CN105911512A - Intelligent electric energy meter constant test system and test method thereof - Google Patents

Abstract

The invention discloses an intelligent electric energy meter constant test system, comprising: a standard source, a standard meter, at least one electric energy meter to be tested, an error calculator, and a communication interface. It is characterized in that the standard source can set the voltage and current arbitrarily And power factor, provide three-phase voltage to the standard meter and the detected voltage circuit, provide three-phase current to the current circuit; The voltage circuits of each phase of the described detected meter and the standard meter are connected in parallel, and the electric energy meter and the The current circuits of each phase of the standard meter are connected in series; the electric energy meter and the standard meter are respectively connected to the error calculator through a communication interface. The present invention is based on the traditional standard meter method. Under the selected operating conditions, the tested meter and the standard meter are operated simultaneously for a period of time, and the electric energy indications of the two are compared to obtain the error of the tested electric energy meter. According to the relationship between the error and the basic error limit of the tested electric energy meter, it can be judged whether the constant of the checked meter meets the requirements under the selected operating conditions.

Description

A smart electric energy meter constant test system and test method

technical field

The invention belongs to the technical field of electric energy measurement, and in particular relates to an intelligent electric energy meter constant test system and a test method thereof.

Background technique

The constant of the smart electric energy meter is a numerical value representing the relationship between the electric energy recorded by the meter and the corresponding test output value. The measured cumulative electric energy is recorded by the counter, and the corresponding test output value can be output by the pulse output device. The number is calculated. According to the requirements of GB/T 17215.321, the relationship between the test output of the electric energy meter and the display indication should be consistent with the nameplate mark.

At present, there are three kinds of constant test methods for smart electric energy meters: counting and reading pulse method, running word test method and standard meter method. The counting and reading pulse method is to change the last digit of the counter of the electric energy meter under test by at least 1 digit under the condition of reference frequency, reference voltage, maximum current and power factor of 1, and then check whether the output pulse number meets the corresponding requirements. Requirements: The test method is to connect two reference meters in series with the current lines of each tested meter, and connect the voltage lines in parallel. Under the conditions of reference frequency, reference voltage, maximum current and power factor of 1, make the tested meter The number of changes in the last digit of the meter is not less than the specified number, and then check whether the indications of the reference meter and other meters under inspection meet the corresponding requirements; the standard meter method is to compare the current of the meter under inspection with a standard electric energy meter The lines are connected in series and the voltage lines are connected in parallel. Under the conditions of reference frequency, reference voltage, maximum current and power factor of 1, it is tested whether the error of the tested meter meets the requirements after running for a period of time.

Among them, the counting and reading pulse method requires the output pulse number N and the electric energy value calculated by the electric energy meter constant C to be consistent with the recorded value of the meter, which has the disadvantage of poor operability; Among the watt-hour meters to be tested, two watt-hour meters with relatively stable errors and known constants are selected as reference meters, and the test results are easily affected by the error stability of the reference meters. The traditional standard meter method is simple and easy to implement, but it is only tested under the conditions of reference frequency, reference voltage, maximum current and power factor of 1. The following also meets the requirements.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a smart meter constant test system and method for checking the relationship between the electric energy recorded by the smart meter and the corresponding test output value under different operating conditions. Whether the relationship is consistent with the nameplate mark.

In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:

An intelligent electric energy meter constant test system, comprising: a standard source, a standard meter, at least one electric energy meter to be tested, an error calculator, and a communication interface, characterized in that the standard source can arbitrarily set voltage, current and power factor, Provide three-phase voltage to the standard meter and the detected voltage circuit, and provide three-phase current to the current circuit; the voltage circuits of each phase of the tested meter and the standard meter are connected in parallel, and the electric energy meter and the standard meter are connected in parallel. The current lines of each phase are connected in series; the electric energy meter and the standard meter are respectively connected to the error calculator through a communication interface.

Preferably, the electric energy meter and the standard meter have the same wire.

Preferably, the communication interface is RS485.

Preferably, when the specifications of the at least one checked electric energy meter are the same, all the current lines of the checked electric energy meters in the system are connected in series, and all the voltage lines are connected in parallel.

During the test, first select a standard meter, connect the tested meter in parallel with the voltage circuit of the standard meter, and connect the current circuit in series; apply a voltage U on the voltage circuit, which is equal to the reference voltage U _n of the tested meter; Apply I, and I≥I _st , where: I _st is the starting current of the meter under test; the phase between the voltage applied by the voltage line and the current applied by the current line can be set arbitrarily, that is, the power factor is

Make the selected standard meter and the checked meter run for a period of time t at the same time, and t≥t _m , where t _m is the shortest test time to meet the requirements; then calculate the error γ of the checked meter: Among them: E' is the indicated value of electric energy taken by the tested electric energy meter within the time period t, and E is the indicated value of electric energy taken by the standard electric energy meter within the period of time t.

If E _m is the minimum energy value passed by the tested meter that meets the requirements, in order to reduce the error of the tested meter, the constants of the standard electric energy meter and the resolution of the tested meter and other influencing factors should be used to reduce the error introduced by The electric energy E'≥E _m passed by the meter under test within time t;

_Em can be obtained by the following formula:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}$

In the above formula, R is the apparent resolution of the watt-hour meter to be checked; b is the load current of the watt-hour meter to be checked when the load current is I and the power factor is The basic error limit below.

t _m can be obtained by the following formula:

At this time, the following methods can be used to judge whether the electric energy meter constant test meets the requirements: when , then the constant test of the tested electric energy meter is when the load current is I and the power factor is meet the requirements; when , then the constant test of the tested electric energy meter is when the load current is I and the power factor is The following does not meet the requirements.

It should be noted that this method can arbitrarily select the current amplitude and power factor under the conditions of U= _Un and _I≥Ist to judge whether the constants of the electric energy meter under test meet the requirements under different operating conditions; For electric energy meters of the same specification, all the current lines of the electric energy meters can be connected in series, and all the voltage lines can be connected in parallel. By reading the error γ of each tested meter, it can be judged whether the constants of all the tested meters meet the requirements.

Compared with the prior art, the beneficial effect of the present invention is: the present invention is based on the traditional standard meter method, under selected operating conditions, the tested meter and the standard meter are operated simultaneously for a period of time, and the distance between the two The electric energy indication value is compared to obtain the error of the electric energy meter under test. According to the relationship between the error and the basic error limit of the electric energy meter under test, it can be judged whether the constant of the electric energy meter under test meets the requirements under the selected operating conditions.

Description of drawings

Fig. 1 is a schematic diagram of the present invention;

Fig. 2 is a constant test flow chart of the present invention.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

An intelligent electric energy meter constant test system of the present invention includes: a standard source, a standard meter, at least one electric energy meter to be tested, an error calculator, and a communication interface. It is characterized in that the standard source can set the voltage, current and The power factor provides three-phase voltage to the standard meter and the detected voltage circuit, and provides three-phase current to the current circuit; the tested meter and each phase voltage circuit of the standard meter are connected in parallel, and the electric energy meter and the The current circuits of each phase of the standard meter are connected in series; the electric energy meter and the standard meter are respectively connected to the error calculator through a communication interface.

Preferably, the electric energy meter and the standard meter have the same wire.

Preferably, the communication interface is RS485.

Preferably, when the specifications of the at least one checked electric energy meter are the same, all the current lines of the checked electric energy meters in the system are connected in series, and all the voltage lines are connected in parallel.

Taking the electric energy meter to be checked as an electric energy meter whose accuracy is A grade as an example, it is illustrated that the invention is carried out Electric energy meter constant test under certain conditions: the standard source can set the voltage, current and power factor arbitrarily, provide three-phase voltage to the standard meter and the voltage line to be tested, and provide three-phase current to the current line. The voltage lines of each phase of the tested meter and the standard meter are connected in parallel, and the current lines of each phase of the electric energy meter and the standard meter are connected in series. During the test, the reference voltage U _n of the electric energy meter is applied to the voltage line; I is applied to the current line, and I≥I _st is satisfied, where: I _st is the starting current of the meter under test. In this example, the standard source is controlled so that the voltage in phase with the current, that is,

Make the selected standard meter and the meter under test run for a period of time t at the same time, and t≥t _m , the shortest test time t _m to meet the requirements can be obtained by the following formula:

Among them, E _m is the minimum electric energy value passed by the tested meter that meets the requirements, which can be obtained by the following formula:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}$

In the formula, R is the apparent resolution of the watt-hour meter to be checked; b is the load current of the watt-hour meter to be checked when the load current is I and the power factor is The basic error limit below.

The error calculator is connected through a communication interface such as RS485, and reads the value of the electric energy indication value E' of the tested electric energy meter within the t period of time and the value of the electric energy indication value E of the standard electric energy meter within the t period of time, and Calculate the error of the checked table

because According to the value of the load current I, the expression of the basic error limit b of the tested meter can be obtained:

$\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 2.5</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; I</span>}& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; 2.5</span>}& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; 2.0</span>}& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

In the formula, I _st is the starting current, I _min is the minimum current, I _tr is the turning current, and I _max is the maximum current. The above current indicators are provided by the meter manufacturer and comply with R46 international recommendations, EN50470 standards or other standards Provisions.

According to the relationship between the error γ of the checked meter and b/10, it can be determined whether the constant of the checked meter meets the requirements: when , the constant of the watt-hour meter to be tested is when the load current is I and the power factor meet the requirements under the conditions; when , the constant of the watt-hour meter to be tested is when the load current is I and the power factor The following does not meet the requirements.

It should be noted that the meter under test in the schematic diagram shown in Figure 1 is three-phase four-wire, and the standard meter during the test should also be three-phase four-wire. If the meter under test is three-phase three-wire or single-phase, the corresponding The standard meter should also be three-phase three-wire or single-phase. The connection mode between the standard source, the meter under test and the standard meter is changed according to the type of the meter.

Shown in Fig. 2 is constant test flowchart of the present invention, and concrete steps are as follows:

Step 1, according to the current parameters of the meter under test, select the constant test current I and power factor

Step 2, according to the value of the test applied current I, determine the basic error limit b under the load point;

Step 3, determine the minimum electric energy value E _m passed by the tested meter;

Step 4, determine the shortest test time t _m that satisfies the requirements of the constant test;

Step 5, connect the voltage circuit of the tested meter and the standard meter in parallel, and apply a voltage U _n ; connect the tested meter and the current circuit of the standard meter in series, and apply a current I; the standard meter and the tested meter run at the same time for a period of time t;

Step 6, judge whether t≥t _m is satisfied; if it is satisfied, go to step 7, if not, return to step 5, and reselect the running time t;

Step 7, the error calculator calculates the error of the checked meter

Step 8, judge whether it is satisfied If it is satisfied, then the constant test of the tested meter is in the load current I and power factor Conditions are qualified, if not satisfied, the constant test of the tested meter is in the load current I and power factor conditions fail.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand; it can still be described in the foregoing embodiments Modifications are made to the technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (5)

1. an intelligent electric energy meter constant pilot system, including: standard source, standard scale, at least one is tested Electric energy meter, error op device, communication interface, it is characterised in that described standard source can arbitrarily setting voltage, Electric current and power factor, provide three-phase voltage, to current circuit to standard scale and detected voltage circuit Three-phase current is provided；Described tested table is the most in parallel with each phase voltage circuit of described standard scale, described electric energy meter All connect with each phase current circuit of described standard scale；Described electric energy meter and described standard scale are each via communication Interface is connected with described error op device.

A kind of intelligent electric energy meter constant pilot system the most according to claim 1, it is characterised in that institute State electric energy meter and the same same line of described standard scale.

A kind of intelligent electric energy meter constant pilot system the most according to claim 1, it is characterised in that institute Stating communication interface is RS485.

A kind of intelligent electric energy meter constant pilot system the most according to claim 1, it is characterised in that institute State the specification of at least one tested electric energy meter identical time, the current circuit of each tested electric energy meter in system is whole Series connection, voltage circuit is the most in parallel.

5. an intelligent electric energy meter constant test method, including:

Step 1, takes the tested table of same kind and standard scale, and according to each current parameters of tested table, selectivity constant is tested Electric current I and power factor

Step 2, applies the value of electric current I, determines the limit of intrinsic error b under this POL according to test；

Step 3, determines the minimum energy value E that tested table is passed through_m；

Step 4, determines minimum test duration t meeting constant test requirements document_m；

Step 5, by parallel to tested table and standard scale voltage circuit, applies voltage U_n；By tested table and standard Table current circuit is connected, and applies electric current I；Standard scale and tested table run a period of time t simultaneously；

Step 6, it may be judged whether meet t >=t_m；If meeting and carrying out step 7, if being unsatisfactory for, return step 5, Reselect operation time t；

Step 7, error op device calculates the error of tested tableWherein: E' is tested electric energy The electric energy indicating value that table was walked within the t section time, E is by being walked in the standard electric energy meter t section time at runtime Electric energy indicating value；

Step 8, it may be judged whether meetIf meeting, the test of the most tested table constant at load current I and Power factorUnder the conditions of qualified, if being unsatisfactory for, the test of the most tested table constant load current I and power because of NumberUnder the conditions of defective.