CN110703085B - Relay fault detection method for grid-connected inverter - Google Patents
Relay fault detection method for grid-connected inverter Download PDFInfo
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- CN110703085B CN110703085B CN201911092406.6A CN201911092406A CN110703085B CN 110703085 B CN110703085 B CN 110703085B CN 201911092406 A CN201911092406 A CN 201911092406A CN 110703085 B CN110703085 B CN 110703085B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The invention discloses a Relay fault detection method of a grid-connected inverter, wherein resistors are connected in parallel between inverter relays Relay1 and Relay2 and grid-side inverters Relay3 and Relay4, and Relay sampling signals are obtained by sampling two sides of the resistors; driving and disconnecting all relays, and judging whether the Relay3 on the power grid side has an adhesion fault or whether the Relay3 and the Relay4 have adhesion faults at the same time; driving and closing a grid-side Relay Relay3, judging whether an adhesion fault exists in a grid-side Relay Relay4 or not, outputting open-loop voltage by an inverter side, driving and disconnecting a grid-side Relay Relay3, and judging whether an adhesion fault exists in an inverter-side Relay Relay1 or whether adhesion faults exist in both Relay1 and Relay 2; the inverter side outputs open-loop voltage to drive the closed inverter side relays Relay1 and Relay2, and whether the inverter relays Relay1 and/or Relay2 can not be closed is judged; and the inverter side open-loop voltage is turned off, the inverter side relays Relay1 and Relay2 are driven to be disconnected, the power grid side relays Relay3 and Relay4 are turned on, whether the power grid side relays Relay3 and/or Relay4 can not be turned on or not is judged, and detection steps are reduced.
Description
Technical Field
The invention belongs to the field of inverter relay detection, and relates to a relay fault detection method for a grid-connected inverter.
Background
In the field of grid-connected power generation systems, the primary premise is to accurately judge the quality of a relay at a power grid end. Because the relay needs to transmit larger current, especially for the grid-connected inverter with longer service time, metal contacts in the relay are easily adhered and cannot be disconnected in time, and further a series of uncontrollable factors can be brought. It is necessary to recognize whether each relay is stuck or can be closed. The existing relay fault detection method has more complicated steps, and the method and the steps for optimizing the relay fault detection logic are one of the problems to be solved in the field of inverters.
Disclosure of Invention
In order to solve the above technical problems, an object of the present invention is to provide a method for detecting a fault of a relay of a grid-connected inverter, which optimizes and reduces detection steps when determining whether each relay has a fault.
In order to achieve the purpose, the invention adopts the technical scheme that:
a Relay fault detection method of a Grid-connected inverter is characterized in that resistors are connected between an inverter Relay (Relay 1, Relay 2) and a Grid-side inverter (Relay 3, Relay 4) in parallel, both sides of the resistors are sampled to obtain Relay sampling signals, and Grid sampling signals are sampled between the photovoltaic input line L and the photovoltaic input line N to obtain Grid sampling signals;
the relay fault detection method comprises the following steps:
driving and disconnecting all relays, judging whether Relay sampling signals are smaller than a first threshold value, if so, judging that the power grid side Relay3 has an adhesion fault or the power grid side Relay3 and the Relay4 have adhesion faults at the same time; if the result is negative, entering the next step;
driving and closing the power Grid side Relay3, judging whether the absolute value of the difference value between the Relay sampling signal and the Grid sampling signal is greater than a second threshold value, and if so, judging that the power Grid side Relay4 has an adhesion fault; if the result is negative, entering the next step;
the inverter side outputs open-loop voltage to drive and disconnect the grid side Relay3, whether a Relay sampling signal is smaller than a third threshold value or not is judged, if yes, it is judged that the inverter side Relay1 has an adhesion fault or the inverter side Relay1 and the Relay2 have adhesion faults at the same time; if the result is negative, entering the next step;
the inversion side outputs open-loop voltage, the inversion side relays Relay1 and Relay2 are driven to be closed, whether Relay sampling signals are larger than a fourth threshold value or not is judged, and if the result is yes, the next step is carried out; if the result is negative, determining that the inverter Relay Relay1 and/or Relay2 cannot be closed;
closing the inverter side open-loop voltage, driving to disconnect the inverter side relays Relay1 and Relay2 and close the Grid side relays Relay3 and Relay4, judging whether the absolute value of the difference value between the Relay sampling signal and the Grid sampling signal is smaller than a fifth threshold value, and if so, finishing self-checking; and if the result is negative, determining that the power grid side Relay Relay3 and/or Relay4 cannot be closed.
Preferably, the control system of the Grid-connected inverter generates a driving signal Inv _ Relay for controlling opening and closing of the inverter-side relays Relay1 and Relay2, a driving signal Grid _ Relay _ L for controlling opening and closing of the Grid-side Relay3, and a driving signal Grid _ Relay _ N for controlling opening and closing of the Grid-side Relay 4. The opening and closing of the four relays are controlled by the three driving signals, so that the detection steps are greatly simplified.
More preferably, the driving signals Inv _ Relay, Grid _ Relay _ L, and Grid _ Relay _ N are implemented by an IO port configuration of an MCU of the control system.
Preferably, the delay sampling signal is a voltage value on two sides of the resistor.
Preferably, the Grid sampling signal is a voltage value between the photovoltaic input line L and the photovoltaic input line N.
Compared with the prior art, the invention has the following advantages by adopting the scheme:
according to the relay fault detection method of the grid-connected inverter, the on-off of the two inversion side relays is controlled simultaneously, the resistors are connected between the inversion side relays and the grid side relays in parallel for sampling to obtain the relay sampling signals, whether the relays have the faults of adhesion or non-closeability is judged according to the sampling signals and the grid side sampling signals, whether each relay has the faults can be confirmed, and the detection steps are optimized and reduced.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of a relay testing arrangement according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a fault detection method according to an embodiment of the invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention may be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The first to fifth thresholds (Delta 1 to Delta 5) mentioned herein are values set based on values obtained by tests during operation of the grid-connected inverter system and taking a certain margin into consideration. The thresholds corresponding to different grid-connected inverters are different from each other.
The embodiment provides a relay fault detection method for a photovoltaic grid-connected inverter, and fig. 1 shows a hardware system schematic diagram of a relay circuit applied to the fault detection method. Referring to fig. 1, the relay is disposed between the inverter INV and the Grid. The Relay specifically comprises four relays including an inversion side Relay and a power grid side Relay, wherein the inversion side Relay comprises an inversion side Relay Relay1 and an inversion side Relay2, and the power grid side Relay comprises a power grid side Relay3 and a power grid side Relay 4. The inverter is electrically connected to a photovoltaic input line L of a power grid through an inverter side Relay1 and a grid side Relay3 in sequence, and the inverter is electrically connected to a photovoltaic input line N of the power grid through an inverter side Relay2 and a grid side Relay4 in sequence. Resistors are connected between the inverter-side relays Relay1 and Relay2 and the grid-side inverters Relay3 and Relay4 in parallel, namely, one ends of the resistors are connected between the inverter-side Relay1 and the inverter-side Relay2, and the other ends of the resistors are connected between the grid-side inverter Relay3 and the grid-side inverter Relay4 for sampling.
In this embodiment, the on/off of each relay is controlled by a control system of the grid-connected inverter. Specifically, the MCU of the control system generates three driving signals, i.e., a driving signal Inv _ Relay, a driving signal Grid _ Relay _ L, and a driving signal Grid _ Relay _ N. The driving signal Inv _ Relay is used for simultaneously controlling the opening and closing of the inverter side relays Relay1 and Relay 2; the driving signal Grid _ Relay _ L is used for controlling the opening and closing of the power Grid side Relay Relay 3; the driving signal Grid _ Relay _ N is used for controlling the opening and closing of the Grid-side Relay 4. The three driving signals are realized through the configuration of an IO port of the MCU of the control system.
In this embodiment, whether an adhesion fault or a non-closeable fault exists in each relay is judged through two sampling signals. The two sampling signal signals are respectively a Relay sampling signal and a Grid sampling signal. The delay sampling signal is specifically a voltage value at two sides of the resistor R; the Grid sampling signal is specifically a voltage value between the photovoltaic input line L and the photovoltaic input line N.
The detection logic of the relay is as follows:
the MCU controls the driving signals Inv _ Relay, Grid _ Relay _ L and Grid _ Relay _ N to be turned off, all relays 1-Relay 4 are turned off at the moment, and whether the relays Relay3 are adhered or not or whether the relays Relay3 and Relay4 are adhered at the same time is detected; if yes, reporting the fault of the relay, and if not, entering the next step;
the MCU controls a driving signal Grid _ Relay _ L to be turned on, the Relay Relay3 is closed at the moment, and whether the Relay Relay4 is adhered or not is detected; if yes, reporting the fault of the relay, and if not, entering the next step;
the method comprises the steps that an inversion side outputs open-loop voltage of power Grid feedforward, an MCU controls a driving signal Grid _ Relay _ L to be turned off, all relays 1-Relay 4 are turned off at the moment, and whether relays Relay1 are adhered or not or whether relays Relay2 are adhered or not or whether relays Relay1 and Relay2 are adhered at the same time are detected; if yes, reporting the fault of the relay, and if not, entering the next step;
the inverter side outputs open-loop voltage fed forward by a power grid, the MCU controls a driving signal Inv _ Relay to be turned on, at the moment, a Relay1 and a Relay2 are closed, and whether a Relay1 and a Relay2 are closed is detected; if yes, entering the next step, and if not, reporting the fault of the relay;
switching on and switching off the ring voltage, controlling the driving signal Inv _ Relay to be switched off by the MCU, switching on Grid _ Relay _ L and Grid _ Relay _ N, switching off the Relay Relay1 and the Relay Relay2 at the moment, switching on the Relay Relay3 and the Relay Relay4, and detecting whether the Relay Relay3 and the Relay Relay4 are switched on at the moment; if yes, the relay detection is finished, and if not, the relay fault is reported.
Referring to fig. 2, the method for detecting a relay fault of a grid-connected inverter of the present embodiment specifically includes the following steps:
starting to enter self-checking;
driving and disconnecting all relays;
judging whether the Relay sampling signal is smaller than a first threshold value; if the result is yes, namely the Relay sampling signal is less than Delta1, judging that the grid-side Relay3 has an adhesion fault or the grid-side relays Relay3 and Relay4 have adhesion faults at the same time; if the result is negative, entering the next step;
driving and closing the grid-side Relay Relay 3;
judging whether the absolute value of the difference value of the Relay sampling signal and the Grid sampling signal is greater than a second threshold value or not; if the result is yes, namely ABS (Grid sampling signal-Relay sampling signal) > Delta2, judging that the Grid-side Relay Relay4 has an adhesion fault; if the result is negative, entering the next step;
the inverter side outputs open-loop voltage to drive and disconnect the grid side Relay 3;
judging whether the delay sampling signal is smaller than a third threshold value; if the result is yes, namely the Relay sampling signal is less than Delta3, judging that the adhesion fault exists in the inverter-side Relay1 or the adhesion faults exist in both the inverter-side Relay1 and the Relay 2; if the result is negative, entering the next step;
the inversion side outputs open-loop voltage to drive and close the relays Relay1 and Relay2 on the inversion side;
judging whether the delay sampling signal is greater than a fourth threshold value; if the result is yes, namely the Relay sampling signal is more than Delta4, then the next step is carried out; if the result is negative, judging that the inverter Relay1 or the Relay2 cannot be closed or the inverter relays Relay1 and Relay2 cannot be closed at the same time;
turning off the inverter side open-loop voltage, driving to disconnect the inverter side relays Relay1 and Relay2 and to close the grid side relays Relay3 and Relay 4;
judging whether the absolute value of the difference value of the Relay sampling signal and the Grid sampling signal is smaller than a fifth threshold value or not; if the result is yes, namely the Relay sampling signal is less than Delta5, finishing the self-checking; if the result is negative, the power grid side Relay3 or Relay4 is judged to be incapable of being closed, or the power grid side relays Relay3 and Relay4 are judged to be incapable of being closed at the same time.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are preferred embodiments, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (3)
1. A Relay fault detection method of a Grid-connected inverter is characterized in that resistors are connected between an inverter Relay (Relay 1, Relay 2) and a Grid-side inverter (Relay 3, Relay 4) in parallel, both sides of the resistors are sampled to obtain Relay sampling signals, and Grid sampling signals are sampled between the photovoltaic input line L and the photovoltaic input line N to obtain Grid sampling signals; the Relay sampling signal is a voltage value on two sides of the resistor, and the Grid sampling signal is a voltage value between the photovoltaic input line L and the photovoltaic input line N;
the relay fault detection method comprises the following steps:
driving and disconnecting all relays, judging whether Relay sampling signals are smaller than a first threshold value, if so, judging that the power grid side Relay3 has an adhesion fault or the power grid side Relay3 and the Relay4 have adhesion faults at the same time; if the result is negative, entering the next step;
driving and closing the power Grid side Relay3, judging whether the absolute value of the difference value between the Relay sampling signal and the Grid sampling signal is greater than a second threshold value, and if so, judging that the power Grid side Relay4 has an adhesion fault; if the result is negative, entering the next step;
the inverter side outputs open-loop voltage to drive and disconnect the grid side Relay3, whether a Relay sampling signal is smaller than a third threshold value or not is judged, if yes, it is judged that the inverter side Relay1 has an adhesion fault or the inverter side Relay1 and the Relay2 have adhesion faults at the same time; if the result is negative, entering the next step;
the inversion side outputs open-loop voltage, the inversion side relays Relay1 and Relay2 are driven to be closed, whether Relay sampling signals are larger than a fourth threshold value or not is judged, and if the result is yes, the next step is carried out; if the result is negative, determining that the inverter Relay Relay1 and/or Relay2 cannot be closed;
closing the inverter side open-loop voltage, driving to disconnect the inverter side relays Relay1 and Relay2 and close the Grid side relays Relay3 and Relay4, judging whether the absolute value of the difference value between the Relay sampling signal and the Grid sampling signal is smaller than a fifth threshold value, and if so, finishing self-checking; and if the result is negative, determining that the power grid side Relay Relay3 and/or Relay4 cannot be closed.
2. The relay fault detection method according to claim 1, characterized in that: the control system of the Grid-connected inverter generates a driving signal Inv _ Relay for controlling the opening and closing of the inverter-side relays Relay1 and Relay2, a driving signal Grid _ Relay _ L for controlling the opening and closing of the Grid-side Relay3, and a driving signal Grid _ Relay _ N for controlling the opening and closing of the Grid-side Relay 4.
3. The relay fault detection method according to claim 2, characterized in that: the driving signals Inv _ Relay, Grid _ Relay _ L and Grid _ Relay _ N are realized through the IO port configuration of the MCU of the control system.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112986809B (en) * | 2021-01-27 | 2022-11-18 | 苏州海鹏科技有限公司 | Relay detection circuit suitable for photovoltaic inverter and detection method thereof |
| CN112964981B (en) * | 2021-02-05 | 2023-01-24 | 苏州海鹏科技有限公司 | Three-phase photovoltaic inverter relay fault detection method |
| CN112986813B (en) * | 2021-03-05 | 2023-03-21 | 苏州海鹏科技有限公司 | Relay detection circuit and detection method of single-phase grid-connected photovoltaic inverter |
| CN113904361A (en) * | 2021-08-09 | 2022-01-07 | 爱士惟新能源技术(江苏)有限公司 | Grid-connected and off-grid switching circuit, energy storage inverter system and self-checking method thereof |
| CN113937807A (en) * | 2021-08-09 | 2022-01-14 | 爱士惟新能源技术(江苏)有限公司 | Relay detection method of energy storage inverter, grid-connected and off-grid switching circuit and system |
| CN114137405A (en) * | 2021-11-25 | 2022-03-04 | 沃太能源股份有限公司 | Fault detection method for relay device and device thereof |
| CN115166508B (en) * | 2022-09-08 | 2022-11-22 | 深圳市云天数字能源有限公司 | Failure detection method and relay failure detection device for grid-connected inverter |
| CN115184838B (en) * | 2022-09-08 | 2023-01-31 | 深圳市云天数字能源有限公司 | Relay short circuit failure detection method and device |
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