Large scale virtual power plant of Rosenheim is counting on SAE telecontrol technology

Description

Since 2005, Stadtwerke Rosenheim has been building a virtual power plant with its own and third party facilities. In 2009, an existing pool, the so-called Pool North, was taken over. Since 2011, the public utility has been marketing tertiary controls independently. The ProCoS process control system from KISTERS is used to control and monitor the wide range of individual systems.
Today, Stadtwerke Rosenheim can offer positive and negative tertiary control power and, in addition, negative secondary control power. However, not only the marketing component of the standard benefit, but also the renewable energy plants direct marketing and/or the stock market marketing Day-Ahead and Intraday is very successfully pursued. For the latter types of marketing a timetable-oriented driving style of the systems is necessary.
For each plant or technical unit that is integrated into the virtual power plant, a data link for the exchange of process information had to be set up. The public utility company decided early on to rely on SAE telecontrol technology. Not least because older SAE-FW 4/40 devices were already successfully installed in the acquired Pool North for the technical connection of the systems. New, smaller systems are currently mainly equipped with FW-5 device technology.
As justification for the use of SAE telecontrol technology, Mr Vogler, the project manager of the virtual power plant at the Stadtwerke Rosenheim, lists the following:

• clear and fast parametrisation of the systems with setIT
• simple integration of control programs into the stations with codeIT; in particular for the rolling storage of set point schedules
• the simplest, needs-based expandability of the stations with additional input/output modules and communication modules
• optimal price/performance ratio for applications of Stadtwerke Rosenheim
• fast/short delivery times

Furthermore, Mr Vogler explains: “Especially the last mentioned point is very important to us, because after conclusion of the contract with a new pool partner of our department the technical connection or the integration into the virtual power plant has to be carried out as fast as possible. From our previous experience, we can say that almost every connection of a technical unit is a small project (“copy and paste” is very rare). This concerns:

• Communication interfaces to the customer systems
• Modbus RTU or Profibus or galvanic input/output
• Communication with the headquarters at Stadtwerke Rosenheim
• Installation options of the components on the customer side
• Behaviour of the system in case of power failure

We decided at an early stage to manufacture the necessary control cabinets in our workshop as needed and quickly. ”

Systems that are outside of Stadtwerke’s communication network are connected via GPRS/UMTS services or directly via DSL. Stadtwerke Rosenheim uses LUCOM modems for mobile communications. The VPN tunnels are set up in the modem or in the FW-5 systems. At the headquarters, the VPN connections are managed via appropriate high-performance routers with a firewall.

In the Stadtwerke Rosenheim’s virtual power plant, external plants are integrated with which renewable energy direct marketing and control power marketing are carried out. Currently, they include about 30 biogas plants in the area of Rosenheim, whose entirety is referred to as virtual land plant. This is where the public utility company attaches especially great importance to a partnership-based cooperation on equal footing with the respective plant operators.

These biogas plants are connected via FW-5 systems. In order to avoid having the higher-level renewable energy feed-in management of the upstream distribution system operator “collide” with the switching measures of the direct marketer, essentially the following concept is implemented:
Switching commands of the distribution system operator are switched as signal inputs on the stations of the direct marketer. At this point, the renewable energy cut-off is prioritised over the switch measures of the direct marketing.

Especially in these applications, Mr. Vogler explains, the control functions that are to be implemented in the FW-5 substations are important. The following functions are required here:

• Implementation of pulse to permanent command
• Behaviour of the station when activated
• Behaviour of the station when the connection is interrupted
• Storage of set point profiles, day-ahead rolling
• Priority switching of the renewable energy control before control commands for direct marketing.

If systems that are currently only part of direct marketing are also marketed in control energy, it is necessary to provide additional information about the system. Here, as Mr. Vogler points out, we are well served with the SAE FW-5 technology, as these devices can be easily expanded in a modular way.
The expansion of the virtual power plant, in particular with the integration of suitable facilities from the region, is constantly being pushed forward, taking into account the various possible market opportunities. The connection of new plants to the headquarters in Rosenheim can now be carried out quickly and efficiently. This is not least due to the successful use of SAE telecontrol technology.