Abb Schweiz Ag

Hitachi Energy Ltd

Abb Research Ltd.

Abb Power Grids Switzerland Ag

Nilanga Abeywickrama

Tord Bengtsson

Joachim Schiessling

Tommy Larsson

Cecilia Forssen

Robert Saers

Subrat Sahoo

Jonas Hedberg

Bengt-Olof Anders Stenestam

Niklas Gustavsson

Svante Karlsson

Anders Brokvist

Marko Viitala

The present disclosure relates to a method for monitoring a power device. The method includes obtaining at least one frequency spectrum of at least one physical component of the power device, wherein the at least one frequency spectrum comprises at least one eigenfrequency of the at least one physical component of the power device; measuring, using at least one sensor, a vibroacoustic signal of the power device; and determining a signal contribution of the at least one physical component of the power device to the vibroacoustic signal based on the obtained at least one frequency spectrum. The present disclosure also relates to a respective monitoring device and a system including at least one sensor and a monitoring device.

Monitoring of a power device

The disclosure relates to a method for monitoring a vacuum on-load tap changer including determining a total main vacuum interrupter opening time as a time elapsed between a first point in time and a second point in time, a total resistor vacuum interrupter opening time as a time elapsed between the third point in time and the fourth point in time, a circulating current time as a time elapsed between the second point in time and the third point in time, and/or a switch time as the sum of the total main vacuum interrupter opening time, the total resistor vacuum interrupter opening time and the circulating current time.

Pressure pulse diagnostics of an OLTC

The present invention relates to a method and monitoring device, for monitoring N number of transformer bushings operating in substantially the same environment. N being any number more than 1. The method comprises estimating an absolute value for the capacitances of each of the bushings, the absolute values for the capacitances being denoted C, and estimating an absolute value for the loss factor or the power factor of each of the bushings, the absolute values for the loss factors or the power factors being denoted F. X is a number representing which bushing the value is associated to and X larger than 1. The method further comprises calculating Δ-values for all C values and Δ-values for all F values, according to:Δ, for all values up to, and including, Δ,Δ, for Δ,Δ, for all values up to, and including, Δ,Δ, for Δ,and determining whether the Δ-values are within predefined ranges.

Relative bushing parameter method to avoid temperature influence in transformer absolute bushing parameter monitoring

A method of determining the capacitance and loss-factor of each of a plurality of capacitive components of an electrical power device, wherein the method includes: a) obtaining for each capacitive component a respective capacitance value and loss-factor value, and b) processing the capacitance values and the loss-factor values, wherein the processing involves removing a common influence of temperature on the capacitance values from the capacitance values and removing a common influence of temperature on the loss-factor values from the loss-factor values to obtain for each capacitive component a temperature-compensated capacitance value and a temperature-compensated loss-factor value.

Method and device for determining capacitive component parameters

The invention is concerned with a monitoring device, method and computer program product for monitoring a transformer having a tap changer. The transformer has at least two magnetically coupled windings and a tap changer having impedance elements and a changeover switch configured to gradually pass the impedance elements when changing between two tap changer positions during a tap change operation. The method is performed in the monitoring device and including: obtaining waveforms of measured power transmission properties recorded at the first and second transformer sides, processing the recorded waveforms for obtaining at least one waveform (Ploss) representing a tap change operation, and extracting information indicative of the performance of the tap change from the at least one waveform that represents the tap change operation.

Monitoring a transformer comprising a tap changer

A system and a method for determining the power loss of a transformer. The method includes measuring voltage and current at the primary side of the transformer, calculating input power by multiplying the measured current and voltage on the primary side of the transformer; measuring voltage and current at the secondary side of the transformer, calculate a nominal error ratio, calculating output power by multiplying the measured current and voltage on the secondary side of the transformer. The method further involves calculating a first corrected power loss by means of multiplying the input power with the nominal error ratio and subtract the output power.

Method and system for measuring power loss in a power transformer

The invention is concerned with a protection device, method and computer program product for protecting a transformer including a tap changer and a transformer arrangement including a transformer and a protection device. The transformer has at least two magnetically coupled windings with terminals (MT, MT, MT, MT) at which power enters and exits the transformer and a tap changer having impedance elements and a switch configured to gradually connect the impedance elements when changing between two tap changer positions during a tap changing operation. The method is performed in the protection device and includes: obtaining measurements of power transmission properties (Iin, Uin, Iout, Uout) at the magnetically coupled windings, estimating energy deposited in the impedance elements during a tap changing operation based on the measured physical properties, comparing the estimated deposited energy with a failure threshold, and protecting the transformer in case the threshold is exceeded, wherein the estimating of the deposited energy includes determining the power loss of the transformer between the terminals (MT, MT) where power enters and the terminals (MT, MT) where power leaves the transformer and integrating the power loss.

Protecting a transformer comprising a tap changer

A system for monitoring transformer bushings sensors, wherein first and second bushing sensors are connected to a common first phase of a high voltage source, and the third and fourth bushing sensors are connected to a common second phase of the high voltage source. A first time series is generated from the first and second bushing sensors during a predetermined time interval. A second time series, is generated from the third and fourth bushing sensors during the predetermined time interval. A correlation model for the first and second time series for determining a difference between a measured signal and an estimated signal, and generating a signal indicative of a bushing problem the difference is larger than a threshold.

Method for monitoring transformer bushings and a system therefor

A method of determining phasor components of a periodic waveform, wherein the method includes: a) sampling the periodic waveform, b) determining a frequency spectrum of the sampled periodic waveform by means of a frequency transform utilizing a Gaussian window function, wherein a ratio ndefined by the duration of the sampling of the periodic waveform divided by the width parameter of the Gaussian window function is at least 5, c) selecting a region of the frequency spectrum containing a frequency peak defined by a group of consecutive frequency bins each being defined by a frequency value and a magnitude value, and d) determining phasor components of the periodic waveform based on the group of consecutive frequency bins.

Method and system for determining phasor components of a periodic waveform

A transformer diagnosis apparatus and method which can advantageously be used for on-line diagnosis of a transformer, and by which transformer properties may be monitored and/or determined. The diagnosis method includes collecting, for at least two different transformer loads, measurements of a current being indicative of the transformer load, as well as measurements of at least one further transformer AC signal. The method further includes deriving, from the collected measurements, at least two values of a quantity which depends on a transformer property as well as on transformer load; and determining, from the derived values, a set of coefficient(s) of a relation for how the quantity is expected to vary with transformer load. The method further includes using the determined coefficient(s) in performing a diagnosis of the transformer.

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