Helmuth Lardschneider , ELA for Progea
Controllers, Thermal Management
Modern ski resorts are the heart of the tourist trade in mountain holiday locations. Tourists spending their holidays in the mountains constitute a major part of hotel tourism economy in winter along with other activities such as dining, handicrafts, transportation, and access to the ever-increasing fast and capacious ski lifts.
This usually depends on whether there is enough snow, with the entire economy of the big hotel resorts relying on snow on the ski slopes. Furthermore, the snow must be a certain consistency and quality to ensure that skiers and snowboarders enjoy their winter holiday experience. It is for this reason that the local ski resort community in St. Moritz has placed its trust in modern technology to produce artificial snow to ensure that the ski slopes remain open and in operation.
The snow making system needs to be well engineered, not only to guarantee both quality and snow productivity, but primarily to optimize energy and water consumption in way that is also environment friendly. To accomplish this, the best automation technology available both in terms of hardware (considering below zero temperatures and temperature changes) and in terms of supervision and control management software were obtained.
Artificial snow process
Artificial snow is produced with a process that replicates the natural snow process based on water. The water is pumped through nebulizers defined “snow cannons”, positioned in those points where snow is needed. The water is pumped and nebulized when entering the machine to form very small droplets of water, which are frozen instantly upon contact with the air below zero temperatures (usually below -6 °C, -7 °C) to then become tiny ice crystals.
Practically, the snow cannon imitates the natural snow process in fast motion. In addition, it is essential that the temperature and humidity conditions are ideal. For instance, the transformation of water to snow is more effective when there is low humidity. By obtaining this condition the structure of the frozen particles become more compact and spherical and therefore greater in density than natural snow (see Figure 1).
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Figure 1: The snow generators are complex machines that need the right technology and know-how to operate properly
The St. Moritz – Engadin Project
The “St. Moritz Engdain Mountains” consortium needed to modernize and unify all the ski resort snow generator management systems on both their North and West ski slopes. The West ski slope has a snow making system installed in the 90’s by DEMA (now DEMACLENKO), which provides a series of 250 underground wells for storing the artificial snow with 6 connected pumping stations, which supply water at 1800 to 2900 meters above sea level. The total power generating capacity installed is 7 MWatt. The system used on the North slope was also installed in the 90’s by a company called SUFAG. It has 200 wells and 3 pumping stations with a power generating capacity of 4 MWatt. The unification project focused on optimizing system management by creating one unique monitoring and control system to improve operability efficiency and optimize and reduce energy and water consumption (see Figure 2).
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Figure 2: The complex network architecture of the entire ski resort using optic fiber
The project engineering and deployment was commissioned to FREY AG, a company from Stans, Switzerland, who sought collaboration with ELA Srl, a company from Laion (Bolzano), for their expertise and experience in projects such as this one. After carefully assessing various technology system architectures the Movicon 11.3 SCADA platform was chosen along with field Saia PLCs. The Movicon Scada platform was specifically chosen for its project modularity that enabled the union of the two ski slope systems design engineered by two different companies. The North ski slope project was assigned to FREY AG, while the West ski slope project was assigned to ELA Srl.
Based on the Movicon project modularity, the projects were designed with Parent-Child architecture. The Parent project therefore disposes the resources of the various Child projects which remain independent and exist on their own. This enabled the Movicon project designed by FREY AG for the North slope and the Movicon project designed by ELA Srl for the West slope to unite in one ‘Parent’ project as one unique project while at the same time maintaining the two development teams and projects separate and independent.
The architecture includes an unmanned server station located in the valley of Moritz-Signal. This station is connected in network, using optical fiber, to the client stations and various PLCs located throughout the ski slopes. The two remaining supervision stations are allocated at the mountain terminal stations and are operated by personnel from the Croviglia, Celerina, Trutz ski lift terminal stations and the main Signal Station (see Figure 3).
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Figure 3: One of the ski lift stations used to reach the top of the St. Moritz – Celerina ski resort pistes
The Saia PLCs are connected in net to the central supervision station where there are 13 main control stations connected in Ethernet using optic fiber with a series of substations connected in a RS485 sub network using the Gateway Master technology betweem the Saia PLCs. The Movicon supervision uses its native ‘Multiport’ I/O driver for Saia which is capable of connecting to any Saia device with all available protocol including S-Bus.
St. Moritz new ski slope supervision system’s main task was to distribute control stations through one system with centralized and standardized management based on modern and popular user interface criteria. This was to be implemented with the purpose of re-modernizing the St. Moritz and Celerina control stations.
This would allow management staff to access any one of the functionalities within the system from any one of the control stations using the same interface. Furthermore, the continuously manned Corviglia control station, would assume the central role in managing the whole system (see Figure 4).
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Figure 4: One of the Movicon supervision system control station terminals at St. Moritz – Engadin
In addition to this, the supervision system had to ensure that the user authentication management remained centralized to allow new system users access to the system from any control station terminal using the web as well.
All these requirements were taken into full consideration when evaluating which Scada platform to adopt as well as the capacity to be managed by the two different developer teams: FREY AG and ELA Srl.
The choice of using the Movicon technology was successful, satisfying the fundamental requirements due to its expandability and design engineering modularity. It must also be recognized that the project had to be predisposed for integrating with the ropeway system management. In addition the design engineers were given little time to complete the project. This was due to the fact that the short summer period at high altitude meant that they had to work fast to design, install and get the system up and running before the winter season set in.
This did not hinder the engineers who were able to complete work in time and with success to the great satisfaction of the clients and co-operation of the different company developer teams, the potentiality of the Movicon platform and the Progea technical support services. The new supervision system now enables the client to start producing artificial snow from as early as October. This means that they can completely cover the slopes with artificial snow in time for the Christmas holiday season before the freezing temperatures of December set in.
Main system functionalities
The Movicon supervision system manages a total of 4,500 variables, organized in data structures to enable smooth system parameterization, making data easier to manage in the PLC and organize in the supervisor. The various modular projects can be accessed from the various area workstation terminals spread throughout the North and West ski slopes.
The Movicon supervision system enables the complete management of the pumping stations using parameterized screen page interfaces to quicken repetitive function programming and drastically reduce risk of errors. All the pumps of each station are completely controlled individually using manual and automatic commands. The functional parameter definitions are recorded in appropriated databases to ensure traceability and data protection. Purposely defined algorithms enable energy consumption optimization that can be analyzed statistically in detailed reports.
Artificial snow is produced completely in automatic using the snow generator management system defined also as snow cannons. Maps of the whole skiing resort complex are managed on screen on the supervisor side so that the existing 150 generators can be easily localized and configured (see Figure 5). These generators can also be dismantled by hand and repositioned where required. The supervisor uses a parameterization system that enables configurations to be read from the field. It also allows each generator to be displayed with its status on screen maps. The area map layout on screen shows the location and status of each generator so that they can be individually analyzed in detail. The parameterized page contains all the information about the machine processes (startup, alarms, shutdown, production, etc.) and retrieved measure values (air temperature, corona discharge, water, humidity, water pressure, wind speed and direction, etc.).
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Figure 5: Maps of the whole skiing resort complex are managed on screen so 150 generators can be easily localized and configured
An interesting feature to note is that any one of the generators can be physically positioned and reconnected in any part of the ski resort complex without needing any program modification. By using just the one command, the supervisor updates the configuration to point to the specified addresses even when physically present in different PLCs. This is made possible by the “Hot” driver’s capacity to automatically reconfigure.
Historical logging and Analysing
Each individual snow generator records all the process information on a relational database based on SQL Server, using the native Movicon data logger tools. For example, the measure values include air temperature and wet bulb, air humidity and efficiency. All consumptions are historically logged, such as duration of time in service divided by temperature ranges, water consumption and energy consumption. This enables partial or total consumptions to be consulted by filtering them by period and other filter selection types.
Reports and Trends using the powerful Movicon analytic tools are also used for presenting recorded data in various graphical charts according to selected period.
The pumping stations are also managed in the same way by recording process data, value behavior such as water level, input and output pressure and flow values and more.
The supervision system collects and centralizes alarm data from modular projects (child) so that it can be distributed to the various workstations for viewing diagnostics both as realtime events and recorded events. The system manages a total of 3,800 alarms divided by area and severity. By using the Movicon diagnostic system and functions, staff can easily manage the snow generation under all circumstances in response to the information displayed by the system on screen. The efficient alarm management enables maintenance and service staff to intervene with preventive or corrective procedures immediately and obtain complete control of the whole system from any position throughout the entire ski resort complex. In addition, Movicon manages notification of events with SMS, Email or Voice mail to enable quick intervention by on-call duty staff in certain situations when the different areas are left unmanned.
User and Password Management
The supervisory system handles all modular (child) and parent project users in a centralized management. Movicon enables the various projects, whether modular or client-server architecture, a continuous synchronized user profile management. It can also be used for those users inserted by clients during runtime mode. The system defines seven user levels (1024 can be defined with Movicon) and an administration level to allow access to certain system commands according to user responsibility status.
Web Client and Terminal Server
The supervisory system offers the use of a management within its architecture to handle different client stations using the Windows Terminal Server function when the client station is connected in LAN with the ski resort complex’s local network. Even though momentarily not in use, Movicon is predisposed with a Movicon Web Client feature which enables staff to access the system through the web by iPhone, iPad or mobile device with any browser.
We would like to thank Mr Helmut Lardschneider and Alfi Piazza from Ela Srl