Non-intrusive residential load monitoring method and device

Abstract

The present invention relates to a non-invasive residential load monitoring method and device. The non-invasive residential load monitoring method is: measuring the carrier input impedance (spectrum) of each residential load of the same category at the electric meter, and using the carrier input impedance (spectrum) of each residential load as an identification feature to realize the identification of each residential load of the same category. The non-invasive residential load monitoring device includes a carrier signal transceiver unit, a transformer, a measuring resistor, a capacitor, a voltage and current measurement module and a signal processing module; the carrier signal transceiver unit, the measuring resistor and the primary side of the transformer are connected in series to form a first loop, the capacitor, the secondary side of the transformer and the residential load to be detected are connected in series to form a second loop, the voltage and current measurement module is connected to the second loop, and the signal processing module is connected to the voltage and current measurement module. The present invention can realize the effective identification of residential loads of the same type, and solves the problem that the existing non-invasive load monitoring scheme cannot solve.

Description

Technical Field

[0001] The present invention belongs to the field of non-intrusive load monitoring and decomposition on the power demand side, is applied to the marketing department of a power enterprise, serves the development and promotion of integrated energy services, and specifically relates to a non-intrusive residential load monitoring method and device. Background Art

[0002] Advanced metering infrastructure (AMI) is the support for two-way interaction between power supply companies and energy users. Traditional load monitoring uses an invasive method, which requires the installation of specific sensors on each monitored electrical equipment. However, in reality, considering that residential users' electrical equipment is user assets, power supply companies have no right to deal with it and there is a potential risk of infringing user privacy. Therefore, non-invasive load monitoring methods are more easily accepted by all parties.

[0003] Non-intrusive load monitoring (NILM) was proposed by Hart in the 1980s. It specifically refers to the processing and analysis of the total load data collected at the electricity meter to identify each household electrical device and its working status. The unique information that reflects the power consumption status of the electrical equipment during operation is called load signatures (LS), which is the main basis for the existing NILM.

[0004] The existing implementation architecture based on NILM residential electricity consumption behavior analysis is as follows: Figure 1 As shown in the figure, it relies on the LS data collected by smart meters during the operation of power equipment, where historical data is used for load feature training and classifier design, and real-time data is compared with trained historical data for the decomposition and detection of current power consumption behavior. The current NILM has not yet found a way to break through this architecture.

[0005] With the continuous deepening of NILM research and the introduction of various training algorithms, the load recognition rate of NILM has been significantly improved, but there are still some problems that have not been effectively solved. Figure 2 As shown in the upper right corner, refrigerator 1 and refrigerator 2 are of the same type, with the same parameters and the same working conditions. It is difficult to effectively identify them under the existing NILM technical framework, which is a problem that needs to be solved urgently. Summary of the invention

[0006] The object of the present invention is to provide a non-intrusive residential load monitoring method and device that can effectively identify loads of the same category.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A non-intrusive residential load monitoring method is used to identify multiple residential loads of the same category. The non-intrusive residential load monitoring method is: measuring the carrier input impedance of each of the residential loads of the same category at the electric meter, and using the carrier input impedance of each of the residential loads as an identification feature to achieve identification of each of the residential loads of the same category.

[0009] The carrier input impedance spectrum of each of the residential loads of the same category is measured at the electric meter, and the carrier input impedance spectrum of each of the residential loads is used as an identification feature quantity to realize the identification of each of the residential loads of the same category.

[0010] Actively inject a carrier signal into the residential loads, thereby obtaining the carrier input impedance of each of the residential loads.

[0011] Actively inject carrier signals of different frequencies into the residential loads, thereby obtaining the carrier input impedance spectrum of each of the residential loads.

[0012] The carrier input impedance of the residential load depends on the power line carrier input impedance.

[0013] The non-intrusive resident load monitoring method is applied after preliminary classification of resident loads and quantitative determination of each classification of resident loads.

[0014] A non-invasive residential load monitoring device is used to implement the aforementioned non-invasive residential load monitoring method, the non-invasive residential load monitoring device comprises a carrier signal transceiver unit, a transformer, a measuring resistor, a capacitor, a voltage and current measurement module and a signal processing module; the carrier signal transceiver unit, the measuring resistor and the primary side of the transformer are connected in series to form a first loop, the capacitor, the secondary side of the transformer and the residential load to be detected are connected in series to form a second loop, the voltage and current measurement module is connected to the second loop and is used to measure the voltage across the residential load to be detected and the current in the second loop and output a corresponding measurement signal, the signal processing module is connected to the voltage and current measurement module and is used to perform data processing to obtain the carrier input impedance or carrier input impedance spectrum of the residential load to be detected to realize the identification of each residential load of the same category.

[0015] The carrier signal transceiver unit is embedded in the electric meter.

[0016] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the present invention can realize the effective identification of the same type of residential loads, and solves the problem that the existing non-invasive load monitoring solution cannot solve. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 This is the architecture diagram for analyzing residential electricity consumption behavior based on NILM.

[0018] Attached Figure 2 Schematic diagram of the same load problem that is difficult to identify with the existing NILM.

[0019] Attached Figure 3 The flowchart of the non-intrusive residential load monitoring method of the present invention is shown in FIG.

[0020] Attached Figure 4 Schematic diagram of the non-intrusive resident load monitoring device of the present invention.

[0021] Attached Figure 5 Schematic diagram of the distributed parameter model of power lines.

[0022] Attached Figure 6 Schematic diagram of power lines for a single branch node.

[0023] Attached Figure 7 It is a cross-sectional diagram of a four-core cable power line.

[0024] Attached Figure 8 Schematic diagram of the impedance measurement method of the power line carrier communication channel.

[0025] Attached Fig. 9 It is the time-frequency diagram of power line carrier impedance.

[0026] Attached Fig.10 This is a schematic diagram of the decomposition of residential loads.

[0027] Attached Fig.11 The following is a diagram of the power line carrier impedance spectrum.

[0028] Attached Fig.12 This is the power line carrier impedance spectrum diagram under scenario 2.

[0029] Attached Fig.13 This is the power line carrier impedance spectrum diagram under scenario three. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

[0031] Embodiment 1: As shown in the attached Figure 3 As shown, the identification of resident loads includes two parts: preliminary category identification of resident loads based on the existing NILM method and quantitative judgment of resident loads in each category, and identification of multiple resident loads of the same category after preliminary category identification of resident loads and quantitative judgment of resident loads in each category.

[0032] The specific method of the first part is: use the electricity meter to collect the electricity consumption data of residential users to obtain the corresponding load imprint data, use these data to perform feature training, and then combine the real-time electricity consumption data to perform preliminary identification of electrical equipment, that is, category identification, and also judge the number of electrical equipment of each category.

[0033] The second part is the non-intrusive residential load monitoring method of the present invention, which is used to identify multiple residential loads of the same category. The non-intrusive residential load monitoring method is: measuring the carrier input impedance of each residential load of the same category at the electric meter, and using the carrier input impedance of each residential load as the identification feature to realize the identification of each residential load of the same category. Furthermore, the carrier input impedance spectrum of each residential load of the same category can be measured at the electric meter, and the carrier input impedance spectrum of each residential load can be used as the identification feature to realize the identification of each residential load of the same category. The carrier input impedance of the residential load depends on the carrier input impedance of the power line.

[0034] The non-intrusive residential load monitoring method mainly includes the following steps: after confirming the same load identification requirements, input (sweep) carrier impedance data, thereby confirming the impedance (spectrum) characteristics of the same type of loads to obtain identification results.

[0035] When the above scheme is implemented, a carrier signal is actively injected into the residential load to obtain the carrier input impedance of each residential load, or carrier signals of different frequencies are actively injected into the residential load to obtain the carrier input impedance spectrum of each residential load.

[0036] As attached Figure 4 As shown, a non-intrusive residential load monitoring device for implementing the aforementioned non-intrusive residential load monitoring method includes a carrier signal transceiver unit (carrier signal generator), a transformer, a measuring resistor, a capacitor, a voltage and current measurement module, and a signal processing module. The carrier signal transceiver unit, the measuring resistor and the primary side of the transformer are connected in series to form a first loop, the capacitor, the secondary side of the transformer and the residential load to be detected are connected in series to form a second loop, the voltage and current measurement module is connected to the second loop and is used to measure the voltage at both ends of the residential load to be detected and the current in the second loop and output the corresponding measurement signal, the signal processing module is connected to the voltage and current measurement module and is used to perform data processing to obtain the carrier input impedance or carrier input impedance spectrum of the residential load to be detected to realize the identification of each residential load of the same category. The carrier signal transceiver unit is embedded in the electric meter.

[0037] The explanations for the above scheme are as follows:

[0038] 1) Power line distributed parameter model

[0039] In order to solve the problem of identifying the same load, the concept of power line carrier input impedance is introduced here. Power line carrier communication is a unique communication method widely used in low-voltage areas. The basic principle is to use the power line that transmits electric energy to transmit carrier communication signals to achieve data transmission within a short distance without the need to build a dedicated communication line. Since the power line carrier uses a high-frequency transmission source, a distributed parameter model should be used at the distance scale of the user-side load network, such as Figure 5 shown.

[0040] like Figure 3 As shown, assuming that the current in the tiny length element dx at a distance x from the starting end is i and the terminal voltage is u, then the current in the next tiny element after dx is The terminal voltage u BC After accounting for small increments, According to Kirchhoff's voltage law, the equation of loop ABCDA is shown in equation (1):

[0041]

[0042] After sorting, we can get:

[0043]

[0044] According to Kirchhoff's current law, the equation of node B is:

[0045]

[0046] Ignoring the second-order infinitesimals, we can get:

[0047]

[0048] After rearranging the formula, the telegraph equation of the distributed parameter circuit is obtained as follows:

[0049]

[0050]

[0051] Assume that the rotation vectors corresponding to the voltage u and current i on the transmission line can be expressed as and Substituting it into equation (2) and equation (4), we can get:

[0052]

[0053]

[0054] Let Z0=R0+jωL0, Y0=G0+jωC0, then equation (7) and equation (8) can be rewritten as:

[0055]

[0056]

[0057] make is the propagation constant of the electric line. By taking the derivative of the above two equations and rearranging them, we can get:

[0058]

[0059]

[0060] The above two equations are solved to obtain:

[0061]

[0062]

[0063] Where: K1~K4 are integral constants, which depend on the boundary conditions of the power lines. It is called the characteristic impedance of the power line. The relationship between K1 to K4 can be expressed as:

[0064] K3=K1 / Z c ,K4=-K2 / Z c (15)

[0065] The voltage and current at the beginning of the power line are known to be and Substituting into equations (13) and (14), we obtain:

[0066]

[0067] Therefore, the expression of the power line transmission equation is:

[0068]

[0069]

[0070] The instantaneous value expressions of voltage and current on the power line are:

[0071]

[0072]

[0073] Where: δ is the characteristic impedance of the power line Z c The above analysis is based on lossless transmission lines. In actual working conditions, the line attenuation needs to be considered, such as Figure 6 shown.

[0074] Figure 6It is a simple power line with three branch lines. However, due to multipath reflection, there are countless transmission paths on the power line. The transmission factor of each path is the product of the reflection coefficient r and the transmission coefficient t, and its value is less than or equal to 1. The attenuation of the power line transmission channel is related to the frequency and transmission distance. The attenuation of the channel A(f,x) can be expressed as:

[0075]

[0076] Where: i is the number of the power line path; k is the attenuation coefficient, 0.5<k<1; a0, a1 are the attenuation coefficients; d i is the length of path i. The general model of transmission on a power line is:

[0077]

[0078] Where: g i is the weight coefficient of the i-th path, τ i is the time delay of path i. Considering the multipath effect in power line carrier communication, the transmission function model of the power line is:

[0079]

[0080] Where: N T is the total number of possible power line transmission paths.

[0081] Figure 7 It is the most commonly used four-core cable power line in the residential load network. Since the power line is regarded as a part of the network in the user-side load network, the basic physical parameters of the power line will directly affect the parameters such as the characteristic impedance and propagation constant of the line. The conductivity σ C , relative dielectric constant ε r , relative magnetic permeability μ r As well as the power line parameters such as the spatial position between each conductor will affect the resistance R0 per unit length of the power line, the inductance L0 per unit length, the conductance G0 between unit length wires, and the capacitance C0 between unit length wires.

[0082] 2) Power line carrier input impedance and measurement

[0083] Under the transmission line transient model, the time domain solutions u(x, t) and i(x, t) of the transmission line equation can be expressed as:

[0084]

[0085]

[0086] Where: f + represents the positive traveling wave of the carrier, f -It represents the reverse traveling wave of the carrier. The carrier has the phenomena of generation, propagation and reflection in the process of power line transmission. Assume that the load impedance matrix of the terminal is Z l , the reflection coefficient matrix is ​​Γ V , the voltage transformation matrix of the load network is T V , the reflection coefficient matrix of the terminal and the starting point is:

[0087] Γ V (l) = [Z l -Z c ]·[Z l +Z c ] -1 (26)

[0088] Γ V (0) = T V ·e -γl ·T V -1 ·Γ V (0)·T V ·e -γl ·T V -1 (27)

[0089] Therefore, the input impedance of the corresponding measurement point is:

[0090] Z x =Z c ·[I N +Y C ·Γ V (x)·Z c ]·[I N -Y C ·Γ V (x)·Z c ] -1 (28)

[0091] Where: I N is the user-side network N×N current matrix, Y C is the characteristic admittance matrix.

[0092] Since the transmission line is regarded as a part of the load network structure under distributed parameters, the input impedance of the power load of the same type, same parameters and same working conditions at the meter is different, such as Figure 8 FIG. 1 is a typical method for measuring impedance of a power line carrier communication channel. The frequency-converting carrier signal source is applied to realize the spectrum scanning of the input carrier at the measurement point. The input impedance of the power line carrier communication channel at the measurement point is equivalent to: and A high-precision measurement impedance is connected in series Its value is known and low temperature drift. Voltage on and Voltage on It can be accurately measured and regarded as a known quantity. Using formula (29), we can know the power line impedance The specific value of .

[0093]

[0094] Where: U XX is the real part of the voltage shared by the power line input impedance; U XY is the imaginary part of the voltage shared by the power line input impedance, U SX To measure the real part of the voltage shared by the impedance with high precision, U SY It is used to measure the imaginary part of the voltage shared by the impedance with high precision. The schematic diagram of the carrier transceiver unit is as follows: Figure 4 shown.

[0095] In the actual working environment, the carrier transmitting and receiving unit is embedded in the smart meter, and the carrier signal is connected to the capacitor element through a 1:1 transformer to form a coupling circuit. On the one hand, it couples the transmitted signal to the low-voltage power line channel, and on the other hand, it isolates the strong current, avoids the interference of the industrial frequency power signal on the measurement result, and improves the signal-to-noise ratio. Figure 4 The voltage U between points B1 and B2 is B With current I B The ratio of is the input impedance of the channel. When the transformer ratio is 1:1, U C It can be approximately regarded as B Equal, I C It can be approximately regarded as B Equal, and I C =U S / Z S . Therefore, the modulus of the system input impedance is:

[0096]

[0097] Relying on the carrier transmission unit to inject carrier signals of different frequencies to obtain impedance values ​​at different frequencies to achieve impedance sweeping, compared with the traditional NILM, the same load can be identified without introducing new algorithms. The active sensing method of the power system load network based on the power line carrier impedance characteristics is the inheritance and development of the existing NILM technology. The proposed user-side load network solves the problem that the existing methods cannot achieve load location positioning and status monitoring of electrical equipment that is not in working state. Based on the power line carrier impedance, it solves the problem that the existing methods cannot achieve the identification of electrical equipment of the same type, same parameters and same working conditions.

[0098] This solution is aimed at load perception and identification on the power demand side. Based on the existing NILM, the patent proposes an active perception method for the load network of the power system based on the power line carrier impedance characteristics. In order to address the problems that the current NILM has not yet solved, a method for power line carrier input impedance spectrum analysis is proposed. Based on the carrier high-frequency distributed parameter model, the characteristic impedance of the power line itself is regarded as part of the power load network, which realizes the effective distinction between loads of the same type, the same parameters and the same working conditions, overcomes the difficulty of existing non-invasive load monitoring and decomposition methods in identifying the same load, and realizes active perception on the power demand side. The advantages of the technical solution applied for compared with the existing technology can be summarized as follows:

[0099] (1) Considering the power line as part of the load network, the input impedance and load impedance of the residential load can be effectively distinguished under the high-frequency distributed parameter model, which provides a basis for the accurate identification of the residential load network and expands the monitoring scope of the power grid marketing department;

[0100] (2) The signal injection method is introduced into NILM, changing the passive load imprint into active network perception, and relying on the power line carrier impedance spectrum obtained by active injection to realize load monitoring and identification. Even household appliances that have not been in operation for a long time can be shown in the impedance spectrum diagram;

[0101] (3) For loads of the same type, parameters and working conditions, considering that the physical distances of the power lines from the measurement points are different, the proposed power line carrier impedance spectrum is used to distinguish and identify the same loads.

[0102] In order to verify the effectiveness and scientificity of the proposed method, a set of experiments was designed for residential loads under realistic working conditions, including three air conditioners of the same type, parameters and working conditions. Fig. 9 shown.

[0103] (1) Air conditioning test under the same operating conditions

[0104] The test verification was carried out in a certain household. The details of the household's electrical equipment are shown in Table 1, where "√" indicates operation and "×" indicates non-operation. There are three air conditioners of the same type, same parameters and same working conditions, which use a three-phase four-wire power supply.

[0105] Table 1 Electrical equipment used in a certain household

[0106]

[0107] like Fig.10 As shown in the figure, this is the electricity consumption curve of this household on a certain day. Since the sampling period of the electricity meter is 15 minutes, there are 96 sampling points.

[0108] In the first scenario, there are few other electrical appliances in operation in the household. A1 and A2 represent two air conditioners with the same parameters in different locations in the same operating state. The power line carrier impedance spectrum is shown in the figure below. Fig.11 shown.

[0109] In scenario 2, there are many other electrical appliances in operation in the household. B1 and B2 represent two air conditioners with the same parameters in different locations in the same operation state. The power line carrier impedance spectrum is shown in the figure below: Fig.12 shown.

[0110] In scenario 3, other electrical appliances in the household are in working state. C1, C2 and C3 represent three air conditioners with the same parameters in different locations in the same working state. The power line carrier impedance spectrum is shown in the figure below: Fig.13 shown.

[0111] like Figures 11 to 13 As shown in the figure, under different actual working conditions, the three identical air conditioners can be identified and distinguished according to the power line carrier impedance spectrum, which solves the current NILM application problems and realizes the practicality test of the proposed method. It is worth noting that under actual working conditions, when the load of the same electrical equipment is small under large load and strong interference, such as when the same load is a low-power lighting lamp under actual working conditions, its positioning and identification cannot be achieved.

[0112] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-intrusive residential load monitoring method for identifying multiple residential loads of the same category, characterized in that: The non-intrusive residential load monitoring method is as follows: the transmission line is regarded as a part of the load network structure, and the carrier input impedance of each residential load of the same category is measured at the electric meter. The input impedance of the electric load of the same type, the same parameters and the same working condition at the electric meter is different. The carrier input impedance of each residential load is used as an identification feature quantity to realize the identification of each residential load of the same category, and the carrier signal is actively injected into the residential load to obtain the carrier input impedance of each residential load. The carrier input impedance of the residential load depends on the carrier input impedance of the power line. The non-intrusive resident load monitoring method is applied after preliminary classification of resident loads based on the NILM method and quantitative determination of each category of resident loads.

2. The non-intrusive residential load monitoring method according to claim 1, characterized in that: The carrier input impedance spectrum of each of the residential loads of the same category is measured at the electric meter, and the carrier input impedance spectrum of each of the residential loads is used as an identification feature quantity to realize the identification of each of the residential loads of the same category.

3. The non-intrusive residential load monitoring method according to claim 2, characterized in that: Actively inject carrier signals of different frequencies into the residential loads, thereby obtaining the carrier input impedance spectrum of each of the residential loads.

4. A non-intrusive resident load monitoring device, used to implement the non-intrusive resident load monitoring method according to claim 1 or 3, characterized in that: The non-intrusive residential load monitoring device includes a carrier signal transceiver unit, a transformer, a measuring resistor, a capacitor, a voltage and current measurement module and a signal processing module; the carrier signal transceiver unit, the measuring resistor and the primary side of the transformer are connected in series to form a first loop, the capacitor, the secondary side of the transformer and the residential load to be detected are connected in series to form a second loop, the voltage and current measurement module is connected to the second loop and is used to measure the voltage across the residential load to be detected and the current in the second loop and output corresponding measurement signals, and the signal processing module is connected to the voltage and current measurement module and is used to perform data processing to obtain the carrier input impedance or carrier input impedance spectrum of the residential load to be detected to identify each of the residential loads of the same category.

5. The non-intrusive residential load monitoring device according to claim 4, characterized in that: The carrier signal transceiver unit is embedded in the electric meter.

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