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Hydroelectric power: grid safety

Reliable, precise and easy to handle – these are just some of the reasons Lukas Anlagenbau GmbH have adopted the ABB CM-UFD.M31 grid feeding monitoring relay. This device has set new standards for the Bavarian company in dealing with network and system protection of distributed generation plants.

 

Mankind has used the power of water for centuries. Today water as a source of renewable energy is in increasing demand. 

“Hydroelectric power is a reliable source of power, more reliable than wind,” said Bernhard Schedl, buyer for Lukas Anlagenbau GmbH.

The company has built hydroelectric plants for more than 50 years and is located in the Upper Palatinate region of Germany, with its headquarters in Albersrieth. The company designs and constructs systems for hydroelectric power plants and artificial lakes with power generating capacities that range from 5 kW to 10 MW. The company offers services that encompass all mechanical and hydraulic engineering sectors (structural metalwork) as well as low-voltage applications and control systems for hydroelectric power plants, and to date it has built over 700 systems throughout the world, however, the new regulation of the “Verband der Electrotechnik” (VDE-AR-N 4105) has forced many operators of hydroelectric plants to conform to new standards.

The regulation concerns all distributed generation systems connected to low-voltage networks and has required, since the 1 August 2011, frequency-dependent active power reduction to guarantee system stability in the event of low or high frequencies. The aim of the standard is to guarantee a safe grid and a high-quality operating system for power supply. To ensure Lukas Anlagenbau GmbH complies with the VDE-AR-N 4105 regulations the company has been using ABB’s CM-UFD.M31 grid feeding monitoring relays since autumn 2015. Designed for distributed generation systems, it detects over- and under-voltages and changes in grid frequency. As soon as the values measured are outside the threshold values set, for example in the event of an unstable grid, anomalies, or grid maintenance, the CM-UFD.M31 trips the interface switch.

As a result, the hydroelectric power plant is isolated from the public grid. The error is displayed by means of LEDs and an error message appears on the screen.

Easy to use and many functions

Lukas Anlagenbau GmbH mainly uses the device on low-voltage systems.

"Handling of the relay is intuitive,” stated Peter Heller, project manager in charge of hydroelectric engineering projects at Lukas. “It is easy to use and extremely easy to install, occupying less space on the DIN rail. The screen is large and the values measured are easy to read. Thanks to its clear text, I receive precise messages. This is safe and practical."

Given that the upper value of the trip frequency threshold varies from region to region, it is easy to configure for a rapid start-up.

“The device is pre-configured in an ideal manner,” stated Bernhard Schedl. “The lower threshold value of 47.5 Hz is set as default on the CM-UFD.M31. We only need to change the upper trip frequency, as determined by the parameters of the respective power providers. The ABB device can be set with decimal precision. The device differs from others of this type due to its measurement precision and tripping commands.”

“The CM-UFD.M31 is our leading relay. Resistant and reliable.”

ABB’s grid feeding monitoring relay also has two inputs for the feedback signal from the interface switch, which is used to monitor the feedback loop.

“In this way, the relay detects when the system is off,” said Peter Heller. “If a permissible frequency is detected, the system switches on again automatically. This is very practical because it means there is no need to intervene.

“The owner of the distributed generation and the power provider have full control over the system and are certain of its operation in all situations. The designer also positively assessed the selectable vector shift detection system. Other devices do not have this function,” said Heller. “The vector shift detection is very useful for synchronous systems. In this way, grid anomalies, such as voltage drops, can be identified much faster and as a result the reliability of the tripping process is increased.”

Every parameter can be adjusted individually on the CM-UFD.M31 grid feeding monitoring relay.

"Depending on the system, we can decide whether we need the vector shift detection,” continued Heller.

The new leading relay

The two experts from Lukas Anlagenbau GmbH said that the most important advantages of the ABB relay are the great ease of use, the inclusion of all the necessary functions and the precise monitoring of the feedback loop.

"ABB is synonymous with quality,” added Peter Heller. “Furthermore, the price/performance ratio is optimal and delivery times are short – an advantage for our warehouse. The device’s capabilities fully satisfy our needs. It’s a complete package.”

Lukas Anlagenbau GmbH has been using the CM-UFD.M31 grid feeding monitoring relay to modernize over 60 hydroelectric power plants.

“Even in the future, when installing new plants, ABB’s device will be our first choice for network and system protection,” said Bernhard Schedl. "The CM-UFD.M31 is resistant and reliable. We are extremely satisfied.”

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