Energy Automation for the Holborn Europa Raffinerie GmbH

Overview

Automatic switching, motor drive automatics and control systems for the HV/MV supply system

Supply security is the omnipresent subject to petrochemical plants, which directly affects the quality of the end product. The modernisation of such plants therefore demands for sophisticated automation concepts - a job for experts.

The Holborn refinery in Hamburg is one of the largest petrochemical plants in northern Germany.

In order to sustan the highest possible quality level of the end products gas, propellant and heating oil, a complete concept is demanded regarding supply security. A main reason for that is the acute threat of an explosion due to a supply system failure - caused by heat-exchanger unit failure on supply breakdown.

Additionally, long-lasting failures lead to considerable efforts in terms of restarting the petrochemical processes combined with loss of production.

The reconstruction of the plant which started in 1999 also required a step-by-step implementation of the automation concept that presupposed most possible unaffected production at the same time.

Finally, the automation expert Sprecher Automation (Linz, Austria) and several Alstom subsidiaries were seen as best suited to cope with the given specifications.

In July 2003, the final plant section was put into operation. There was no further use for the traditional control system, which was superseded by the new control system ESC (electrical switchgear control) / IMOS.

Beside data allocation, event logging and command output, also time-critical processes like the detection of voltage dip within milliseconds were applied.

Details

Former control system with hardware logics (transistor modules) and new system with control and monitoring facilities

Automatic switching, motor drive automatics and control systems for the HV/MV supply system

Power supply

In order to avoid a worst-case scenario - a total supply failure - in the most effective way, the systems were implemented multiply protected in a matter of principle.

The basic requirements for the new power supply concept were two independent main feeders (110 kV).

These feeders are dimensioned in such a way to provide full power supply to the plant via one feeder.

Above and beyond, there are several emergency supplies (6 kV) for particularly critical plant sections.

Feeding is carried out through medium-voltage (MV) switchgears which are located around premises.

 

Autarkic concepts

Each switchgear house with its MV and LV switchgears forms one autarkic unit. Because old and new automation technology has to communicate, existing technology had to be integrated for communication between the several switchgear houses.

Information about existing MV cells was directly transmitted into the central station computer. Every cell consists of specific input/output modules to minimise the effects due to a failure.

Monitoring takes place via HMI. All system-relevant data as position indication of disconnectors, earthing switchers, circuit breakers and measured values like load current, voltage, apparent, active and reactive power is displayed. In addition, the data is transmitted to a front end computer via optical fibres, which further transmits the data to the superior control room.

The new Kilohertz receiver (2x3 pieces)

Do not disturb

With the fulfilment of the customer requirement - no impairment of production during reconstruction of the system - Sprecher Automation and Alstom cleared an important hurdle. In spite of step-by-step reconstructioning of the switching houses, the functionalities of a comprehensive automatic system had to be additionally guaranteed and adapted to the new conditions bit-by-bit.

Because basic data is transmitted with 2,4 kH signals between the MV substation, a new development was necessary in order to meet this demand. Due to the fact, that tests could not be run in the “hot plant”, all functions had to be tested in the laboratory. In order to simulate under real-time conditions, all automation components of a MV substation were set up and wired to transducers. Also, real-time supply system conditions were precisely simulated.

 

Precisely checked

There are two independent busbar systems which act as the relevant MV switchgear elements. Both busbars are supplied by different feeders. The MV switchgears, which electrically supply motor drives or subsystems are connected via these busbar systems. Thereby, the busbars can be connected via a bus sectionalising point.

In normal mode, both feeders are active and the coupling switch is off. Automatic switching detects voltage dips > 250 ms and instantly kicks in protection security procedures. In other words: automatic switching to another busbar in the event of a voltage dip.

Before, the failure-affected motors have to be disconnected from the system. After switching, they must be reconnected to the system one after the other again. In case both feeders fail, an emergency feeder is activated whereas flexibility is also guaranteed. The reconnection procedure of the motor drives is carried out upon a predefined priority list. If required, the priority list can be changed without configuration efforts. The connection staggering is necessary due to the required and higher starting current. On simultaneous connection of all motor drives, the protection facilities would be activated and therefore initiating.

In case one of the main feeders actually fails, all MV substations switch to the “hale” feeder. Essentially, all switchings have to be coordinated between the MV switchgears, because the start current is very high given such circumstances. On reconnecting the strongest motor drive (5,6 MW) to the system for instance, no other switchings are allowed in the other MV substations.

All relevant and event-related data is then transmitted via the independent communication line (2,4 kHz signals).

System overview 110/6 kV
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