Hydroelectricity – Nature and Technology in Harmony
BEW (Bayerische Elektrizitätswerke GmbH) generates around 1.1 billion kWh of environmentally-friendly power per year using renewable hydroelectricity, making it one of Bavaria’s leading operators of hydroelectric power stations. All 36 of the hydroelectric power stations BEW operates are exclusively ‘run-of-river’ plants. As the water never stops flowing, these are designed for continuous operation, providing sustainable power around the clock and making a major contribution in the transfer to alternative energy sources.
Top priority must be given to a reliable power supply for the technical systems inside the power plant that are critical for its operation, i.e. its internal power requirements. All the regulation and control functions for the vast number of actuators in the power plant and particularly for the turbine units that lie at its heart, are based on gathering data seamlessly from a large number of measurement points. One of BEW's most ambitious aims is to achieve an unmanned operating regime that is remotely monitored at minimum cost, day and night.
To achieve this, a wide-ranging initiative was set up in order to update the equipment for the electrical and control systems within the power plants. After an intensive planning phase, BEW implemented the resulting strategy for the first time in 2012 at the ‘run-of-river’ hydro power plant at Rhien, owned by Rhein-Main-Donau AG.
Following a competitive tender process, BENNING was selected as the partner of choice for the power supply systems.
BENNING and BEW had already worked together for over 30 years. Throughout this time, BENNING had demonstrated how robust, reliable and efficient its equipment is in a number of different projects.
The automation project was started at the Leipheim site, owned by Obere Donau Kraft - werke AG (ODK). Modernising the ‘run-of-river’ hydro power plant, situated directly on the Danube in the Swabian rural district of Günzburg, will be carried out working with tried and tested partners, as in the additional hydroelectric power plants on the Lech, Iller and Danube rivers.
The company responsible for implementing the extensive modernisation measures is KIMA Automatisierung of Gronau which has already undertaken a number of power plant modernisation projects in collaboration with BENNING (including those at Offingen, Gundelfingen and Faimingen). In the system used by BEW, BENNING had to demonstrate before the project could be technically authorised that, based on comprehensive tests, the modular industrial type rectifier, the TEBECHOP 3000 HDI could cope with the loads occurring in the power plant, particularly in the event of an emergency shutdown.
In this scenario, an emergency shutdown means that as there is suddenly no generator load on the turbine units, they overspeed when the load is removed, so that frequencies of over 70 Hertz may occur initially before the automatic frequency controls react to mitigate the enormous release of kinetic energy.
It is precisely at the beginning of these unplanned operating conditions that it is absolutely vital to have an secure power supply for the internal requirements of all the significant technical systems in the plant to prevent.
KIMA Gesellschaft für elektronische Steuerungstechnik und Konstruktion mbH [English: “Company for Electronic Control Technology and Design Ltd”] was founded in1987 in Gronau and, with more than 100 employees, provides engineering services in the field of control and regulation technology. KIMA develops customised applications – from initial engineering right through to commissioning – for a wide variety of processes in manufacturing and process technology. KIMA supplies complex control and regulating systems worldwide to a wide variety of industrial sectors, such as cement, food processing, hydroelectricity and environmental technology, including redundant, high availability/safety-related control systems.
The in-house power supply developed by BENNING includes rectifier systems (110V/100A) of type TEBECHOP 3000 HDI, DC/DC-converters (110V/24V) in the series TEBECHOP HDDC and power inverter systems of the INVERTRONIC compact type (230 V/20 kVA). When mains power is available these systems supply the loads and provide the charging current or float voltage for the batteries that were also supplied by BENNING.
This ensures that, if the mains supply fails, the batteries are available at full capacity and that the various loads receive a reliable power supply during the transition period, without any interruption in power. The modular rectifiers and inverters supplied are specifically robust systems designed for industrial applications.
Maximum equipment availability is achieved by means of parallel switching of power supply modules fitted with hot plug-in technology providing n+1 or n+2 redundancy. In addition, the performance of the system can be flexibly adapted at any time by adding or removing plug-in modules, without causing any interruption to the supply to the consumers load.
Remote Access Function
In order to enable a fully-automated, unmanned operation of the ‘run-of-river’ power plant, it is necessary to have remote access to all the technical systems in the power plant. The power supply system is therefore equipped with the BENNING MCU (multipoint control unit) enabling connection via Profibus to the BEW state-of-the-art central control room, providing reliable, problem-free remote access from the control room to the entire power supply system and the whole of the plant’s technological systems. Thanks to the highly efficient data capture and the actuation technology via remote management, the system is always under complete control in 'unmanned' mode. Plans for Further Collaboration There are already plans to continue the partnership, which demonstrates the power plant operator is confident in BENNING’s supply of both products and services.
Since entering into service in 1961, the two Kaplan turbines with a maximum joint output of 9,370 Kilowatts, have generated an average of around 50 million kWh of power per year. Compared with conventional power generation, this means eliminating roughly 35,000 tonnes of carbon dioxide emissions a year.