阅读说明：本技术 基于矩阵理论的互感器接线判断方法 (Mutual inductor wiring judgment method based on matrix theory ) 是由 张鹏程 郭志强 卢松林 宁振 于 2020-03-05 设计创作，主要内容包括：本发明提供了基于矩阵理论的互感器接线判断方法,其特征在于,包括对三相电网电压和三相负载电流进行采集,计算各参数的相角,对电压和电流进行多种组合,求解各种组合下功率因数；根据实际用电情况和接线情况进行预设,比较各种组合的功率因数与预设的功率因数阈值,判断是否满足预设情况,并组成8个3×3的矩阵；根据实际CT接线情况,选取两个3×3的矩阵,通过矩阵的秩或行列式等方法判断矩阵是否有唯一解；若存在唯一解,则可求解出该CT方向情况下的电流互感器与电压的对应关系,否则还需进一步判断。本发明可使得在现场接线关系模糊的情况下,通过合理设置,自动分析出对应的接线关系。(The invention provides a mutual inductor wiring judgment method based on a matrix theory, which is characterized by comprising the steps of collecting three-phase power grid voltage and three-phase load current, calculating phase angles of all parameters, carrying out various combinations on the voltage and the current, and solving power factors under various combinations; presetting according to the actual power utilization condition and the wiring condition, comparing the power factors of various combinations with a preset power factor threshold value, judging whether the preset condition is met, and forming 8 3 × 3 matrixes; selecting two 3 x 3 matrixes according to the actual CT wiring condition, and judging whether the matrixes have unique solutions or not by methods such as the ranks or determinants of the matrixes and the like; if the unique solution exists, the corresponding relation between the current transformer and the voltage under the condition of the CT direction can be solved, and otherwise, further judgment is needed. The invention can automatically analyze the corresponding wiring relation through reasonable setting under the condition that the field wiring relation is fuzzy.)

1. The mutual inductor wiring judgment method based on the matrix theory is characterized by collecting three-phase power grid voltage and three-phase load current, presetting a current mutual inductor anisotropic phase, a negative power phase and a power factor threshold value, analyzing the direction of the current mutual inductor and the corresponding relation of the voltage connection phase through information such as power factors under various voltage and current combinations, and specifically comprising the following steps of:

1) collecting three-phase power grid voltage and three-phase load current, and calculating fundamental wave power factors of the voltage and the current under various combinations (including current inverting direction);

2) aiming at the actual situation of the site, the anisotropic phase, the negative power phase and the power factor threshold of the current transformer can be preset by referring to data of a main station, an ammeter and the like;

3) the calculated fundamental wave power factor is compared with a set power factor threshold, if the calculated fundamental wave power factor exceeds the set threshold, the result of the combination is 1, otherwise, the result is 0, and a 3 multiplied by 24 matrix is obtained;

4) and selecting two 3 x 3 matrixes according to the reverse phase of the CT, judging whether the two matrixes respectively have unique solutions, if so, solving, and otherwise, judging the wiring relation by other methods.

2. The matrix theory-based transformer wiring judgment method according to claim 1, wherein the SDFT algorithm is used to find fundamental wave components of grid voltage and load current, and the fundamental wave phase angle is mainly found to be used for calculating a Displacement Power Factor (DPF).

3. The method for judging the wiring of the mutual inductor based on the matrix theory as claimed in claim 1, wherein mathematical modeling is performed according to the possibility existing in the existing place, and two matrices with opposite meanings are solved to obtain the combination modes in different wiring modes.

4. The method for judging the wiring of the mutual inductor based on the matrix theory as claimed in claim 1, wherein the rank of the matrix is judged by solving a determinant mode, and the voltage and current corresponding relation under the precondition is solved according to a mathematical model and a physical meaning.

5. The method for judging the wiring of the mutual inductor based on the matrix theory according to claim 1, wherein the method is suitable for high-voltage transmission lines and low-voltage distribution lines, can be installed at a trunk line and a branch line, is applied to power monitoring and power management, and is flexible and convenient to apply.

Technical Field

The invention relates to the field of power monitoring and management, in particular to a mutual inductor wiring judgment method based on a matrix theory.

Background

The on-site low-voltage distribution area has complex environment, causes such as non-standard or inconvenient construction and the like, easily causes disorder of the distribution lines, and causes obstacles to judgment of the corresponding relation between voltage and current. If power monitoring is performed on a wiring having an unknown relationship, an event detection error, a failure false alarm, and the like may be caused, and if power quality is managed, a power quality problem may be increased, and even a safety event may be caused. Therefore, it is important to clearly card the relationship between the voltage and the current of the low-voltage distribution network. Generally speaking, the judgment of the voltage-current relationship by human has certain difficulty, power failure and other operations which affect power utilization are possibly required, and a certain misjudgment probability exists, so that a scheme of automatic identification by using an algorithm of the equipment is designed, and a series of problems caused by human judgment can be avoided.

Disclosure of Invention

The invention aims to provide a mutual inductor wiring judgment method based on a matrix theory, which comprises the steps of collecting three-phase voltage and three-phase current by using equipment, carrying out a series of pairing combination on the voltage and the current, calculating active power and power factors under each combination, carrying out true and false judgment on whether conditions are met, combining a plurality of matrixes, carrying out matrix rank calculation or determinant calculation on each matrix, selecting the condition with a unique solution, and reducing the wiring condition.

The invention provides a mutual inductor wiring judgment method based on a matrix theory, which comprises the following steps:

sampling three-phase power grid voltage and three-phase load current, calculating fundamental wave components of the power grid voltage and the load current, including amplitude and phase information, randomly combining the fundamental wave components of the three-phase power grid voltage and the three-phase load current, and calculating fundamental wave power factors under various combinations;

forming a matrix consisting of 1 and 0 according to a plurality of power factors obtained by combination and a set power factor limit value, wherein 1 represents that the power factor obtained by combination exceeds the power factor limit value, namely the power factor is true, and 0 represents that the power factor obtained by combination is lower than the power factor limit value, namely the power factor is false;

the matrix is separated into 8 3 x 3 matrixes according to the CT direction, two matrixes are extracted according to possible CT directions, the rank or the determinant of the matrix is obtained, if the rank or the determinant of the matrix is 3 or is not 0, a unique solution is proved in the case, and the unique solution in the case, namely the direction of each current transformer and the pairing relation of each current transformer and a voltage terminal are obtained.

Wherein, still include:

and calculating fundamental wave components of the voltage and the current by adopting an SDFT algorithm, solving a cosine value of the phase difference by using a result of a fundamental wave phase, and performing subsequent judgment by taking a Displacement Power Factor (DPF) as a power factor.

If the power of a certain phase is negative, namely the power of the phase is negative due to the fact that power generation equipment such as photovoltaic equipment exists in the certain phase, the CT or the voltage can be preset to be negative, and then subsequent judgment can be carried out.

The invention has the beneficial effects; according to the method, the corresponding relation between the voltage and the current transformer is judged by using the equipment, manual investigation is replaced, and self-adaptive adjustment can be performed through software, so that the power monitoring and the power quality control of the power distribution network with a fuzzy line relation can be guaranteed.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic diagram of a distribution room and a device connection provided in an embodiment of the present invention;

fig. 2 is a structural diagram of a current transformer wiring judgment method according to an embodiment of the present invention;

fig. 3 is a flowchart of a current transformer wiring judgment algorithm provided in the embodiment of the present invention.

Detailed Description

The core of the invention is to provide a mutual inductor wiring judgment method based on a matrix theory, which can be matched with any three-phase distribution line and carries out combined analysis and judgment on the basis of the collected three-phase power grid voltage and three-phase load current.

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is an application environment of the method, a plurality of voltage and current relationships are fuzzy on site, and a monitoring device or a management device also has the condition of inconvenient wiring and is difficult to correspond to the wiring relationship between the voltage and the current and the direction of the current, fig. 2 is a general idea of the detection method, and the wiring relationship between the voltage and the current and the direction of the current can be obtained according to a plurality of determinable preconditions, so that the problem of fig. 1 is solved.

Fig. 3 is a flowchart of a current transformer wiring judgment algorithm provided in the embodiment of the present invention, where the algorithm includes:

1) collecting three-phase power grid voltage and three-phase load current, and mainly solving the angle of each phase voltage and current by using an SDFT algorithm or a phase-locked algorithm;

2) checking whether the direction of CT of a certain phase is inconsistent with the direction of other two phases on site, if so, selecting the phase from the CT opposite phases, and if not, setting the option to be 0; judging whether a certain phase has negative power (namely power generation) through a master station or a household meter and the like, and setting corresponding values in the negative power phase and a power factor threshold;

3) solving fundamental power factors for all the voltage and current combinations, and calculating the power factors when the current is negative so as to analyze the CT reverse connection condition;

4) comparing the fundamental power factor with a set power factor limit value, judging whether the fundamental power factor is higher than the set power factor limit value, if the absolute value of the obtained power factor result is higher than the set power factor limit value, the result under the combination is 1, otherwise, the result is 0;

from 3) and 4), it can be seen that there are 8 cases in total, namely, the directions of CTA/CTB/CTC are: positive/negative/positive/negative. Thus 4) the resulting matrix is a 3 × 24 matrix, i.e. 8 3 × 3 matrices, each 3 × 3 matrix corresponding to a set of CT directions.

5) Selecting two 3 x 3 matrixes according to the preset CT anisotropic phase, wherein the two matrixes are reserved and are respectively analyzed and judged as the CT anisotropic phase is unknown whether negative or positive;

6) judging whether the two matrixes have unique solutions or not respectively, and if the matrixes are full-rank matrixes, judging that the matrixes have unique solutions according to the rank correlation principle of the matrixes; since the full rank matrix is also an invertible matrix and the order of the matrix is 3 × 3, whether there is a unique solution can also be determined by calculating a determinant.

If a certain matrix has a unique solution, the corresponding relation between the current transformer and the voltage can be deduced through the position of 1, and the actual direction of the current transformer can be obtained from the CT direction corresponding to the matrix; if both matrixes have unique solutions, both possibilities exist, and other methods are needed to be checked; if neither matrix has a unique solution, further investigation is required.