CN112462318A

CN112462318A - Ammeter wiring detection method, distributed power generation system and power generation source

Info

Publication number: CN112462318A
Application number: CN201910841603.7A
Authority: CN
Inventors: 俞雁飞; 倪华; 尚玉宝
Original assignee: Sungrow Power Supply Co Ltd
Current assignee: Sungrow Power Supply Co Ltd
Priority date: 2019-09-06
Filing date: 2019-09-06
Publication date: 2021-03-09

Abstract

The invention provides an ammeter wiring detection method, a distributed power generation system and a power generation source, wherein the ammeter wiring detection method comprises the following steps: controlling a power generation source to sequentially operate under a first working condition and a second working condition, and acquiring metering parameters of an ammeter in a distributed power generation system meeting preset conditions under corresponding working conditions; and then, according to the recording parameters of the power supply under the first working condition, the recording parameters of the power supply under the second working condition, the metering parameters of the ammeter under the first working condition and the metering parameters of the ammeter under the second working condition, calculating to obtain the parameter change values of each phase of the power generation source and the ammeter respectively, sequencing the parameter change values of each phase of the power generation source and the parameter change values of each phase of the ammeter according to a preset sequence to obtain the three-phase arrangement sequence of the power generation source and the three-phase arrangement sequence of the ammeter, judging whether the two three-phase arrangement sequences are the same, and judging whether the wiring of the ammeter has a wrong phase if the two three-phase arrangement sequences are different, so that the problem that the wiring of the ammeter is connected in a wrong phase can be.

Description

Ammeter wiring detection method, distributed power generation system and power generation source

Technical Field

The invention relates to the technical field of power electronics, in particular to an ammeter wiring detection method, a distributed power generation system and a power generation source.

Background

In recent years, distributed power generation represented by photovoltaic power generation has been rapidly developed, and in order to avoid the impact of distributed power generation sources on a large power grid, governments of various countries set policies to guide distributed power generation to be consumed. Typical policies include grid-connected point feed power limits that require that the power output by the distributed generation source to the large grid must not exceed a certain limit, such as a limit of 70% or 0%.

The distributed power generation system is characterized in that an electric meter is installed at a grid-connected point, the electric meter is used for measuring the power of the grid-connected point and feeding the power back to the distributed power generation source, the distributed power generation source compares the power of the grid-connected point with a threshold value, and the output power is adjusted in real time, so that the power of the grid-connected point does not exceed the preset threshold value.

If the power generation source is a three-phase power generation source and the electric meters at the grid-connected point are three-phase electric meters, the electric meters at the grid-connected point are easy to be connected in a wrong phase. When the wiring of the electric meter is connected in a wrong phase, the measured power of the grid-connected point is incorrect and the power of the grid-connected point is limited by the distributed power generation source to fail.

Disclosure of Invention

In view of this, embodiments of the present invention provide an electric meter wiring detection method, a distributed power generation system, and a power generation source, where the electric meter wiring detection method is used to detect a wiring state of an electric meter, so as to avoid problems that a measured grid-connected point power is incorrect and a grid-connected point power limitation failure of the distributed power generation source is caused due to wrong connection of electric meter wirings.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

the invention discloses an ammeter wiring detection method in a first aspect, which is applied to a controller of a power generation source in a distributed power generation system and comprises the following steps:

controlling the power generation source to sequentially operate under a first working condition and a second working condition, and acquiring metering parameters of electric meters in the distributed power generation system meeting preset conditions under corresponding working conditions;

when the power generation source is a three-phase power generation source, calculating to obtain a parameter change value of each phase of the power generation source according to the recording parameter of the power generation source under the first working condition and the recording parameter of the power generation source under the second working condition, and sequencing the parameter change values of each phase of the power generation source according to a preset sequence to obtain a three-phase sequence of the power generation source;

calculating to obtain each phase parameter change value of the ammeter according to the metering parameters of the ammeter under the first working condition and the metering parameters of the ammeter under the second working condition, and sequencing each phase parameter change value of the ammeter according to the preset arrangement sequence to obtain a three-phase arrangement sequence of the ammeter;

judging whether the two three-phase arrangement sequences are the same;

and if the two three-phase arrangement sequences are different, judging that the wiring of the ammeter is in wrong phase connection.

Optionally, in the above method for detecting connection of an electric meter, after determining that there is a misphase connection in the connection state of the electric meter, the method further includes:

and taking the three-phase sequencing sequence of the power generation source as a nominal sequence of the electric meter, and re-marking the subsequent metering parameters of the electric meter in the nominal sequence.

Optionally, in the method for detecting the wiring of the electric meter, the preset condition is that at least one phase parameter of the metering parameters is different from the other two phase parameters.

Optionally, in the method for detecting the connection of the electric meter, the controlling the power generation source to sequentially operate under a first working condition and a second working condition, and acquiring the metering parameters of the electric meter in the distributed power generation system meeting the preset conditions under the corresponding working conditions includes:

and controlling the output power of the power generation source in a mode of injecting negative-sequence active current into a control loop of the power generation source so as to obtain the metering parameters which meet the preset conditions in the electric meter.

Optionally, in the above method for detecting connection of an electric meter, at least one of the first operating condition and the second operating condition is: the working condition that electric energy is absorbed from a power grid to charge the power generation source;

after controlling the power generation source to sequentially operate under a first working condition and a second working condition and acquiring the metering parameters of the electric meters in the distributed power generation system meeting the preset conditions under the corresponding working conditions, the method further comprises the following steps:

when the power generation source is a single-phase power generation source or a three-phase power generation source, determining the wiring state of the ammeter by judging whether the variation relation of the metering parameters of the ammeter under different working conditions corresponds to the working condition variation relation of the power generation source;

and if the wiring state is reverse connection, performing reverse processing on subsequent metering parameters of the ammeter.

Optionally, in the method for detecting the connection of the electric meter, the determining the connection state of the electric meter by determining whether a variation relationship of the metering parameter of the electric meter under different working conditions corresponds to a variation relationship of the working condition of the power generation source includes:

judging whether the magnitude relation between the recording parameters of the power generation source under the first working condition and the recording parameters of the power generation source under the second working condition is the same as the magnitude relation between the metering parameters of the ammeter under the first working condition and the metering parameters of the ammeter under the second working condition;

if the two size relations are the same, the electric meter is judged to be in positive connection;

and if the two size relations are different, judging that the electric meter is in reverse connection.

Optionally, in the method for detecting the connection of the electric meter, after the controlling the power generation source to sequentially operate under the first working condition and the second working condition and acquiring the metering parameters of the electric meter in the distributed power generation system meeting the preset conditions under the corresponding working conditions, the method further includes:

when the power generation source is a single-phase power generation source or a three-phase power generation source, controlling the power generation source to sequentially operate under a plurality of working conditions again, and acquiring the metering parameters of the ammeter meeting preset conditions under corresponding working conditions; the number of the working conditions of the plurality of working conditions is greater than a working condition threshold value;

determining the wiring state of the ammeter by judging whether the variation relation of the metering parameters of the ammeter under different working conditions corresponds to the working condition variation relation of the power generation source;

taking the wiring state with the largest proportion in all the determined wiring states of the electric meters as the final wiring state; alternatively, the first and second electrodes may be,

and determining the occupation ratio of each state in the wiring states of the electric meter, and taking the wiring state with the occupation ratio exceeding the occupation ratio threshold value as a final wiring state.

Optionally, before controlling the power generation source to sequentially operate under a first working condition and a second working condition and acquiring the metering parameters of the electric meters in the distributed power generation system meeting the preset conditions under the corresponding working conditions, the method further includes:

calculating a load consumption power change value within a preset time length;

judging whether the load consumption power change value is smaller than a preset threshold value or not;

and if the load consumed power change value is smaller than the preset threshold value, the step of controlling the power generation source to sequentially operate under a first working condition and a second working condition and acquiring the metering parameters of the electric meters in the distributed power generation system meeting the preset conditions under the corresponding working conditions is executed.

Optionally, after determining that there is a misphase connection in the connection of the electric meter, or determining the connection state of the electric meter, the method further includes:

and recording and storing the wiring state of the electric meter, and re-executing the step of controlling the power generation source to sequentially operate under the first working condition and the second working condition when the alternating current power failure is identified each time or the communication with the electric meter is interrupted.

Optionally, in the above method for detecting the wiring of the electric meter, the recording parameter and the metering parameter are active power, reactive power or apparent power.

The invention discloses a power generation source of a distributed power generation system, wherein a controller in the power generation source is used for executing the electric meter wiring detection method.

A third aspect of the present invention discloses a distributed power generation system, including: an electricity meter and a power generation source as described above;

and the alternating current side of the power generation source is connected with a power grid through the electric meter.

Optionally, in the above distributed power generation system, a load is further included, and the load is coupled between the power generation source and the electric meter.

Optionally, in the above distributed power generation system, the power generation source includes:

the converter of taking energy storage device or energy storage interface to, and, at least one photovoltaic cell board.

Based on the ammeter wiring detection method provided by the embodiment of the invention, the ammeter wiring detection method is applied to a controller of a power generation source in a distributed power generation system, and the method comprises the steps of firstly controlling the power generation source to sequentially operate under a first working condition and a second working condition, and acquiring metering parameters of an ammeter in the distributed power generation system meeting preset conditions under corresponding working conditions; when the power generation source is a three-phase power generation source and the ammeter is a three-phase ammeter, calculating to obtain a change value of each phase parameter of the power generation source according to the recording parameter of the power generation source under the first working condition and the recording parameter of the power generation source under the second working condition, sequencing the change values of each phase parameter of the power generation source according to a preset sequencing sequence to obtain a three-phase sequencing sequence of the power generation source, calculating to obtain a change value of each phase parameter of the ammeter according to the metering parameter of the ammeter under the first working condition and the metering parameter of the ammeter under the second working condition, and sequencing the change values of each phase parameter of the ammeter according to the preset sequencing sequence to obtain a three-phase sequencing sequence of the ammeter; and then through judging whether two three-phase arrangement sequences are the same, if not the same, judge that the wiring of ammeter has wrong phase connection, can detect out through above-mentioned scheme whether the ammeter wiring state has wrong phase connection to avoid because of the ammeter wiring is wrong phase connection, the grid-connected point power measurement that leads to is incorrect and the power of power generation source restriction grid-connected point fails.

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, 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 two distributed power generation systems according to an embodiment of the present disclosure;

fig. 2 to fig. 3 are two flow charts of electric meter wiring detection provided in the embodiment of the present application;

fig. 4 to fig. 5 are schematic structural diagrams of two distributed power generation systems provided in the embodiments of the present application;

fig. 6 to 8 are flowcharts illustrating three types of electric meter connection detection provided in the embodiment of the present application;

fig. 9 is a schematic structural diagram of a distributed power generation system according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present invention will be 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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.

In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

It should be noted that the distributed power generation system is a system including a power generation source, and referring to fig. 1, the system includes a power generation source composed of a photovoltaic panel 101 and an inverter 102, a load 103, and an electricity meter 104. The controller of the power generation source is the controller of the inverter 102. The inverter 102 may be a three-phase inverter, or may be another inverter.

Specifically, in the system, the photovoltaic cell panel 101 is connected to a power grid through an inverter 102 and an electric meter 104 in sequence, and a load 103 is connected between the inverter 102 and the electric meter 104 in parallel. The inverter 102 may read the metering data of the electric meter 104 by way of communication. The communication modes comprise RS485, Ethernet, infrared communication, power line carrier communication, pulse reading and the like.

The inverter 102 may also calculate the power, the power generation amount, and the like consumed by the load 103 according to parameters such as the power and the power generation amount output by the inverter and the power generation amount measured by the electric meter 104, so as to manage the power and the energy of the whole system.

As can be seen, the output terminals of the inverter 102 are a1, B1, C1, and N1. Wherein, A1, B1 and C1 respectively represent a live wire of one phase, and N1 represents a zero wire. The inverter 102 may convert the dc power output by the photovoltaic panel 101 into ac power for transmission to the ac power grid. A1, B1, C1 and N1 at the output of the inverter 102 are connected to A, B, C, N of the grid through the electric meter 104.

And when the wiring at the two ends of the ammeter is not in the default corresponding relation, the wiring state of the ammeter is in the wrong connection. Wherein, the default corresponding relationship is: a1 for A, B1 for B, and C1 for C. If the A1 corresponds to B, B1 corresponds to C, C1 corresponds to A, the wiring of the electric meter is considered to have wrong connection.

However, in practical applications, the connection state of the electric meter often causes a wrong connection, and when the connection state of the electric meter causes a wrong connection, the metering parameters of the electric meter may be wrong, which may result in incorrect metering of the grid-connected point power in the system and failure of the power generation source in limiting the grid-connected point power.

Therefore, the embodiment of the invention provides an ammeter wiring detection method, which is used for detecting the wiring state of an ammeter so as to avoid the problems that the power of a metered grid-connected point is incorrect and the power of a distributed power generation source limiting grid-connected point fails due to the fact that the ammeter wiring is in wrong connection.

Referring to fig. 2, the method for detecting the wiring of the electric meter is applied to a controller of a power generation source in a distributed power generation system, and mainly includes the following steps:

s201, controlling the power generation source to sequentially operate under a first working condition and a second working condition, and acquiring the metering parameters of the electric meters in the distributed power generation system meeting preset conditions under the corresponding working conditions.

It should be noted that the working conditions of the power generation source include: the working condition that the power generation source is charged by absorbing electric energy from the power grid and the working condition that the power generation source is discharged and merged into the power grid. The preset condition is that at least one phase parameter in the metering parameters is different from the other two-phase parameters.

Optionally, the output power of the power generation source may be controlled by injecting a negative-sequence active current into a control loop of the power generation source to obtain a metering parameter satisfying a preset condition in the electricity meter.

The output power of the power generation source can be controlled in a mode of injecting negative-sequence active current into a control loop of the power generation source under the first working condition or the second working condition so as to obtain the metering parameters meeting the preset conditions in the electric meter.

In practical application, according to application environment and requirements, under which working condition the metering parameter meeting the preset condition is obtained can be selected by self, and the working condition corresponding to the metering parameter meeting the preset condition is not specifically limited, so that the metering parameter meeting the preset condition is protected.

It should also be noted that, the metering parameters meeting the preset conditions in the electric meter may be obtained in other manners, and the present application is not limited specifically, and all belong to the protection scope of the present application.

And when the power generation source is a three-phase power generation source and the electric meter is a three-phase electric meter, executing the following steps:

s202, calculating to obtain each phase parameter change value of the power generation source according to the recording parameters of the power generation source under the first working condition and the recording parameters of the power generation source under the second working condition, and sequencing the each phase parameter change values of the power generation source according to a preset arrangement sequence to obtain a three-phase arrangement sequence of the power generation source.

The preset arrangement sequence can be ascending or descending, and is selected according to the application environment and the user requirement, and the application is not particularly limited and belongs to the protection scope of the application.

In practical application, the difference between the recorded parameters of the power source under the first working condition and the recorded parameters of the power source under the second working condition can be calculated to obtain the parameter change value of each phase of the power source, and the obtained parameter change values of each phase are sorted according to an ascending order or a descending order to obtain the three-phase arrangement sequence of the power source.

S203, calculating to obtain each phase parameter change value of the ammeter according to the metering parameters of the ammeter under the first working condition and the metering parameters of the ammeter under the second working condition, and sequencing the each phase parameter change values of the ammeter according to a preset arrangement sequence to obtain a three-phase arrangement sequence of the ammeter.

It should be noted that the preset arranging order selected in step S203 should be the same as the preset arranging order selected in step S202, that is, both the preset arranging order and the preset arranging order are in an ascending order or a descending order.

In practical application, the difference calculation can be carried out on the metering parameters of the electric meter under the first working condition and the metering parameters of the electric meter under the second working condition to obtain the parameter change values of each phase of the electric meter, and then the obtained parameter change values of each phase are sorted according to an ascending order or a descending order to finally obtain the three-phase arrangement sequence of the electric meter.

And S204, judging whether the two three-phase arrangement sequences are the same.

It should be noted that, whether the two three-phase sequencing sequences are the same or not can be determined by determining whether the sequencing position of each phase in the three-phase sequencing sequence of the power generation source is the same as the corresponding sequencing position of each phase in the three-phase sequencing sequence of the electric meter. For example, if the three phases of the power generation source are arranged in the order: the phase A > the phase B > the phase C, and the three phases of the ammeter are sequenced as follows: and if the phase B is greater than the phase C and greater than the phase A, the sequencing position of each phase in the three-phase sequencing sequence of the power generation source is different from the corresponding sequencing position of each phase in the three-phase sequencing sequence of the electric meter, namely the two three-phase sequencing sequences are different.

If the two three phases are not in the same arrangement order, step S205 is executed. And if the two three phases are arranged in the same sequence, judging that the wiring of the electric meter is not in wrong phase connection.

And S205, judging that the connection of the electric meter has wrong connection.

The execution sequence of steps S202 and S203 is not limited to the execution sequence shown in fig. 2. Step S202 may be executed after step S203 is executed, or both steps may be executed simultaneously, and the specific execution order depends on the application environment, and is within the scope of the present application.

In the embodiment, firstly, the power generation source is controlled to sequentially operate under a first working condition and a second working condition, and the metering parameters of the electric meter in the distributed power generation system under the condition that the corresponding working conditions meet the preset conditions are obtained; when the power generation source is a three-phase power generation source and the ammeter is a three-phase ammeter, calculating to obtain a change value of each phase parameter of the power generation source according to the recording parameter of the power generation source under the first working condition and the recording parameter of the power generation source under the second working condition, sequencing the change values of each phase parameter of the power generation source according to a preset sequencing sequence to obtain a three-phase sequencing sequence of the power generation source, calculating to obtain a change value of each phase parameter of the ammeter according to the metering parameter of the ammeter under the first working condition and the metering parameter of the ammeter under the second working condition, and sequencing the change values of each phase parameter of the ammeter according to the preset sequencing sequence to obtain a three-phase sequencing sequence of the ammeter; and then judging whether the two three-phase arrangement sequences are the same or not, and if not, judging that the wiring of the electric meter is in wrong phase connection. Through the scheme, whether the wiring of the electric meter has errors or not can be detected, so that the phenomenon that the power metering of the grid-connected point is incorrect and the power of the grid-connected point is limited by a power generation source and fails due to the fact that the wiring of the electric meter is connected in a wrong phase is avoided.

Optionally, referring to fig. 3, in another embodiment of the present application, after the step S205 is executed to determine that there is a misphase connection of the connection lines of the electric meter, the method further includes:

s301, carrying out first correction processing on subsequent metering parameters of the ammeter.

Specifically, the first correction processing is: and taking the three-phase sequencing sequence of the power generation source as a nominal sequence of the electric meter, and re-marking the subsequent metering parameters of the electric meter in the nominal sequence. The metering parameters can be parameters such as current, voltage, power and power generation amount.

It should be noted that, after it is determined that the wiring of the electric meter is connected in a wrong phase, the first correction processing is performed on the subsequent metering parameters of the electric meter, and then the corrected metering parameters of the electric meter are used for managing the power and energy of the system, so that the fault tolerance of the system is improved. In addition, the subsequent metering parameters of the electric meter are corrected by a pure software algorithm, and the hardware cost is not required to be increased.

Referring to fig. 2 to 4, the following describes a specific example of determining the connection state of the electricity meter as a faulty connection.

It should be noted that the power generation source in this example is a three-phase power generation source, that is, the inverter 102 is a three-phase inverter, the electric meter 104 is a three-phase electric meter, and at least one of the metering parameters of the electric meter 104 under the first operating condition and/or the second operating condition is different from the other two-phase parameters.

It should be noted that common phase-staggered connections are two-phase cross-staggered connections and three-phase sequential staggered connections, and this example takes three-phase sequential staggered connections as an example. The detection method of the two-phase cross misconnection is the same as that of the three-phase sequential misconnection, and reference can be made to the corresponding example of the three-phase sequential misconnection, and details are not repeated.

As shown in fig. 4, a1 phase output from the inverter 102 is connected to the B phase of the electricity meter 104, B1 phase is connected to the C phase of the electricity meter 104, and C1 phase is connected to the a phase of the electricity meter 104.

Firstly, the inverter 102 is operated under a first working condition, and first three-phase active power is output: pinv _ a1 for a1 phase, Pinv _ B1 for B1 phase, Pinv _ C1 for C1 phase, first three-phase active power measured by the electricity meter 104: pgrid _ A1 for A1 phase, Pgrid _ B1 for B1 phase, and Pgrid _ C1 for C1 phase. Then, the inverter 102 is operated under a second working condition to output a second three-phase active power: pinv _ a2 for a2 phase, Pinv _ B2 for B2 phase, Pinv _ C2 for C2 phase, and the second three-phase active power measured by the electricity meter 104: pgrid _ A2 for A2 phase, Pgrid _ B2 for B2 phase, and Pgrid _ C2 for C2 phase.

And, Pinv _ a1 ═ Pinv _ B1 ═ Pinv _ C1, and Pinv _ a2 > Pinv _ B2 > Pinv _ C2.

Normally, the active power output by the inverter 102 is three-phase symmetric power, and the output active power only has a positive sequence component, that is, Pinv _ a1 ═ Pinv _ B1 ═ Pinv _ C1, but the output power of the inverter 102 can be controlled by injecting a negative sequence active current into the control loop of the inverter 102, so as to obtain that at least one phase parameter of the metering parameters of the electric meter 104 is different from the other two phase parameters, that is, Pinv _ a2 > Pinv _ B2 > Pinv _ C2.

Calculating the difference value of the output power of each phase of the inverter 102 under the first working condition and the second working condition, and sequencing to obtain:

(Pinv_A1-Pinv_A2)＜(Pinv_B1-Pinv_B2)＜(Pinv_C1-Pinv_C2)-(a)，

namely, a 1-phase power variation < B1-phase power variation < C1-phase power variation.

Calculating the difference value of the output power of each phase of the electric meter 104 under the first working condition and the second working condition, and sequencing to obtain:

(Pgrid_B1-Pgrid_B2)＜(Pgrid_C1-Pgrid_C2)＜(Pgrid_A1-Pgrid_A2)-(b)，

namely B1 phase power change < C1 phase power change < a1 phase power change.

As can be seen from the equations (a) and (B), the phase sequence output by the inverter 102 is different from the phase sequence measured by the electric meter 104, where B measured by the electric meter 104 corresponds to phase a1 output by the inverter 102, C measured by the electric meter 104 corresponds to phase B1 output by the inverter 102, and a measured by the electric meter 104 corresponds to phase C1 output by the inverter 102.

The subsequent inverter 102 should take its own phase sequence as the nominal sequence of the data measured by the electric meter 104 when acquiring the data measured by the electric meter 104 for system power or energy management. That is, the collected data of the phase a of the electricity meter 104 is used as the data of the electricity meter corresponding to C1, the collected data of the phase B of the electricity meter 104 is used as the data of the electricity meter corresponding to a1, and the collected data of the phase C of the electricity meter 104 is used as the data of the electricity meter corresponding to B1. At this time, the calculated three-phase load power is: phase A: pload _ a ═ Pinv _ a1-pgird _ B1, phase B: pload _ B ═ Pinv _ a2-pgird _ C1, phase C: pload _ C ═ Pinv _ A3-pgird _ a 1.

It should be noted that, in practical applications, there are other cases where three phases are sequentially connected in a staggered manner. The other three-phase sequential misconnection cases are similar to those shown in this example, and are not described again, and all belong to the protection scope of the present application.

In practical application, if the positive direction of the metering current of the electric meter is defined differently, the formulas used by the electric meter for metering parameters are also different.

Referring to fig. 1, if the positive direction of the current measured by the electric meter 104 is defined as the direction from the grid to the inverter 102, that is, the direction indicated by the arrow in the figure, and the active power is taken as an example, the power consumption of the load 103 is:

Pload＝Pinv+Pgrid；

where Pload represents the power consumption of the load 103, Pinv represents the active power output by the inverter 102, and Pgrid represents the active power measured by the electric meter 104.

Referring to fig. 5, if the wiring of the electric meter is opposite to that of fig. 1, the positive direction of the current measured by the electric meter 104 is defined as the direction from the inverter 102 to the grid, and the positive direction of the current is indicated by the arrow. If the load 103 is power calculated according to the formula Pload ═ Pinv + Pgrid, the result will be wrong. Because the positive direction of the current metered by the electricity meter 103 is redefined, the calculation formula for the power consumed by the load 103 is changed to:

Pload＝Pinv-Pgrid。

in practical application, the problem that errors occur in the calculation result due to the fact that the wiring mode of the electric meter is changed, namely the wiring of the electric meter is reversely connected and a power calculation formula is not replaced in time often occurs.

Therefore, on the basis of fig. 2, an embodiment of the present invention further provides an electric meter wiring detection method for detecting whether the wiring state of the electric meter is positive or negative.

When the connection state of the electric meter is judged to be positive connection or reverse connection, the number of phases of the power generation source and the electric meter is not limited. In practical applications, the power generation source and the electric meter are both three-phase models or single-phase models.

When the wiring state of the electric meter is judged to be positive connection or negative connection, at least one of the first working condition and the second working condition is as follows: and absorbing electric energy from the power grid to charge the power generation source. In practical application, the power generation source can be controlled to operate under the first working condition as a discharging working condition, the metering parameters of the electric meter in the distributed power generation system under the discharging working condition are obtained in a communication mode, and then the power generation source is controlled to operate under the second working condition as a charging working condition, and the metering parameters of the electric meter under the charging working condition are obtained in a communication mode again.

Of course, the first working condition that the power generation source operates to first may be controlled to be the charging working condition, and the second working condition that the power generation source operates to second may be the discharging working condition, or both the first working condition and the second working condition that the power generation source operates to successively may be controlled to be the charging working condition.

Referring to fig. 6, after step S301 is executed to control the power generation source to sequentially operate under the first working condition and the second working condition, and obtain the metering parameters of the electric meter in the distributed power generation system meeting the preset conditions under the corresponding working conditions, a specific execution process for determining whether the connection of the electric meter is a positive connection or a negative connection mainly includes the following steps:

s601, determining the wiring state of the ammeter by judging whether the variation relation of the metering parameters of the ammeter under different working conditions corresponds to the working condition variation relation of the power generation source.

The working condition change relationship is a change relationship of a current direction instruction of the power generation source when the characteristic working conditions are switched, or a change relationship of a recording parameter of the power generation source when the characteristic working conditions are switched.

In practical application, the wiring state of the ammeter can be determined by judging whether the variation relationship of the metering parameters of the ammeter under different working conditions corresponds to the variation relationship of the current direction instruction of the power generation source during the switching of the working conditions, or the wiring state of the ammeter can be determined by judging whether the variation relationship of the metering parameters of the ammeter under different working conditions corresponds to the variation relationship of the recording parameters of the power generation source during the switching of the working conditions.

Fig. 7 is an embodiment of determining the connection state of the electric meter by determining whether the variation relationship of the metering parameters of the electric meter under different working conditions corresponds to the variation relationship of the working conditions of the power generation source in step S601, which includes three steps S701 to S703:

s701, judging whether the size relationship between the recording parameters of the power supply under the first working condition and the recording parameters of the power supply under the second working condition is the same as the size relationship between the metering parameters of the electric meter under the first working condition and the metering parameters of the electric meter under the second working condition.

In practical application, the recording parameters of the power supply under the first working condition and the recording parameters of the power supply under the second working condition can be compared or subjected to difference operation, and the size relationship between the recording parameters of the power supply under the first working condition and the recording parameters of the power supply under the second working condition is determined; similarly, the measurement parameters of the electric meter under the corresponding working conditions can be compared for operation, or difference operation is carried out, and the size relationship between the measurement parameters of the electric meter under the first working condition and the measurement parameters of the electric meter under the second working condition is determined; and finally, comparing the obtained magnitude relation of the recording parameters of the power generation source with the magnitude relation of the metering parameters of the electric meter, and judging whether the two magnitude relations are the same.

Of course, other manners may also be adopted to determine whether the magnitude relationship of the recording parameter of the power generation source and the magnitude relationship of the metering parameter of the electric meter are the same, which is not specifically limited herein and belongs to the protection scope of the present application.

Optionally, if the power generation source is a three-phase power generation source and the electric meter is a three-phase electric meter, the recording parameter of the power generation source and the metering parameter of the electric meter are both three-phase parameters, and both the two size relationships are corresponding comparison relationships of three-phase data.

After step S701 is executed, if the two size relationships are the same, that is, the size relationship between the obtained recording parameter of the power generation source and the size relationship between the obtained metering parameter of the electric meter are the same, step S702 is executed; if the two size relationships are different, that is, the obtained size relationship between the recording parameters of the power generation source and the size relationship between the metering parameters of the electric meter are different, step S703 is executed.

And S702, judging that the electric meter is in positive connection.

And S703, judging that the electric meter is reversely connected.

It should be noted that, the recording parameter of the power generation source and the metering parameter of the electricity meter are active power, reactive power or apparent power. In practical application, electrical parameters such as active current and reactive current can be selected and used for ammeter wiring detection, and the method is not specifically limited and belongs to the protection range of the method.

And S602, if the wiring state is reverse connection, performing second correction processing on subsequent metering parameters of the ammeter.

The second correction processing is: and carrying out negation processing on the subsequent metering parameters of the ammeter. The metering parameters can be parameters such as current, power generation and the like.

In the embodiment, the power generation source is controlled to sequentially operate under a first working condition and a second working condition, and the metering parameters of the electric meter in the distributed power generation system under the corresponding working conditions are obtained; determining the wiring state of the ammeter by judging whether the variation relation of the metering parameters of the ammeter under different working conditions corresponds to the working condition variation relation of the power generation source; and finally, if the wiring state is reverse connection, performing second correction processing on the subsequent metering parameters of the ammeter, namely performing reverse processing on the subsequent metering parameters of the ammeter, so that incorrect power metering of the grid-connected point and failure of limiting the power of the grid-connected point by a power generation source due to reverse connection of the ammeter can be avoided. And the corrected metering parameters of the electric meter are adopted to manage the power and the energy of the system, so that the fault tolerance of the system is improved. In addition, the subsequent metering parameters of the electric meter are corrected by a pure software algorithm, and the hardware cost is not required to be increased.

It should be noted that, in the prior art, there is also a method for detecting connection of an electric meter current transformer applied to an energy storage system, which mainly determines whether a discharge power variation or a charge power variation of the energy storage system is consistent with a power variation detected by an electric meter by causing the energy storage system to perform at least two discharge actions with different powers and/or at least two charge actions with different powers, thereby determining whether the primary electric meter current transformer is connected in the positive direction or in the reverse direction. However, compared with the method for detecting the wiring of the electric meter, the method only supports one wiring mode of the electric meter, the wiring modes of other electric meters are defined as abnormal wiring, and after a fault is detected, the wiring needs to be manually replaced, so that the construction cost is increased. According to the ammeter wiring method provided by the invention, after the wiring state is judged to be abnormal, the metering parameters of the subsequent ammeter are corrected without changing the wiring, so that the operation difficulty of constructors is reduced. In addition, the method in the prior art cannot detect the interphase wiring error of the multiphase electric meter, and has obvious limitation in practical application.

The following describes a specific example of determining whether the electric meter connection is positive or negative in the electric meter connection detection method with reference to fig. 1, 5 to 7.

Firstly, controlling an inverter 102 to operate under a first working condition, and outputting first active power Pinv _1, wherein the active power metered by an ammeter 104 is Pgrid _ 1; further controlling the inverter 102 to operate to a second working condition, outputting a second active power Pinv _2, wherein the active power metered by the ammeter 103 is Pgrid _ 2; that is, step S301 is executed to control the power generation source to sequentially operate under the first working condition and the second working condition, and obtain the metering parameters of the electric meter in the distributed power generation system under the corresponding working conditions.

Assuming that the power Pload consumed by the load 103 is not changed, the wiring sequence of the electric meter 104 is determined according to the relative relationship between the active power Pgrid _1 and the active power Pgrid _2 measured twice by the electric meter 104.

If the connection mode of fig. 1 is adopted, Pload ═ Pinv _1+ Pgrid _1 ═ Pinv _2+ Pgrid _2, that is, Pgrid _1-Pgrid _2 ═ Pinv _2-Pinv _1- (1);

if the connection mode of fig. 5 is used, Pload ═ Pinv _1-Pgrid _1 ═ Pinv _2-Pgrid _2, that is, Pgrid _1-Pgrid _2 ═ Pinv _1-Pinv _2- (2);

therefore, the connection mode of the electric meter 104 can be determined by judging that Pgrid _1 and Pgrid _2 conform to the formula (1) or (2), that is, the step S601 is executed to determine the connection state of the electric meter by judging whether the transformation relationship of the metering parameters of the electric meter corresponds to the operating condition variation relationship of the power generation source under different operating conditions. The working condition change relationship of the power generation source is the change relationship of the recording parameters of the power generation source when the working conditions are switched. Similarly, it is also determined whether the magnitude relationship between the recording parameter of the power supply under the first operating condition and the recording parameter of the power supply under the second operating condition is the same as the magnitude relationship between the metering parameter of the electric meter under the first operating condition and the metering parameter of the electric meter under the second operating condition, corresponding to step S701.

If the electric meter 104 is in the connection mode of fig. 1, the power consumed by the load 104 should be calculated according to the formula Pload ═ Pinv + Pgrid; if the electricity meter 104 is connected in the manner shown in fig. 5, the power consumed by the load 104 should be calculated according to the formula Pload-Pinv-Pgrid.

If the connection mode of the electric meter 104 corresponding to fig. 1 is defined as positive connection, that is, the connection mode satisfying the formula (1) is positive connection, the connection mode of the electric meter 104 of fig. 5 is reverse connection, that is, the connection mode satisfying the formula (2) is reverse connection. At this time, the calculation formula of the power consumed by the load 103 defaults to: if the connection mode of the electricity meter 104 in fig. 5 is also calculated by a calculation formula of the power consumption of the default load 103, the obtained result will be erroneous. If the result is correct, after the reverse connection is determined, the subsequent measurement parameters of the electric meter 103 should be subjected to the negation processing. That is, if the connection state is reverse connection, the step S602 is executed to perform the second correction process on the subsequent measurement parameters of the electric meter.

Similarly, if the meter 104 is connected in the manner shown in fig. 1, the following equation is satisfied:

and Pgrid _1-Pgrid _2 ═ Pinv _2-Pinv _1, that is, the step 701 is executed, that is, the magnitude relationship between the recording parameter of the power supply under the first working condition and the recording parameter of the power supply under the second working condition is the same as the magnitude relationship between the metering parameter of the electric meter under the first working condition and the metering parameter of the electric meter under the second working condition, and the electric meter is determined to be in a positive connection state.

If the electric meter 104 is in the connection mode of fig. 5, the following formula is satisfied:

and Pgrid _1-Pgrid _2 ═ Pinv _1-Pinv _2, that is, if the magnitude relationship between the recording parameter of the power supply under the first working condition and the recording parameter of the power supply under the second working condition is different from the magnitude relationship between the metering parameter of the electric meter under the first working condition and the metering parameter of the electric meter under the second working condition, the electric meter is determined to be in reverse connection in the step 701.

It should be noted that, the connection mode of the electric meter 104 corresponding to fig. 5 may also be defined as positive connection, and then the connection mode of the electric meter 104 of fig. 1 is reverse connection, and no matter what connection mode of the electric meter 104 is defined as positive connection or reverse connection, the electric meter connection detection may be performed by referring to the above-mentioned modes, and details are not described here again.

It should be further noted that, if the power generation source is a three-phase power generation source and the electric meter is a three-phase electric meter, it is determined that the connection mode of the electric meter is positive connection or negative connection, and the following steps may be performed:

referring to fig. 3, the inverter 102 is operated under a first operating condition to output a first three-phase active power: pinv _ a1 for a1 phase, Pinv _ B1 for B1 phase, Pinv _ C1 for C1 phase, first three-phase active power measured by the electricity meter 104: pgrid _ A1 for A1 phase, Pgrid _ B1 for B1 phase, and Pgrid _ C1 for C1 phase. Then, the inverter 102 is operated under a second working condition to output a second three-phase active power: pinv _ a2 for a2 phase, Pinv _ B2 for B2 phase, Pinv _ C2 for C2 phase, and the second three-phase active power measured by the electricity meter 104: pgrid _ A2 for A2 phase, Pgrid _ B2 for B2 phase, and Pgrid _ C2 for C2 phase.

Because:

Pgrid_1＝Pgrid_A1+Pgrid_B1+Pgrid_C1；

Pgrid_2＝Pgrid_A2+Pgrid_B2+Pgrid_C2；

Pinv_1＝Pinv_A1+Pinv_B1+Pinv_C1；

Pinv_2＝Pinv_A2+Pinv_B2+Pinv_C2；

the electric meter 104 can be determined to be connected in the forward direction or the reverse direction according to the method corresponding to the above example. That is, if the power generation source is a three-phase power generation source, that is, the inverter 102 is a three-phase inverter, and the electric meter 104 is a three-phase electric meter, then both the recording parameter of the power generation source and the metering parameter of the electric meter 104 are three-phase parameters, and both the two size relationships are corresponding comparison relationships of three-phase data. For a specific determination process, reference may be made to the above example, which is not described herein again.

It should be further noted that, the above examples are described by using direct access type electric meters, and for the electric meters using mutual inductor access type, the method provided by the present invention may also be used to detect positive and negative connection and misconnection of the mutual inductor, and perform corresponding processing on the electric meter read data according to the detection result, which is not described herein again and belongs to the protection scope of the present application.

Optionally, in order to improve the detection accuracy and reduce the influence of load fluctuation on the electric meter wiring detection, the electric meter wiring detection may be performed when the load is stable. For example, the power generation source may calculate the power change consumed by the load for a period of time, and if the power change consumed by the load for the period of time is small, the power change consumed by the load for the period of time is considered to be relatively stable.

Optionally, in another embodiment of the present application, after step S205 is executed to determine that the wiring of the electric meter is in a faulty connection, or step S601 is executed to determine the wiring state of the electric meter by determining whether the variation relationship of the metering parameter of the electric meter under different operating conditions corresponds to the operating condition variation relationship of the power generation source, the method for detecting the wiring of the electric meter further includes:

and recording and storing the wiring state of the electric meter, and detecting the wiring of the electric meter again when the alternating current power failure is identified each time or the communication with the electric meter is interrupted.

It should be noted that, after detecting the connection state of the electric meter, the inverter may record and store the connection state, and may detect again each time the ac power failure is identified or when the communication with the electric meter is interrupted, so as to prevent the connection sequence of the electric meter from being changed due to the network side maintenance.

Optionally, referring to fig. 8, in another embodiment of the present application, after step S201 is executed, the method further includes that when the power generation source is a single-phase power generation source or a three-phase power generation source:

s801, controlling the power generation source to operate under a plurality of working conditions again, and obtaining the metering parameters of the electric meter meeting the preset conditions under the corresponding working conditions.

And the number of the working conditions of the plurality of working conditions is greater than the working condition threshold value.

It should be noted that the working condition threshold may be set according to the application environment and the user requirement, and the specific value is not specifically limited in this application.

Of course, the larger the working condition threshold value is, the more accurate the determined electric meter wiring state is, but the risk of increasing loss, increasing cost and reducing the service life of components is faced.

S802, determining the wiring state of the ammeter by judging whether the variation relation of the metering parameters of the ammeter under different working conditions corresponds to the working condition variation relation of the power generation source.

It should be noted that, for the relevant description of step S802, reference may be made to the relevant description of the embodiment corresponding to fig. 3, and details are not described here again.

After step S802 is executed, step S803 or step S804 can be selected and executed according to the application environment and the user requirement.

And S803, taking the wiring state with the largest occupation ratio in all the determined wiring states of the electric meters as the final wiring state.

S804, determining the occupation ratio of each state in the wiring states of the electric meter, and taking the wiring state with the occupation ratio exceeding the occupation ratio threshold value as a final wiring state.

The occupation ratio threshold value can be set by self according to the application environment and the user requirement, and is not applied for specific limitation.

It should be noted that, in addition to the connection state with the largest ratio and the connection state with the ratio exceeding the ratio threshold as the final connection state, other statistical methods may be used to determine the final detection result. For example, the mean value, the median or the root mean square value of the variation relationship under a plurality of working conditions are adopted, and the wiring mode of the electric meter is finally determined according to the positive and negative of the variation relationship under the plurality of working conditions.

It should be noted that the present embodiment is applicable to the case of determining whether the connection state of the electric meter is positive connection, reverse connection, or misconnection. For the description and the specific process for determining the positive connection, the reverse connection or the misconnection, reference may be made to the foregoing embodiments, which are not described herein again, and all belong to the scope of the present application.

In this embodiment, the power generation source is controlled to operate under multiple working conditions to obtain multiple sets of judgment parameters, and then multiple judgments are performed to determine multiple connection states of the electric meter, so as to reduce the influence of load fluctuation on the detection algorithm and improve the detection accuracy.

It should be noted that other types of distributed power generation sources are also applicable to the present invention, such as a pure energy storage inverter, a wind power generation source, a fuel cell power generation source, and the like, and all belong to the protection scope of the present application.

The invention further discloses a power generation source of the distributed power generation system, and the controller in the power generation source is used for executing the electric meter wiring detection method in any embodiment.

It should be noted that the power generation source is composed of a photovoltaic panel and an inverter, and the controller in the power generation source is generally the controller in the inverter.

Another embodiment of the present invention further discloses a distributed power generation system, including: an electricity meter and a power generation source as described in any of the above embodiments.

Wherein, the alternating current side of the power generation source is connected with a power grid through an electric meter.

Optionally, the distributed power generation system further comprises a load coupled between the power generation source and the electricity meter.

Optionally, the power generation source of the distributed power generation system comprises: the converter of taking energy storage device or energy storage interface to, and, at least one photovoltaic cell board.

In practical applications, the method for the controller in the inverter to perform the electric meter wiring detection may be limited in some situations, for example, when the light is insufficient or at night, the inverter may be difficult to operate to the ideal first operating condition and the ideal second operating condition. The inverter with the energy storage device or the energy storage interface can overcome the defects, that is, the inverter can be: and the converter is provided with an energy storage device or an energy storage interface. As shown in fig. 9, the energy of the inverter can flow in two directions, so that the first working condition and the second working condition which are more ideal can be output in a power absorption mode, that is, in a mode of making the output power be a negative value, and further, the method for detecting the wiring of the electric meter is more timely and reliable.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ammeter wiring detection method is characterized in that a controller applied to a power generation source in a distributed power generation system comprises the following steps:

judging whether the two three-phase arrangement sequences are the same;

2. The method of claim 1, further comprising, after determining that there is a misphase connection in the meter wiring state:

3. The method of claim 1, wherein the predetermined condition is that at least one of the metering parameters is different from the other two-phase parameters.

4. The ammeter wiring detection method of claim 3, wherein the controlling the power generation source to sequentially operate under a first working condition and a second working condition and obtaining the metering parameters of the ammeter in the distributed power generation system meeting the preset conditions under the corresponding working conditions comprises:

5. The method of claim 1, wherein at least one of the first operating condition and the second operating condition is: the working condition that electric energy is absorbed from a power grid to charge the power generation source;

6. The method for detecting the wiring of the ammeter according to claim 5, wherein the determining the wiring state of the ammeter by judging whether the variation relationship of the metering parameters of the ammeter under different working conditions corresponds to the variation relationship of the working conditions of the power generation source comprises:

7. The electric meter wiring detection method according to claim 5, wherein after the controlling of the power generation source to sequentially operate under the first working condition and the second working condition and the obtaining of the metering parameters of the electric meters in the distributed power generation system meeting the preset conditions under the corresponding working conditions, the method further comprises:

when the power generation source is a single-phase power generation source or a three-phase power generation source, controlling the power generation source to sequentially operate under a plurality of working conditions again, and acquiring the metering parameters of the ammeter meeting preset conditions under the corresponding working conditions; the number of the working conditions of the plurality of working conditions is greater than a working condition threshold value;

8. The electric meter wiring detection method according to any one of claims 1 to 7, wherein before controlling the power generation source to sequentially operate under the first working condition and the second working condition and acquiring the metering parameters of the electric meters in the distributed power generation system meeting the preset conditions under the corresponding working conditions, the method further comprises:

calculating a load consumption power change value within a preset time length;

9. The method of any one of claims 1 to 7, wherein determining that there is a misconnection of the wiring of the electric meter or determining the wiring status of the electric meter further comprises:

10. The meter wiring detection method of any of claims 1-7, wherein said recorded parameters and said measured parameters are active power, reactive power, or apparent power.

11. A power generation source for a distributed power generation system, wherein a controller in the power generation source is configured to perform a method of meter wiring detection as claimed in any one of claims 1 to 10.

12. A distributed power generation system, comprising: an electricity meter and a power generation source according to claim 11;

13. The distributed power generation system of claim 12, further comprising a load coupled between the power generation source and the electricity meter.

14. The distributed power generation system of claim 12, wherein the power generation source comprises: