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Customer application September 18, 2020
Reliably Managing a Power Plant Portfolio

Balancing power is indispensable when acute imbalances in the electrical grid must be compensated for – however, successfully marketing power balancing is challenging. High demands are placed on the supply of balancing power: It must be reliably available within a very short time. The Trianel Municipal Utility Cooperative trusts automation solutions from WAGO to operate their virtual power plant: The entire communication system runs on the PFC200 Telecontrol PLC.

The energy transition is accelerating. After phasing out nuclear power, the federal government is now preparing to phase out coal-fired electrical generation. The first brown coal generating plants should be shut down by 2022. The resulting gap is being quickly filled by renewable energy suppliers like solar farms and wind turbines – their share of the electrical supply is supposed to rise from the current 30 percent to 80 percent by 2050. For the energy system, however, this transition to eco-power is anything but easy. Because solar and wind energy fluctuate depending on the weather, the electrical grid must be balanced by intelligent load management to keep it at a stable frequency of 50 hertz at all times. To achieve this, the large transmission network operators use “balancing power” or a “power reserve,” which they procure from registered suppliers. If there is not enough current in the network, these suppliers feed in reserve energy; during excess power situations, they withdraw current. This load management succeeds by using virtual power plants, which can accurately run their output up or down within seconds.

Advantages of WAGO Telecontrol Technology:

  • WAGO’s flexible PFC200 telecontrol PLC provides the highest computing power in the smallest space
  • Secure, economical access to distant plants, e.g. for monitoring energy distribution networks
  • The easy-to-use remote control interface offers a high degree of cybersecurity

A Virtual Power Plant Consisting of Several Hundred Systems

In order for sufficient balancing energy to be available at all times, the network operators use auctions to obtain their balancing power at primary, secondary and tertiary reserve levels. The tenders with the most economical prices are accepted. The Trianel GmbH municipal utility cooperative from Aachen participates in these daily and weekly auctions as one of the leading electrical vendors in Germany. The corporation has operated a balancing energy pool since 2013 and currently bundles several hundred systems with a total output of more than 700 megawatts. The system includes a wide variety of generation and storage technologies, as well as industrial consumers. “Our virtual power plant is naturally open both to municipal utilities and also to all operators of suitable generating and consuming systems. They are connected to our control system and can thus be used automatically when needed,” explains Nico Bürker from Trianel.

Prices under Pressure

In practice, biogas systems, storage facilities and other energy-related systems are operated as usual. If the network operator calls for balancing power, then an algorithm in the control system selects the suitable systems and controls them from the control center. Virtual power plants are especially adept at cushioning short-term fluctuations in the electrical grid, as they enjoy a high degree of flexibility due to their pool of many smaller systems. However, it is becoming increasingly difficult for the operators to function economically. As the wholesale prices for electricity continue to drop, an increasing number of power suppliers is trying to compete in the balancing power market. The result is an increase in supply and falling prices. “In light of increasing price pressures, efficiency is mandatory for us,” says Bürker.

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» The versatility of WAGO’s telecontroller, in connection with the service associated with a reputable manufacturer, were decisive for our decision. «

Nico Bürker, Trianel

Focus on System Control

Trianel reacts by constantly optimizing the processes and technology in its virtual power plant and in its marketing strategies. Special attention is paid to system controllers, which must function quickly and securely in order to ensure smooth monitoring and control of the systems. Trianel links individual systems to its own control system using WAGO’s compact PFC200 Controller. The decisive advantage: WAGO’s controller combines high performance with important security functions in a compact housing. It has thus become an unobtrusive key player in the virtual power plant; it transmits tightly synchronized current output data from the pool members to the control center and receives the supply needs in turn. “The versatility of WAGO’s telecontroller, in connection with the service associated with a reputable manufacturer, were decisive for our decision. The fact that WAGO also supplies a complete solution in the form of a control cabinet gives us the option of expediting commissioning,” says Bürker, explaining the decision to use WAGO technology.

A Variety of Functions in a Small Space

In WAGO’s pre-assembled distribution boxes, the standard configuration includes the 750-8202/025-001 Telecontrol PLC, together with an external router for data transmission, digital input/output modules, analog input/output modules, an EPISTRON® COMPACT Power Supply and an interface terminal block assembly. The PFC200 provides the highest computing power in the smallest space thanks to its Cortex A8 processor. Two ETHERNET ports and additional interfaces, such as CAN, PROFIBUS and RS-232/RS-485, are available for communication with the control system. WAGO’s telecontrol PLC is programmable per IEC 61131. It supports both the IEC 60870-5-104 telecontrol protocol and the IEC 60870-5-101 serial protocol; communication complies with IEC 61850. In addition to programming the PFC200, the CODESYS development environment can also be used for visualizing the processes.

Reliable – and Secure

The controller provides two ETHERNET interfaces for the TCP/IP-based IEC 60870-5-104 protocol and a serial interface for the IEC 60870-5-101 protocol. A software tool is integrated so that the IEC communication can be established easily. The software also reduces the task to merely parameterizing individual settings. In addition to the variety of functions, the PFC200 offers a high level of IT security – an aspect which is becoming more and more important to the energy supply. The federal government has just classified the networks and power generation systems as critical infrastructure following numerous IT security failures in the past year. Through the use of WAGO’s telecontrol PLC, a VPN tunnel can be established directly via OpenVPN or IPsec in order to transmit encrypted data to the control center. This means that an upstream VPN router is no longer necessary.

Partners for Coming Challenges

This solution was compelling to Trianel. Automation technology from WAGO also plays an important role in Trianel’s plans for the future. The corporation is currently expanding its system to include the functions of the primary reserve. This form of balancing power must be available to the network within thirty seconds, unlike secondary and tertiary reserves, which have five and fifteen minute supply requirements, respectively. The firm currently only supplies secondary and tertiary reserves. “Primary reserve power places additional demands on the remote control PLC with respect to measuring and control functions,” explains Bürker. He is convinced that WAGO will have the correct automation solution on hand for these more complex demands too.

Author: Daniel Wiese

Photo: WAGO

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