ELCOME Dear friends of protection and control engineering, in our current article, our guest author Ruben Winter (B.Eng M.Sc, Product Marketing Clipline Energy, Phoenix Contact GmbH & Co. KG, Blomberg) will present a highly interesting contribution to increasing the plant safety of a medium voltage substation of the Rheinenergie in the north of Cologne. Have fun while reading!
Smaller and more modern: The new medium-voltage switchgear of the Rheinenergie in the Worringen substation Chorweiler comprises 22 air-insulated fields in a compact station.
In the city of Cologne and the surrounding area, Rheinenergie AG operates the distribution grid. In the course of the continuous network expansion and the modernization of the network an important main distribution station was renewed. Through the use of the Fame test plug system, system and personnel safety will be considerably increased in the regular examination of the protection technology.
As a regional energy supply company for power, gas, water and heat based in Cologne, Rheinenergie AG provides around 2.5 million people, industry, trade and industry with energy and drinking water. GEW Köln holds 80 per cent of the shares, which directly and indirectly owns the city of Cologne as a holding company. The remaining 20 percent are held by RWE AG.
In order to supply the City of Cologne and the surrounding area with electrical energy, the Rheinenergie operates a 110 kV network as well as an underground medium-voltage network. Over all voltage levels, the power supply network - with all lines and cables - has a total length of approximately 19,000 km.
The Worringen substation
The new switchgear for the increase of security of supply was built in the urban area of Chorweiler in the north of Cologne. Until now, the town districts of Roggendorf and Themenhofen were supplied by a switchgear built in 1963. The former 25 kV power supply and the corresponding transformers were already built back a few years ago so that the switchgear could still be used for the energy distribution on the 10 kV voltage level.
The switchgear from 1963 was replaced by an arc fault-proof switchgear with significantly increased system and personal protection
"The maintenance of the old system was no longer economical," explains protection engineer Karsten Martin from Rheinenergie AG.
Responsible for the protection systems of the Rheinenergie: Karsten Martin saves a lot of time with Fame.
"We have also built a considerably smaller building for the new station." The new medium-voltage switchgear is supplied by three feeders from the Fühlingen substation. With its total of 22 control panels, the system supplies 28 surrounding local network stations via two rings. In addition to the auxiliary transformer there is another transformer with a power of 630 kVA, which directly supplies the surrounding customers from the station. In addition, there are two E-coils for compensation of the capacitive earth currents in the building, as well as a remote control cabinet for the connection to the grid line.
The new switchgear was manufactured by Elatec Power Distribution GmbH. The Elatec M13 switchgear, which has a short-circuit alternating current of 31.5 kA according to IEC 62271-200, is characterized by its extremely compact design. A digital protection and field device has been installed in each control panel to protect the system and the network.
A special feature of this system is that the interlocks of some protective devices within the switchgear have been realized with the IEC 61850 communication standard. The GOOSE (Generic Object Oriented Substance Events) protocol is a real-time network protocol for controlling devices over Ethernet networks.
Safe maintenance through our own planning
The telecontrol engineering comes from the Cologne company SAE IT-systems GmbH & Co. KG - the company has made a name for itself as a manufacturer of powerful remote control and station control technology for the areas of electricity, water, gas, district heating and infrastructure. The safety devices communicate with the remote control systems FW-50 and FW-5 of the SAE IT-systems via IEC 60870-5-103 protocol. The connection of the station to the network control station is made by IEC 60870-5-104 protocol.
"We plan the low-voltage switchgear cabinet in which the control components as well as the protection equipment are installed, and we also carry out commissioning," explains Martin. "This makes the maintenance as well as the regular inspection of the system much easier." The fact that it is so much easier now is also due to the use of the Fame test sys- tem from Phoenix Contact. Thus the Rheinenergie has developed a company-wide quasi-standard, which is binding for all new plants. "On the test strip of the plug-in system, we carry the measured values of the three external phase currents, the current of the neutral conductor, the associated voltages as well as the trigger signal," explains Martin. "When the test plug is plugged in, the signals are first disconnected, then the current transformers are short-circuited and then the voltage and current transformers are separated."
The leading short circuit of the current transformers plays an important role. In addition, compliance with the switching sequence prevents unwanted tripping of the circuit breaker and thus grid failures. The colored test sockets attached to the plug can also be used to carry out measurements and tests on the protective relay. The safety test sockets are arranged offset, so that touch-protected measuring cables can be connected without difficulty. Colored markings facilitate the assignment of the signals when connecting the test device.
The new medium voltage switchgear of the Rheinenergie was supplied by Elatec, the series terminals and the Fame test plug system are from Phoenix Contact.
Safety and flexibility with Fame
The Fame plug itself is coded like the test plug - so it is ensured that only the correct plug is plugged. Due to the modular design of the test plug, it was possible to create configurations that are specifically designed to meet the requirements of Rheinenergie. In addition to the test plug for the protective relay, a second plug has been developed with which special measurements are carried out. By means of bridges with handle, the configuration can be changed before use on site. The test plug is configured before it is inserted into the test plug - this significantly increases the safety of the test procedure.
"Because the switching sequence is configured in the measuring plug, only the bridge of the plug has to be modified, if necessary," emphasizes Martin. "If, for example, we want to grind an amperemeter in order to measure the transformer currents during operation, we can remove the short-circuiting bridges." The leading contact between the two contact zones of the spring in the basic block ensures the connection without interruption of the transformer circuits. The tripping circuits are separated before the separation of the signal and transformer circuits. For this purpose, the test plugs from the Fame program have three pin lengths, which can be configured for each pole according to the respective application.
The prolonged pins on the contacts of the off circuits prevent unintentional tripping of the circuit breaker during plugging and testing. "The switching sequence has already been defined in the plug," Martin says, "there will be no longer any failure times due to fault trips." In this way, the Fame test plug system increases operational and supply safety.
Safe, fast and comfortable testing - Rheinenergie AG uses the Fame test system to modernize its networks.
For the energy of the Rheinenergie, Fame offers many advantages due to its flexibility and modularity as well as its safety in the application. Martin: "The Fame solutions we have configured to meet our needs can be purchased through separate item numbers - we do not have to reconfigure them with each order." In addition, the Fame system fits seamlessly into the terminals used in the row- Program Clipline complete. Thus the same accessories are used for both, simplifying procurement and storage. The connection technology of Phoenix Contact is also an advantage when connecting the protective relay, as is the case with the test plug system itself - the leading short circuit is already integrated in the plug connector. "We will continue to rely on the Phoenix Contact test system Fame from Phoenix Contact for our ongoing modernization and grid expansion measures," says Martin.