Smart meters gateways must meet certain technical requirements in Germany. Some of the newly developed gateways have additional features that offer providers a competitive advantage...
As the communication unit, the smart meter gateway is the necessary precondition for systematic digitization of the distribution network. Thus, it is a central component of a successful “Energiewende” i.e. the German energy turnaround. In recent years, the metering and communication system was defined in elaborate consultations with trade associations under the auspices of the BMWi and the Federal Office for Information Security (BSI). The aim was to design a system that would satisfy Germany’s strict data protection standards, meet the requirements of the intelligent distribution network and fulfill various market roles.
Now the first smart meter gateways developed in compliance with regulatory requirements are ready for field testing. Utilities and manufacturers are using the newly developed prototypes currently in laboratory and field. For the first time, they have the chance to get a more concrete idea of the gateways that will be used in the coming smart meter rollouts.
These devices are designed according to the requirements of the Federal Office for Information Security (BSI), the Physikalisch-Technische Bundesanstalt (PTB) and the Forum Network Technology / Network Operation in the VDE (FNN).
The guidelines ensure that the equipment offers all of the below:
Safe transmission of data
An essential prerequisite for the success of an intelligent distribution networks is secure data transmission. This is ensured by means of the BSI protection profile and the technical guidelines. The smart meter gateway is located at the center of the BSI protection profile. A so-called gateway administrator is responsible for all processes on the gateway and controls these processes. Using the BSI specified WAN (Wide Area Network) interface, the gateway communicates with the gateway administrator. For security reasons, all communication links originate from the smart meter gateway. In order to be able to react to spontaneous events to the gateway, the gateway administrator can initiate a connection via a wake-up service. With the BSI certified protection profile Gateways, highly secure communications equipment for the entire smart grid is now available.
In order to increase energy efficiency and reduce CO2 emissions, the consumer must be given incentives to save energy. A crucial point is the visualization of consumption and current tariffs. In accordance with the technical directive, a freely accessible HAN (Home Area Network) port is required for the gateway so that an in-home display can be connected to it.
Switching producers and appliances
The technical directive sets out a CLS (Controllable-Local System) interface to perform switching operations for consumption and feeding systems for the gateway. The interface allows remote access to regulated generators (photo-voltaic systems, combined heat and power) and interruptible appliances (heat pumps, chargers for electric vehicles). The gateway cannot switch itself off through the CLS interface but forwards the commands via a transparent proxy channel to an external switching device.
Load and display time-dependent rates
As a technical requirement, the metering system requires a bidirectional communication connection and a corresponding set of tariffs. This is provided by the gateway, with its dynamic tariff profile compliant with the BSI’s technical guidelines. Communication and collective tariffs are processed by the gateway. Plans envisage time- and load-variable tariffs as well consumption variable and event-dependent rates. The latter enable utility companies to send a different tariff level to the gateway. Reasons may, for example, be weather changes that have relevance for PV feed-in systems.
Additional functions – an overview
The BSI requirements and the FNN specification sheet are interpreted as minimum requirements; i.e. manufacturers have the ability to integrate other functions. At the same time technical features such as power consumption and start-up times, aren’t fixed. Here, therefore, is the place where the key differences between the devices will be found.
Only gateways that have switching outputs fully support smart grid requirements. It is only through switching outputs that the gateway has direct access to feed-in and appliances, and executes the switch itself. Smart meters with switching outputs form the basis for technical production management. The distribution network study commissioned by BMWi shows how smart meters, due to the high security requirements, constitute the ideal technical realization of such a production management and are a crucial step towards reducing the cost of network expansion.
The only gateway which is currently offering this function is Landis+Gyr’s S560. It has four switching outputs, allowing, for example, throttling according to the four stages required by photo-voltaic systems. Alternatively, four appliances can be connected to the S 560 and controlled by it. The L+G S560 Smart Meter Gateway is thus itself an automation tool and allows load management or control of a CHP plant by the operator of a virtual power plant. Reading out and controlling the equipment is also required for the newly regulated direct marketing of renewable energy plants. Plant operators are not only required to directly market the energy produced, they can also choose transmit it to a service provider. Since the FNN has specified no control outputs and only minimum requirements have been defined, gateways with additional switching outputs are a matter of course. Due to regulatory delays, however, it can be assumed that the control boxes will only become available after 2016.
In the long term, the gateway will also be able to interpret data and react directly via the switching outputs. In this manner, the gateway becomes a decentralized switching unit with intelligent evaluation of the network status for the network management.
The faster a gateway boots up, the faster it is available again at power failures. Unbilled periods are considerably reduced. A further advantage is the reduction of installation time. During the installation of tens or hundreds of thousands of metering systems, this acceleration is a significant cost factor.
Low energy consumption
The energy consumption for the metering system is provided by the meter operator according to the metering system regulation. The “Bundesnetzagentur,” the German federal regulator for energy and telecommunications, will determine which level of energy consumption is acceptable. Suppliers must therefore use gateways that are below this specified energy consumption. Even now, the choice of a gateway which is economical as possible is recommended because energy use of the metering systems themselves accrues as operating costs for the meter operator. Another advantage: the lower the energy consumption, the lower the temperature development in the devices. A high temperature can cause the unit to fail and to shorten its life-span.
An additional wire-MBUS interface has the advantage that more MBUS devices (eg. gas or heat meters) can be connected. If it is applied as a wired interface, not just a local readout of the devices is possible; it also reduces the problem of radio penetration in basements and enhances the power of the connected device’s battery life.
Protected HAN interface
The BSI requires a HAN interface that is accessible to the end user so that he can turn on a display. A second - plumbed - HAN interface allows the network operator to connect equipment for power circuit in a protected area, without the consumer being able to access to it. Thus, the circuits can be performed safely in the red phase of the traffic light model BDEW.
Integrated mobile communications with LTE modem
The sooner a communication technology in the gateway is available, the sooner the gateway can be installed. It is assumed that about 50 percent of the units will work with the mobile communication network, as this will be the most widely used and most mature technology in the first phase of the rollout. Since LTE (Long Term Evolution) is the wireless technology of the future, an integrated LTE modem is crucial for the sustainability of the gateway. A gateway with LTE modem should also be backward compatible and support the 3G and 2G technologies so that users can utilize the gateway. all areas of the network areas.
Added value through additional features
It is already clear: The additional features, developed alongside the legally required ones, offer providers a competitive advantage. Fast boot-up times and maximum interfaces are not just little extras – they contribute to a large extent help to make the rollout as economical as possible and clear the way for the smart grid of the future.