At a glanceSpecial requirements, such as isolatednetworks, or unique ambient condi-tions require custom planning and de-sign of a power system. Siemens Pow-er Technologies International (SiemensPTI) has long-term experience in de-veloping individual solutions for powersystems of any kind, including:

· state-of-the-art technologies, withsolutions for advanced planninganalyses

· high-end software tools from thePSS® product suite to design yournetwork for safe, reliable operation

· support to determine possible weakpoints and to define necessary miti-gation measures.

The challengeSpecial power supply systems are oc-casionally required for unique electrici-ty end-user needs. Among these are:

· offshore installations in the oil andgas industry

· converter-fed underwater pumpingstations

· networks for ships or mobile manu-facturing plants

· underwater DC systems

· underwater systems for powerevacuation in wind farms

· supply of offshore installations fromashore and/or among one another

· special isolated networks such asLNG systems or mines

Our solutionAll these special requirements and sys-tems call for different planning anal-yses to ensure safe and reliable opera-tion of the specialized power supplysystem, despite the many componentsand aspects involved. Using compre-hensive know-how and long-term ex-perience, Siemens PTI offers solutionsfor power supply systems of any kind.

Figure 1: Container vessel

Application example – containervesselAn example of a special electricity sys-tem is a container vessel with a gener-ation/distribution system with wasteheat recovery. This modern generationsystem enables clean, economic powergeneration from the exhaust gas onboard of a vessel. The energy surplus,available from the exhaust gas flow, inaddition to the demand of the turbo-charger, is utilized to drive the turbo

generator. This generation concept isshown in figure 2.

The generation system consists of asteam turbine generator, which usesthe exhaust gas of the exhaust boiler,and three additional diesel generatorswhich are operated depending on theship’s operational mode.

In harbor mode, an adequate numberof diesels will be running dependingon the load situation. In maneuvermode, the shaft generator/motor willnot be in operation. Above a minimumspeed of the main engine, the exhaustboiler produces enough steam to driveand synchronize the steam generatorto the busbar. The production of wasteheat is not sufficient for utilizing thefull rating of the steam generator incruise mode.

Figure 2: Generation concept for a containervessel

Thrusters are used for maneuvering inand out of the port. Standby power forstart and full-load use of thrusters willbe fed in depending on the maneuver-ing situation. In sea mode, the steamgenerator produces the maximum pos-sible power. As required, the shaftgenerator/motor will serve as primarymotor by supporting the steam enginewith excess energy, or producing addi-tional energy as a generator.

Special powersupply systemsInnovative solutions for exceptionalsystem planning tasks

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The shaft generator/motor mode canbe selected by the operator.

During the thermal run up, the mainengine is supported by the shaft mo-tor. In case of energy surplus, the shaftmotor load is reduced. In case of ener-gy shortage, the shaft motor switchesto generator mode. If the demand inpower cannot be supplied by the mainengine and shaft generator, a dieselwill be started. Only if all diesels are inoperation and the required energy issupplied, the power of the shaft motoris reduced.

To control and coordinate all modesand power interconnection, a powermanagement system (PMS) is neces-sary to automatically coordinate theoperation and startup of diesels andthe mode change of the shaft gener-ator/motor. The coordination and rulesfor the PMS are designed and tuned bysimulation of the whole generation/distribution system given generationand load situations.

In all operation modes, the reliabilityof the system is critical. Outages ofgenerator units, outages of the shaftgenerator/motor and fault situations

have to be managed in such a way thatgeneration is not interrupted. The PMScoordinates the pre-fault situationswith suitable reserve, and in addition,uses a load shedding system as back-up reserve.

Application example:Underwater pumping stationIn a number of oil fields, with distan-ces up to 50 km of the platform, un-derwater pumps need to be installedto keep up the pressure and to evacu-ate the oil. Using the simulation toolPSS®NETOMAC, the complete design ofsuch a system is modeled and simula-tions support the analysis and optimi-zation. Standard components are usedor optimized (standard indirect voltageconverter, standard cable operated at62% of the rated voltage due to har-monics, standard pump-transformer).The converter transformer is designedfor frequencies ranging from about0 Hz to 100 Hz. Control is optimizedfor all frequencies in steps of 10 Hz tominimize the harmonic stresses on themotor and for the system to functionwithout a communication link to themotor.

The result is a robust system with min-imal cost and a minimum number ofdevices (no additional filtering or con-trolling devices).

Figure 3: Configuration of a multi-phase un-derwater booster station

Figure 4: Electrical circuit and voltage and cur-rent at the sending end (U1, I1) and receivingend (U2, I2) of the converter configurationwith and without optimized pulse patterns

40 Hz-operation:

0 32 64

1pu

1pu

0 32 64

optimised pulse patternsstandard pulse patterns

msmst t

1 kA

1 kA

U2

U1

I1

I2

40 Hz-operation:

0 32 64

1pu

1pu

0 32 64

optimised pulse patternsstandard pulse patterns

msmst t

1 kA

1 kA

U2

U1

I1

I2

M~~ 30 km

15 kV 1 kV

1 MW1 2

0.69 kV

sendingend

receivingend

Published bySiemens AG 2017

Energy Management DivisionFreyeslebenstrasse 191058 Erlangen, Germany

For more information, please contact:power-technologies.energy@siemens.com

AL=N, ECCN=EAR99Subject to changes and errors. The infor-mation given in this document only con-tains general descriptions and/or perfor-mance features which may not alwaysspecifically reflect those described, orwhich may undergo modification in thecourse of further development of theproducts. The requested performance fea-tures are binding only when they are ex-pressly agreed upon in the concluded con-tract.