Power Management
Smart energy needs smart component solutions
Smart energy management will need smart component solutions but, as Steve Drumm explains, these will need to be safe, reliable and effective
S
mart meters and smart energy management will require smart component solutions. The challenge for the smart meter designer is to ensure that the new smart meter is inherently safe, reliable and provides effective, efficient energy management.
The new generation of smart meters will employ state of the art, low power electronics to provide a greater level of intelligence and functionality within the meter. Utility companies will require reliable, low maintenance and long-life meters and they will typically need to offer a ‘fit and forget’ operating lifetime of 30years.
As distributed power generation sources such as solar, wind and other renewables gain greater usage with industrial, commercial and residential users the smart energy grid will also need to evolve. The smart meter will become an integrated part of the networked or intelligent home. A domestic energy management resource will consist of a smart meter, a ‘home area network’ to communicate between devices in the homes and a ‘wide area network’ communications to provide data to the supplier. Europe currently has 240m electricity meters in use today: most of which are expected to be replaced by smart meters by 2020. It is estimated that approximately 78m of these meters will need to use AC latching and power relays to manage the supply and measurement of electricity to the user. Switching solutions and components specifically designed for this applications market are emerging, including electro-mechanical relays, connectors, switches and sensor components.
Switching relays A lot of effort is being made by manufacturers to improve the efficiency of relays where the key characteristics of switching capacity, switching endurance, coil type, load isolation and physical construction can have a notable impact on the overall energy efficiency. New products
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are also being introduced to address the characteristics of new classes of applications that are emerging from the drive for smart energy use. Supply service control relays will be
required to manage the supply of electricity in smart meters and utility companies will want to control the ability to connect or disconnect the AC supply to the smart meter by PLC or by wireless M2M communication such as SMS, GSM or LW. Switching relays will therefore play a
central role of efficient energy management in the smart meter, ensuring that all of, or part of the system is fully powered down and consuming no energy when not in use. A latching, single pole electro-mechanical relay with a maximum current rating of up to 120A at 250V AC would meet the needs of a smart meter employed in a commercial, residential or light industrial environment.
Local energy management As the volume introduction of the smart meter and the intelligent networked home draws nearer the ability to provide local control for AC power outlets via USB, wireless or remote control increases. Highly compact switching relays will be required to provide switching performance for a variety of loads and will need to be able to withstand impulse rating of 10kV between the coil and contacts. Ripple Control (RC) or local load control is a technology used to control and provide quick and direct influence on the network load without any network limitations. Tariff switching and monthly demand reset can be implemented along with the control of storage and direct control heaters. Ripple control receivers can be implemented directly within the smart electricity meter. The RC receiver will respond to RC control signals transmitted on the electricity grid by a load control centre. Innovations in relays for domestic ripple
control receivers include the use of silver- tin-indium (Ag-Sn-In) contacts, which can deliver double the standard switching performance.
Components in Electronics
The smart meter will also need to ensure tamper proof operation. If the meter is subject to tampering this must be detected and acted upon. The meter should have the ability to safely and securely disconnect the AC supply. Sub-miniature switches such as the D2F from Omron, features dimensions of 12.8mm (w) x 6.5mm (h) x 5.8mm (d), and can provide dependable anti-tamper detection by being used as ‘open cover’ detectors. The switches incorporate roller or hinge lever and pin plunger actuators which are ideal for detecting unauthorised opening. These insertion moulded PCB mounted switches incorporate a snapping mechanism made with two highly precise spilt springs which will ensure a long and reliable service lifetime.
The snap-action D2MQ ultra sub-
miniature switch provides even more compact mechanical dimensions 6.5mm (h) 8.2mm (w) 2.7mm (d) and a weight of only 0.3g. Featuring gold plated (Au-P) contacts for micro load switching the D2MQ is ideal for smart metering applications where size is extremely limited and high reliability is paramount. To ensure the reliability and consistent operation of the smart meter, internal sub systems of the smart meter will interface with each other via thin, flexible FPC (flat printed circuit) cables. FPC connectors feature a secure rotary ‘back lock’ latch mechanism that does not release if the FPC is lifted or excess force is applied to the latching mechanism. The twist resistant design does however allow the FPC to be easily and safely removed in all directions after the locking mechanism has been released.
Sensor solutions
The smart gas meter will also require sensor solutions to accurately detect and monitor the flow and usage of gas. Precision MEMS mass flow sensors now include new compact models that are capable of measuring mass flow velocity and mass flow rate movement with highly repeatable accuracy. Omron’s D6F is, for example, a MEMs flow sensor chip that can accurately detect the mass flow rates from 10 to 50litres/minute. Compact dimensions of 30mm (d) x 78mm (w) x 30mm (h) lend themselves to smart metering applications. Each sensor allows precise detection of
mass flows with a resolution of 0.5cm/second and an accuracy of +/-3% full scale deflection. The D6F uses underside gas entry and exit via 5mm integral channels. When mounted horizontally with suitable “O” rings this maximises precision and ensures stable and repeatable results.
The high sensitivity of the D6F sensors is achieved using a MEMS flow chip. Measuring only 1.5mm” x 0.5mm thick, the chip incorporates two thermopiles and a miniature heater element. The two thermopiles are used to measure heat symmetry deviations caused by the passing gas flow. A thin layer of insulating film protects the sensor chip from exposure to gas. When there is no gas flow, the temperature distribution concentrated around the heater is uniform. When a gas flow is subjected, the temperature on the side of the heater facing the flow cools and the side away from the flow warms up (heat symmetry collapses). This difference of temperature appears as a difference in the thermopile’s electromotive force, from which the mass flow velocity and mass flow rate can be measured. Utilising double chip patented design this flow technology is now being offered as a standard and custom OEM sensor module with gas channel architecture, signal conditioning driver circuit and termination to enable high accuracy and repeatable performance for smart metering applications.
The design and implementation of smart meters and new energy management systems needs to provide the consumer with tangible benefits and that will reduce energy consumption and give cost savings. Additional features can also be implemented to give the user greater control and knowledge of his energy consumption. The technology, systems and
component technology is now available to produce smart energy management systems and smart meters. The component solutions used will need to ensure the new smart meter provides safe, fault free operation and is inherently reliable.
Omron Electronic Components |
www.omron.eu
Steve Drumm is Market Development Manager at Omron Electronic Components Europe
www.cieonline.co.uk
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