Abstract: A method and system for measuring broadband impedance of a renewable energy power generation device. A voltage disturbance is injected into the renewable energy power generation device by using a disturbance injection device, and three-phase voltage and three-phase current of each of preset measurement points are acquired. Relevant variables before the renewable energy power generation device is decoupled from a measurement device and impedance of a power grid, are calculated according to the three-phase voltage and the three-phase current of each of the preset measurement points. Impedance of the renewable energy power generation device after being decoupled from the measurement device and the impedance of the power grid, is calculated.

Abstract: A method for monitoring the condition of a coil, wherein the coil is part of a device for determining at least one process variable of a medium in a container, includes applying an electrical excitation signal to the coil and receiving an electrical reception signal from the coil, determining a first value for the reception signal at a first predefinable measurement time, comparing the first value for the reception signal at the first measurement time with a reference value, and determining a condition indicator for the coil on the basis of the comparison. Disclosed also is a device that is designed for carrying out the disclosed method.

Abstract: A circuit for measuring the conductivity of a medical fluid, the circuit comprising: a data collecting cell through which a medical fluid is configured to flow; an input voltage source that provides an input voltage to the data collecting cell; a voltage measurement unit configured to measure the input voltage and an output voltage of the data collecting cell; and a switch in communication with the voltage measurement unit, the switch configured to switch between a first state in which the voltage measurement unit is configured to measure the input voltage and a second state in which the voltage measurement unit is configured to measure the output voltage of the data collecting cell.

Abstract: The invention relates to a method for state monitoring of a coil that is part of a device for determining at least one process variable of a medium in a containment. The method includes supplying the coil with an electrical excitation signal and receiving an electrical, received signal from the coil, ascertaining a first frequency for the excitation signal, in the case of which a first phase shift between the excitation signal and received signal is less than a predeterminable limit value, and ascertaining a state indicator for the coil based on the first frequency. Further disclosed is a device embodied for performing a method of the invention.

Abstract: A system and method for estimation of grid impedance in a power converter controller is disclosed in which a current controller is provided to inject an injection current while operating online and coupled to a power grid at a point of common coupling (PCC), the injection current being benign to an operating current of the power converter. A voltage controller is provided to regulate input voltage of the power converter. An impedance module is provided to determine parameters for the injection current, including injection interval and duration, current magnitude, current frequency, and symmetrical components. The impedance module may extract measurements of current and voltage at the PCC at an operating point shifted from a previous operating point in response to the injection current. The impedance module may extract symmetrical components of current and voltage measurements, and compute estimated grid impedance based on the extracted symmetrical components.

Abstract: A method for detecting low-frequency oscillations, in particular subsynchronous resonances, in a grid is provided. The method includes recording a series of measurements, having measurement points, of a grid variable over a measurement time period, for performing a frequency analysis and multiplying the series a time-dependent sinusoidal test function for the same measurement time period. The test function is characterized by a test frequency and a test angle as phase angle. The series for each measurement point is multiplied by the test function in order to obtain a test product for each measurement point. The method includes adding the test products taking into consideration the mathematical sign thereof to give a product sum, and evaluating, depending on the product sum, whether the series of measurements has a low-frequency oscillation having a frequency in the region of the test frequency and a phase angle in the region of the test angle.

Abstract: The application involves a stability evaluation method and system of direct-drive wind turbine generator, which belongs to the technical field of wind power generation. It solves the problems of poor stability of direct-drive wind turbine generator, low safety performance, failure to realize mutual cooperation between online stability evaluation and parameter adjustment in the existing technology. Firstly, the variation of direct-drive wind turbine generator terminal voltage, current, power and PLL angle of direct-drive wind turbine generator is measured, the terminal energy and the energy negative gradient of direct-drive wind turbine generator is calculated. Then, the system stability is assessed according to the value of energy negative gradient, the influence of the critical parameters on system stability is analyzed and the preliminary adjustment strategy is proposed.

Abstract: The present disclosure refers to a method of measuring resistance of the resistive sensor (5), where the value of resistance of the resistive sensor (5) is determined from its series connection with actively controlled resistor network (3) with selectable value of resistance and with a periodic waveform voltage source (7), and further a device for measuring resistance of the resistive sensor (5) including a periodic waveform voltage source (7), actively controlled resistor network (3), and a resistive sensor (5), wherein the terminals of the periodic waveform voltage source (7) are connected to the first node (2) and the third node (6), terminals of actively controlled resistor network (3) are connected to the first node (2) and the second node (4), and terminals of the resistive sensor are connected to the second node (4) and the third node (6), thus forming a connection in a resistive voltage divider with an automatic selection of one resistor of the divider, and usage of this method for measuring time-vary

Abstract: The present invention relates to a method for monitoring state of a coil having at least two connection wires, which coil is part of an apparatus for determining at least one process variable of a medium in a containment, as well as relating to an apparatus for executing the method. The method, in such case, includes method steps as follows: ascertaining a desired-value of an ohmic total resistance for the coil and the connection wires, supplying the coil with an electrical excitation signal and receiving an electrical, received signal from the coil by means of the two connection wires, ascertaining an actual-value of the ohmic total resistance based at least on the received signal, and comparing the actual-value with the desired-value and ascertaining a state indicator based on the comparison.

Abstract: A parameter monitor and method for monitoring a parameter of a passive component on an integrated circuit. The parameter monitor includes an oscillator circuit. The parameter monitor also includes circuitry configured to measure a first time period of an oscillation of the oscillator circuit with a passive component to produce a first digital count value, to measure second time period of an oscillation of the oscillator circuit without the passive component to produce a second digital count value, and generate a code indicative of a value of or a variation in the value of the passive component using the first and second digital count values.

Abstract: The invention relates to an apparatus for measuring the human body temperature. It comprises of an infrared temperature sensor for performing temperature sampling on a plurality M×N of sampling points, M?3, N?3. The temperatures of the sampling points with temperatures within the effective temperature range of the human body are averaged to obtain the body temperature of the human body. By collecting the temperatures of a plurality of sampling points of the measured object, the invention effectively avoids the errors that measurement of single point may produce (as may be caused by factors such as the environment); by screening for temperatures within the effective temperature range of the human body, the invention effectively avoids errors or interference produced by factors such as clothing or the environment. The improved accuracy and real-time measurement of body temperature bring convenience to people's lives.

Abstract: The disclosure relates to a detection method for an inverter for detecting a grid fault in a power supply grid, includes determining a grid impedance (Z) and/or the rate of change thereof with respect to time (dZ/dt) and/or a rate of change of an absolute value of the grid impedance (Z) with respect to time (d|Z|/dt), comparing the absolute value and/or a real part and/or an imaginary part of the grid impedance (Z) and/or the rate of change thereof with respect to time (dZ/dt) and/or the rate of change of the absolute value of the grid impedance (Z) with respect to time (d|Z|/dt) with respective predetermined limit values. The method also includes detecting a grid fault state based on the comparison, wherein a distinction is drawn between an islanding situation (AID) and a fault ride through (FRT) situation, and signaling an existing islanding situation (AID) or a fault ride through (FRT) situation as a grid fault state.

Abstract: An apparatus includes a voltage source, voltage measurement means and a processing means, and connects to a line to apply and monitor a voltage between the line and earth. The processing means controls the voltage source to transmit and receive communications from the line, via the voltage measurement means. The apparatus also has a first and second current measurement means. The voltage source is connectable to a wire under test to inject a predetermined test voltage on the wire. The wire extends in a first and second direction from the test location. The first current measurement means measures the leakage current from the voltage source flowing along the wire in a first direction, and the second current measurement means determines the leakage current along the wire in a second direction, and the processing means uses the current flows measured by both current measurement means to determine wire insulation properties.

Abstract: A method and apparatus for monitoring an AC line for impedance change. In one embodiment, the method, comprises superimposing a tone on an AC current coupled to the AC line, wherein the tone is a higher frequency than an AC voltage waveform on the AC line; applying a correlation over a sampled AC voltage waveform, obtained by sampling the AC voltage waveform, to generate a correlated signal; and determining whether at least one change in characteristic of the correlated signal occurs.

Abstract: The dry running detection system for a pump includes an ultrasonic transducer (8) designed for arrangement inside a pump housing (24) and electrically connected to a frequency generator (2) producing an electrical signal having a predefined frequency. An analyzing unit (10) of the system analyses the electrical signal applied to the ultrasonic transducer (8) and is designed to detect whether the ultrasonic transducer (8) is in contact with a liquid or not on basis of the signal level of the electrical signal.

Abstract: Measurement devices, systems, and methods to measure a high field conductivity of a fluid are provided herein. The measurement device includes a fluid cell, a pair of electrodes, a voltage switch, and a measurement unit. The fluid cell is on an inclined plane to receive the fluid. The pair of electrodes are connected to the fluid cell. The pair of electrodes are spaced apart from one another to receive the fluid therebetween and positioned parallel to one another to pass an electrical current therethrough. The power unit provides a high voltage power supply to one electrode of the pair of electrodes. The measurement unit measures the electrical current that passes between the pair of electrodes through the fluid.

Abstract: A method and apparatus for monitoring an AC line for impedance change. In one embodiment, the method, comprises superimposing a tone on an AC current coupled to the AC line, wherein the tone is a higher frequency than an AC voltage waveform on the AC line; applying a correlation over a sampled AC voltage waveform, obtained by sampling the AC voltage waveform, to generate a correlated signal; and determining whether at least one change in characteristic of the correlated signal occurs.

Abstract: An antenna is used for radio frequency measurements of cell wall impedance changes due to ion channels. The antenna provides enhanced direct readout of lipid bilayers and cells containing pores and ion channels. The antenna is placed around a nanopore, which may be fabricated from glass, quartz or other material, and is shaped to provide an enhanced sensitivity to electrical activity in the vicinity of the nanopore. As such, the antenna may be of a class of bi-cone- or other stub-antennas providing high gain and broad bandwidth, for example a planar variant of a “bow-tie” antenna. Accordingly, improved sensitivity of at least an order of magnitude may be achieved over past systems.

Abstract: A method for multichannel multifrequency analysis of an object, applying a set of excitation signals to the object and sampling the response signal from the object, using uniform and non-uniform undersampling. Non-uniform sampling of the response signal is performed, i.e., the sampling is performed for two or more different frequencies in one observation time slot. Also, uniform sampling of the response signal is performed, i.e., the sampling of a signal, corresponding to one frequency, is performed for two or more channels within one observation time slot and then sampling the same signal for another frequency for two or more channels within the next observation time slot.

Abstract: A disturbance on an electric signal at an electric connection between an electric power generating system and a power grid is decomposed into a first disturbance with a first strength assigned to the electric power generating system and a second disturbance with a second strength assigned to the power grid. A voltage value of a voltage of the electric signal is measured. A current value of a current of the electric signal is measured. A value of an open circuit voltage of an equivalent voltage source is calculated based on the measured voltage value, the measured current value and a characteristic equivalent impedance of the electric power generating system so that the electric power generating system is in a harmonic model. The strength of the first disturbance is determined based on the calculated value of the open circuit voltage of the equivalent voltage source.

Abstract: A method of measuring biological sample properties and a biological sample property measuring apparatus is provided. A method of measuring biological sample properties includes disposing a biomaterial to contact a sensing unit, detecting a radio frequency (RF) signal flowing through the sensing unit, and obtaining an RF property indicator of the biomaterial based on the detected RF signal.

Abstract: A sensor having integrated electrodes in a single sensor configuration, which is operated by alternating current (AC) including periodic electrical excitation signals of the respective multiple frequencies with the same amplitude for detecting analytes in fluids. The sensor applies a total of an odd number of the identical conductors serving as the respective electrodes, which are positioned equally spaced apart, in order, alignment and parallel with each other. The odd numbered conductors of the total conductors are connected in parallel by a first electrically conducting means serving as a first electrical pole to form a first group of the integrated electrodes. The even numbered conductors are connected in parallel by a second electrically conducting means serving as a second electrical pole to form a second group of the integrated electrodes. The present invention sensor possesses properties of high output, reduced physical size and improved electrical characteristics.

Abstract: A device (10) is disclosed that is suitable for testing an earth connection (30) that is isolated from a mains electricity supply. The device (10) comprises means (14, 40) for electrically connecting the device (10) to the earth connection (30), and means (16, 32) for electrically connecting the device (10) to an electrically conductive item (20) having a capacitance relative to an adjacent surface of the earth that is within a pre-determined range of capacitances. Furthermore, the device (10) includes means for generating an AC signal and delivering the AC signal to the electrically conductive item, and means for determining whether the resistance between the earth connection (30) and earth reference potential is less than a maximum earth resistance value. This determination is achieved by comparing the frequency of the generated AC signal with a pre-determined range of frequencies.

Abstract: An interrogation circuit for a nanowire sensor array and a method for interrogating a nanowire sensor array are provided. The circuit comprises a switch array connected to the nanowire sensor array for selectively connecting first ends of nanowire sensors of the nanowire sensor array to a reference voltage; an integration amplifier (IA) connected to second ends of the nanowire sensors at a first input of the IA and to the reference voltage at a second input of the IA, for generating an oscillating output signal clamped between first and second voltage values; wherein the switch array is further arranged for switching one of the nanowire sensors to be connected in a closed loop with the IA such that a current through said one nanowire sensor periodically charges and discharges an integration capacitor of the IA for determining a resistance of said one nanowire sensor from a frequency of the periodic charging and discharging.

Abstract: A method and apparatus for monitoring an AC line for impedance change. In one embodiment, the method, comprises superimposing a tone on an AC current coupled to the AC line, wherein the tone is a higher frequency than an AC voltage waveform on the AC line; applying a correlation over a sampled AC voltage waveform, obtained by sampling the AC voltage waveform, to generate a correlated signal; and determining whether at least one change in characteristic of the correlated signal occurs.

Abstract: Measuring device for local measurement of an electrical property of the content of a container, wherein at least three electrodes are disposed adjacently of each other in height direction and electrically insulated from each other, wherein each of the electrodes can be connected to an electrical measuring circuit for measuring, via one of the electrodes and one other electrode connected to an electrical earth, the electrical property of the content of the container in the vicinity of the electrodes, and wherein the electrical measuring circuit is adapted to generate at least one electric measuring signal representing the measured electrical property, and a control unit for connecting the one electrode to the electrical measuring circuit and connecting the other electrode to an electrical earth.

Abstract: A variable speed drive for an electric motor has an inverter for receiving pulse width modulation controls. The inverter communicates power signals to a poly-phase electrical motor. A resolver communicates signals from the poly-phase motor back to a motor control. The motor control includes a speed control, a field-oriented control, and a pulse width modulation drive for driving the inverter. The resolver is connected to the speed control and to the field-oriented control, and further communicates with a synchronous compensator. The synchronous compensator is configured to drive the harmonic content at a target frequency or frequencies in a selected signal towards zero over time.

Abstract: A method and device for determining the linear response of an electrical multi-port component has an “estimation procedure” in which an estimated admittance matrix is determined by applying voltages to the ports of the component and measuring the response of the component. The estimation procedure can e.g. consist of a conventional measurement of the admittance matrix. The method further has a “measurement procedure” in which several voltage patterns are applied to the port. The voltage patterns correspond to the eigenvectors of the estimated admittance matrix. For each applied voltage pattern, the response of the component is measured. This allows to measure the linear response of the component accurately even if the eigenvalues of the admittance matrix differ by several orders of magnitude.

Abstract: A plasma processing apparatus includes a radio frequency generator capable of adjusting a target output power level based on the set power level and the offset level to output radio frequency power; a chamber in which a plasma process is performed; and a power detection unit for measuring radio frequency power level fed to the matching unit. The plasma processing apparatus further includes a generator control unit for controlling the radio frequency power such that the radio frequency power level fed to the matching unit reaches the set power level by calculating the offset level based on the difference between the set power level and the power level measured by the power detection unit and transmitting the set power level and the offset level in digital form to the data input terminal of the radio frequency generator.

Abstract: A method is provided for measuring D-Q impedance of a component of a polyphase power grid connected to a grid node, and evaluating the margin of stability at a node using Nyquist diagrams generated from the measured D-Q impedance data. A generator, coupled to the polyphase power grid, is controlled to induce suppressed-carrier stimulus current into the grid node. Circuitry measures response signals of suppressed-carrier form existing within a bus voltage at the grid node and a branch current of the component being measured. The method includes measuring complex voltage components of the response signals contained in the bus voltage and complex current components of the response signals contained in the branch current to form simultaneous equations that are resolved to determine the D-Q impedance parameters Zqq, Zqd, Zdq and Zdd of the measured component.

Abstract: An apparatus and associated method is provided for suspending a test object in a gravitational field from a support member, exciting the test object by noncontactingly engaging it with a predetermined waveform force, and characterizing the test object qualitatively in relation to an observed modal frequency response of the test object to the excitation.

Abstract: An electronic analysis circuit for a multicontact passive-matrix tactile sensor including an electrical supply mechanism powering one of two axes of the matrix, and a mechanism detecting electrical characteristics along the other axis of the matrix, at nodes between the two axes. At least one scanning characteristic is modulated locally or temporally. A multicontact passive-matrix tactile sensor can include such an electronic analysis circuit.

Abstract: Methods to test the operation of the pick-up coil without having to de-energize the power line serving as the power line carrier in order to perform testing on the pick-up coil. A series of at least one test frequency is introduced and parameters of the pick-up coil can be measured to detect the presence or absence of resonant behavior indicative of the health of the pick-up coil. Testing capabilities may be incorporated into a power line carrier receiver and use the connections between the pick-up coils and the receiver to perform the pick-up coil test. Several methods for evaluating the pick-up coil response to a series of test inputs of different frequencies are presented. These methods could be incorporated in a pick-up coil testing device that is independent of a receiver.

Abstract: Methods to test the operation of the pick-up coil without having to de-energize the power line serving as the power line carrier in order to perform testing on the pick-up coil. A sweep wave is introduced and parameters of the pick-up coil can be measured to detect the presence or absence of resonant behavior indicative of the health of the pick-up coil. Testing capabilities may be incorporated into a power line carrier receiver and use the connections between the pick-up coils and the receiver to perform the pick-up coil test. Several methods for evaluating the pick-up coil response to a series of test inputs of different frequencies are presented. These methods could be incorporated in a pick-up coil testing device that is independent of a receiver.

Abstract: A method of measuring the dielectric constant of a powder, including selecting a powder having an unknown first dielectric constant, selecting a liquid having a known second dielectric constant, and introducing a predetermined amount of powder into a predetermined volume of liquid to define a slurry characterized by a known volume fraction of powder. Next, the impedance spectra of the slurry is plotted over a predetermined frequency range, the measured dielectric constant data is read and the appropriate equivalent circuit for the slurry is determined. Appropriate equivalent circuit equations are applied to the measured dielectric constant data and the first dielectric constant is calculated from the appropriate equivalent circuit equations, known volume fraction of powder and measured dielectric constant data.

Abstract: A determination of an equivalent series resistance (ESR) effect for high frequency filtering performance of a filtered feed-through assembly is described. A low frequency signal is introduced to a filtered feed-through assembly. ESR limit of the filtered feed-through is determined based on the low frequency signal.

Abstract: A fluid sensor is constructed to have a pair of electrodes whereas between electrodes there are not additional materials designated to adsorb analytes if their concentrations are high, or there are adsorbents if the analyte concentrations are low. An alternating current voltage of varying frequencies is applied to the electrodes of the sensor by an alternating current device. In return, it detects electrical properties such as impedance and its components, reactance, resistance, and phase angles of the sensor with analytes whereas the analytes reside in or pass through the electrodes at each frequency. Thus a spectrum of electrical properties of the analyte can be established at various applied frequencies. The electrical properties are analyzed by a pattern recognition process, and compared with those of the known fluids. Therefore, the fluid can be detected and identified. A reference sensor is provided with the same configuration of the fluid sensor.

Abstract: A signal injection unit injects a test signal at a main frequency between a reference point of an electric circuit and ground, where the electric circuit is connected with the facility and injects another test signal at a second main frequency between a reference point of the electric circuit and ground. A signal conversion unit measures first and second response voltages and first and second response currents in the electric circuit, where the response voltages and the response currents result from the test signals. A processing device determines impedances to ground of the facility from the response voltages and the response currents, analyses impedances to ground of the facility, where this analysing includes comparing each determined impedance to ground with a predetermined value, and determines a safety state of the disconnected electrical facility based on the analysed impedances to ground.

Abstract: A measurement circuit that has particular application for detecting a high impedance measurement signal from a liquid water sensor. The measurement circuit includes a high impedance resistance-to-frequency conversion circuit that is coupled to the sensor and receives a resistance signal therefrom. The resistance-to-frequency conversion circuit includes an oscillator that converts the resistance signal to a representative frequency. The measurement circuit also includes a frequency-to-voltage conversion circuit that receives the frequency signal from the resistance-to-frequency conversion circuit, and converts the frequency signal to a representative voltage that provides an indication of water on the sensor.

Abstract: A method inspects a process performance of a capacitively coupled plasma processing apparatus which generates a plasma for a plasma processing by applying a radio frequency power between a first electrode and a second electrode disposed in a processing vessel to face the first electrode in parallel. The method includes measuring an impedance of a radio frequency transmission path ranging from a rear surface of the first electrode to a ground potential part and sweeping a frequency to thereby obtain a frequency characteristic of a real resistance component of the impedance; reading a specific property value of a horn-like peak which appears from the frequency characteristic of the real resistance component; and determining efficaciousness or inferiority of the process performance of the plasma processing apparatus based on the peak property value.

Abstract: A patch-clamp system employs a high-frequency characterization of cell wall membranes. Changes in the frequency response of a tank circuit incorporating the cell wall membrane impedance provides highly sensitive and highly time-resolved measurements of ion channel activity.

Abstract: A fluid sensor is constructed to have a pair of electrodes whereas between electrodes there are not additional materials designated to adsorb analytes if their concentrations are high, or there are adsorbents if the analyte concentrations are low. An alternating current voltage of varying frequencies is applied to the electrodes of the sensor by an alternating current device. In return, it detects electrical properties such as impedance and its components, reactance, resistance, and phase angles of the sensor with analytes whereas the analytes reside in or pass through the electrodes at each frequency. Thus a spectrum of electrical properties of the analyte can be established at various applied frequencies. The electrical properties are analyzed by a pattern recognition process, and compared with those of the known fluids. Therefore, the fluid can be detected and identified. A reference sensor is provided with the same configuration of the fluid sensor.

Abstract: A monitoring device for monitoring an array (4) of electrical units, in particular an array of high capacity light emitting diodes (LEDs) (4.1-4.12). The electrical units are connected in series and driven by a constant electric current (I). The monitoring device has a bypass means (4.1a-4.12a) for each electrical unit (4.1-4.12), operable to bypass the respective electrical unit in case of a disconnection of the respective electrical unit, and an evaluation unit (3) connected in parallel with the array (4) of electrical units, said evaluation unit (3) being adapted to determine a total voltage (UT) of the array (4) of electrical units and to output a control signal (CS) indicative of a function status of the array (4) of electrical units in accordance with a value of the total voltage (UT) relative to a predetermined threshold value (VREF). Thus is provided an electric circuitry which allows an easy and reliable detection of a malfunction of the array of electrical units, e.g.

Abstract: Methods to test the operation of the pick-up coil without having to de-energize the power line serving as the power line carrier in order to perform testing on the pick-up coil. A series of test frequencies are introduced and parameters of the pick-up coil can be measured to detect the presence or absence of resonant behavior indicative of the health of the pick-up coil. Testing capabilities may be incorporated into a power line carrier receiver and use the connections between the pick-up coils and the receiver to perform the pick-up coil test. Various methods are disclosed for evaluating the pick-up coil response to a series of test inputs of different frequencies. These methods could be incorporated in a pick-up coil testing device that is independent of a receiver.

Abstract: Methods to test the operation of the pick-up coil without having to de-energize the power line serving as the power line carrier in order to perform testing on the pick-up coil. A series of test frequencies are introduced and parameters of the pick-up coil can be measured to detect the presence or absence of resonant behavior indicative of the health of the pick-up coil. Testing capabilities may be incorporated into a power line carrier receiver and use the connections between the pick-up coils and the receiver to perform the pick-up coil test. Various methods are disclosed for evaluating the pick-up coil response to a series of test inputs of different frequencies. These methods could be incorporated in a pick-up coil testing device that is independent of a receiver.

Abstract: A method is provided for measuring D-Q impedance of a component of a polyphase power grid connected to a grid node, and evaluating the margin of stability at a node using Nyquist diagrams generated from the measured D-Q impedance data. A generator, coupled to the polyphase power grid, is controlled to induce suppressed-carrier stimulus current into the grid node. Circuitry measures response signals of suppressed-carrier form existing within a bus voltage at the grid node and a branch current of the component being measured. The method includes measuring complex voltage components of the response signals contained in the bus voltage and complex current components of the response signals contained in the branch current to form simultaneous equations that are resolved to determine the D-Q impedance parameters Zqq, Zqd, Zdq and Zdd of the measured component.

Abstract: A determination of an equivalent series resistance (ESR) effect for high frequency filtering performance of a filtered feed-through assembly is described. A low frequency signal is introduced to a filtered feed-through assembly. ESR limit of the filtered feed-through is determined based on the low frequency signal.

Abstract: A method for measuring a stability margin at a node of a polyphase power grid injects suppressed-carrier stimulus into a node of the power grid by low-level amplitude modulation of the output voltage of a pre-exiting generator connected to the node. Response signals are obtained and product demodulated on a per-phase basis and summed in three-phase groups. Demodulated and summed responses contain signals that represent the suppressed-carrier impedance upstream and downstream of the stimulus injection point, and are processed to determine the stability margin at the node.

Abstract: A high-frequency measurement unit includes a signal detector for detecting a high-frequency signal, and a calibration coefficient storage for storing calibration coefficients Cmin and Cmax used to calibrate a value Amin detected at the lowest limit frequency fmin and a value Amax detected at the uppermost limit frequency fmax to a proper measurement value Asmin and to a proper measurement value Asmax, respectively. The high-frequency measurement unit further includes a frequency detection unit for detecting a frequency fm of the high-frequency signal, a calibration coefficient calculation unit for calculating a calibration coefficient Cm for the frequency fm, and a calibration unit for calibrating the value Am detected by the signal detector to a proper measurement value Asm by using the calibration coefficient Cm calculated by the calibration coefficient calculation unit.

Abstract: Known measuring instruments generate a test signal for application to a target device. Linear analogue to digital converters are then used to produce data samples representing the voltage across and the current through the device and these data samples are used to calculate impedance as a function of frequency. The A/D conversion process can be expected to worsen with reducing signal levels. This problem is overcome, in the invention, by using a logarithmic level detector (9) to produce analogue signals that represent logarithms of the voltage across and current through the device (7).