阅读说明：本技术 一种台区阻抗的实时计算方法 (Real-time calculation method for distribution room impedance ) 是由 李梦宇 刘林青 李翀 王鸿玺 张超 王洋 于 2020-05-14 设计创作，主要内容包括：本发明涉及一种台区阻抗的实时计算方法,其包括如下步骤：(1)依据用电信息采集系统,抽取原始数据；(2)对原始数据进行处理；(3)对配电网线路进行简化,依据处理后的数据进行阻抗计算。本发明结合变电台区的一般特点,在研究HPLC高频采集数据的基础上,提出了一种适用于变电台区低压侧配电线路阻抗的实时计算方法,监测阻抗的变化,能够发现配电线路老化、台区供电范围过大、窃电与违约用电行为等异常情况,为配变台区的技改大修及运行维护提供科学依据。(The invention relates to a real-time calculation method of platform zone impedance, which comprises the following steps: (1) extracting original data according to the power utilization information acquisition system; (2) processing the original data; (3) simplifying the power distribution network line, and performing impedance calculation according to the processed data. The invention provides a real-time calculation method suitable for the impedance of a distribution line on the low-voltage side of a transformer area on the basis of researching high-frequency HPLC (high performance liquid chromatography) data by combining with the general characteristics of the transformer area, monitors the change of the impedance, can find abnormal conditions such as aging of the distribution line, overlarge power supply range of the transformer area, electricity stealing and default electricity using behaviors and the like, and provides scientific basis for technical modification and major repair and operation maintenance of the distribution transformer area.)

1. A real-time calculation method for distribution room impedance is characterized by comprising the following steps:

(1) extracting original data according to the power utilization information acquisition system;

(2) processing the original data;

(3) simplifying the power distribution network line, and performing impedance calculation according to the processed data.

2. The method for calculating the transformer area impedance in real time as claimed in claim 1, wherein in the step (1), the original data comprises a user number, a current transformer multiplying factor, a voltage transformer multiplying factor, data acquisition time, three-phase voltage and three-phase current.

3. The method of claim 1, wherein in the step (2), the raw data processing comprises data cleaning, current transformation and screening of valid data.

4. The method of claim 3, wherein the data cleaning process comprises: and eliminating abnormal data and supplementing missing values according to a Lato criterion and an interpolation method.

5. The method of claim 4, wherein the current transformation process comprises: and converting the multiplying power of the current transformer recorded by the power utilization information acquisition system and the acquired data of the electric energy meter into the primary side current of the user.

6. The method of claim 5, wherein the step of screening the valid data comprises: at a certain moment, if the load current of the user is 0, the influence of the user on the station area at the moment is not considered.

7. The real-time calculation method of the platform area impedance according to claim 6, wherein the impedance calculation process is as follows:

(a) simplifying the power distribution network line;

(b) calculating the equivalent voltage and the equivalent current of the user side according to the current and voltage data of the user side;

(c) and calculating the total impedance of the distribution lines under the distribution area.

8. The method of claim 7, wherein the step (a) is equivalent to that the main line is located at the same dividing point as each branch.

9. The method as claimed in claim 8, wherein in step (b), the user-side equivalent voltage is:

the equivalent current at the user side is as follows:

wherein, U₁To U_nUser side voltages of user 1 to user n, respectively; the user side currents of the users 1 to n are respectively I₁To I_n。

10. The method of claim 9, wherein in step (c), the total impedance of the distribution line under the distribution area is calculated as R according to formula (11)_∑：

Wherein, U_cIs the supply side voltage.

Technical Field

The invention belongs to the field of power distribution networks, and particularly relates to a real-time calculation method for distribution room impedance.

Background

The power distribution network is a 'life line' of people production and life, is the 'last kilometer' of power supply, and the safety and stability of the power distribution network directly influence the power utilization reliability of power consumers. The transformer area is an important component of the power distribution network, is responsible for power supply of low-voltage users, has the characteristics of wide distribution range, numerous quantity and complex topological structure, and becomes a monitoring blind area due to loss of distribution line information under the transformer area and shortage of power utilization information of the users for many years.

The line loss refers to all electric energy loss generated in the electric energy transmission process of the power grid operation enterprise, and is a general term of comprehensive electric energy loss of the power grid. The line loss in the power operation of the distribution network system can be divided into theoretical line loss, management line loss, statistical line loss, rated line loss and the like. The theoretical line loss is determined by the current power grid load condition and parameters of power supply equipment in the process of power grid transmission and distribution, cannot be avoided, can be obtained through theoretical calculation, and is also called technical line loss; the management line loss is various losses caused by errors of various metering devices and meters, human factors and other unknown factors in the process of electric power marketing operation, and can be called controllable loss. The statistical line loss is also called actual line loss or assessment line loss, is a difference value calculated according to the reading of the electricity purchasing and selling meters, namely the difference value between the electricity supply quantity and the electricity selling quantity, and is the basis for assessing the line loss index of an enterprise at a higher level. Statistical line loss is generally equal to the sum of theoretical line loss and managed line loss.

The reduction of the distribution network line loss can start from two aspects of reducing the management line loss and reducing the technical line loss respectively, along with the increasing standardization of management and the popularization of intelligent electric meters, the management line loss is greatly reduced in recent years, and the technical line loss generated by equipment factors still exists. The loss is reduced technically, namely, the loss of the distribution network is reduced by analyzing the reasons of the technical line loss and then adopting technical means in a targeted manner. The technical line loss reflects the loss of electric energy generated by the impedance of the distribution network in corresponding time periods in the transmission, transformation and distribution processes.

The transformer area impedance is a main factor for generating the technical line loss of the transformer area, can directly reflect the 'health' degree of the transformer area, and is mainly represented as follows:

1. as the operation age increases and the platform area equipment ages, the insulation level of the platform area equipment is gradually reduced, which causes the phenomena of electric leakage and electric discharge and changes the impedance of the platform area;

2. the topological structure of the power distribution network changes constantly, the power supply quality of a distribution area is affected by the access of new users and the expansion of old users, the optimization cannot be achieved by a traditional mode of manual decision, and the impedance of the distribution area is abnormal due to the overlarge power supply radius and unreasonable load distribution.

The traditional theoretical line loss calculation method needs an accurate topological structure and the electrical quantity of each branch, so that the cost is huge for a huge, complex and variable transformer area, and the method is difficult to realize. With the popularization and application of the HPLC technology, the power utilization information of low-voltage users is enriched, and a new method is provided for calculating the impedance of the transformer area.

Disclosure of Invention

The invention provides a real-time calculation method suitable for the impedance of a distribution line on the low-voltage side of a transformer area on the basis of researching high-frequency HPLC (high performance liquid chromatography) data by combining with the general characteristics of the transformer area, monitors the change of the impedance, can find abnormal conditions such as aging of the distribution line, overlarge power supply range of the transformer area, electricity stealing and default electricity using behaviors and the like, and provides scientific basis for technical modification and major repair and operation maintenance of the distribution transformer area.

The invention adopts the following technical scheme:

a real-time calculation method of platform area impedance comprises the following steps:

(1) extracting original data according to the power utilization information acquisition system;

(2) processing the original data;

(3) simplifying the power distribution network line, and performing impedance calculation according to the processed data.

Further, in the step (1), the original data includes a user number, a current transformer multiplying factor, a voltage transformer multiplying factor, data acquisition time, three-phase voltage and three-phase current.

Further, in the step (2), the raw data processing includes data cleaning, current conversion and screening of valid data.

Further, the data cleaning process is as follows: and eliminating abnormal data and supplementing missing values according to a Lato criterion and an interpolation method.

Further, the current conversion process is as follows: and converting the multiplying power of the current transformer recorded by the power utilization information acquisition system and the acquired data of the electric energy meter into the primary side current of the user.

Further, the process of screening the valid data comprises: at a certain moment, if the load current of the user is 0, the influence of the user on the station area at the moment is not considered.

Further, the impedance calculation process is as follows:

(a) simplifying the power distribution network line;

(b) calculating the equivalent voltage and the equivalent current of the user side according to the current and voltage data of the user side;

(c) and calculating the total impedance of the distribution lines under the distribution area.

Further, in the step (a), the power grid line is equivalent to the boundary point of the trunk line and each branch line being at the same position.

Further, in the step (b), the user-side equivalent voltage is:

the equivalent current at the user side is as follows:

wherein, U₁To U_nUser side voltages of user 1 to user n, respectively; user 1 to user nRespectively of current I at the subscriber side₁To I_n。

Further, in the step (c), the total impedance of the distribution line under the distribution area is calculated as R through the formula (11)_∑：

Wherein, U_cIs the supply side voltage.

The invention has the beneficial effects that:

1. the method provided by the invention has wide application range and is easy to popularize. According to the method, the topological structure and the line information of the distribution transformer area do not need to be known, the impedance of the transformer area can be calculated only by utilizing the high-frequency collected user power consumption data of HPLC, the definition and the extraction of the related data both follow a standard design scheme, and the method can be widely applied to the impedance calculation of the transformer area.

2. The method provided by the invention is simple in calculation and strong in real-time performance. The method has low requirement on data volume, can realize the calculation of the impedance of the distribution area only by the power consumption data of the distribution area and the user at the same time, and has a quick calculation process.

3. The method provided by the invention has the advantages of rich data sources and strong expansibility. The impedance calculated by the method is used as basic data, an acquisition strategy of HPLC can be combined, the power utilization information data is fully utilized, a post-processing method is added, the accuracy and precision of calculation can be further improved, and application scenes are rich.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Fig. 2 is a schematic diagram of a distribution network.

Fig. 3 is an equivalent circuit diagram of a power distribution network.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. 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 application.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways than those described herein, and it will be apparent to those of ordinary skill in the art that the present application is not limited to the specific embodiments disclosed below.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

Fig. 1 is a schematic flow chart of the present invention, and for a distribution area to which an HPLC technology has been applied, target data may be directly obtained by a system, or a data extraction program may be written to obtain power consumption data of the distribution area and a user, so as to perform calculation, and obtain impedance of the distribution area at a certain time.

Firstly, according to the standardized design of the electricity consumption information acquisition system, the raw data and the data source which need to be extracted are shown in table 1.

TABLE 1 Source data case

The extraction of the related data can be directly obtained by the power utilization information acquisition system, and an SQL program for extracting the related data can also be written, specifically comprising the following steps:

select

ed.cons_no,ed.ct,ed.pt,

ee.data_time,

ee.ua,ee.ub,ee.uc,

ee.ia,ee.ib,ee.ic,

from e_data_mp ed,e_mp_curve ee

where ed.id＝ee.id(+)

and ed.mp_type＝1

secondly, processing the extracted data according to the following principle:

1. and (6) data cleaning. And eliminating abnormal data and supplementing missing values according to a Lato criterion and an interpolation method.

2. And (4) current conversion. Due to different multiplying powers of the current transformers of the users, the multiplying powers of the current transformers recorded by the system and the collected data of the electric energy meter need to be converted into primary side currents of the users, and therefore the calculation standards are unified.

3. And rejecting users with load current of 0. At a certain moment, if the load current of the user is 0, the influence of the user on the station area at the moment is not considered.

Fig. 2 is a diagram of a general distribution network line, and fig. 3 is a diagram of an equivalent circuit obtained by simplifying a distribution network line according to the electrical characteristics of the line, that is, the boundary point of a trunk line and each branch line is the same.

In FIG. 3, U_cFor supply side voltage, P_cFor the active power of the power supply side, I is the main circuit current, R is the main circuit impedance, U₁To U_nUser side voltages, P, for user 1 to user n, respectively₁To P_nUser side active power, R, of user 1 to user n, respectively₁To R_nBranch impedances, U, of subscriber 1 to subscriber n, respectively_mIs the intermediate node voltage.

By using the method, 212 user electricity consumption data under a certain area are extracted, wherein 86 users with 0 current are extracted, and the voltage and current data of the rest 126 users with loads are shown in the following table. (at this point in time, the table area summary table voltage U_c＝239.3V)

Table 2 user voltage and current units: v, A

Third, calculation of data

From KVL and KCL, one can obtain:

the following can be obtained in a simultaneous manner:

let R 'be equivalent impedance from user 1 to region'₁And then:

due to impedanceProportional to the current, the weights of the equivalent impedances of the users 1 to n in the distribution area can be set as w₁To w_nAnd then:

the total impedance of the distribution line under the distribution area is set as R_∑And then:

in conjunction with the above formula, one can obtain:

according to general distribution lines characteristics, ordinary distribution station district is through a cable junction distribution transformer and table case, then divide into each branch road and lead to the user, has promptly:

namely: the voltage of the dividing point of the trunk circuit and each branch circuit is half of the average value of the voltage of the transformer area side and the voltage of the user side.

The trunk impedance is then:

in summary,

further calculated from the data obtained in table 2 are:

according to equation (11), we obtain:

therefore, the impedance value of the transformer area at a certain moment can be calculated by acquiring the electrical data of the transformer area side, and the voltage and current data of the user side. Through multipoint measurement and calculation, the accuracy of the calculated impedance can be further improved by utilizing a statistical method.