A high-precision reactive power calculation method based on asynchronous sampling

Abstract

The present invention discloses a high-precision reactive power calculation method based on asynchronous sampling, comprising the following steps: (1) AD sampling voltage U and current I; (2) storing the current value in the current cycle; (3) performing 33rd-order HiBert transformation on the current of three cycles; (4) extracting the current transformation value of the second cycle; (5) calculating reactive power Q. The present invention can accurately calculate reactive power in a multi-operation and multi-task state, has high precision and high adaptability, and meets standard requirements; the present invention can save system operation space by only transforming current; the present invention is stable and has high reliability in the actual operation of electrical equipment.

Description

Technical Field

[0001] The invention relates to power distribution automation, and in particular to a high-precision reactive power calculation method based on asynchronous sampling. Background Art

[0002] In the operation of the power system, the power factor reflects the degree to which the apparent power output of the power supply is effectively utilized. Therefore, the greater the active power and the smaller the reactive power, the greater the power factor, the better. In this way, most of the apparent power will be used to supply active power, and the reactive power in the circuit will be reduced to a minimum, thereby increasing the power of electric energy transmission. Therefore, being able to accurately calculate reactive power plays an important role in improving power factor, increasing power efficiency, and electric energy metering.

[0003] In existing power equipment, there are many methods for measuring or calculating reactive power, but the calculation accuracy of reactive power is always unsatisfactory. For example, many measuring devices calculate reactive power through traditional Fast Fourier Transform (FFT). This method is simple to calculate but has high requirements on the accuracy of collected data, and there are fence effects and spectrum effects. Some scholars have optimized it through windowing functions and interpolation algorithms, but this makes the algorithm complicated and increases the amount of calculation; there is also a method of calculating reactive power by directly shifting the phase of the sampling point by 1 / 4 cycle and then performing convolution. This method is more accurate under synchronous sampling of the fundamental wave, but once the sampling is asynchronous sampling or there are harmonics, this method is no longer applicable.

[0004] When there are a large number of interharmonics or serious harmonic pollution in the system, the above methods based on optimization algorithms such as FFT will not be able to achieve the reactive power accuracy required by the power grid. The algorithm based on phase shift of 1 / 4 cycle will fail under asynchronous sampling. In addition, the artificial intelligence algorithm that scholars are currently inclined to study trains samples of multi-layer neural networks. This method uses mathematical tools to process data efficiently, but its data model is complex to build and converges slowly. Its reliability needs to be deeply analyzed in the actual application of electrical equipment. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a high-precision reactive power calculation method based on asynchronous sampling with high accuracy and high adaptability.

[0006] Technical solution: The high-precision reactive power calculation method based on asynchronous sampling described in the present invention adopts the Hilbert transform current and then convolution integral method to calculate reactive power. The specific steps are as follows:

[0007] (1) AD collects voltage U and current I in real time;

[0008] (2) The current value in the current cycle is stored. The current value I[n] of 32 points is selected on average in each cycle. This is to achieve high-precision calculation and reduce the system operation time.

[0009] (3) In order to improve the accuracy of this method, the current value in one cycle of step (2) is extended to the next two cycles I[n+64] n*1 , according to the HiBert coefficient matrix, the current value I′[n] in three cycles with a 90° left phase shift is obtained, and the formula is as follows:

[0010]

[0011] Where H[m] 1*m is the coefficient matrix of HiBert, k is the fixed parameter of the coefficient matrix of HiBert, which is solved according to the actual operating status;

[0012] (4) Extract the current value of the second cycle of I′[n] in step (3), shift it right by 180° to obtain I″[n], and the formula is as follows:

[0013] I″ [n] = -I′ [n]

[0014] (5) Calculate the HiBert reactive power at 33rd order using the following formula:

[0015]

[0016] Among them, I′[n] is the current after Hibert transformation, and U[n] is the voltage corresponding to the second cycle current.

[0017] A computer storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned high-precision reactive power calculation method based on asynchronous sampling.

[0018] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the high-precision reactive power calculation method based on asynchronous sampling is implemented.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages: 1. The present invention can accurately calculate reactive power in multi-operation and multi-tasking states, has high precision and high adaptability, and meets standard requirements; 2. The present invention can save system operating space by only converting current; 3. In the actual operation of electrical equipment, it performs stably and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0022] like Figure 1 As shown, a high-precision reactive power calculation method based on asynchronous sampling includes the following steps:

[0023] (1) AD collects voltage U and current I in real time;

[0024] (2) Storing the current value in the current cycle. In order to improve the computing power, this method selects the current value I[n] of 32 points on average in each cycle;

[0025] (3) In order to improve the accuracy of this method, the current value in one cycle of step (2) is extended to the next two cycles I[n+64] n*1 , according to the HiBert coefficient matrix, the current value I′[n] in three cycles with a 90° left phase shift is obtained, and the formula is as follows:

[0026]

[0027] Where H[m] 1*m is the coefficient matrix of HiBert, k is the fixed parameter of the coefficient matrix of HiBert, which is solved according to the actual operating status;

[0028] (4) Extract the current value of the second cycle of I′[n] in step (3), shift it right by 180° to obtain I″[n], and the formula is as follows:

[0029] I″ [n] = -I′ [n]

[0030] (5) Calculate the HiBert reactive power at 33rd order using the following formula:

[0031]

[0032] Where I′[n] is the current after Hibert transform, and U[n] is the voltage corresponding to the current.

[0033] A computer storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned high-precision reactive power calculation method based on asynchronous sampling.

[0034] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the high-precision reactive power calculation method based on asynchronous sampling is implemented.

Claims

1. A high-precision reactive power calculation method based on asynchronous sampling, characterized in that: The following steps are involved: (1) AD collects voltage U and current I in real time; (2) storing the current value in the current cycle; (3) Extend the current value within one cycle of step (2) to the next two cycles I[n+64] n*1 , according to the HiBert coefficient matrix, the current value I′[n] in three cycles with a 90° left phase shift is obtained, and the formula is as follows: Where H[m] 1*m is the coefficient matrix of HiBert, k is the fixed parameter of the coefficient matrix of HiBert, which is solved according to the actual operating status; (4) Extract the current value of the second cycle of I′[n] in step (3), ensure that the value is not lost, and shift right 180° to obtain I″[n], the formula is as follows: I″ [n] =-I′ [n] (5) Calculate the HiBert reactive power at 33rd order using the following formula: Where I″[n] is the current after Hibert transformation, and U[n] is the voltage corresponding to the second cycle current.

2. A high-precision reactive power calculation method based on asynchronous sampling according to claim 1, characterized in that: In step (2), the current values ​​I[n] of 32 points are selected on average in each cycle.

3. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a high-precision reactive power calculation method based on asynchronous sampling as described in any one of claims 1 to 2 is implemented.

4. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, a high-precision reactive power calculation method based on asynchronous sampling is implemented as described in any one of claims 1-2.

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