PLC on vacation

How industrially proven control technology optimizes the energy consumption of a premium holiday village in Carinthia.

The holiday village Moserhof lies in the middle of the marvelous landscape of the Carinthia Möll valley. Nine quaint, fully equipped wooden houses, a small chapel in the village square, a spa cottage with extensive spa area and a pond form the idyllic setting of the holiday paradise on the banks of the River Möll which is near to the farm and stables of the Moserhof itself. The guests shall want for nothing – however the owners Gerhild and Heinz Hartweger pay particular attention to a sustainable, resource efficient handling of the environment. And this includes the efficient use of thermal and electrical energy. The local specialist for automation engineering Nikolaus Hartweger has realized a clever energy optimizing system based on VIPA control technology and Profibus communication – which has delivered demonstrable success. 

Vacation on a farm, at a a riding stable and in an exclusive alpine village with four star comfort – this and much more is offered at Moserhof in the community Penk/ Carinthia near High Tauern National Park. Whether hiking, climbing, mountain cycling, alpine riding or skiing - various leisure time activities are offered for each season.  Gerhild and Heinz Hartweger took over the parental farm with dairy cows and agriculture and set up the first guest rooms. Later, the riding hall was added. A large fire destroyed the entire property a few years ago. Mr. and Mrs. Hartweger not only succeded in rebuilding the manor house and the riding school, they also realized a dream - they built a premium holiday village for families. This includes six solid wooden houses and three historical alpine cabins, which were taken down elsewhere and rebuilt in Moserhof. The individual houses have bedrooms, living room, kitchen and bathroom, which, despite the rustic charm, are exclusively equipped (incl. flat screen SAT-TV) for up to eight persons. The bath house with a Finnish sauna, herbal sauna, infrared cabin, panorama relaxation room, fireplace, herbal and tea bar as well as a bathing room for different bathing treatments turns out to be a real spa oasis in the middle of the village. A barefoot path made of wood, stones and herbs leads directly from the spa area to the river bank of the river Möll, where there is a small bathing pond.

Energy control from the tablet PC

Whether a guest wishes to visit the sauna outside the regular opening times, or someone hadn’t turned the light off in the riding stable, or one of the village houses has to be heated – all this can easily be managed from the office computer in the farmhouse or via mobile Tablet PC and smartphone. “This is very convenient”, says Heinz Hartweger. “Previously I always had to go into the bath house to turn on the sauna – now I do this from my dining table”. The remote control capability is only one convenient aspect of the installed energy optimizing system, which his cousin Nikolaus Hartwenger “had persuaded him to have”, as the owner says jokingly, and he was initially very skeptical about it. “I am not a fan of computer and other electronics – but this solution saves me money”. With this he spoke about the main benefit of the system, namely the permanent energy control and optimization. Nikolaus Hartwenger has been self-employed for about 10 years and had already implemented numerous electronic and automation projects. “In my opinion the most important requirement of energy optimization – whether in the area of building or industry – is to control everything form one central processor. Only when all the data of the whole periphery is collected and managed by a common intelligence, is the optimization potential fully realized.” The success of the project proves him right. Since his energy optimizing system has been running at Moserhof, the total power consumption has reduced, so the power input of 55 kW as contracted with KELAG – the Carinthia power company – was not exceeded once. So, there haven’t been any additional costs for electricity due to short-term peak loads. Heinz Hartweger, head of Moserhof, even expects to reduce the power input and so downgrade the rate with KELAG.

The control engineering at the holiday village

The industrially approved SPEED7 CPU from VIPA 315-2AG12 operates as the control engineering heart of the energy optimizing system. “I almost always use VIPA controllers and periphery units”, Nikolaus Hartweger said. “Here the price-performance ratio, the quality, and above all the support of VIPA Elektronik Systeme in Vienna are perfect. The SPEED7 CPUs are faster than comparable products and have functions on board as a standard that you only receive as an option anywhere else. This simply enables more flexibility in project planning.” The PLC receives, via Profibus, the latest energy data of the main power supply with three phase currents from the network analyzer unit manufactured by Janitza. All decentralized “VIPA 200V” I/O stations distributed at Moserhof are also connected to the central controller via Profibus. Currently, besides parts of the main house and the central woodchips heater, the stables, the workshop and the bathhouse are connected to the energy optimizing system. “one cottage after another is connected in succession”, Nikolaus Hartweger explained. Lighting, heating including warm water preparation, air conditioning and the individual sauna stoves are controlled – even the sockets in the bath house are integrated into the concept. “So this ensures that the tea maker doesn’t run all night”, the automation expert said as an example. Another special feature of his concept is that Nikolaus Hartweger deploys the battery free remote switches from EnOcean instead of the usual light switch. “I am fascinated by the used Energy Harvesting technology. The user does not need to worry about batteries that, with other wireless solutions, have to be exchanged at some point, because it does not exist here. The EnOcean reception modules can easily be coupled with the VIPA I/O modules.”

The process of optimization

Nikolaus Hartweger programs the energy optimizing system with Step7 from Siemens, the whole application runs on the VIPA CPU. “The compatibility with the Siemens world makes the VIPA controllers so practical.” The controller collects all energy values and calculates from this the current total energy consumption. Consumers are specifically disconnected as soon as the value reaches the limit value of the connected power. “The measuring interval is 15 minutes at KELAG. If a consumption peak is reached within this time it will be charged. I have created an index, a kind of priority list. On basis of this list the controller manages the power supply of the individual participant so that within a 15 minutes interval no load peaks ever occur”, Nikolaus Hartweger explained the functional principle. “it doesn’t matter at all if, for example, the heater in the sauna is switched off for three minutes. The guest doesn’t sweat any less because of it. But under certain circumstances it is also sufficient to deactivate the air conditioning in the workshop for a short time, because just at this moment several powerful hairdryers are being used in the holiday village at the same time." A touch panel with integrated web server is used as an HMI unit in the control cubicle of the main control on site – this practical feature enables the access on the visualization via each web browser and therefore also via mobile devices such as a Smartphone or tablet PC as mentioned at the beginning of the article. The clearly designed visualization not only gives information about the latest energy values but also depicts them graphically. Various consumption and trend curves are available – from voltage curves, through phase current, up to network symmetry. The parameters collected from their own weather station, such as temperature, humidity, wind direction and intensity of the sun, are fed into the system and contribute to energy optimization. The recording of all energy data is still made via a 16 GB CF card in the panel – in future all data will be transmitted automatically to a server. “The entire system is prepared in such a way to be very useful to me”, said Moserhof owner Heinz Hartweger about the solution. “I get information at all times with only a few mouse clicks.” His cousin added: “And we can show KELAG the actual consumption values in case of discrepancies in the invoice.”

From Thomas Reznicek, Chief editor Austromatisierung, Austria