| Datacentre power
ELECTROMAGNETIC CLUTCH The prime starter system consists of standard engine starting motors. The clutch is maintenance-free and guarantees diesel engine start at all times, thanks to the redundant start feature.
mtu Kinetic PowerPack: how does it work? CONTROL SYSTEM
KS Vision HMI control system: class-leading elecrical and mechanical monitoring including load level, mains failures, input and output voltage, frequencies and power factor. Data logging feature records all historic events.
POWER PANEL
A power panel comprising input, output and automatic bypass circuit breakers.
SYNCHRONOUS MACHINE Four-pole synchronous machines from various manufacturers, designed to not exceed Class F temperature rises; right-sized for the application and able to absorb load harmonics.
mtu DIESEL ENGINE Complying with the latest emissions standards; preheated pre-lubricated, quick start and not running during conditioning mode.
KINETIC ENERGY MODULE Patented ‘accu’ provides stored kinetic energy to ride through mains interruptions. Designed for 10y bearing life.
Kinetic PowerPack systems are supplied from Liege, by Belgian company Kinolt, which Rolls-Royce Power Systems took over in 2020. They are sold under the brand name mtu Kinetic PowerPack.
Kinolt’s technology comprises a constantly rotating kinetic energy storage unit with flywheel, an mtu diesel engine, and a generator that doubles as an electric motor for the purpose of compensation, depending on the operating mode. A special control unit, with accompanying switchgear and a choke that acts as a line filter, completes the system. In ‘conditioning mode’, power from the public grid drives the synchronous generator, which acts as an electric motor in this operating mode. This in turn drives the flywheel of the kinetic energy storage unit, which weighs tons and employs a double rotor configuration. This serves as the kinetic energy ‘accumulator’, which stores energy and makes it available in the event of a power outage. If the public power grid fails, the systems intervene immediately and without interruption because they are already in action anyway. Part of the energy stored in the flywheel is used to drive the generator, which begins producing electrical power. Meanwhile, another part of the stored rotational energy is used to facilitate very fast start-up of the diesel engine. Within the shortest possible time the engine reaches its rated power output and can start producing electrical power via the generator and stabilising the flywheel. This happens ‘naturally’, without any gap or interruption – constituting an uninterruptible power supply.
VIBRATION ISOLATION
Thanks to the solid base frame with isolators between frame and equipment and direct
Main components of the mtu Kinetic PowerPack
Is a battery required? No. With Kinolt’s dynamic UPS technology,
no battery is needed. Previously, Rolls-Royce only had mtu standby generator sets in its portfolio for dealing with power outages. These require a certain amount of time to get going, however. To bridge that gap and ensure an uninterrupted flow of power, it has often been necessary to resort to batteries. In Kinolt’s system, however, no such battery system is needed, since the energy in the kinetic energy storage unit can be made available immediately for generating power until the mtu diesel engine comes on-stream. As already touched upon, the flywheel consists of two rotating elements: an outer rotor running freely around an inner rotor which is driven by the main shaft and rotates at 1500 rpm (50 Hz case or 1800 rpm for 60 Hz). It has two sets of windings: a three- phase alternating current winding; and a direct current winding. When the public power grid is running normally, ie, in conditioning mode, the AC winding is energised to create a rotating magnetic field that rotates the outer rotor at a maximum speed of 3000 rpm. This external rotor is advantageous for kinetic energy storage as the amount of kinetic energy increases exponentially as the distance from the centre of rotation increases. In independent mode, when the system is supplying emergency
power, the DC winding is fed and the outer rotor is electrically coupled to the inner rotor by induction. Its kinetic energy is transferred to the inner rotor – driving it. This energy transfer is regulated by precise control of the current fed into the DC winding. The kinetic energy accumulator is an entirely brushless system.
Above: In ‘conditioning mode’, when the mains supply is within tolerance, the synchronous machine is acting as a motor, driving the main shaft and thus the accumulator, storing kinetic energy. When the inner rotor rotates at 1500 rpm, 50 Hz (or at a speed of 1800 rpm in the case of a 60 Hz system), the outer rotor rotates at maximum 3000 rpm, which is advantageous for kinetic energy storage.
Above: In ‘independence mode’, during mains failure or voltage perturbation, the stored kinetic energy is transferred to the kinetic energy accumulator acting as a generator. This happens without any interruption to the user. Shortly after, the diesel engine starts and couples to the kinetic energy accumulator by latching the electromagnetic clutch. The energy is then relayed from the diesel engine to the synchronous machine and then to the loads.
www.modernpowersystems.com | March 2023 | 33
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