Electric energy meter and active electric energy measurement method

Abstract

The present application discloses an electric energy meter and an active electric energy measurement method. The electric energy meter includes: a signal acquisition unit for acquiring voltage and current signals from a dynamic load; a multiplier for obtaining an instantaneous power signal; a low-pass filter having an input connected to the multiplier, and an output connected to a start-up metering control unit and an active power accumulation unit, wherein the low-pass filter is used to filter the instantaneous power signal to obtain an instantaneous active power signal; a start-up metering control unit for determining whether the instantaneous active power signal meets preset conditions, and if so, sending a start signal; and an active power accumulation unit for obtaining active electric energy based on the received start signal. The electric energy meter of the present invention solves the problem of electric energy values ​​being lost in some time periods when using traditional active electric energy measurement methods in dynamic load scenarios.

Description

Technical Field

[0001] The present application belongs to the technical field of electric energy metering, and more specifically, relates to an electric energy meter and an active electric energy measurement method. Background Art

[0002] The massive influx of complex, highly volatile, and highly random dynamic loads connected to the power grid (such as electric arc furnaces and high-speed rail locomotives) often results in significant deviations in the metering performance of electricity meters under these dynamic loads. Dynamic loads refer to loads that periodically or randomly draw rapidly varying power from the grid, or to rapidly varying power supply loads from renewable energy sources such as photovoltaic or wind power.

[0003] To prevent meter creep, a startup power threshold is typically set. Energy metering only starts when the instantaneous active power exceeds the threshold. The discrete voltage signal is multiplied by the discrete current signal to generate the instantaneous power signal; this signal is then passed through a low-pass filter to obtain the instantaneous active power signal. Traditional active energy measurement methods use the startup power threshold at the input of the low-pass filter. This method misses energy values ​​for some time periods and, under dynamic load test signals with rapid on-off cycles, can lead to significant metering errors.

[0004] Therefore, it is desired to invent an electric energy meter and an active electric energy measurement method that can effectively solve the problem of electric energy values ​​being lost in some time periods when the electric energy meter measures active electric energy due to the use of traditional active electric energy measurement methods. Summary of the Invention

[0005] In view of this, the present invention provides an electric energy meter and an active electric energy measurement method, the main purpose of which is to solve the problem that the electric energy value of part of the time period is lost due to the use of traditional active electric energy measurement methods when the electric energy meter performs active electric energy measurement.

[0006] In order to solve the above problems, the present invention provides an electric energy meter, which includes a signal acquisition unit, a multiplier, a low-pass filter, a start-up metering control unit and an active power accumulation unit;

[0007] The signal acquisition unit is used to obtain voltage signals and current signals in the dynamic load;

[0008] The multiplier is used to multiply the voltage signal and the current signal to obtain an instantaneous power signal;

[0009] The input end of the low-pass filter is connected to the multiplier, and the output end of the low-pass filter is connected to the startup metering control unit and the active power accumulation unit. The low-pass filter is used to filter the instantaneous power signal to obtain an instantaneous active power signal, and transmit the instantaneous active power signal to the startup metering control unit and the active power accumulation unit;

[0010] The start-up metering control unit is connected to the low-pass filter and the active power accumulation unit, and is configured to receive the instantaneous active power signal transmitted by the low-pass filter, and determine whether the instantaneous active power signal meets a preset condition, and if so, send a start signal to the active power accumulation unit;

[0011] The active power accumulation unit is configured to receive the instantaneous active power signal transmitted by the low-pass filter, receive the start signal sent by the start-up metering control unit, and accumulate the instantaneous active power signal within an accumulation time based on the start signal to obtain active electric energy.

[0012] Optionally, the signal acquisition unit includes a voltage acquisition module and a current acquisition module, wherein the voltage acquisition module is used to acquire the voltage signal in the dynamic load, and the current acquisition module is used to acquire the current signal in the dynamic load.

[0013] The present invention also provides an active electric energy measurement method, comprising:

[0014] Acquire a voltage signal u(n) and a current signal i(n) in a dynamic load, and multiply the voltage signal u(n) and the current signal i(n) to obtain an instantaneous power signal p(n);

[0015] Filtering the instantaneous power signal p(n) to obtain an instantaneous active power signal p0(n);

[0016] It is determined whether the instantaneous active power signal p0(n) meets a preset condition. If so, the instantaneous active power signal p0(n) is accumulated within an accumulation time to obtain active electric energy.

[0017] Optionally, filtering the instantaneous power signal p(n) to obtain the instantaneous active power signal p0(n) includes:

[0018] Get the sampling response coefficient h(n) of the low-pass filter;

[0019] The instantaneous power signal p(n) is convolved with the sampling response coefficient h(n) to obtain the instantaneous active power signal p0(n), where:

[0020] p0(n)=p(n)*h(n)=[u(n)×i(n)]*h(n); (1)

[0021] Where * represents the convolution operator, n represents the number of n-th sampling points, and n is a positive integer.

[0022] Optionally, it also includes:

[0023] The voltage signal u(n), the current signal i(n) and the instantaneous power signal p(n) are respectively mapped to the N-dimensional Euclidean space to obtain the mapped voltage signal vector U, current signal vector I and instantaneous power signal vector P, where:

[0024] U=[u(0),u(1),…,u(N-1)] T , (2)

[0025] I=[i(0),i(1),…,i(N-1)] T , (3)

[0026] P=[p(0),p(1),…,p(N-1)] T =U⊙I, (4)

[0027] Where ⊙ represents the Hadamard product operation of the matrix.

[0028] Optionally, the low-pass filter is a rectangular window low-pass filter, and in the rectangular window low-pass filter, the sampling response coefficient h(n) is expressed as:

[0029] h(n)=1 / L h , (5)

[0030] Among them, L h is the length of the rectangular window low-pass filter.

[0031] Optionally, obtaining the cumulative number of sampling points N′ of the voltage or current signal;

[0032] Based on formula (1), formula (4) and formula (5), N′+L h The -1-dimensional instantaneous active power signal vector P0 is expressed as:

[0033]

[0034]

[0035]

[0036] Where H is defined as the low-pass filter convolution and measurement matrix, and h(0), h(1), h(L h -2) and h(L h -1) are the sampling response coefficients in the rectangular window low-pass filter.

[0037] Optionally, the determining whether the instantaneous active power signal p0(n) satisfies a preset condition, and if so, accumulating the instantaneous active power signal p0(n) within an accumulation time to obtain active electric energy, includes:

[0038] Get the sampling time interval T of the voltage or current signal s ;

[0039] The instantaneous active power signal p0(n) is compared with the preset starting power threshold P TV In comparison, if p o (n)≥P TV And 0≤n≤N′+L h -2, then in (N′+L h -2)×T s The instantaneous active power signal p0(n) is accumulated within the time to obtain the active electric energy.

[0040] Optionally, the active electric energy is obtained by the following formula:

[0041]

[0042] Wherein, e0(N′) is the active electric energy.

[0043] Optionally, based on formula (6), define the cumulative sum operation

[0044] Where p0(j) is the jth instantaneous active power value, and 0≤j≤n;

[0045] Based on formula (10), formula (9) can be expressed as:

[0046]

[0047] Among them, p o (n)≥P TV , and 0≤n≤N′+L h -2.

[0048] The electric energy meter of the present invention first obtains the voltage signal and current signal in the dynamic load through the signal acquisition unit, and multiplies the voltage signal and the current signal through the multiplier to obtain the instantaneous power signal, then filters the instantaneous power signal through the low-pass filter to obtain the instantaneous active power signal, and finally judges whether the instantaneous active power signal meets the preset conditions by starting the metering control unit. If it meets the conditions, the instantaneous active power signal is accumulated by the active power accumulation unit within the accumulation time to obtain active electric energy; the starting metering control unit of the electric energy meter is connected to the output end of the low-pass filter, so that the method of judging whether the instantaneous active power signal meets the preset conditions is improved from the traditional judgment at the input end of the low-pass filter to the judgment at the output end of the low-pass filter. This improvement fundamentally solves the problem of the loss of electric energy values ​​in some time periods caused by the use of traditional active electric energy measurement methods in dynamic load scenarios, and effectively improves the accuracy of active electric energy measurement under dynamic load conditions.

[0049] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0051] Figure 1 This is a structural block diagram of an electric energy meter according to an embodiment of the present application.

[0052] Figure 2 This is a flow chart of a method for measuring active electric energy according to another embodiment of the present application;

[0053] Figure 3 This is a test waveform diagram of an active electric energy measurement method according to another embodiment of the present application; DETAILED DESCRIPTION

[0054] Various aspects and features of the present application are described herein with reference to the accompanying drawings.

[0055] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

[0056] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0057] These and other characteristics of the present application will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0058] It should also be understood that although the present application has been described with reference to certain specific examples, those skilled in the art will readily be able to implement many other equivalent forms of the present application.

[0059] The above and other aspects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0060] Specific embodiments of the present application will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments described are merely examples of the present application and may be implemented in a variety of ways. Familiar and / or repetitive functions and structures are not described in detail to avoid obscuring the present application with unnecessary or redundant details. Therefore, the specific structural and functional details described herein are not intended to be limiting, but rather serve merely as a basis and representative basis for the claims to teach those skilled in the art to variously utilize the present application with substantially any suitable detailed structure.

[0061] This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which may all refer to one or more of the same or different embodiments according to the present application.

[0062] Example 1

[0063] like Figure 1 As shown, an embodiment of the present invention discloses an electric energy meter, which includes a signal acquisition unit, a multiplier, a low-pass filter, a start-up metering control unit, and an active power accumulation unit:

[0064] A signal acquisition unit, used to obtain voltage and current signals from dynamic loads;

[0065] A multiplier, used to multiply the voltage signal and the current signal to obtain an instantaneous power signal;

[0066] The input end of the low-pass filter is connected to the multiplier, and the output end of the low-pass filter is connected to the startup metering control unit and the active power accumulation unit. The low-pass filter is used to filter the instantaneous power signal to obtain an instantaneous active power signal, and transmit the instantaneous active power signal to the startup metering control unit and the active power accumulation unit;

[0067] The start-up metering control unit is connected to the low-pass filter and the active power accumulation unit, and is used to receive the instantaneous active power signal transmitted by the low-pass filter, and to determine whether the instantaneous active power signal meets the preset conditions, and if so, to send a start signal to the active power accumulation unit;

[0068] The active power accumulation unit is used to receive the instantaneous active power signal transmitted by the low-pass filter, receive the start signal sent by the start metering control unit, and accumulate the instantaneous active power signal within the accumulation time based on the start signal to obtain active electric energy.

[0069] In an embodiment of the present invention, the signal acquisition unit includes a voltage acquisition module and a current acquisition module, wherein the voltage acquisition module is used to obtain the voltage signal in the dynamic load, and the current acquisition module is used to obtain the current signal in the dynamic load; at the same time, the voltage signal and the current signal are both digital signals.

[0070] Furthermore, in an embodiment of the present invention, the length of the low-pass filter is an integer multiple of the number of sampling points per cycle of the voltage or current signal. In practical applications, if the number of sampling points per cycle of the voltage or current signal is 256, the low-pass filter length can be 256, 512, 1024, etc.

[0071] Specifically, under the sinusoidal waveform on-off dynamic test signal, the error of its measurement algorithm is independent of the length of the low-pass filter, the measurement error is not affected by the length of the low-pass filter, and the measurement error is kept within 10 -5 It is 2 orders of magnitude better than traditional algorithms.

[0072] In summary, in the embodiments of the present invention, Figure 1 As shown by the middle dotted line, the access position of the metering control unit is changed from the traditional low-pass filter input terminal to the low-pass filter output terminal. This improvement fundamentally solves the problem of losing electric energy values ​​in some time periods due to the traditional active energy measurement method in dynamic load scenarios.

[0073] Example 2

[0074] like Figure 2 As shown, an embodiment of the present invention discloses a method for measuring active electric energy, comprising:

[0075] S1: Obtain the voltage signal u(n) and current signal i(n) in the dynamic load, and multiply the voltage signal u(n) and the current signal i(n) to obtain the instantaneous power signal p(n).

[0076] In the embodiment of the present invention, the instantaneous power signal p(n) is expressed as:

[0077] p(n)=u(n)×i(n).

[0078] Specifically, under actual grid conditions, dynamic load fluctuations are large, the change process is complex and diverse, and it exhibits distortion characteristics. Therefore, the voltage signal u(n) and current signal i(n) are mainly obtained through the following steps: first, the load current signal and load voltage signal are collected; then, the collected small signal is amplified, and finally, it is converted into a suitable digital signal.

[0079] S2: Filter the instantaneous power signal p(n) to obtain the instantaneous active power signal p0(n).

[0080] In an embodiment of the present invention, a sampling response coefficient h(n) of a low-pass filter is obtained;

[0081] The instantaneous power signal p(n) is convolved with the sampling response coefficient h(n) to obtain the instantaneous active power signal p0(n), where:

[0082] p0(n)=p(n)*h(n)=[u(n)×i(n)]*h(n), (1)

[0083] Where * represents the convolution operator, n represents the number of n-th sampling points, and n is a positive integer.

[0084] In an embodiment of the present invention, the active electric energy measurement method further includes:

[0085] The voltage signal u(n), current signal i(n) and instantaneous power signal p(n) are mapped to N-dimensional Euclidean space respectively to obtain the mapped voltage signal vector U, current signal vector I and instantaneous power signal vector P, where:

[0086] U=[u(0),u(1),…,u(N-1)] T , (2)

[0087] I=[i(0),i(1),…,i(N-1)] T , (3)

[0088] P=[p(0),p(1),…,p(N-1)] T =U⊙I, (4)

[0089] Where ⊙ represents the Hadamard product operation of the matrix.

[0090] In the embodiment of the present invention, the low-pass filter is a rectangular window low-pass filter. In the rectangular window low-pass filter, the sampling response coefficient h(n) is expressed as:

[0091] h(n)=1 / L h , (5)

[0092] Among them, L his the length of the rectangular window low-pass filter.

[0093] Specifically, in an electric energy metering chip, a rectangular window low-pass filter is usually used to measure active electric energy.

[0094] In an embodiment of the present invention, the cumulative number of sampling points N′ of the voltage or current signal is obtained;

[0095] Based on formula (1), formula (4) and formula (5), N′+L h The -1-dimensional instantaneous active power signal vector P0 is expressed as:

[0096]

[0097]

[0098]

[0099] Where H is defined as the low-pass filter convolution and measurement matrix, and h(0), h(1), h(L h -2) and h(L h -1) are the sampling response coefficients of the rectangular window low-pass filter.

[0100] Specifically, H is defined as the low-pass filter convolution and measurement matrix with N′ columns and N′+L rows. h -1, the matrix elements are composed of the sampling response coefficients of the rectangular window low-pass filter; at the same time, the low-pass filter convolution and measurement matrix H proposed in this application uses a matrix image to show the calculation process of the active power output by the low-pass filter, and intuitively shows the active power value during the time period lost by the traditional algorithm.

[0101] Furthermore, formula (6) can also be expressed as:

[0102] P0=[p0(0),p0(1),…,p0(L h -1),p0(L h ),…,p0(N'-1),p0(N'),…,p0(N'+L h -2)] T .

[0103] S3: Determine whether the instantaneous active power signal p0(n) meets a preset condition. If so, accumulate the instantaneous active power signal p0(n) to obtain active electric energy.

[0104] In the embodiment of the present invention, the sampling time interval T of the voltage or current signal is obtained. s ;

[0105] Compare the instantaneous active power signal p0(n) with the preset starting power threshold PTV In comparison, if p o (n)≥P TV And 0≤n≤N′+L h -2, then in (N′+L h -2)×T s The instantaneous active power signal p0(n) is accumulated within the time to obtain the active electric energy.

[0106] In the embodiment of the present invention, the active electric energy is obtained by the following formula:

[0107]

[0108] Among them, e0(N′) is the active electric energy.

[0109] Based on formula (6), the cumulative sum operation is defined as

[0110] Where p0(j) is the jth instantaneous active power value, and 0≤j≤n;

[0111] Based on formula (10), formula (9) can be expressed as:

[0112]

[0113] Among them, p o (n)≥P TV , and 0≤n≤N′+L h -2.

[0114] Specifically, in this application, p o (n)≥P TV , and 0≤n≤N′+L h -2 is a preset condition, which can also be called a constraint condition, that is, the active power p output by the rectangular window low-pass filter o (n) is greater than or equal to the preset starting power threshold P TV When p o (n) is less than the preset starting power threshold P TV When , the accumulation operation stops.

[0115] Furthermore, e o (N′) is (N′+L h -2)×T s Active energy within a certain time period. In practical applications, the preset starting power threshold P TV Preferably 0.04U n I b , where U n is the rated voltage of the energy meter, I b It is the basic current of the energy meter.

[0116] To sum up, in an embodiment of the present invention, the active electric energy measurement method first obtains the voltage signal and current signal in the dynamic load, and multiplies the voltage signal and the current signal to obtain an instantaneous power signal, then filters the instantaneous power signal to obtain an instantaneous active power signal, and finally determines whether the instantaneous active power signal meets the preset conditions. If so, the instantaneous active power signal is accumulated within the accumulation time to obtain active electric energy; after filtering, the active electric energy measurement method determines whether the instantaneous active power signal meets the preset conditions, and if so, starts active electric energy accumulation. The present invention improves the constraint conditions for starting the metering control unit, solves the problem of inaccuracy of the traditional active electric energy measurement algorithm under dynamic load scenarios, effectively improves the accuracy of active electric energy measurement under dynamic load conditions, and provides technical guarantees for the fairness and justice of electric energy metering.

[0117] In addition, the active electric energy measurement method of the present invention is compared with the traditional active electric energy measurement method, and the specific contents are as follows:

[0118] The traditional method of measuring active energy is:

[0119]

[0120] The constraints are:

[0121] P(k)≥P TV , k>0, and 0≤n <N′。

[0122] P(k) is the active power of the kth cycle of p(n), and its calculation formula is:

[0123]

[0124] In formula (13), L c is the number of sampling points per cycle of the voltage and current signals. Other parameters are the same as those in this application.

[0125] According to the traditional active energy measurement method, it is known that whether the start threshold condition is met at the input of the low-pass filter, and the [N', N'+L h -2] time p(k) does not meet the threshold condition, then part of the energy value of this time period will be lost during the accumulation process

[0126] In contrast, in this application, the electric energy accumulation formula is:

[0127]

[0128] And the constraints are stipulated as follows: p o (n)≥P TV And 0≤n≤N′+Lh -2; When the active power p output by the low-pass filter o (n) greater than or equal to the starting power threshold P TV When p o (n) Less than the starting power threshold P TV When the active power accumulation unit is [0, N′+L h -2] time to the low-pass filter output active power signal p o (n) is accumulated, and there is no loss of accumulated power time.

[0129] Furthermore, Figure 3 The following is a test waveform diagram of an active energy measurement method according to an embodiment of the present application. Figure 3 It can be seen that the amplitudes of the voltage and current signals are normalized. The voltage signal is a stable sinusoidal waveform, and the current signal is divided into a steady-state waveform and a dynamic waveform. The dynamic current waveform is a sinusoidal current waveform with an on-off ratio of 8:8, that is, the on time is 8 sinusoidal cycles, the off time is also 8 sinusoidal cycles, and so on. Under the steady-state current waveform, the measurement error of the traditional active energy measurement algorithm and the improved active energy measurement algorithm of the present invention can reach 10 -15 Under the dynamic load condition of current on-off ratio of 8:8, the error of traditional active energy measurement algorithm is 10 -3 The error of the improved active energy measurement algorithm of the present invention is 10 -5 Magnitude.

[0130] The traditional algorithm will lose [N',N'+L h -2] time, which is related to the length of the low-pass filter L h Under the dynamic current test signal, the error test was carried out on the low-pass filter lengths of 256, 1024 and 1536 respectively, and it was found that the measurement error of the traditional algorithm ranged from 10 -3 The magnitude increased to 10 -2 The improved measurement algorithm proposed in this invention has a measurement error of 10 -5 The magnitude is not affected by the filter length.

[0131] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.

Claims

1. An electric energy meter, characterized in that: The electric energy meter includes a signal acquisition unit, a multiplier, a low-pass filter, a start-up metering control unit and an active power accumulation unit; The signal acquisition unit is used to obtain voltage signals and current signals from the dynamic load; The multiplier is used to multiply the voltage signal and the current signal to obtain an instantaneous power signal; The input end of the low-pass filter is connected to the multiplier, and the output end of the low-pass filter is connected to the startup metering control unit and the active power accumulation unit. The low-pass filter is used to filter the instantaneous power signal to obtain an instantaneous active power signal, and transmit the instantaneous active power signal to the startup metering control unit and the active power accumulation unit; The low-pass filter is a rectangular window low-pass filter; The start-up metering control unit is connected to the low-pass filter and the active power accumulation unit, and is configured to receive the instantaneous active power signal transmitted by the low-pass filter, and determine whether the instantaneous active power signal meets a preset condition, and if so, send a start signal to the active power accumulation unit; The active power accumulation unit is used to receive the instantaneous active power signal transmitted by the low-pass filter, receive the start signal sent by the start metering control unit, and based on the start signal, accumulate the instantaneous active power signal within the accumulation time to obtain active electric energy, wherein the instantaneous active power signal p0(n) is compared with the preset start power threshold P TV In comparison, if p o (n)≥P TV And 0≤n≤N′+L h -2, then in (N′+L h -2)×T s The instantaneous active power signal p0(n) is accumulated within the time to obtain the active electric energy, wherein n represents the number of n-th sampling points, n is a positive integer, N' is the cumulative number of sampling points of the voltage or current signal, L h is the length of the rectangular window low-pass filter, T s Indicates the sampling time interval of the voltage or current signal.

2. The electric energy meter according to claim 1, characterized in that The signal acquisition unit includes a voltage acquisition module and a current acquisition module, wherein the voltage acquisition module is used to acquire the voltage signal in the dynamic load, and the current acquisition module is used to acquire the current signal in the dynamic load.

3. A method for measuring active electric energy, characterized in that: include: Acquire a voltage signal u(n) and a current signal i(n) in a dynamic load, and multiply the voltage signal u(n) and the current signal i(n) to obtain an instantaneous power signal p(n); Filtering the instantaneous power signal p(n) to obtain an instantaneous active power signal p0(n); Determine whether the instantaneous active power signal p0(n) meets the preset conditions, and if so, accumulate the instantaneous active power signal p0(n) within the accumulation time to obtain active electric energy; wherein, the determination of whether the instantaneous active power signal p0(n) meets the preset conditions, and if so, accumulate the instantaneous active power signal p0(n) within the accumulation time to obtain active electric energy, includes: obtaining a sampling time interval T of a voltage or current signal s ; The instantaneous active power signal p0 (n) and the preset starting power threshold P TV In comparison, if p o (n)≥P TV And 0≤n≤N′+L h -2, then in (N′+L h -2)×T s The instantaneous active power signal p0(n) is accumulated within the time to obtain the active electric energy, wherein n represents the number of n-th sampling points, n is a positive integer, N' is the cumulative number of sampling points of the voltage or current signal, L h is the length of the low-pass filter, which is a rectangular window low-pass filter, T s Indicates the sampling time interval of the voltage or current signal.

4. The active electric energy measurement method according to claim 3, characterized in that: The filtering of the instantaneous power signal p(n) to obtain the instantaneous active power signal p0(n) includes: Get the sampling response coefficient h(n) of the low-pass filter; The instantaneous power signal p(n) is convolved with the sampling response coefficient h(n) to obtain the instantaneous active power signal p0(n), where: p0(n)=p(n)*h(n)=[u(n)×i(n)]*h(n); (1) Where * represents the convolution operator.

5. The active electric energy measurement method according to claim 4, characterized in that: Also includes: The voltage signal u(n), the current signal i(n) and the instantaneous power signal p(n) are respectively mapped to the N-dimensional Euclidean space to obtain the mapped voltage signal vector U, current signal vector I and instantaneous power signal vector P, where: U=[u(0),u(1),…,u(N-1)] T , (2) I=[i(0),i(1),…,i(N-1)] T , (3) P=[p(0), p(1),..., p(N-1)]T=U⊙I, (4) Where ⊙ represents the Hadamard product operation of the matrix.

6. The active electric energy measurement method according to claim 5, characterized in that: In the rectangular window low-pass filter, the sampling response coefficient h(n) is expressed as: h(n)=1 / L h , (5) Among them, L h is the length of the rectangular window low-pass filter.

7. The active electric energy measurement method according to claim 6, characterized in that: Obtain the cumulative number of sampling points N' of the voltage or current signal; Based on formula (1), formula (4) and formula (5), N′+L h The -1-dimensional instantaneous active power signal vector P0 is expressed as: Where H is defined as the low-pass filter convolution and measurement matrix, and h(0), h(1), h(L h -2) and h(L h -1) are the sampling response coefficients in the rectangular window low-pass filter.

8. The active electric energy measurement method according to claim 7, characterized in that: The active electric energy is obtained by the following formula: Wherein, e0(N′) is the active electric energy.

9. The active electric energy measurement method according to claim 8, characterized in that: Based on formula (6), the cumulative sum operation is defined as Where p0(j) is the jth instantaneous active power value, and 0≤j≤n; Based on formula (10), formula (9) can be expressed as: Among them, p o (n)≥P TV , and 0≤n≤N′+L h -2.

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