Optimizing Storage and Energy Use in an Autonomous Home Using NI Single-Board RIO

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"Because it is compact and has a powerful processor and high memory, the NI Single-Board RIO device easily integrated with the existing electrical installations to play a large role in the autonomous home management."

- Jean-Luc AMALBERTI, Pierre CANAT, David FREY, IUT1 de Grenoble

The Challenge:
Interfacing energy storage devices with a communication network for precise control of energy use in the “Canopea” house, winner of the Solar Decathlon Europe 2012 challenge.

The Solution:
Using an NI Single-Board RIO device to ensure communication between storage devices and other equipment in the house.

Jean-Luc AMALBERTI, Pierre CANAT, David FREY - IUT1 de Grenoble

The Solar Decathlon Europe challenge is an international competition for 18 teams from 11 countries to design and build a solar home that decreases energy use. The teams met in September 2012 in Madrid to compete in 10 events, including architecture and energy efficiency.

Our team, Rhône Alpes, in association with architecture schools in Grenoble and Lyon, ENSE3, research laboratories and industrial partners, the IUT 1 of Grenoble, and the Department of Electrical Engineering, actively participated in this contest. We created the intelligent energy management of the building. The home is on display in Madrid and open to the public.

Energetically Optimized and Automated Home

The level of housing is an apartment of 75 square meters. The roof is made with 100 square meters of photovoltaic module bi-glasses that let in some filtered daylight but capture almost all of the solar energy, hence the name Canopea (from canopy).

LED lighting can enhance the exterior architecture of the building, whereas consumption optimization of interior lighting and precise management of energy provide low power consumption.

During peak hours, the house can become autonomous and does not need the network power. In case of power failure, the house can autonomously operate for 48 hours. The fully automated system is controlled by an iPad, and the system comes with instructions to generate energy-saving functions.

Home Energy Management

A Studer Innotec inverter charger performs the energy management. This reversible inverter features an off-line to connect consumers and photovoltaic generators with the AC output OUT. The inverter charger is reversible and can recharge both via the network (AC IN) and by the photovoltaic (AC OUT) by adapting the rates and hours of operation desired. In degraded mode, it also provides a fictitious voltage for the operation of photovoltaic inverters and the use of solar panels to power the house.

A rechargeable LiFePO4 battery management system (BMS) offers the smoothing of consumption by erasing peak hours usage and providing autonomy in degraded mode when the house is isolated from the network.

NI Single-Board RIO Links Heterogeneous Devices

All household equipment communicates via Modbus Ethernet. However, the two cores for power management—the inverter charger on one side and the battery and its BMS on the other—do not have a suitable communication protocol. The inverter charger uses a proprietary serial protocol, and the BMS includes an analog output to represent the charge of the battery.

To ensure communication between these devices, we used an NI sbRIO-9632 embedded control and acquisition device and its serial port to communicate with the inverter charger. We can retrieve information from it by generating the appropriate frames and storing them on the memory card. We set up a Modbus TCP server on the NI Single-Board RIO device so that other devices can access this data. The LabVIEW Modbus over TCP functions greatly simplified program development as well as helped us control the inverter charger and reset the card.

When we developed the BMS, we used the NI Single-Board RIO device to determine the charge of the battery through its analog inputs. This led to an interface with the BMS and the charger inverter, and ensures the safety of the battery.

Embedded Control Element

Unlike in an industrial automated system, we did not have robots in which to store the intelligent part of the house. Because it is compact and has a powerful processor and high memory, the NI Single-Board RIO device easily integrated with the existing electrical installations to play a large role in the autonomous home management.

Ultimately, the NI Single-Board RIO device provided storage and the provision of key electrical magnitudes from the battery and the inverter charger. It also gave us the calculation of the charge and discharge of the battery and, thus, the control of the inverter charger. With the device, the system received control commands from the human machine interface (HMI) to impact the different equipment. Finally, it improved the implementation strategies inherent in the management of electrical energy to optimize available electrical energy and minimize the use of distribution networks of electric energy.

First Place Overall

Our “Canopea” home competed against 17 other projects from around the world. It received a first place overall award in the 10 trials during which the candidates were evaluated and ranked on the operation aspects of the house, including comfort, innovation, and architecture.

Author Information:
Jean-Luc AMALBERTI, Pierre CANAT, David FREY
IUT1 de Grenoble
151, rue de la Papeterie
38400 Saint-Martin-d'Hères

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