use of no ink eliminates the risk of spillage and also makes the equipment lighter. Most importantly, thermal printers use far less power than other conventional printers. Bluetooth technology implemented in the printer functions in power saving mode while providing a secure means of communication with the mobile handset.
Working of the system can be described as follows: First, YES Bank Ltd (YBL) shares the customer’s details including his account balance for the day. Following this, the business correspondent agent (BC agent) enters his login request through the mobile device. On successful BC login, the customer is asked to provide his debit card to swipe through the card slot in the Bluetooth printer. A debit card validation request is sent to the UPASS server. Upon successful validation, one-time password (OTP) and withdrawal details are sent to the customer’s registered mobile number. Else, an error message is displayed on the mobile screen.
OTPs are used because these are invulnerable to the drawbacks of static passwords where a hacker can make use of the password to access the account. This is of high significance in a rural setting where the users might not be tech savvy to understand the importance of keeping a password secure.
The OTP generated is shared with the BC agent and entered through the mobile device. Next, the OTP validation request is sent to UPASS backend server. After successful validation, the amount to be withdrawn is entered through the mobile device, and the mapping and validation are done at the UPASS backend server.
Finally, a transaction receipt command is sent to the mobile device. The receipt is printed through the thermal printer, and the cash as well as transaction receipt are handed over to the customer. The transaction is concluded with a confirmation SMS sent to the customer, and End of Day data is shared by the BC with YES Bank for the customer’s account updation.
The team faced its share of difficulties while creating such an innovative solution.
Vaibhav Peshney, regional financial inclusion leader, YES Bank, shares some of the challenges, “The major challenge was to develop the system from a normal collection device to a mobile banking product. Customization of the back-end servers and the front-end interface was a major task. Even for some of us who had been working in this sector for a considerable number of years, understanding the exact need of the target customer was again a challenge. In fact, these challenges only pushed us to think frugal and come up with our very own Frugal Innovation for Financial Inclusion (FI4FI) programme; YES Sahaj is one such innovation under this initiative.”
Rupesh Kumar, financial inclusion leader, adds, “For the initial workable collection module, it took only four months time for a basic product as cable collection device to be in place. The credit goes to both the teams for their dedicated efforts. We had to customize the product for banking requirements and standards and then train their back-end team to deal with the banking standards. After that, it has been continuous research and development which has helped in adding new features from time to time.”
Future expansion plans
Financial inclusion is an evolving sector. Customizing the product to the needs of the customers is a learning experience for all the players in this field. Amulya Bisht, associate, cites the example of YES Sahaj micro ATM, “YES Bank itself has gone through many phases of development to come out from a mere field collection device to a withdrawal and deposit platform and now to a complete doorstep micro-ATM-cum-teller. In coming days, many new features, including a more secure transaction mode, along with product customization to address other standard banking products like over- draft facility, will be added to it.”
The standalone services for micro ATM will be charged on a per-transaction basis. This amount will be very small as compared to the wage loss incurred by customers in visiting the banking premises.
Dept. of ECE
Rajeev Gandhi Memorial College of Engineering and Technology
|Rajeev Gandhi Memorial College of Engineering and Technology|