Monitoring device

Abstract

A monitoring device (10) for monitoring a parameter value associated with an alternating current power supply or an alternating current component (12) of a power supply in an electrical distribution network (1), the monitoring device comprising: a sensor device (14) which, in use, is electrically connected to the electrical distribution network (1) or otherwise monitors the electrical distribution network (1); and a control unit (16) operable to determine a magnitude of the selected frequency for the voltage using an output of the sensor device (14). The method allows the operation of the device to be controlled as a function of supply from the network, independent of signal components from the rotating power converter.

Description

Technical Field

[0001] The present disclosure relates to a monitoring device, and more particularly to a monitoring device for monitoring the state of a generator or a power source (such as a power converter, a battery, or a mobile power source). More specifically, the present disclosure relates to a device for online monitoring of the state of a generator or a power source for a distribution network, so as to be able to use the information of the state to control the operation of a load or a device. Background Art

[0002] Due to the existence of periods with different levels of demand, the power supply provided through a distribution network or a power grid is affected by demand fluctuations. Especially during peak hours, such as morning or evening rush hours, relatively high demand usually occurs.

[0003] For this reason, various methods are being developed to measure power demand, so as to control the operation of devices according to the power supply and the state of the generator. For example, in many scenarios, if the energy use can be delayed or temporarily reduced, such as when a washing machine is heating or an electrical device is charging, such changes may be tolerable or even imperceptible. Therefore, during peak demand periods, these loads can be reduced and / or delayed until off-peak hours.

[0004] One method proposed by the inventors is to deduce whether there is an excess supply or high demand from the frequency fluctuations in the alternating current signal of the device or the alternating current component of the voltage signal. This method is based on the recognition that many types of power supplies use rotating generators, such as turbines. In this case, the change in the rotation frequency can be manifested as a frequency fluctuation in the voltage, thereby affecting the voltage supplied to the device. An increased frequency can be associated with an increased supply, while a lower frequency can be associated with a reduced supply or a relatively high demand. For power sources that avoid using rotating energy for power generation, the practicality of this method is poor. For example, a voltage source converter or an inverter, such as a battery or a mobile power source, may provide an almost constant sinusoidal alternating current voltage with relatively small frequency fluctuations.

[0005] By reducing or completely avoiding the dependence on the periodic signal caused by the fluctuations of the rotating generator, the present invention aims to provide an alternative or extended solution to the existing methods. Summary of the Invention

[0006] According to a first aspect of the present disclosure, there is provided a monitoring device for monitoring a parameter value associated with an alternating current (AC) power source or an alternating current component of a power source in a distribution network. The monitoring device includes: a sensor device that is electrically connected to the distribution network or otherwise monitors the distribution network in use; and a control unit that is operable to use the output of the sensor device to determine the amplitude of a selected frequency for the voltage.

[0007] In some embodiments, the control unit is configured to determine the amplitude of the signal at a preset frequency.

[0008] For example, the amplitude can be determined by performing a spectral analysis on the voltage signal to extract the component at a specific frequency (e.g., 50 Hz).

[0009] In some embodiments, the preset frequency is a frequency value in the range between 45 Hz and 55 Hz, preferably 50 Hz.

[0010] The frequency value can be higher than 46, 47, 48, or 49 Hz. The frequency value can be lower than 54, 53, 52, or 51 Hz.

[0011] In some embodiments, the preset frequency is a frequency value in the range between 55 Hz and 65 Hz, preferably 60 Hz.

[0012] The frequency value can be higher than 56, 57, 58, or 59 Hz. The frequency value can be lower than 64, 63, 62, or 61 Hz.

[0013] In some embodiments, the device is configured to derive the amplitude from an input value in a waveform region where there is no peak of the monitored waveform.

[0014] In some embodiments, the device is configured to determine data points representing at least two slopes of the waveform, determine the intersection point between the two slopes, and interpret the intersection point of the slopes as the amplitude.

[0015] The waveform can be a waveform component of the signal at the preset frequency.

[0016] In some embodiments, the device is configured to perform a spectral analysis on the waveform to derive the amplitude.

[0017] It should be understood that the spectral analysis of the waveform can allow, for example, determining the shape of a pure sine wave, which may have an amplitude different from that of the measured waveform.

[0018] In some embodiments, when analyzing the AC signal or the waveform of its preset wavelength, the control unit uses a technique based on the recursive Discrete Fourier Transform (DFT) to derive the amplitude.

[0019] In some embodiments, when analyzing the AC signal or the waveform of its preset wavelength, the control unit uses a technique based on the Fast Fourier Transform (FFT) to derive the amplitude.

[0020] In some embodiments, when analyzing the waveform of the AC signal or its preset wavelength, the control unit uses a technique based on the Fast Sine Transform (FST) to derive the amplitude.

[0021] In some embodiments, when analyzing the waveform of the AC signal or its preset wavelength, the control unit uses a technique based on the Fast Cosine Transform (FCT) to derive the amplitude.

[0022] In some embodiments, the device is used to control the operation of electrical equipment, electrical storage devices, intelligent electrical devices, and / or electrical heating devices such as storage heaters or water heaters.

[0023] The device can be used to control the charging or use of a battery or a mobile power source.

[0024] In some embodiments, the device is used to continuously determine two or more continuously calculated amplitudes and derive the available supply change in the distribution network from the change between the continuously calculated amplitudes.

[0025] In some embodiments, the control unit is used to interpret an increase value of the amplitude as an indication of an increased supply in the distribution network.

[0026] In some embodiments, the control unit is used to interpret a decrease value of the amplitude as an indication of an excessive demand in the distribution network.

[0027] In some embodiments, the device is used to determine the difference between the amplitude and the measured amplitude and use the difference to derive an efficiency value indicating the losses in the distribution network.

[0028] In some embodiments, the control unit is used to interpret an increase in the efficiency value as an indication of an increased supply from the distribution network, and / or interpret a decrease in the amplitude as an indication of an excessive demand from the distribution network.

[0029] According to a second aspect of the present disclosure, there is provided a method for monitoring a parameter value associated with an AC power source or an AC component of a power source in a distribution network. The method includes: using a sensor device electrically connected to the distribution network or otherwise monitoring the distribution network, determining the amplitude of a selected frequency based on the output of the sensor device, and controlling the operation of a load or a device based on the change between consecutive amplitudes.

[0030] In some embodiments, the method includes: using the sensor device to determine the amplitude at frequency values in a region between 45 Hz and 55 Hz and / or in a region between 55 Hz and 65 Hz.

[0031] The frequency values can be 50 Hz or 60 Hz respectively.

[0032] In some embodiments, the device is configured to derive the amplitude from an input value in a waveform region where there is no peak of the monitored waveform.

[0033] In some embodiments, the method includes: determining data points representing at least two slopes of a waveform, determining an intersection point between the two slopes, and interpreting the intersection point of the slopes as the amplitude.

[0034] In some embodiments, the method includes: performing a spectral analysis on the waveform to derive the amplitude.

[0035] In some embodiments, the method includes: controlling the operation of electrical equipment, electrical storage devices, smart electrical devices, and / or electrical heating devices such as storage heaters or water heaters.

[0036] In some embodiments, the method includes: continuously determining the amplitude and deriving a change in available supply in the distribution network from a change in the amplitude.

[0037] Any one or more embodiments described with respect to the first aspect can be combined with any one or more embodiments described with respect to the second aspect. Any one or more embodiments of the second aspect can include one or more steps of using the configuration of any one or more embodiments of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, where:

[0039] Figure 1 is a schematic diagram of a power grid monitoring device;

[0040] Figure 2 is a diagram illustrating an exemplary waveform for explaining the present disclosure; and

[0041] Figure 3 is a flowchart showing exemplary steps of a method of operating a device. DETAILED DESCRIPTION

[0042] Figure 1Shows a schematic arrangement of a monitoring system 10 for an electrical grid 1, which monitoring system 10 supplies electrical power from a generator or power source 12 to a load, such as a device 20 connected to the electrical grid 1 to be powered or charged via the electrical grid 1. The monitoring system 10 includes a control device 16, which control device 16 includes one or more sensors 14 constituting a sensor device to measure or record the amplitude of a signal, such as the amplitude of a voltage, and provides the output of the sensors 14 as sensor measurement results to a control unit 16. The sensors 14 can be connected to the electrical grid 1 or otherwise used to monitor the output of the electrical grid 1. Suitable sensor or instrument devices capable of recording voltage signals are known to those skilled in the art and will not be discussed in detail herein.

[0043] Although the device 20, the control unit 16 and the sensors 14 are shown separately in Figure 1 , it should be understood that one or more of the sensors 14 and / or the control unit 16 can be components of the device 20. For example, they can be components on a printed circuit board. As an alternative or in addition, one or more of the sensors 14 and / or the control unit 16 can be separate devices for communicating with the device 20. Suitable communication protocols for wireless or wired communication are known and will not be described in detail herein. Similarly, multiple control units 16 can be used to jointly affect the operation of one or more common devices 20, and / or one or more devices 20 can be controlled by one or more common control units 16.

[0044] The control unit 16 is used to control the operation of a switch 22, for example by responding to the output from one or more sensors 14, to control the operation of the device 20. It should be understood that the switch 22 is only an exemplary configuration for enabling the control unit 16 to operate the device 20 in one of two or more different operating modes. Certain types of devices 20 can be operated without triggering a physical switch. A variety of methods for controlling the operation of the device 20 are known to those skilled in the art and will not be elaborated herein. The control unit 16 can control the operation of the switch 22, but instead operate the device 20 in any one of a variety of modes, such as switching between a high-performance mode and a low-performance mode, or between a fast-charging mode and a low-speed charging mode, etc.

[0045] The monitoring device 10 is used to analyze the signal from the power grid 1 and determine the voltage amplitude representing the amplitude of the voltage signal for a preset voltage wavelength. The wavelength can be selected by a suitable wavelength filter. For example, a waveform with a preset wavelength can be selected using Fourier transform technology to extract a sine wave component of 50 Hz or other wavelength in the voltage signal. The present disclosure is considered to be applicable to wavelengths (frequencies) of 50 Hz or 60 Hz, corresponding to the fundamental wavelengths of the European and North American power distribution networks, respectively. However, the present disclosure is not necessarily limited to a specific wavelength, and other reference wavelengths may also be used. It is understood that a reduction in voltage, such as a measured voltage of 48 Hz instead of the expected nominal 50 Hz, or a measured voltage of 58 Hz instead of the expected nominal 60 Hz, indicates that there is an excess demand for electricity relative to the supply of the power source 12.

[0046] The present disclosure is based on the understanding that if the voltage amplitude is measured directly from the AC voltage signal at the device 20, its amplitude may be lower than the voltage signal amplitude measured at the power source 12. This is due to the loss 3 (here indicated by a dashed rectangle) in the power grid 1, which is caused by the low transmission efficiency of the transmission line and transmission equipment between the power source 12 and the device 20, as well as other unknown factors and influences, such as fluctuations in the number of connected and / or disconnected loads, etc. In the present disclosure, it is assumed that the loss 3 is difficult to quantify.

[0047] refer to Figure 2 , the graph 30 in the figure shows a waveform that can be obtained by measuring the voltage amplitude. It is understood that the waveform shown in the figure is a complete cycle AC waveform at a single wavelength, which may correspond to a 50Hz or 60Hz waveform, which can be obtained by analyzing the measured voltage signal. In the case of no loss, it is expected that after measuring and extracting a preset wavelength waveform of, for example, 50Hz, an ideal or nearly ideal sinusoidal waveform 36 can be obtained, which has a lossless amplitude peak 40.

[0048] However, due to the existence of Figure 1 The loss shown is 3 (see Figure 1 ), the waveform actually obtained may present a more "flat" shape, that is, the actual waveform 32. The actual waveform 32 can be regarded as the difference between the lossless sine waveform 36 and the loss waveform 34. If the measurement is not performed separately at the power supply 12, and only the actual AC voltage is measured at the device 20, the shape of the loss waveform 34 may not be known, resulting in the inability to determine the amplitude of the loss 3, and therefore the amplitude peak 40 of the lossless waveform 36 cannot be directly measured by the AC voltage close to the device 20.

[0049] If the magnitude of loss 3 is unknown, or cannot be derived with the required accuracy, or cannot be determined with sufficient time resolution, it can be understood that in this case, it is almost impossible to determine the magnitude of the sine waveform 36 by the waveform 32 at the measuring device 20.

[0050] Therefore, although measuring the magnitude of the waveform 32 may be meaningful in some scenarios, the measurement result may reflect the magnitude change affected by the fluctuation of the grid loss 3, rather than only reflecting the voltage magnitude that should be measured directly at the power supply 1, or both.

[0051] To be able to determine the accurate magnitude, the present disclosure proposes to analyze by measuring the slope of the waveform 32 - namely an ascending slope and a descending slope - in the following way: measure multiple points, such as 38a, 38b (here are two points on the descending slope) and 39a, 39b (here are two points on the ascending slope), and determine the intersection position of their extension lines by two adjacent slopes (i.e., the ascending slope and the descending slope), and use this as the position of a magnitude, which represents the lossless magnitude peak 40, that is, the waveform magnitude expected to be measured in the absence of loss. This enables the calculated magnitude to be used as an indication of the lossless magnitude, that is, the magnitude expected to be obtained when directly measuring at the power supply 1. The positions of points 38b, 39a, 39b can be dynamically determined relative to the peak and / or baseline of the actual waveform 32, for example, select 30% and 50% of the magnitude of the actual waveform 32, or other appropriate values. For a sine waveform, the region where its magnitude is approximately between 35% and 50% can be considered to be in the relatively linear region of the sine waveform. In this region, the points on the sine waveform are closer to the baseline and farther from the peak, so they are less susceptible to peak flattening or other loss effects.

[0052] The lossless calculated magnitude can be achieved through only five calculation steps: among them, two steps are used to determine two data points 39b, 39a on one slope, another two steps are used to determine two data points 38a, 38b on the return slope, and the fifth step is used to calculate the intersection point 40 of these two slopes. It can be understood that relying on fewer calculation steps enables more calculations of the lossless magnitude to be performed within a given time, thereby improving the time resolution of such measurements.

[0053] In scenarios where the waveform signal can be assumed to be symmetric, the calculation amount can be further reduced. If the positions of the slope data points 38a, 38b are known to be symmetric with the data points 39a, 39b, the calculation can be simplified to two steps: namely, determine two data points (for example, 38a, 38b), and calculate the intersection point 40 based on these two data points and their corresponding mirror / inverted values.

[0054] As an alternative or in addition, the waveform can also be processed by spectral analysis to determine the peak amplitude of a pure sine wave at a specific wavelength (e.g., 50 Hz or 60 Hz), as understood by those skilled in the art. Although using two data points may mathematically result in multiple possible outcomes, it is understood that a definite amplitude result can be determined by comparison with the expected wavelength (e.g., 50 Hz), and / or by comparison with consecutive measurement results. Multiple suitable spectral analysis methods are known to those skilled in the art, including recursive discrete Fourier transform (DFT), fast Fourier transform (FFT), fast sine transform (FST), fast cosine transform (FCT), and other suitable techniques.

[0055] As described above, since it can be assumed that the basic form of the waveform is a sine curve, by periodically sampling the measurable waveform 32, data points can be obtained from regions far from the peak, specifically data points located in a region closer to the baseline, approximately 30% to 50% of the peak amplitude. For example, a linear region of a sine wave can be derived by a first-order approximation in a Taylor series expansion, where the first-order expansion is in a linear form. Other suitable methods can also be employed depending on the required accuracy level. In this way, spectral analysis can be used as an alternative or in addition to geometric analysis. In other words, spectral analysis can use data from regions far from the peak amplitude as input, typically in a region at approximately 30% to 50% of the peak amplitude, and this region is usually within the linear or approximately linear region of the sine wave function, to calculate the amplitude representing the lossless peak amplitude. This approach avoids the need to use the measured peak amplitude data points.

[0056] By measuring and comparing consecutive amplitudes representing the lossless amplitude, the device allows sensors 14 to be placed near, inside, or around the device 20 to determine fluctuations in the voltage amplitude at the power supply 1. It is understood that the monitoring system can obtain measurement data at regular time intervals. These regular time intervals can be hundreds or thousands of times per second, or smaller or larger intervals, such as once per minute or once every few minutes, such as once every five minutes. It is understood that this provides a corresponding high time resolution for determining supply and demand fluctuations, thus allowing the operation of the device 20 to be controlled within short time intervals.

[0057] By comparing the voltage amplitude with one or more previous lossless amplitude peaks 40, it can be determined whether the voltage amplitude increases or decreases. In addition, the behavior of the voltage amplitude over time can also be determined. This may enable the voltage amplitude to be correlated with the time of day, weekdays, the time of each weekday, etc.

[0058] As an alternative or in addition, the monitoring system 10 can include a configuration that enables it to measure an efficiency value or a loss value, which is the difference between the lossless calculated voltage amplitude and the actual measured voltage amplitude. The efficiency value or loss value can be understood as an indication of losses in the power distribution network. The monitoring system 10 can include a configuration that enables it to determine whether the loss 3 is increasing or decreasing, for example, by comparing the changes in successive efficiency values or loss values.

[0059] As an alternative or in addition, the monitoring system 10 can also compare the lossless amplitude with the loss value. The monitoring system 10 can derive a loss ratio as the ratio between the loss value and the calculated (lossless) voltage amplitude. The monitoring system 10 can include a configuration that allows it to determine whether the loss rate is increasing or decreasing, for example, by comparing the changes in successive loss rate values.

[0060] If the lossless voltage amplitude increases, it can be interpreted as indicating a supply surplus. If the lossless voltage amplitude decreases, it can be interpreted as indicating an increased demand for the power source 12. The control unit 16 can control the operation of the device 20 based on the determination of the state of the power source 12 by the control unit 20.

[0061] Go to Figure 3 , which shows exemplary steps of a method 50 for monitoring parameter values associated with an AC power source in a power distribution network. The parameter can be the lossless amplitude or peak value representing the AC signal. In step 52, a sensor device is provided to monitor the AC signal in the power distribution network. The sensor device can be used to determine the waveform of the AC signal at a preset wavelength (e.g., at 50 Hz or 60 Hz). In an optional step 54, the method is used to determine the amplitude of the measured AC signal or the waveform at the preset wavelength. It should be understood that in the absence of further information, the amplitude of the measured AC signal can be lower than the lossless amplitude that the signal would be expected to have in the absence of losses. In step 56, the calculated amplitude is determined. The calculated amplitude can be regarded as an indication value of the lossless amplitude. Step 56 can include or be provided by step 58, in which, as described above with respect to Figure 2In the described manner, the lossless amplitude is determined based on the intersection between two slopes. Step 56 may include or be provided by step 60, in which spectral analysis using a technique such as Fourier transform-based technique is used to determine the lossless amplitude, where the Fourier transform-based technique may be a recursive discrete Fourier transform (DFT), fast Fourier transform (FFT), fast sine transform (FST), fast cosine transform (FCT), or other suitable technique. Step 58 and 60 may be performed simultaneously, sequentially, or only one of step 58 or 60 may be executed. The input for step 58 and / or 60 may be a waveform region removed from the peak amplitude of the measured AC signal, for example, obtained from the linear region of a sine waveform. In optional step 62, the loss value may be determined as the difference between the measured amplitude obtained in optional step 54 and the calculated amplitude obtained in steps 56, 58, and / or 60. In step 64, a further calculated amplitude is determined, and / or a further loss value is determined. In step 66, the continuously calculated amplitudes are compared with a reference value. The reference value may be a baseline reference, such as a baseline value of zero, or one or more previously calculated amplitudes. In step 66, it is determined whether the change between the calculated amplitude and / or loss value is positive or negative, i.e., whether it indicates an increase or decrease in the peak amplitude, and / or whether it indicates an increase or decrease in the loss value.

[0062] In step 68, the operation of the load or device is controlled based on the change determined in step 66. For example, in step 68, the operation of an energy storage device, or an intelligent electrical device, a battery and / or a mobile power source, or an electric heating device such as a storage heater or a water heater may be controlled.

[0063] Although specific embodiments of the present disclosure have been described above, it should be understood that various modifications and changes can be made without departing from the scope of the present disclosure defined by the appended claims.

Claims

1. A monitoring device for monitoring a parameter value associated with an AC power source or an AC component of a power source in a distribution network, characterized in that, The monitoring device includes: a sensor device that is electrically connected to the power distribution network in use or otherwise monitors the power distribution network; and a control unit that is operable to use the output of the sensor device to determine the amplitude of a selected frequency for a voltage.

2. The device according to claim 1, characterized in that, Wherein, The control unit is used to determine the amplitude of the signal at a preset frequency.

3. The device according to claim 2, wherein, Wherein, The preset frequency is a frequency value in the region between 45 Hz and 55 Hz, preferably 50 Hz.

4. The device according to claim 2, characterized in that, Wherein, The preset frequency is a frequency value in the region between 55 Hz and 65 Hz, preferably 60 Hz.

5. The device according to any one of the preceding claims, characterized in that, The device is used to derive the amplitude from input values in a waveform region where there is no peak of the monitored waveform.

6. The device according to any one of the preceding claims, characterized in that, The device is used to determine data points representing at least two slopes of a waveform, determine the intersection point between the two slopes, and interpret the intersection point of the slopes as the amplitude.

7. The device according to any one of the preceding claims, characterized in that, The device is used to perform a spectral analysis of the waveform to derive the amplitude.

8. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit uses a technique based on recursive discrete Fourier transform when analyzing the AC signal or the waveform of its preset wavelength, so as to derive the amplitude.

9. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit uses a technique based on fast Fourier transform when analyzing the AC signal or the waveform of its preset wavelength, so as to derive the amplitude.

10. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit uses a technique based on fast sine transform when analyzing the AC signal or the waveform of its preset wavelength, so as to derive the amplitude.

11. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit uses a technique based on fast cosine transform when analyzing the AC signal or the waveform of its preset wavelength, so as to derive the amplitude.

12. The device according to any one of the preceding claims, characterized in that, The device is used to control the operation of electrical equipment, electrical storage devices, intelligent electrical devices, and / or electrical heating devices such as storage heaters or water heaters.

13. The device according to any one of the preceding claims, characterized in that, The device is used to continuously determine two or more continuously calculated amplitudes and derive the available supply change in the power distribution network from the change between the continuously calculated amplitudes.

14. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit is used to interpret an increase value indicating the amplitude as an indication of an increased supply in the power distribution network.

15. The device according to any one of the preceding claims, characterized in that, Wherein, The control unit is used to interpret a decrease value indicating the amplitude as an indication of an excessive demand in the power distribution network.

16. The device according to any one of the preceding claims, characterized in that, The device is used to determine the difference between the amplitude and the measured amplitude and use the difference to derive an efficiency value indicating the loss in the power distribution network.

17. The device according to claim 15, characterized in that, Wherein, The control unit is used to interpret an increase in the efficiency value as an indication of an increased supply from the power distribution network, and / or interpret a decrease in the amplitude as an indication of an excessive demand from the power distribution network.

18. A method for monitoring a parameter value associated with an AC power source or an AC component of a power source in a distribution network, characterized in that, Including: Using a sensor device electrically connected to the power distribution network or otherwise monitoring the power distribution network, determining the amplitude of a selected frequency based on the output of the sensor device, and controlling the operation of a load or device based on the change between continuous amplitudes.

19. The method according to claim 18, characterized in that, Wherein, The method includes: using the sensor device to determine the amplitude at a frequency value in the region between 45 Hz and 55 Hz and / or between 55 Hz and 65 Hz, and the frequency values are preferably 50 Hz or 60 Hz respectively.

20. The method according to claim 18 or 19, characterized in that, The sensor device is used to derive the amplitude from an input value in a waveform region where there is no peak of the monitored waveform.

21. The method according to any one of claims 18 to 20, characterized in that, Wherein, The method includes: determining data points representing at least two slopes of the waveform, determining an intersection point between the two slopes, and interpreting the intersection point as the amplitude.

22. The method according to any one of claims 18 to 21, characterized in that, Including performing a spectral analysis on the waveform so as to derive the amplitude.

23. The method according to any one of claims 18 to 22, characterized in that, Including controlling the operation of an electrical device, an electrical storage device, an intelligent electrical device, and / or an electrical heating device such as a storage heater or a water heater.

24. The method according to any one of claims 18 to 23, characterized in that Wherein, The method includes: continuously determining the amplitude and deriving a change in the available supply in the distribution network from the change in the amplitude.

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