Rolls-royce Corporation

Ge Energy Power Conversion Technology Gmbh

Lihua Hu

David Reginald Trainer

Stephen Andrew Long

Martin Samuel Butcher

Michael P Hirst

Allan David Crane

Huw Llewelyn Edwards

Richard Ian Stephens

Stuart J Galloway

Teng Long

Michael Peter Hirst

A power distribution system includes power converter systems electrically connected to a distribution bus which defines a point of common coupling. Each power converter system includes a power converter with semiconductor switching devices controlled using a pulse width modulation strategy with a switching frequency. A controller for each power converter system applies a spectrum analysis process to the respective power converter system that uses measured or derived zero sequence currents associated with the respective power converter system to determine the location of a ground fault within the power distribution system. Each controller applies a switching frequency process where the switching frequency of the power converter of at least one of the power converter systems is different from the switching frequency of the power converter of at least another one of the power converter systems during at least part of the time that the spectrum analysis process is applied.

Ground fault protection methods

A converter control arrangement () for regulating the output current of a dc source power converter () comprises a current regulator () for regulating the output current based on a comparison of an output current value (I) of the dc source power converter () with a desired target current value (I). When the output voltage value (V) of the dc source power converter () is within a normal operating voltage range between minimum and maximum voltage values (V, V) defined with respect to a voltage reference value (V) of the dc source power converter (), the converter control arrangement () controls the target current value (I) so that it is equal to a desired reference current value (I). When the output voltage value (V) is outside the normal operating voltage range, which typically indicates a fault condition, the converter control arrangement () modulates the reference current value (I) to provide a target current value (I) that is less than the reference current value (I).

Control arrangement and method for regulating the output current of a dc source power converter connected to a multi-source dc system

A converter control arrangement for regulating the output voltage of a dc source power converter connecting an ac system to a HVDC system to enable dc electrical power to be supplied from the ac system to the HVDC system comprises a dynamic droop control device including first and second droop controllers in which the droop rate of the second droop controller is greater than the droop rate of the first droop controller. The converter control arrangement comprises a voltage regulator for regulating the output voltage of the dc source power converter by comparing an output voltage value with a target voltage value derived by combining a reference voltage value and a droop voltage value provided by the dynamic droop control device. The reference current value is the desired output current value of the dc source power converter and defines, in combination with the reference voltage value, a target operating point.

Control arrangement and method for regulating the output voltage of a dc source power converter connected to a multi-source dc system

Within generator systems maintenance of stability in terms of voltage is desirable. Generally, several generators will be arranged in parallel within the generator system with one generator voltage controlled to provide dynamic responsiveness to load switching. With regard to some loads which are generally of an active nature, the capacity of a first generator, which is voltage controlled, may be insufficient to adequately avoid transient voltage instability. By providing an actuator signal from a load to act as a pre-emptive or forward feed to an electrical current controlled generator, that second electrical current generator can be arranged to provide additional or reduced electrical current to avoid system voltage instability.

Generating system

An earthing arrangement for a DC electrical system (), the electrical system () comprises a plurality of earthing points (A,B,C) and each earthing point (A,B,C) is directly and permanently connected to earth () by a high impedance connection (A,B,C). Each earthing point (A,B,C) is selectively connectable to earth () in electrical parallel with the high impedance connection (A,B,C) by a solid connection (A,B,C) and a switch (A,B,C). In first mode of operation the switch (A) between the earthing point (A) and the earth () of only one of the plurality of earthing points (A,B,C) is closed.

Earthing arrangement for a DC electrical system and a method of operating an earthing arrangement for a DC electrical system

Electrical power generation systems typically comprise an electrical power distribution arrangement in which a number of electrical power generators are coupled in parallel. In such circumstances in order to avoid conflict generally a first electrical power generator is controlled with a voltage controller while second electrical power generators have electrical current controllers. As loads are switched into and out of the electrical distribution system in normal operation the first electrical power generator and its voltage controller can accommodate voltage dynamics and therefore maintain a desired voltage. However, in order to accommodate heavier loads switching, the dynamic operation of the electrical current controller is achieved through utilizing operational voltage margins from a desired voltage as control signals to the electrical current controller. A threshold is provided above which the electrical voltage margin must operate and regimes are provided to determine continued increase or fall in the operational voltage to allow continued dynamic control of the electrical current in order that voltage stability can be re-established with regard to electrical power distribution arrangements.

Method and system for electrical power generation

In a DC electrical power system used in an aircraft, an earthing arrangement is provided between electrical power supply rails in the form of a pair of capacitors with a mid electrical voltage earthing point, having an earthing path, in which electrical resistance is provided to limit electrical current flow and therefore allow continued operation despite the earth fault.

Earthing arrangement

A generator control arrangement for an electrical power generator, the arrangement comprising a controller arranged to regulate output voltage from a generator to a target value, the controller including a voltage comparator for comparing a presented voltage with a desired output voltage, the presented voltage derived in a transfer comparator by combination of a reference voltage value and an error value between a reference electrical current value and a measured electrical current value subject to a processor gain whereby the processor gain can be specifically set at zero to enable control by voltage or the processor gain can be specifically set at greater than zero to enable control by electrical current.

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Rugby, United Kingdom

Lihua Hu