METHOD AND SYSTEM FOR DETERMINING PHASOR COMPONENTS OF A PERIODIC WAVEFORM

The present disclosure relates to a method of determining phasor components of a periodic waveform, wherein the method comprises: 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 np defined by the duration (T0) of the sampling of the periodic waveform divided by the width parameter (tw) 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.

PROTECTING A TRANSFORMER COMPRISING A TAP CHANGER

The invention is concerned with a protection device, method and computer program product for protecting a transformer comprising a tap changer and a transformer arrangement comprising a transformer and a protection device. The transformer has at least two magnetically coupled windings with terminals (MT1, MT2, MT3, MT4) at which power enters and exits the transformer and a tap changer comprising 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 comprises: obtaining (32) measurements of power transmission properties (Iin, Uin, Iout, Uout) at the magnetically coupled windings, estimating (34, 38, 46) energy deposited in the impedance elements during a tap changing operation based on the measured physical properties, comparing (40) the estimated deposited energy with a failure threshold, and protecting (42) the transformer in case the threshold is exceeded, wherein the estimating of the deposited energy comprises determining the power loss of the transformer between the terminals (MT1, MT2) where power enters and the terminals (MT3, MT4) where power leaves the transformer and integrating the power loss.

RELATIVE BUSHING PARAMETER METHOD TO AVOID TEMPERATURE INFLUENCE IN TRANSFORMER ABSOLUTE BUSHING PARAMETER MONITORING

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 (S2) an absolute value for the capacitances of each of the bushings, the absolute values for the capacitances being denoted Cx, and estimating (S3) 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 Fx. X is a number representing which bushing the value is associated to and X largerthan 1. The method further comprises calculating (S4) ?-values for all C values and ?-values for all F values, according to: ?Cx = Cx - Cx+1, for all values up to, and including, ?CN-1, ?CN = CN C1, for ACN, ?Fx = Fx - Fx+1, for all values up to, and including, ?FN-1, ?FN = FN F1, for ?FN, and determining (S5) whether the ?-values are within predefined ranges.

METHOD AND DEVICE FOR DETERMINING CAPACITIVE COMPONENT PARAMETERS

The present disclosure relates to 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 comprises: 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.

A METHOD AND A SYSTEM FOR MEASURING POWER LOSS IN A POWER TRANSFORMER

The present invention relates to a system and a method for determining the power loss of a transformer (100). The method comprises measuring (201) voltage and current (V~H, I~H) at the primary side (101) of the transformer, calculating input power (202) by multiplying the measured current and voltage on the primary side (101) of the transformer; measuring (203) voltage and current (V~L, I~L) at the secondary side (102) 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 (206) a first corrected power loss by means of multiplying the input power with the nominal error ratio and subtract the output power.

A METHOD AND A SYSTEM FOR MEASURING POWER LOSS IN A POWER TRANSFORMER

The present invention relates to a system and a method for determining the power loss of a transformer (100). The method comprises measuring (201) voltage and current (V~H, I~H) at the primary side (101) of the transformer, calculating input power (202) by multiplying the measured current and voltage on the primary side (101) of the transformer; measuring (203) voltage and current (V~L, I~L) at the secondary side (102) 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 (206) a first corrected power loss by means of multiplying the input power with the nominal error ratio and subtract the output power.

METHOD AND DEVICE FOR DETERMINING CAPACITIVE COMPONENT PARAMETERS

The present disclosure relates to 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 comprises: 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.

MONITORING A TRANSFORMER COMPRISING A TAP CHANGER

The invention is concerned with a monitoring device, method and computer program product for monitoring a transformer comprising a tap changer. The transformer has at least two magnetically coupled windings and a tap changer comprising 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 comprises: obtaining (50) waveforms of measured power transmission properties recorded at the first and second transformer sides, processing (52, 54, 56) the recorded waveforms for obtaining at least one waveform (Ploss) representing a tap change operation, and extracting (56, 60) 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

The invention is concerned with a monitoring device, method and computer program product for monitoring a transformer comprising a tap changer. The transformer has at least two magnetically coupled windings and a tap changer comprising 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 comprises: obtaining (50) waveforms of measured power transmission properties recorded at the first and second transformer sides, processing (52, 54, 56) the recorded waveforms for obtaining at least one waveform (Ploss) representing a tap change operation, and extracting (56, 60) information indicative of the performance of the tap change from the at least one waveform that represents the tap change operation.

PROTECTING A TRANSFORMER COMPRISING A TAP CHANGER

The invention is concerned with a protection device, method and computer program product for protecting a transformer comprising a tap changer and a transformer arrangement comprising a transformer and a protection device. The transformer has at least two magnetically coupled windings with terminals (MT1, MT2, MT3, MT4) at which power enters and exits the transformer and a tap changer comprising 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 comprises: obtaining (32) measurements of power transmission properties (Iin, Uin, Iout, Uout) at the magnetically coupled windings, estimating (34, 38, 46) energy deposited in the impedance elements during a tap changing operation based on the measured physical properties, comparing (40) the estimated deposited energy with a failure threshold, and protecting (42) the transformer in case the threshold is exceeded, wherein the estimating of the deposited energy comprises determining the power loss of the transformer between the terminals (MT1, MT2) where power enters and the terminals (MT3, MT4) where power leaves the transformer and integrating the power loss.

METHOD AND SYSTEM FOR DETERMINING PHASOR COMPONENTS OF A PERIODIC WAVEFORM

The present disclosure relates to a method of determining phasor components of a periodic waveform, wherein the method comprises: 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 np defined by the duration (T0) of the sampling of the periodic waveform divided by the width parameter (tw) 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 Measuring Power Loss In A Power Transformer

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. 1. A method for determining power loss in a transformer , comprising:measuring voltage and current at a 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 a secondary side of the transformer;calculating output power by multiplying the measured current and voltage on the secondary side of the transformer;calculating a nominal error ratio;calculating a first corrected power loss by means of multiplying the input power with a first correction factor which is the complex conjugate of the nominal error ratio and subtract the output power{'sup': '˜', 'claim-text': {'br': None, 'i': n', '/n, 'sup': '˜', 'sub': IL', 'IH, '=(1+ε)/(1+ε)'}, 'wherein the nominal error ratio n/n is{'sub': IL', 'IH, 'where εis a complex number representing the error in the current measurement on the secondary side of the transformer, and εis a complex number representing the error in the current measurement on the primary side of the transformer.'}2. The method according to claim 1 , further including:calculating a voltage error ratio; andwherein the calculation of the corrected power loss further involves multiplying the output power with the voltage error ratio.3. The method according to claim 2 , wherein the voltage error ...

Protecting a transformer comprising a tap changer

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 (MT1, MT2, MT3, MT4) 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 ...

Method And System For Determining Phasor Components Of A Periodic Waveform

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. 115-. (canceled)16. A method of determining phasor components of a periodic waveform , wherein the method comprises:a) sampling the periodic waveform,{'sub': p', '0', 'w', '0', 'w', 'w', '0, 'b) determining a frequency spectrum of the sampled periodic waveform by means of a frequency transform utilizing a Gaussian window, wherein a ratio ndefined by the duration (T) of the sampling of the periodic waveform divided by the width (t) of the Gaussian window is at least 5, where the Gaussian window is defined by the Gaussian function ê(−((t−T/2)/t)̂2), where tis the width of the Gaussian window and Tis the duration of the sampling of the periodic waveform,'}{'b': 0', '6, 'c) selecting a region of the frequency spectrum containing a frequency peak (P) defined by a group of consecutive frequency bins (H-H) each being defined by a frequency value and a magnitude value, and'}{'b': 0', '6, 'd) determining phasor components of the periodic waveform based on the group of consecutive frequency bins (H-H).'}17. The method according to claim 16 , wherein step d) involves estimating an amplitude of the frequency peak and a frequency of the frequency peak by adapting the amplitude and frequency of a Gaussian function that is based on the Fourier transform of the ...

Method and system for determining phasor components of a periodic waveform

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 np defined 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.

Monitoring A Transformer Comprising A Tap Changer

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. 11214. A monitoring device for monitoring a transformer comprising a tap changer , said transformer having at least two magnetically coupled windings arranged at a first and a second transformer side and the tap changer having impedance elements (R , R) and a switch configured to gradually pass the impedance elements when changing between two tap changer positions (P , P) during a tap change operation , the monitoring device comprising:a waveform analyzer operative toobtain waveforms of measured power transmission properties (Iin, Uin, Iout, Uout) recorded at the first and second transformer sides, said measured power transmission properties being currents and/or voltages,process the recorded waveforms for obtaining at least one waveform representing a tap change operation, andextract information (ODT, AMP) indicative of the health of the tap change from said at least one waveform that represents the tap change operation,wherein the extracted information includes an operation duration time (ODT) covering at least a part of the tap change operation and/or an amplitude (AMP) of said at least one waveform representing the tap change operation ...

Method and system for measuring power loss in a power transformer

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 for monitoring transformer bushings and a system therefor

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 and device for determining capacitive component parameters

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.

Protecting A Transformer Comprising A Tap Changer

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. 112341214. A protection devices for protecting a transformer comprising a tap changer , said transformer having at least two magnetically coupled windings with terminals (MT , MT , MT , MT) at which power enters and exits the transformer , and the tap changer having impedance elements (R , R) and a switch configured to gradually connect the impedance elements when changing between two tap changer positions (P , P) during a tap changing operation , the protection device including:a control unit operative toobtain measurements of power transmission properties (Iin, Uin, Iout, Uout) at the magnetically coupled windings,estimate energy deposited in the impedance elements during a tap changing operation based on the measured power transmission ...

Method and apparatus for transformer diagnosis

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.

Method And Device For Determining Capacitive Component Parameters

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. 1. 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 comprises:a) obtaining for each capacitive component a respective capacitance value and loss-factor value, andb) 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,wherein the processing involves transforming by means of a first eigenvector matrix a capacitance vector for which each element is a respective one of the capacitance values, to obtain a transformed capacitance vector, and transforming back the transformed capacitance vector with the inverse of an adjusted first eigenvector matrix to obtain an adjusted capacitance vector, which as its elements contains the temperature-compensated capacitance values, wherein the adjusted first eigenvector matrix has the elements of one of the eigenvectors set to zero, wherein the eigenvector which has its elements set to ...

Monitoring a transformer comprising a tap changer

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.

Method And Apparatus For Transformer Diagnosis

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. 1. A transformer diagnosis method for a transformer having at least a load winding and a source winding , the method comprising:collecting, in a transformer diagnosis apparatus comprising a processor, for at least two different transformer loads, measurements of a current being indicative of the transformer load, and measurements of at least one further transformer AC signal;deriving, in the transformer diagnosis apparatus from the collected measurements, at least two values of a quantity which depends on at least one transformer property as well as on transformer load;determining, in the transformer diagnosis apparatus from the derived values, a set of coefficient(s) of a relation for how said quantity is expected to vary with transformer load, characterized bysaid relation being based on a transformer model in which effects of magnetizing currents in the transformer core, leakage inductances and effective resistances of the primary and secondary windings are taken into account, and wherein at least one parameter of the model corresponds to one of said at least one transformer property; andusing at least one of said coefficient(s) in ...

Method for Monitoring Transformer Bushings and a System Therefor

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. 1. A method for monitoring transformer bushings , comprising:recording time series comprising information from a first bushing sensor, a second bushing sensor, a third bushing sensor, and a fourth bushing sensor, wherein the first bushing sensor and the second bushing sensor are connected to a common first phase of a high voltage source, and the third bushing sensor and the fourth bushing sensor are connected to a common second phase of the high voltage source;generating a first time series comprising information from the first bushing sensor and the second bushing sensor during a predetermined time interval;generating a second time series, substantially simultaneously with the first time series, comprising information from the third bushing sensor and the fourth bushing sensor during the predetermined time interval;generating a correlation model for the first time series and the second time series;measuring a first signal corresponding to a measurement of the first time series;measuring a second signal corresponding to a measurement of the second time series;determining a difference between the measured first signal or the measured second signal, and an estimated first signal or an estimated second signal being estimated by means of the ...

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

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

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 (S2) an absolute value for the capacitances of each of the bushings, the absolute values for the capacitances being denoted C x , and estimating (S3) 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 . X is a number representing which bushing the value is associated to and X larger than 1. The method further comprises calculating (S4) Δ-values for all C values and Δ-values for all F values, according to: Δ C X = C X - C X+1 , for all values up to, and including, ΔC N-1 , Δ C N = C N - C 1 , for ΔC N , Δ F X = F X - F X+1 , for all values up to, and including, ΔF N-1 , Δ F N = F N - F 1 , for ΔF N , and determining (S5) whether the Δ-values are within predefined ranges.

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

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 x , 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 . 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 C X =C X −C X+1 , for all values up to, and including, Δ C N−1 , Δ C N =C N −C 1 , for Δ C N , Δ F X =F X −F X+1 , for all values up to, and including, Δ F N−1 , Δ F N =F N −F 1 , for Δ F N , and determining whether the Δ-values are within predefined ranges.

A method for monitoring transformer bushings, and a system therefor

The present invention relates to a method and a system for monitoring transformer bushings. The method comprises recording time series (401,402) comprising information from a first bushing sensor, a second bushing sensor, a third bushing sensor, and a fourth bushing sensor, wherein the first bushing sensor and the second bushing sensor are connected to a common first phase of a high voltage source, and the third bushing sensor and the fourth bushing sensor are connected to a common second phase of the high voltage source. The method further comprises generating a first time series comprising information from the first bushing sensor and the second bushing sensor during a predetermined time interval, generating a second time series, substantially simultaneously with the first time series, comprising information from the third bushing sensor and the fourth bushing sensor during the predetermined time interval, and generating a correlation model (403) for the first time series and the second time series measuring a first signal (404) corresponding to a measurement of the first time series, measuring a second signal (405) corresponding to a measurement of the second time series, determining a difference (406) between the measured first signal or the measured second signal, and an estimated first signal or an estimated second signal being estimated by means of the correlation model and the measured first or second signal, and generating a signal indicative of a bushing problem (407) if it is determined that the determined difference is larger than a predetermined threshold value.

Monitoring a transformer comprising a tap changer

The invention is concerned with a monitoring device, method and computer program product for monitoring a transformer comprising a tap changer. The transformer has at least two magnetically coupled windings and a tap changer comprising 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 comprises: obtaining (50) waveforms of measured power transmission properties recorded at the first and second transformer sides, processing (52, 54, 56) the recorded waveforms for obtaining at least one waveform (Ploss) representing a tap change operation, and extracting (56, 60) information indicative of the performance of the tap change from the at least one waveform that represents the tap change operation.

Determining states of electrical equipment using variations in diagnostic parameter prediction error

Embodiments are disclosed for determining states of electrical equipment using diagnostic parameter prediction error. A prediction error value is determined for a plurality of predicted diagnostic parameter values over a predetermined time period for at least one component of an electrical equipment. The prediction error value suppresses variations observed in behavior of the at least one component. The determined prediction error value is compared to an expected prediction error value. An indication of a state of the at least one component is selectively generated based on the comparison.

Pressure pulse diagnostics of an oltc

The disclosure relates to a method for monitoring a vacuum on-load tap changer (1) comprising determining (S4) a total main vacuum interrupter opening time (TMV) as a time elapsed between a first point in time (t1) and a second point in time (t2), a total resistor vacuum interrupter opening time (TRV) as a time elapsed between the third point in time (t3) and the fourth point in time (t4), a circulating current time (TCC) as a time elapsed between the second point in time (t2) and the third point in time (t3), and/or a switch time (TS) as the sum of the total main vacuum interrupter opening time (TMV), the total resistor vacuum interrupter opening time (TRV) and the circulating current time (TCC).

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

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 Cx, 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 Fx. 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:ΔCX=CX−CX+1, for all values up to, and including, ΔCN−1,ΔCN=CN−C1, for ΔCN,ΔFX=FX−FX+1, for all values up to, and including, ΔFN−1,ΔFN=FN−F1, for ΔFN,and determining whether the Δ-values are within predefined ranges.

Pressure pulse diagnostics of an on-load tap changer

The disclosure relates to a method for monitoring a vacuum on-load tap changer (1) comprising determining (S4) a total main vacuum interrupter opening time (TMV) as a time elapsed between a first point in time (t1) and a second point in time (t2), a total resistor vacuum interrupter opening time (TRV) as a time elapsed between the third point in time (t3) and the fourth point in time (t4), a circulating current time (TCC) as a time elapsed between the second point in time (t2) and the third point in time (t3), and/or a switch time (TS) as the sum of the total main vacuum interrupter opening time (TMV), the total resistor vacuum interrupter opening time (TRV) and the circulating current time (TCC).

Dispositivo de proteção e método para a proteção de um transformador

A presente invenção refere-se a um dispositivo de proteção, a um método e a um produto de programa de computador para a proteção de um transformador que compreende um comutador de derivação e uma disposição de transformador que compreende um transformador e um dispositivo de proteção. O transformador tem pelo menos dois enrolamentos acoplados de maneira magnética aos terminais (MT1, MT2, MT3, MT4) nos quais a energia entra e sai do transformador e um comutador de derivação que inclui os elementos de impedância e um interruptor configurado para conectar de forma gradual os elementos de impedância quando alterar entre duas posições do comutador de derivação durante uma operação de comutação de derivação. O método é realizado no dispositivo de proteção e compreende: obter (32) as medições de propriedades de transmissão de energia (Iin, Uin, Iout, Uout) nos enrolamentos acoplados de maneira magnética; estimar (34, 38, 46) a energia depositada nos elementos de impedância durante uma operação de comutação de derivação com base nas propriedades físicas medidas; comparar (40) a energia depositada estimada com um limite de falha; e proteger (42) o transformador caso o limite seja ultrapassado, em que a estimativa da energia depositada compreende determinar a perda de energia do transformador entre os terminais (...).

Sistema e método para determinar perda de energia em um transformador, meio legível por computador e sinal

A presente invenção refere-se a um sistema e a um método de determinação da perda de energia de um transformador (100). O método compreende medir (201) a voltagem e corrente (V~H, I~H) no lado primário (101) do transformador, calcular a energia de entrada (202) pela multiplicação da corrente e da voltagem medidas no lado primário (101) do transformador; medir (203) a voltagem e a corrente (V~L, I~L) no lado secundário (102) do transformador, calcular uma razão de erro nominal, calcular a energia de saída pela multiplicação da corrente e voltagem medidas no lado secundário do transformador. O método envolve adicionalmente o cálculo (206) de uma primeira perda de energia corrigida por meio da multiplicação da energia de entrada pela razão de erro nominal e subtração da energia de saída.

Monitoring of a power device

The present disclosure relates to a method for monitoring a power device. The method comprises 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 comprising at least one sensor and a monitoring device.

Monitoring of a power device

The present disclosure relates to a method for monitoring a power device. The method comprises 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 comprising at least one sensor and a monitoring device.

Monitoring of a power device

The present disclosure relates to a method for monitoring a power device. The method comprises 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 comprising at least one sensor and a monitoring device.

A method and a fault locator system for determining a location of a fault in a transmission line

A method (1000) and a fault locator system (100) for determining a location of a fault in a transmission line are provided. The method comprises determining (1001) arrival times of travelling waves at a first location and a second location, determining (1002) the location of the fault based at least on a difference between the first and second arrival times and a wave speed of travelling waves along the transmission line, sampling (1010) signals of the transmission line, at a modulation rate, using Delta-Sigma modulation at the first and second locations, filtering (1021) the signals sampled at the first and second locations, and providing (1025), at an output rate, output samples based on the filtered signals, wherein the determination of the arrival times are based on sets of the output samples, and wherein the modulation rate is higher than the first and second sampling rates.

Dispositivo de monitoramento para monitorar um transformador e método para o monitoramento de um transformador

A presente invenção refere-se a um dispositivo de monitoramento, a um método e a um produto de programa de computador para monitorar um transformador que compreende um comutador de derivação. O transformador tem pelo menos dois enrolamentos acoplados de maneira magnética e um comutador de derivação que compreende os elementos de impedância e um comutador configurado para passar de forma gradual os elementos de impedância ao comutar entre duas posições do comutador de derivação durante uma operação de comutação de derivação. O método é realizado no dispositivo de monitoramento e compreende: obter (50) as formas de onda de propriedades de transmissão de energia medidas registradas no primeiro e no segundo lado do transformador; processar (52, 54, 56) as formas de onda registradas para obter pelo menos uma forma de onda (Ploss) que representa uma operação de comutação; e extrair (56, 60) a informação indicativa do desempenho da comutação de derivação a partir de pelo menos uma forma de onda que representa a operação de comutação de derivação.

Monitoring a transformer comprising a tap changer

A method for monitoring a transformer (10) comprising a tap changer (16), wherein extracted information comprises a circulating current amplitude (A_C) and/or a circulating current time (tc) covering at least a part of the tap change operation represented by at least one current difference waveform, and/or a transition current time (t_R) covering at least a part of the tap change operation represented by at least one power loss waveform.

Substation equipment monitoring using a scada system

There is provided mechanisms for monitoring substation equipment. A method is performed by a SCADA system. The method comprises obtaining data/signal values of parameters monitored in the substation equipment. The method comprises associating each data/ signal value with at least one attention indicator. The method comprises determining one attention indicator value for each of the attention indicators by processing those data/ signal values that are associated with the respective attention indicators. All attention indicators for all monitored parameters have one and the same nominal attention indicator value acting as a threshold for abnormal behavior of the substation equipment. The method comprises providing an alert indication to a human machine interface (HMI) when at least one of the attention indicator values is above the nominal attention indicator value.

Monitoring a transformer comprising a tap changer

A method for monitoring a transformer (10) comprising a tap changer (16), wherein extracted information comprises a circulating current amplitude (AC) and/or a circulating current time (tC) covering at least a part of the tap change operation represented by at least one current difference waveform, and/or a transition current time (tR) covering at least a part of the tap change operation represented by at least one power loss waveform.

Monitoring of a power device

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.