Articles and whitepapers

digitalSTROM - Intelligent Automation over Powerline (4/1/2010)

By Lukas Widmer, digitalSTROM

Building automation has still a long way to go - just 5% of some 30 billion electrical devices in Europe are networked, and the vast majority consumes energy with no intelligence at all. Networking involves a lot of elaborate planning and extra expense, which means that the in the domestic sector, it is mainly the wealthy or technophiles who network their electrical devices.

Many people have reservations about home automation systems because they don't want to lose having simple control, such as turning a light on or off, and they may not like the fact that the nodes and central controller use additional electricity. There are however, new technologies such as digitalSTROM which combine convenience in the home with a reduction in energy consumption.

The main component of digitalSTROM is a chip that is smaller than your fingernail. This is installed directly inside electrical devices, and networks them via the existing power cabling in the home. digitalSTROM supports functions such as lighting and venetian blind control, automatic cut-off of certain devices and measurement of power consumption right down to individual device level.

The digitalSTROM chip measures 4x6mm. It is located at top right on the PCB.

Convenience

It's the same old story: as you leave home, you can't remember if you've switched everything off. Or you're sitting in an armchair, the film starts, and so now all of the lamps in the room should be dimmed. With digitalSTROM, this simply involves a push of a button. Programmed lighting moods for the entire room can be selected from any of the lamps. And when you leave the house, all electrical devices can be switched off using an 'Everything-off' button, including the coffee machine and the TV which would otherwise carry on consuming electricity in standby. Of course, the freezer and the aquarium pump stay switched on.

Unlike other technologies, digitalSTROM-ready devices can also be operated conventionally. A light can still be switched on and off by pushing a button as usual. It takes a multiple click to open up the world of scene configurations. Familiar analogies are adopted: an energy display, which can be plugged into any socket, shows normal, raised and above-average power consumption in green, amber and red, like a traffic light. The fact that devices are individually identifiable and can communicate with one another opens up far-reaching options. For example, the light in an apartment can flash when the doorbell is rung, an invaluable benefit for people with impaired hearing. In fact any number of such functions can be supported.

The energy display, which can be used in any socket, shows the current power consumption.

The high-voltage chip

The core technology of digitalSTROM comprises the 4x6mm high-voltage chip, which is directly connected to the mains voltage. This can be installed by manufacturers in their appliances, or it can be retrofitted. Its dimensions make it around 50 times smaller than conventional solutions, and it consumes 10 to 30 times less energy than previous systems. Despite its small size, the chip combines over 40 functions: processor, sensor control, leading and trailing edge dimmers, over-voltage protection, energy metering, automatic switch-on and switch-off, overload protection and modem to name but a few. Optionally the chip can be complemented by a 230V power output stage to dim lights for example.

Each chip has a unique number similar to a barcode. This enables the relevant electrical devices to be controlled separately and to communicate with one another. In principle, this is feasible for every power-consuming device, be it a lamp, the blinds or the hi-fi system.

The high-voltage chip turns individual power-gobbling instruments into an orchestra that can be conducted. The power consumption is now visible and measurable, down to the device level. For example, a defective device which consumes too much power, can be identified easily and quickly. Money can also be saved if the refrigerator cools while electricity is cheap, by responding to a message sent by the power station via the Internet. Applied on a larger scale, the technology can facilitate greater use of energy from renewable sources.

digitalSTROM is not a remote control or monitoring system - the user always has total control over the data. It is the user who determines what should be visible beyond the power circuit of their home and whether their devices are to respond to external communications. It is also possible to operate a digitalSTROM installation without any connection to the Internet. The signals transmitted within the power circuit are also hacker-proof.

Installation

The basis of any digitalSTROM installation is a room and a power circuit. For the devices to be able to communicate with one another, a digitalSTROM meter (dSM) is installed next to the automatic circuit-breaker in the electrical fuse box. In turn, multiple digitalSTROM meters can communicate with one another via a standardised protocol, and they also facilitate communication with a digitalSTROM server (dSS), which, also mounted on the DIN rail, permits connection to the Internet.

digitalSTROM connects each electrical device via the house or apartment power network, and also connects to the Internet if desired.

The mode of communication differs from that of conventional powerline communication (frequency overlapping method). digitalSTROM is digital communication close to the zero passage of the sine wave of alternating current, with simultaneous output blockage.

One digitalSTROM meter is installed in the DIN rail per power circuit.

Installation of digitalSTROM is simple: the electrician installs one digitalSTROM meter per room and, if more extensive functions are desired, a digitalSTROM server on the DIN rail. Conventional light sensors are equipped with a digitalSTROM chip in a lustre terminal, as are lamps or blinds, which are not digitalSTROM-ready when they leave the factory. There is a colour code for terminals and associated functions, so that all devices following the same colour in a power circuit obey the corresponding commands.

The chip on its PCB fits into the housing of a lustre terminal.

digitalSTROM operation is based on statements such as 'It is too dark', 'It is too hot' or 'I am leaving the apartment'. An appropriate response to these conditions is allocated to the individual devices. The basic functions are designed for 'plug and play' so that a new device can be used immediately after it has been plugged in. Individual programming can be done either by calling up the programming mode via a conventional push button, or via a computer connected to the digitalSTROM server via TCP/IP.

No new wiring is required since digitalSTROM is based entirely on existing power lines. This saves planning and material costs in new builds, and low-cost retrofitting in existing residences since there is no need to open up walls etc. Subsequently, any number of new devices can be integrated in the system without any installation and reprogramming costs. Computer programs will be available for programming, which are simple enough for anyone to operate and do not require any programming skills, and since the server software is available as an open source solution, a large number of programs are expected to be developed.

A German-Swiss development

digitalSTROM combines convenience, safety and energy-conservation with a low-cost OEM and retrofittable solution. It was developed by chip designer Wilfried Beck and the architect and computer scientist Ludger Hovestadt, professor at the Swiss Federal Institute of Technology in Zurich (ETH). Together they founded aizo, a company based in Wetzlar and Zurich, which develops the chip and will be selling it from summer 2010. To ensure that digitalSTROM becomes a standard, a non-profit organisation, digitalSTROM.org has been founded under the patronage of ETH Zurich. This brings together installation engineers, industry, power supply companies and developers. The first products of the digitalSTROM.org members are expected from autumn 2010.

Lukas Widmer is Head of Communications for the digitalSTROM.org. This is responsible for technological development, certification of products, and definition of hardware and software standards, as well as providing a forum for its members.

www.digitalstrom.org