CN103383414A - Computing method applied to voltage included angle of power distribution terminal - Google Patents

Abstract

The invention discloses a computing method applied to a voltage included angle of a power distribution terminal. Voltages are acquired through an acquisition circuit in the power distribution terminal, relevant processing is performed on the voltages subjected to acquisition processing through an arithmetic device in the power distribution terminal to obtain a corresponding operation result, an arc cosine table which is made according to the operation result in advance is stored in a storage of the power distribution terminal, and the voltage included angle corresponding to the operation result is found through automatic retrieval. According to actual measurement, the computing method can work out the required voltage included angle accurately to meet actual application under the premise of enough sample data, the operation is not affected by signal frequency changes, the floating point operation is avoided, and the operation efficiency is improved.

Description

A Calculation Method of Voltage Angle Applied to Power Distribution Terminal

technical field

The invention relates to circuit data processing, in particular to a method for calculating voltage angles applied to power distribution terminals. the

Background technique

The distribution terminal is an important part of the DA (distribution automation) system and is located at the base layer. The real-time data of the DA system, the criterion for automatic fault processing, and the operating conditions of the switchgear are all derived from the power distribution terminal. Operations are performed through power distribution terminals. The reliability and real-time performance of power distribution terminals directly affect the reliability and real-time performance of the entire DA system. the

When measuring the voltage simultaneously, it is necessary to calculate the angle between the two voltages. For the calculation of the included angle of the power distribution terminal, the Fourier transform method is generally used to calculate the imaginary part and the real part of the voltage, and then the arc tangent is used to calculate the included angle of each phase voltage. Fourier calculation requires a complete voltage signal sample, but the voltage signal is a changing process, so when the voltage signal changes periodically, if the sample data is incomplete, the calculation of the real part and the imaginary part will have errors, resulting in errors in the calculation of the included angle , and the calculation of the arctangent involves floating-point operations, which consumes a lot of CPU resources. the

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a voltage angle calculation method applied to power distribution terminals, which can reduce the influence of the frequency of signal changes on the results and improve the removal efficiency. the

The technical solution adopted by the present invention to solve its problem is:

A method for calculating a voltage angle applied to a power distribution terminal, comprising:

Collecting two sets of voltages through the acquisition circuit of the power distribution terminal, the acquisition circuit converts the two sets of voltages into two sets of voltage discrete values corresponding to each other after collecting the two sets of voltages;

The acquisition circuit transmits the processed two sets of corresponding discrete voltage values to the processor of the power distribution terminal, the processor is electrically connected to the acquisition circuit, and the processor calculates the two sets of voltages based on the two sets of corresponding voltage discrete values The result of multiplying two discrete voltage values corresponding to each other in the discrete value, and summing the result obtained after multiplying each two discrete voltage values;

The processor calculates the average value of the multiplication of two discrete voltage values based on the obtained sum value. The average value is used as the numerator, and the product of the voltage effective values corresponding to the two sets of voltage discrete values is used as the denominator to obtain the numerator and denominator The operation value between;

The processor searches the arccosine table according to the calculated value, and finds the angle value corresponding to the calculated value from the arccosine table. The arccosine table is stored in the memory of the power distribution terminal, and the power distribution terminal will automatically retrieve and read Data, the arc cosine table contains angle values corresponding to different operation values.

After the acquisition circuit acquires two sets of voltages, it converts the two sets of voltages into two sets of voltage discrete values corresponding to each other, specifically: the acquisition circuit processes the two sets of collected voltages through the voltage transformer PT, so that the two sets of collected voltages respectively converted into corresponding two sets of differential signals, and the two sets of differential signals are transformed from analog signals into two sets of voltage discrete values corresponding to each other through the AD converter, the AD converter is electrically connected with the voltage transformer PT, and the acquisition circuit is The circuit where the voltage transformer PT and the AD converter are connected. the

The method further includes: before the processor searches the arccosine table according to the calculated value, the processor amplifies the calculated value by 1000 times, correspondingly, the arccosine table is the corresponding arccosine angle after the calculated value is enlarged by 1000 times value. the

The beneficial effects of the present invention are:

The present invention adopts a method for calculating the voltage angle applied to the power distribution terminal. After the acquisition circuit collects the voltage, the specific calculation avoids the influence of the change of the voltage signal, and at the same time simplifies the calculation, avoiding the increase of the calculation load of the CPU by floating-point calculation. .

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and example. the

Fig. 1 is a flow chart of the method of the present invention. the

Detailed ways

When the power distribution terminal judges whether it is a synchronous voltage, it needs to calculate the angle between the two voltages. The present invention provides a method for obtaining the included angle. the

Referring to the flow chart shown in Figure 1, the first is to collect voltage. There is an acquisition circuit inside the power distribution terminal, which can collect voltage. Of course, the signal on the circuit that the acquisition circuit can collect is not limited to voltage, current, resistance, etc. can also be used. The acquisition circuit of the present invention includes a voltage transformer PT and an AD converter, and the voltage transformer PT is electrically connected to the AD converter. When a voltage signal passes through the PT, the PT converts the signal into a differential signal whose Vp-p does not exceed 4V, where Vp-p is the peak value of the converted voltage, and the AD converter receives the differential signal and converts the analog signal into Corresponding discrete data. When the present invention is applied, the acquisition circuit will collect two sets of voltages, and the two sets of voltages will be converted into corresponding two sets of differential signals whose Vp-p does not exceed 4V after PT, and the AD converter receives the two sets of differential signals, and converts It is converted into two sets of voltage discrete values corresponding to each other. the

，其中Ua与Ub分别为两组相互对应的电压离散值，根据此和值得出相互对应的两个离散电压值相乘后的平均值：

，以此平均值为分子，以

与

的乘积为分母，其中与

分别为与

、

对应的电压有效值，得出最终的结果值：

。普遍所知，在计算电压与电流之间的夹角时，可以采用以下公式计算：

，其中为电压电流之间的夹角，P是有功功率，S是视在功率，N为采集的电压数据个数，

与 

分别为有效电压、电流。对比以上公式，则电压之间的夹角，比如电压Ua与Ub之间的夹角则可以通过公式进行计算，其中N值为转换所得离散数据的个数，

与

为转换所得的对应的电压离散数据，

与

分别为与

、

对应的电压有效值，此公式中的分子相当于第一个公式中的功率P，分母相当于第一个公式中的功率S，通过反余弦运算后即可得到相应的电压夹角。  Secondly, the collected and processed voltage is calculated and the calculation result is obtained, and the collected and processed voltage is two groups of corresponding voltage discrete values obtained after processing by the collecting circuit. When the power distribution terminal collects voltage, it can also collect more than two voltages, but when calculating the voltage angle, it calculates two of them. The acquisition circuit transmits the processed two sets of corresponding discrete voltage values to the processor of the power distribution terminal, the processor is electrically connected to the acquisition circuit, and the processor calculates the two sets of voltages based on the two sets of corresponding voltage discrete values The result of multiplying two discrete voltage values corresponding to each other in the discrete value, and summing the result obtained after multiplying each two discrete voltage values, and the processor calculates the multiplication of the two discrete voltage values according to the obtained sum value After the average value, the average value is used as the numerator, and the product of the voltage effective values corresponding to the two sets of voltage discrete values is used as the denominator to obtain the calculated value between the numerator and the denominator. Assuming that each of the two sets of voltage discrete values has N corresponding discrete voltage values, the sum of the two corresponding multiplied results can be obtained:

, where Ua and Ub are two sets of discrete voltage values corresponding to each other, and the average value after multiplying the two discrete voltage values corresponding to each other is obtained according to this sum:

, taking the average value as the numerator, and taking

and

The product of is the denominator, where and

respectively with

,

Corresponding to the effective value of the voltage, the final result value is obtained:

. It is generally known that when calculating the angle between voltage and current, the following formula can be used for calculation:

,in is the angle between the voltage and current, P is the active power, S is the apparent power, N is the number of voltage data collected,

and

are effective voltage and current respectively. Compared with the above formula, the angle between voltages, such as the angle between voltage Ua and Ub, can be calculated by the formula Calculate, where N is the number of converted discrete data,

and

is the converted corresponding voltage discrete data,

and

respectively with

,

Corresponding to the effective value of the voltage, the numerator in this formula is equivalent to the power P in the first formula, and the denominator is equivalent to the power S in the first formula. After the arc cosine operation, the corresponding voltage angle can be obtained.

计算出相应的运算结果，运算结果的值落于区间[－1，1]，然后将运算结果按照反余弦表检索查找出对应的角度值即可。所述反余弦表为事先根据运算结果制作而成，包含有不同运算值所对应的角度值，被存储于配电终端的存储器中，在需要时，配电终端可以自动检索并读取数据。  In order to reduce floating-point operations and save the load on the processor, the present invention only uses

Calculate the corresponding operation result, the value of the operation result falls in the interval [-1, 1], and then search the operation result according to the arc cosine table to find the corresponding angle value. The arc cosine table is made in advance according to the calculation results, contains angle values corresponding to different calculation values, and is stored in the memory of the power distribution terminal. When necessary, the power distribution terminal can automatically retrieve and read the data.

When finally searching the arccosine table based on the result, the operation result will be magnified by 1000 times. Correspondingly, the operation result and the corresponding angle value in the arccosine table are the angle values made after the operation result is enlarged by 1000 in advance. the

Use the method of the present invention to calculate the included angle between the voltages for the four cycle bands respectively. For the specific results, refer to the comparison between the measurement results shown in the table below and the real data. As can be seen from the table, as long as it is ensured There are enough sample data to provide calculation, the present invention can calculate the accurate voltage angle, the calculated voltage angle value fully meets the practical application, and the operation is simple, not affected by the signal frequency change, and avoids the floating point operation, Improved operational efficiency. the

      

The above descriptions are only preferred embodiments of the present invention, and the present invention is not limited to the above-mentioned embodiments, as long as they achieve the technical effects of the present invention by the same means, they should all belong to the protection scope of the present invention.

Claims (3)

1. A calculation method for a voltage angle applied to a power distribution terminal, characterized in that it comprises: Collecting two sets of voltages through the acquisition circuit of the power distribution terminal, the acquisition circuit converts the two sets of voltages into two sets of voltage discrete values corresponding to each other after collecting the two sets of voltages; The acquisition circuit transmits the processed two sets of corresponding discrete voltage values to the processor of the power distribution terminal, the processor is electrically connected to the acquisition circuit, and the processor calculates the two sets of voltages based on the two sets of corresponding voltage discrete values The result of multiplying two discrete voltage values corresponding to each other in the discrete value, and summing the result obtained after multiplying each two discrete voltage values; The processor calculates the average value of the multiplication of two discrete voltage values based on the obtained sum value. The average value is used as the numerator, and the product of the voltage effective values corresponding to the two sets of voltage discrete values is used as the denominator to obtain the numerator and denominator The operation value between; The processor searches the arccosine table according to the calculated value, and finds the angle value corresponding to the calculated value from the arccosine table. The arccosine table is stored in the memory of the power distribution terminal, and the power distribution terminal will automatically retrieve and read Data, the arc cosine table contains angle values corresponding to different operation values. 2. A method for calculating a voltage angle applied to a power distribution terminal according to claim 1, wherein the acquisition circuit converts the two sets of voltages into two sets of mutually corresponding ones after collecting the two sets of voltages. The voltage discrete value is specifically: the acquisition circuit processes the two sets of collected voltages through the voltage transformer PT, so that the two sets of collected voltages are converted into corresponding two sets of differential signals, and the two sets of differential signals are converted from analog signals through the AD converter It is two sets of voltage discrete values corresponding to each other, the AD converter is electrically connected to the voltage transformer PT, and the acquisition circuit is a circuit connected between the voltage transformer PT and the AD converter. 3. A method for calculating the voltage angle applied to power distribution terminals according to claim 1, wherein the method further comprises: before the processor searches the arccosine table according to the calculated value, the processor The calculated value is amplified by 1000 times, and correspondingly, the arccosine table is the corresponding arccosine angle value after the calculated value is amplified by 1000 times.

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