Autonomous controllable gateway electric energy meter dynamic load power calculation method

Abstract

The application discloses a kind of self-controllable gateway electric energy meter dynamic load power calculation methods, belong to electric energy metering technical field.The instantaneous power signal sequence obtained by the point multiplication of voltage signal and current signal is continuously input to the enhanced second-order generalized integrator containing direct current component extraction path, the enhanced second-order generalized integrator introduces direct current component forward integration separation mechanism based on standard SOGI structure, and active power signal RMS value, instantaneous power in-phase and quadrature signal are synchronously output, then active, reactive and apparent power are calculated.The application can complete power solution without relying on phase-locked loop and integral cycle synchronous sampling under non-steady state signal condition, avoids spectrum leakage and fence effect, can provide less deviation measurement result under dynamic load working condition of voltage and current severe fluctuation and rich harmonic, simultaneously, additional phase-shifting link in traditional scheme is saved, with faster dynamic response speed and frequency adaptive capacity.

Description

Technical Field

[0001] This invention relates to the field of electricity metering technology, specifically to a method for calculating the dynamic load power of an independently controllable gate electricity meter. Background Technology

[0002] In the smart grid and electricity market trading system, the gateway electricity meter is a key metering node for trade settlement and grid dispatch control. Its measurement accuracy directly affects the fairness of electricity settlement, the accuracy of line loss analysis, and the scientific nature of load management. Therefore, it places high demands on the real-time performance and accuracy of power calculation.

[0003] Currently, power calculations for energy meters at critical points generally employ strategies based on discrete Fourier transform or periodic sampling integration. Under conditions of stable grid operation and approximately ideal sinusoidal voltage and current waves, these methods can achieve high metering accuracy and good numerical stability through full-cycle synchronous sampling. However, at actual critical metering points, such as electrified railway traction substations, large steel plants, and electric arc furnace load connections, the loads exhibit highly dynamic, strongly nonlinear, and rapidly fluctuating characteristics. Voltage and current signals not only experience drastic amplitude changes but are also rich in harmonic and interharmonic components, often accompanied by fundamental frequency shifts. These non-ideal factors significantly deviate from the steady-state sinusoidal signal assumption upon which traditional algorithms rely. When load changes abruptly or system frequency is disturbed, existing conventional methods struggle to meet the prerequisite of full-cycle synchronous sampling, leading to spectral leakage and picket-fence effects. They fail to accurately track the instantaneous amplitude and phase of the fundamental component in real time, resulting in non-negligible deviations in the calculation of active and reactive power, thus affecting the reliability of accumulated energy values.

[0004] To ensure the accuracy of power metering under complex dynamic load scenarios, there is an urgent need for a power calculation method with small deviation and high dynamic response capability to overcome the insufficient adaptability of existing technologies under non-steady-state signal conditions. Summary of the Invention

[0005] This invention proposes an autonomous and controllable gate energy meter dynamic load power calculation method. Its purpose is to solve the problems of large power calculation deviation and poor dynamic response capability under the working conditions of drastic fluctuations in voltage and current signals, rich harmonic content and fundamental frequency deviation.

[0006] The technical solution of this invention is as follows:

[0007] A method for calculating the dynamic load power of an autonomous and controllable gate energy meter includes:

[0008] Continuous sampling of voltage and current signals yields voltage signal sequences and current signal sequences.

[0009] The values ​​of the voltage signal sequence and the current signal sequence at the same sampling time are multiplied by a dot to obtain the instantaneous power signal at each sampling time, and then the instantaneous power signal sequence is obtained.

[0010] The instantaneous power signal sequence obtained in the previous steps is continuously input into an enhanced second-order generalized integrator that includes a DC component extraction path. This enhanced second-order generalized integrator has a DC component forward integration separation mechanism for synchronously outputting the RMS value of the active power signal. In-phase signal of instantaneous power signal and orthogonal signals of instantaneous power signals ;

[0011] Calculate the active power based on the output of the enhanced second-order generalized integrator. reactive power and apparent power .

[0012] As a further improvement to the aforementioned autonomous and controllable gate energy meter dynamic load power calculation method: In the enhanced second-order generalized integrator, for the first... iteration The input to the enhanced second-order generalized integrator is an integer greater than or equal to 0, and is the first integer in the instantaneous power signal sequence. Value The enhanced second-order generalized integrator is calculated using the following formula:

[0013]

[0014]

[0015]

[0016]

[0017] In the above formula, Indicates integration operation; This is an estimated value for the angular frequency of the power frequency signal; This is an intermediate error variable, representing the error between the feedback value and the input signal; For the first The RMS value of the active power signal output after the next iteration. For the first The in-phase signal of the instantaneous power signal output after the next iteration For the first The orthogonal signal of the instantaneous power signal output after each iteration; and For design parameters, Used to determine the frequency selection characteristics and convergence speed of the enhanced second-order generalized integrator; Used to determine the sensitivity of the enhanced second-order generalized integrator to DC signals.

[0018] As a further improvement to the aforementioned method for calculating the dynamic load power of autonomous and controllable gate energy meters: The value ranges from 0 to 5. The value ranges from 0 to 2.

[0019] As a further improvement to the aforementioned method for calculating the dynamic load power of the autonomous and controllable gate energy meter: before the enhanced second-order generalized integrator begins iteration, the variables are initialized: the initial value of the active power signal RMS value is set. The initial value of the in-phase signal of the instantaneous power signal The initial value of the orthogonal signal of the instantaneous power signal The initial value of the power frequency signal angular frequency estimate Initial value of intermediate error variable .

[0020] As a further improvement to the aforementioned method for calculating the dynamic load power of autonomous and controllable gate energy meters: the integration operation of an enhanced second-order generalized integrator. Discretization is achieved using the backward Euler method, and the difference equation is in the form of:

[0021]

[0022] In the above formula, assume that the current enhanced second-order generalized integrator is performing the th... The calculation is performed in the next iteration. Indicates the integration operation at the th The output value of the next iteration Indicates the integration operation at the th The output value of the next iteration The sampling period for continuous sampling. Indicates the integration operation at the th The input value for the next iteration.

[0023] As a further improvement to the dynamic load power calculation method of the autonomous and controllable gate energy meter: before performing dot multiplication on the values ​​of the voltage signal sequence and the current signal sequence at the same sampling time, the obtained voltage sampling data and current sampling data are first filtered by a bandpass filter to remove harmonic signal interference, so as to obtain the filtered voltage signal sequence and the filtered current signal sequence.

[0024] As a further improvement to the aforementioned method for calculating the dynamic load power of autonomously controllable gate energy meters, active power is calculated. The method is as follows: the RMS value of the active power signal output by the enhanced second-order generalized integrator is directly used as the active power. .

[0025] As a further improvement to the aforementioned method for calculating the dynamic load power of autonomously controllable gate energy meters, the apparent power is calculated. The method is as follows: .

[0026] As a further improvement to the aforementioned method for calculating the dynamic load power of the autonomous and controllable gate energy meter, reactive power is calculated. The method is as follows: .

[0027] As a further improvement to the dynamic load power calculation method of the autonomous and controllable gate energy meter: during the iteration process of the enhanced second-order generalized integrator, the frequency estimation process executed synchronously updates the angular frequency estimate required for the calculation of the enhanced second-order generalized integrator at regular intervals; the frequency estimation process is based on the voltage signal sequence for frequency estimation.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This invention addresses the problem of large power calculation deviations at metering points under dynamic loads by proposing a scheme to directly input the instantaneous power signals of voltage and current into an enhanced second-order generalized integrator that includes a DC component extraction path for calculation. This enhanced second-order generalized integrator introduces a DC component forward integration separation mechanism based on the standard SOGI structure, enabling the simultaneous separation of the active power DC component, the instantaneous power in-phase component, and the quadrature component under non-steady-state signal conditions. Since the entire power calculation link does not rely on a phase-locked loop for phase angle tracking, nor does it need to meet the full-cycle synchronous sampling condition, it fundamentally avoids spectral leakage and the picket-fence effect caused by frequency shifts or load abrupt changes. Therefore, even under conditions of drastic voltage and current fluctuations and abundant harmonics, it can still provide active and reactive power metering results with relatively small deviations.

[0030] 2. This method utilizes the enhanced second-order generalized integrator's ability to separate AC and DC components and decompose orthogonally into 100Hz instantaneous power signals. It simultaneously extracts active power and generates the in-phase and quadrature components required for apparent power calculation within the same computational stage. Compared to traditional methods that require separate phase shifters or quadrature signal generators to obtain reactive power, this method eliminates the need for additional phase shifting, simplifies the computational overhead in the signal processing chain, and avoids the risk of reactive power calculation errors due to insufficient phase shifting accuracy.

[0031] 3. The enhanced second-order generalized integrator in this method applies the error closed loop simultaneously to both the AC separation path and the DC integration separation path, enabling the extraction of the active power DC component to exhibit faster dynamic convergence characteristics than conventional low-pass filters. When the load power undergoes a step change, this enhanced second-order generalized integrator can quickly restore accurate extraction of both the DC and AC components.

[0032] 4. Unlike directly performing SOGI decomposition on the power frequency voltage and current signals, this invention first multiplies the instantaneous voltage and current values ​​to obtain an instantaneous power signal with a frequency twice the power frequency, and then processes it using an enhanced SOGI. Thanks to this, the frequency of the signal to be processed by the enhanced second-order generalized integrator is doubled. Based on the time-domain response characteristics of SOGI itself, its output settling time is further shortened, thus further improving the overall dynamic response speed of power calculation from a fundamental perspective.

[0033] 5. During the operation of the enhanced second-order generalized integrator, this method synchronously uses a voltage signal sequence for frequency estimation and periodically refreshes the angular frequency estimate used by the integrator accordingly. Through this frequency adaptive mechanism, the resonant center of the enhanced second-order generalized integrator can be adjusted according to changes in the actual grid frequency, ensuring that the power separation and calculation accuracy do not deteriorate significantly when the system frequency shifts, thus guaranteeing the adaptability of the method in scenarios with a wide range of frequency variations. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the principle of an enhanced second-order generalized integrator. Detailed Implementation

[0035] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0036] A method for calculating the dynamic load power of an autonomous and controllable gate energy meter includes:

[0037] Step S1: Continuously sample the voltage and current signals to obtain multiple sets of voltage and current sampling data, and save them to the cache.

[0038] According to the Nyquist sampling theorem, the sampling frequency should be greater than twice the highest cutoff frequency of the signal. Empirically, the sampling frequency is preferably more than 10 times the signal frequency. For a 50Hz power frequency signal, the sampling frequency can be considered to be 6.4kHz or 12.8kHz. Let the sampling frequency be... Sampling period .

[0039] Step S2: Preferably, the voltage sampling data and current sampling data obtained in step S1 are filtered by a bandpass filter to remove harmonic signal interference, resulting in a filtered voltage signal sequence and a filtered current signal sequence.

[0040] Digital filter design is a conventional technique, and this step does not provide specific implementation details. Based on engineering experience, a 6th-order Butterworth infinite impulse response (IIR) filter with a passband setting of 45Hz to 55Hz is sufficient to meet the -40dB stopband attenuation requirement. It should be noted that although IIR filters do not satisfy linear phase characteristics, since the voltage and current signals pass through the same filter simultaneously, the filter's effect on their phases can cancel each other out, thus not affecting the accuracy of subsequent power calculations.

[0041] It should be noted that step S2 can be filtered in other ways, and in some scenarios this step can be omitted, and the voltage sampling data and current sampling data obtained in step S1 can be directly used as voltage signal sequence and current signal sequence for subsequent steps.

[0042] Step S3: Perform dot product processing on the values ​​of the voltage signal sequence and the current signal sequence at the same sampling time to obtain the instantaneous power signal at each sampling time, and then obtain the instantaneous power signal sequence.

[0043] Suppose a certain sampling time The instantaneous voltage value corresponding to the voltage signal sequence is The instantaneous current value corresponding to the voltage signal sequence is Then the instantaneous power signal at that moment The calculation formula is:

[0044]

[0045] Arranging the instantaneous power signals at each sampling time in chronological order yields the instantaneous power signal sequence. The sequence of instantaneous power signals is then... The instantaneous power signal is denoted as .

[0046] Based on trigonometric relationships, the instantaneous power signal obtained at this point is a DC component and a frequency of... The superposition of sinusoidal signals, where This is the angular frequency of the power frequency signal. This DC component is the root mean square (RMS) value of the active power signal.

[0047] Step S4: The instantaneous power signal sequence obtained in step S3 is continuously input into an enhanced second-order generalized integrator containing a DC component extraction path. This enhanced second-order generalized integrator, based on the standard SOGI structure, introduces a DC component forward integration separation mechanism to synchronously output the RMS value of the active power signal. In-phase signal of instantaneous power signal and orthogonal signals of instantaneous power signals .

[0048] like Figure 1 The specific calculation process of the enhanced second-order generalized integrator is as follows:

[0049] First, initialize the variables. Set the initial value of the active power signal RMS. The initial value of the in-phase signal of the instantaneous power signal The initial value of the orthogonal signal of the instantaneous power signal The initial value of the power frequency signal angular frequency estimate (Corresponding to a power frequency of 50Hz), and the initial value of the intermediate error variable. .

[0050] Then begin iterative calculation. For the... The next iteration ( Starting from 0), the input to the enhanced second-order generalized integrator is the first [number]th [order] of the instantaneous power signal sequence. Value Each iteration is calculated using the following formula:

[0051]

[0052]

[0053]

[0054]

[0055] In the above formula, This indicates the integration operation. The estimated angular frequency of the power frequency signal is updated periodically during the iteration process by the synchronously executed frequency estimation process (i.e., step S6). This is an intermediate error variable, representing the error between the feedback value and the input signal. For the first The RMS value of the active power signal output after the next iteration. For the first The in-phase signal of the instantaneous power signal output after the next iteration For the first The orthogonal signal of the instantaneous power signal output after each iteration.

[0056] and These are design parameters. Among them, This determines the frequency selection characteristics and convergence speed of the enhanced second-order generalized integrator, with a value ranging from 0 to 5; The larger the value, the faster the convergence speed, but the frequency selection characteristics will deteriorate accordingly. This determines the sensitivity of the enhanced second-order generalized integrator to DC signals, with a value ranging from 0 to 2; A higher value indicates less sensitivity to fluctuating signals, but more stable extraction of the DC component. Considering all performance aspects, and The preferred values ​​can be 2 and 0.5, respectively.

[0057] In practical engineering applications, the above integration operation The backward Euler method is commonly used for discretization, and its difference equation form is as follows:

[0058]

[0059] In the above formula, assume that the current enhanced second-order generalized integrator is performing the th... The calculation is performed in the next iteration. Indicates the integration operation at the th The output value of the next iteration Indicates the integration operation at the th The output value of the next iteration The sampling period for step S1, Indicates the integration operation at the th The input value for the next iteration.

[0060] The principle underlying this step is explained below. Based on trigonometric relationships, assume the input voltage signal... and input current signal They are respectively:

[0061]

[0062]

[0063] In the above formula, The voltage signal amplitude, The amplitude of the current signal. It is the power frequency angular frequency. The initial phase of the voltage signal, This represents the initial phase of the current signal.

[0064] Multiplying the two together yields the instantaneous value of the power signal. And simplify using trigonometric function formulas:

[0065]

[0066] From the above formula, it can be seen that the DC part This is the RMS value of the active power signal.

[0067] While conventional SOGI methods can achieve [the following], Frequency selection of the frequency components yields the in-phase and quadrature components of the power signal, but it cannot directly separate and extract the DC component present in the input signal. This invention adds a forward integrator to the standard SOGI structure, which, when the input error... There are still unexplored areas. When the DC component is compensated, the output of the integrator will continuously change (increase or decrease) until... Stability is achieved only when the output is exactly equal to the DC component of the input signal. In this way, the present invention achieves the synchronous separation and extraction of the DC component, in-phase component, and quadrature component in an instantaneous power signal. Ideally, the final steady-state output of the enhanced second-order generalized integrator is:

[0068]

[0069]

[0070]

[0071] In the above formula, The in-phase signal of the instantaneous power signal These are orthogonal signals of instantaneous power signals. This represents the RMS value of the active power signal.

[0072] It should be noted that, under the operating condition of 50Hz power frequency, the enhanced second-order generalized integrator of this invention directly processes a 100Hz instantaneous power signal. Based on the time-domain response characteristics of SOGI, under the same parameters... Under this value, the higher the frequency of the processed signal, the shorter the time required for the output to stabilize, i.e., the faster the dynamic response speed. Therefore, compared with conventional methods that directly process 50Hz voltage or current signals, the method of this invention has a faster dynamic response speed, with a dynamic response time of approximately 100ms.

[0073] Step S5: Calculate the active power, reactive power and apparent power based on the results output in step S4.

[0074] This step directly calculates the power using the variables output in step S4, avoiding the additional phase-shifting step required when calculating reactive power using conventional methods.

[0075] (1) Calculate active power .

[0076] Active power It is directly equal to the RMS value of the active power signal output by the enhanced second-order generalized integrator, that is:

[0077]

[0078] (2) Calculate the apparent power .

[0079] Using the in-phase signal of the instantaneous power signal output in step S4 Orthogonal signals to instantaneous power signals Apparent power is calculated by taking the square root:

[0080]

[0081] In the above formula, This is the calculated apparent power.

[0082] (3) Calculate reactive power .

[0083] Based on the power triangle relationship, using the active power obtained earlier... and apparent power Calculate reactive power:

[0084]

[0085] The method of this invention obtains apparent power through square root operation, and its dynamic characteristics are significantly better than those of traditional filter methods for extracting signal amplitude. Typically, the dynamic response time of traditional filter methods is approximately 400ms to 800ms, while the dynamic response time of this invention is approximately 100ms, representing a significant improvement in response speed.

[0086] Step S6: Based on the filtered voltage signal sequence obtained in Step S2, frequency estimation is performed to obtain the estimated angular frequency value, which is then used by the enhanced second-order generalized integrator in Step S4. This step is executed synchronously and cyclically with Steps S3 to S5, and the estimated angular frequency value is refreshed periodically. The specific steps for frequency estimation are as follows:

[0087] Step S6-1: Perform zero-crossing detection on the voltage signal sequence and find the zero-crossing position. Compare the voltage sample value corresponding to each sampling point with 0 in turn. If the voltage sample value at a certain moment... The voltage sample value at the next sampling point is less than 0. If the value is greater than or equal to 0, then this is considered a zero-crossing point. The index number corresponding to this moment in the filtered voltage signal sequence is denoted as... and the two sampled values and Save to cache .

[0088] Step S6-2: Following the same judgment criteria as in Step S6-1, continue searching for the next zero-crossing position. Record the index number of the first sampling point corresponding to this zero-crossing position in the filtered voltage signal sequence as... and order Save the two adjacent sampled values ​​near the zero-crossing position to the cache. And respectively recorded as and .

[0089] Step S6-3: Based on caching and The values ​​stored in the database are used to calculate the precise positions of the two zero-crossing points using linear interpolation.

[0090] Using the index number of the voltage signal sequence and Establish a rectangular coordinate system with the difference as the x-axis and the voltage sampling value as the y-axis. (Passing through point...) and points If we draw a straight line, its slope and intercept can be expressed as:

[0091]

[0092]

[0093] The intersection of the straight line and the horizontal axis This is the precise location of the first zero-crossing point, and its calculation formula is:

[0094]

[0095] Similarly, for the second zero-crossing position, the point... and points Draw a straight line, and the point where this line intersects the horizontal axis. The calculation formula is:

[0096]

[0097] Step S6-4: Calculate the signal period based on the precise positions of the two zero-crossing points, thereby obtaining the estimated angular frequency. Angular frequency estimate. The calculation formula is as follows:

[0098]

[0099] In the above formula, The sampling frequency in step S1, The sampling interval between two zero-crossing points represents the period of the signal.

[0100] Using the method described in step S6 above, a frequency estimate can be performed once for each power frequency voltage cycle. In practical engineering applications, to further improve the accuracy of frequency estimation, averaging the results of multiple frequency estimates can be considered.

[0101] By repeatedly executing steps S6-1 to S6-4, the diagonal frequency estimate can be obtained. The system refreshes periodically and continuously provides data to the enhanced second-order generalized integrator in step S4 for iterative calculation.

[0102] It should be noted that, as will be apparent to those skilled in the art, the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics thereof. The scope of the present invention is defined by the claims rather than the foregoing description.

Claims

1. A method for calculating the dynamic load power of an autonomously controllable gate energy meter, comprising: Continuous sampling of voltage and current signals yields voltage signal sequences and current signal sequences. Its characteristic is that it further includes the following steps: The values ​​of the voltage signal sequence and the current signal sequence at the same sampling time are multiplied by a dot to obtain the instantaneous power signal at each sampling time, and then the instantaneous power signal sequence is obtained. The instantaneous power signal sequence obtained in the previous steps is continuously input into an enhanced second-order generalized integrator that includes a DC component extraction path. This enhanced second-order generalized integrator has a DC component forward integration separation mechanism for synchronously outputting the RMS value of the active power signal. In-phase signal of instantaneous power signal and orthogonal signals of instantaneous power signals ; Calculate the active power based on the output of the enhanced second-order generalized integrator. reactive power and apparent power ; In the enhanced second-order generalized integrator, for the first... iteration The input to the enhanced second-order generalized integrator is an integer greater than or equal to 0, and is the first integer in the instantaneous power signal sequence. Value The enhanced second-order generalized integrator is calculated using the following formula: ； ； ； ； In the above formula, Indicates integration operation; This is an estimated value for the angular frequency of the power frequency signal; This is an intermediate error variable, representing the error between the feedback value and the input signal; For the first The RMS value of the active power signal output after the next iteration. For the first The in-phase signal of the instantaneous power signal output after the next iteration For the first The orthogonal signal of the instantaneous power signal output after each iteration; and For design parameters, Used to determine the frequency selection characteristics and convergence speed of the enhanced second-order generalized integrator; Used to determine the sensitivity of the enhanced second-order generalized integrator to DC signals; Before the enhanced second-order generalized integrator begins its iteration, the variables are initialized: the initial value of the active power signal RMS is set. The initial value of the in-phase signal of the instantaneous power signal The initial value of the orthogonal signal of the instantaneous power signal The initial value of the power frequency signal angular frequency estimate Initial value of intermediate error variable .

2. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that: The value ranges from 0 to 5. The value ranges from 0 to 2.

3. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that: Integration operation of the enhanced second-order generalized integrator Discretization is achieved using the backward Euler method, and the difference equation is in the form of: ； In the above formula, assume that the current enhanced second-order generalized integrator is performing the th... The calculation is performed in the next iteration. Indicates the integration operation at the th The output value of the next iteration Indicates the integration operation at the th The output value of the next iteration The sampling period for continuous sampling. Indicates the integration operation at the th The input value for the next iteration.

4. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that: Before performing dot product processing on the voltage and current signal sequences at the same sampling time, the obtained voltage and current sampling data are first filtered by a bandpass filter to remove harmonic interference, resulting in filtered voltage and current signal sequences.

5. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that, Calculate active power The method is as follows: the RMS value of the active power signal output by the enhanced second-order generalized integrator is directly used as the active power. .

6. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that, Calculate apparent power The method is as follows: .

7. The method for calculating dynamic load power of an autonomously controllable gate energy meter as described in claim 1, characterized in that, Calculate reactive power The method is as follows: .

8. The method for calculating dynamic load power of an autonomous and controllable gate energy meter as described in claim 1, characterized in that: During the iteration of the enhanced second-order generalized integrator, a synchronously executed frequency estimation process periodically updates the angular frequency estimates required for the calculation of the enhanced second-order generalized integrator; the frequency estimation process is based on the voltage signal sequence for frequency estimation.

Images