JP5427485B2 - Engine power generator - Google Patents

Description

  The present invention relates to a failure diagnosis method for a power generator driven by an engine.

A conventional technique for a cogeneration system will be described as an example of the present invention.
Highly efficient private power generators have been developed. As a kind of such a private power generator, a small-sized generator is driven by a gas engine (hereinafter simply referred to as engine) using city gas or LP gas as fuel, and hot water is supplied using the exhaust heat of the engine. A household cogeneration system has been put to practical use.
In the engine power generator used in this cogeneration system, a generator is mechanically connected to an engine that burns and rotates gas.
In this engine power generation device, at the time of activation, the engine is activated by causing the generator to function as an electric motor. In a state where the engine starts to rotate, an air-fuel mixture is supplied to the engine and ignition control is performed by an ignition device. As a result, the engine completes explosion and starts to rotate spontaneously. After starting to rotate spontaneously, the rotational drive of the engine by the generator (functioning as an electric motor) is stopped.

Normally, when the engine is completely detonated, the engine speed is increased to a rated speed (for example, 1600 rpm) while adjusting the amount of air-fuel mixture supplied to the engine by controlling the opening of the throttle. When the engine rotates spontaneously at the rated speed, it starts operation of the grid-connected inverter and supplies generated power as household power.
On the other hand, the cooling medium is circulated through the engine and heated, and the cooling medium is further heated by high-temperature exhaust gas discharged from the engine and supplied to a domestic water heater.
Such a cogeneration system is configured to automatically start the engine when an operation command is sent from the water heater.

  In the engine power generator described above, Patent Document 1 proposes to determine that the generator has failed when the DC voltage rectified by the converter drops below a predetermined value.

Japanese Patent No. 3676660

However, the (direct current) voltage may decrease due to a decrease in the rotational speed of the generator due to engine misfire. In this case, the generator itself has not failed and the DC voltage is restored when the misfire is resolved. However, according to the monitoring method of Patent Document 1, even in the case of such recoverable engine trouble, there is a risk that it is determined that the generator has failed. When such a failure is notified to the service center through a communication line, for example, a replacement for the generator determined to be a failure based on this notification is prepared and may be erroneously replaced by a service person.
The present invention has been made based on such a problem, and an object of the present invention is to provide an engine power generator that can detect a failure of a generator with high accuracy.

A generator used in an engine power generation device generally includes a rotor (rotor) having a permanent magnet as a main component and a stator (stator) around which an output winding is wound. In this permanent magnet type synchronous generator, the output voltage increases or decreases in proportion to the rotational speed. Note that this proportionality has a theoretical meaning, and in an actual generator, it is out of perfect proportion due to loss or the like.
Since the rotational speed of the generator follows the rotational speed of the engine, it can be determined that the voltage drop is due to a failure of the generator unless the generator is generating power corresponding to the rotational speed of the engine.

The engine power generation device of the present invention based on the above examination is an engine that outputs rotational force, a permanent magnet synchronous generator that outputs electric power by being driven by the rotational force output by the engine, and a failure of the generator. Failure detection means for determining. When the engine speed is N [rpm] and the voltage based on the electric power output from the generator is Vo [V], the failure detection means of the present invention is such that the engine speed N is not broken. If the engine speed N exceeds the reference speed Ns, the voltage Vo is equal to the engine speed N and the coefficient 1 / c ( When c is lower than a failure occurrence reference value obtained by a product (N / c) with a positive number), it is determined that the generator has failed.
In the present invention, the standard of whether or not the generator is generating electricity corresponding to the engine speed is indicated by N / c. If the voltage Vo is lower than N / c, the failure detection means determines that the generator is not generating power corresponding to the engine speed, that is, the generator is broken. Since this determination takes into account the number of revolutions of the engine, the accuracy is higher than that of determining a failure of the generator only by the voltage Vo. In addition, the failure of the engine can be detected, and the case where the engine is broken is excluded from the target of the failure determination of the generator, so that the failure of the generator can be detected with high accuracy.

  In the engine power generator of the present invention, it is preferable that the failure detection means determine that the generator has failed when a state where the voltage Vo is lower than the failure occurrence reference value continues for a predetermined time. If the voltage Vo is instantaneously lower than the failure occurrence reference value, it is assumed that the generator has not failed. Therefore, when the state where the voltage Vo is lower than the failure occurrence reference value continues for a predetermined time, it is possible to detect the failure of the generator with high accuracy by determining that the generator is broken.

When the engine power generator of the present invention includes an AC / DC converter that converts AC power output from the generator into DC, the output voltage of the AC / DC converter can be used as the voltage Vo. Further, in this case, if a DC / AC inverter that converts the DC power output from the AC / DC converter into AC is provided, the output voltage of the DC / AC inverter can be used as the voltage Vo.

  ADVANTAGE OF THE INVENTION According to this invention, the engine power generator which can detect the failure of a generator with high precision is provided.

It is a figure which shows the structure outline | summary of the cogeneration apparatus which concerns on this Embodiment. It is a figure which shows the electric power feeding part of the cogeneration apparatus which concerns on this Embodiment. It is a flowchart which shows the procedure which judges the failure of a generator in the cogeneration apparatus which concerns on this Embodiment.

Hereinafter, the present invention will be described in detail based on a cogeneration system 1 shown in FIGS.
The cogeneration system 1 includes a power supply unit 3 that generates power and a hot water supply unit 5 that supplies hot water.
<Power supply unit 3>
The power feeding unit 3 is provided with a generator 7 and a gas engine 9 that drives the generator 7. The rotating shaft of the generator 7 and the rotating shaft of the gas engine 9 are mechanically connected. When the gas engine 9 is driven to rotate and the generator 7 is rotated, the generator 7 generates power. The electric power generated by the generator 7 is adjusted by the inverter device 11 for grid connection so that the voltage and the frequency coincide with those of the commercial system 39 as an external power source, and are supplied to the home via the feeder 13 and the distribution board 45. To the power usage apparatus 47.
On the other hand, when electric power is supplied to the generator 7 from the start inverter (AC / DC converter) 37 connected to the commercial system 39, the generator 7 functions as an electric motor and can generate a rotational force to start the gas engine 9. It has become.

  The generator 7 is an AC generator including a rotor connected to a rotating shaft and a stator around which a three-phase output winding is wound. The rotor includes permanent magnets such as ferrite magnets and rare earth magnets as main components, and the generator 7 generates electric power having a voltage proportional to the rotational speed. The output terminal of the three-phase output winding is connected to the inverter device 11. The inverter device 11 converts the alternating current output from the generator 7 into alternating current having the same quality (with respect to voltage, frequency, etc.) as that of the commercial system 39, and synchronizes with the phase of the commercial system 39.

The gas engine 9 is adjusted so that the power generation output is operated at a rating of about 1 kW during driving, and is set so that vibration noise is minimized during this rated operation. In the present invention, the type of the gas engine 9 is not limited. By using a lean burn engine, it is possible to perform efficient power generation with low fuel consumption.
The mixer 69 is supplied with air sucked from the outside through the air cleaner 71 and is also supplied with gas through the gas line. The mixer 69 mixes air and gas to form an air-fuel mixture.
A gas cutoff valve (shutoff valve) 75 and a governor 77 are interposed in the gas line. The governor 77 adjusts the pressure of the gas supplied to the mixer 69. By adjusting the governor 77 with the gas shut-off valve 75 open, the air-fuel ratio of the air-fuel mixture supplied to the gas engine 9 is adjusted.
The air-fuel mixture obtained by mixing air and gas in the mixer 69 is sucked into the gas engine 9 through the throttle 79. At this time, the supply amount of the air-fuel mixture to the gas engine 9 can be adjusted by adjusting the opening of the throttle 79.

  The gas engine 9 is supplied with an air-fuel mixture and is ignited by generating a spark from an ignition plug of the ignition device 65 and is driven to rotate. Note that the ignition timing control of the ignition device 65 is performed by the first control unit 51. Exhaust gas discharged from the gas engine 9 is discharged to the outside through the exhaust gas heat exchanger 17 and a muffler (not shown).

  The power feeding unit 3 is provided with a cooling medium circulation path 15 that passes through the gas engine 9 so that the cooling medium circulates in order to use the exhaust heat of the gas engine 9. Heat is also given to the cooling medium in the cooling medium circulation path 15 from the exhaust gas heat exchanger 17 and the surplus power heater 19.

The surplus power heater 19 is not supplied with power during steady operation. However, when the generator 7 is generating power and the load of the commercial system 39 is suddenly cut off (power failure), the power consumed by the household power usage device 47 is less than 1 kW. In addition, the generated power is supplied to the surplus power heater 19. In this way, the cooling medium in the cooling medium circulation path 15 is heated using the electric power supplied to the surplus power heater 19 and supplied.
The gas engine 9 is provided with a rotation speed sensor 81 for detecting the rotation speed of the cam. The engine speed detected by the speed sensor 81 is sent to the first controller 51.

<Hot water supply section 5>
In the hot water supply section 5, the heated cooling medium in the cooling medium circulation path 15 is transferred to water (hot water) stored in the hot water storage tank 25 by the heat exchangers 21 and 23, or to heating equipment provided in the home (not shown). Warm the water supplied. Further, the hot water supply section 5 is provided with heat exchangers 27 and 29 for heating water to be supplied into the home, and an auxiliary heat source device 31 when the heat source is insufficient.

Next, the control system of the power feeding unit 3 will be described with reference to FIG.
An AC / DC converter 37 and a DC / AC inverter 41 are provided on the inverter board 35 provided in the power feeding unit 3. In the commercial system 39, the voltage and frequency hardly change. However, the voltage and frequency of the electric power generated by the generator 7 are likely to fluctuate depending on the rotational fluctuation of the gas engine 9 or the usage state of the electric power. Therefore, the voltage and frequency of the electric power generated by the generator 7 are matched with those of the commercial system 39 by the AC / DC converter 37 and the DC / AC inverter 41. Among them, the AC / DC converter 37 converts, for example, 270 V and 213 Hz alternating current generated by the generator 7 into about 380 V direct current. The DC / AC inverter 41 converts the converted direct current of about 380V into alternating current of 100V / 200V and 50Hz / 60Hz which is the same as the voltage and frequency in the commercial system 39. The AC / DC converter 37 functions as a startup inverter as described above when the gas engine 9 is started.

  The inverter board 35 is provided with a second control unit 53 that controls the AC / DC converter 37 and the DC / AC inverter 41. The second control unit 53 instructs the semiconductor switch 59 that controls the amount of power supplied to the surplus power heater 19 provided outside the inverter board 35. This instruction is based on PWM (Pulse Wide Modulation) control. Further, the output voltage Vdc (DC voltage) from the AC / DC converter 37 is constantly sent to the second control unit 53.

The inverter board 35 is provided with a control power supply 55 that supplies electric power to the ECU board 49.
The inverter board 35 is provided with a relay 61. In the cogeneration system 1, when electric power is supplied to the commercial system 39 at the time of a power failure, the maintenance work of the electric system corresponding to the power failure is hindered. Therefore, at the time of a power failure, the power supply to the commercial system 39 can be cut off by opening the relay 61 (the state shown in FIG. 2).

  The power feeding unit 3 is provided with an ECU (Engine Control Unit) board 49 that controls the gas engine 9, the throttle 79, the gas shielding valve 75, the ignition device 65, and the like. A first control unit 51 is provided on the ECU board 49. The first controller 51 is notified of the engine speed N [rpm] detected by the speed sensor 81.

  In the cogeneration system 1, a current sensor 43 is provided between the commercial system 39 and the switchboard 45. The current sensor 43 detects the power used by the commercial system 39. Since the rated power output is about 1 kW, when the power used by the power usage device 47 in the home exceeds 1 kW, power is supplied from the commercial system 39 to the power usage device 47 via the switchboard 45.

  However, if the power usage of the power usage device 47 is less than 1 kW, surplus power flows backward to the commercial grid 39. In order to prevent this, the detection result detected by the current sensor 43 is always sent to the second control unit 53 provided on the inverter board 35. When the second control unit 53 detects that the current flowing from the commercial system 39 to the switchboard 45 has decreased based on the sent detection result, the second control unit 53 determines that a reverse power flow may occur. Then, the second control unit 53 sends a PMW control signal to the semiconductor switch 59 that controls the power used by the surplus power heater 19 so that the power corresponding to the surplus power is consumed.

The first control unit 51 and the second control unit 53 constitute a failure detection unit 63 that determines a failure of the generator 7.
While the gas engine 9 is driven and the generator 7 is generating electric power, the engine speed N [rpm] is constantly sent to the first controller 51 from the speed sensor 81 provided in the gas engine 9. It will come. Further, the output voltage Vdc (Vo) [V] from the AC / DC converter 37 is constantly sent to the second control unit 53. Information about the output voltage Vdc is sent from the second control unit 53 to the first control unit 51.

The first control unit 51 determines a failure of the generator 7 using the engine speed N sent from the speed sensor 81 and the output voltage Vdc sent from the second control unit 53. This failure determination procedure will be described with reference to FIG.
When the main switch provided on the control panel 83 is turned on, the cogeneration system 1 is requested to start (S101 in FIG. 3). The main switch can be turned on by the user's operation when hot water supply is required, but can also be turned on automatically by learning the user's operation.

  When the start request is made, next, a sequence of whether or not to start power generation is executed (S103 in FIG. 3). In this sequence, when an abnormality occurs and the cogeneration system 1 is stopped, a process for displaying the fact on the control panel 83 and notifying the user is performed. In this case, the cogeneration system 1 does not start.

  If it is confirmed in S103 that the cogeneration system 1 can be started normally, a power generation start command is issued. The second control unit 53 causes the AC / DC converter 37 to function as a start inverter for the generator 7 and outputs an instruction signal for operating the generator 7 as a motor to the AC / DC converter 37. Following the rotation of the generator 7, the gas engine 9 is rotated. When the gas engine 9 reaches the start preparation completion rotation speed (for example, 200 rpm), the first control unit 51 starts the engine start control. That is, the gas engine 9 is started by operating the throttle 79 and the ignition device 65. Thus, power generation is started by the power generator 7 (S105 in FIG. 3). Here, the AC / DC converter 37 is released from its function as a startup inverter.

  When power generation is started, the first control unit 51 starts detecting the rotational speed N of the gas engine 9 and the second control unit 53 starts detecting the output voltage Vdc from the AC / DC converter 37 (S107 in FIG. 3). ).

The second control unit 53 determines whether or not the detected output voltage Vdc is lower than a reference voltage Vs (for example, 290 V) (Vdc <Vs) (S109 in FIG. 3). During the rated operation of the gas engine 9, the output voltage Vdc is set to 380V. However, when the rotational speed N of the gas engine 9 decreases due to operating conditions, the output voltage Vdc due to the output of the generator 7 decreases in proportion to the decrease in the rotational speed N. For example, when the gas engine 9 misfires, the output voltage Vdc decreases. Therefore, if the output voltage Vdc is less than the reference voltage Vs, it is determined that it is worthy of warning, and is recorded in the second control unit 53 (S119 in FIG. 3). The judgment of the warning may include a result based on a decrease in the output voltage Vdc due to the failure of the generator 7, but if only the output voltage Vdc is used as a judgment factor, as described above, the gas A decrease in the output voltage Vdc due to misfire of the engine 9 is mistaken as a failure of the generator 7. Therefore, in this step S109, when the output voltage Vdc becomes less than the reference voltage Vs, it is recorded as warning information and used for reference when the serviceman performs maintenance on the cogeneration system 1.
In addition, although step S109 is performed in order to detect the failure of the generator 7 with a higher probability, it is not an essential step for the present invention.

  Next, it progresses to step S111 and the presence or absence of the failure of the generator 7 is further determined.

  The first control unit 51 determines whether or not the rotational speed N of the gas engine 9 exceeds the reference rotational speed Ns (N> Ns) (S111 in FIG. 3). The purpose after step S111 is to determine whether or not the gas engine 9 has failed.

As described above, the gas engine 9 may have a reduced rotational speed even if it is not malfunctioning. However, if it is malfunctioning, the rotational speed is considerably reduced from the rated rotational speed each time the engine is started. Frequently occurs. The reference rotational speed Ns is positioned as a threshold at which the gas engine 9 can be regarded as a temporary abnormal state (engine stall) when the rotational speed is less than this (for example, 650 rpm or lower). The first control unit 51 determines that the gas engine 9 has failed if the engine stall in which the rotation speed N is equal to or less than the reference rotation speed Ns is repeated five times or more in 40 minutes (S120 in FIG. 3). , S122). In this case, the first control unit 51 can stop the operation of the gas engine 9 and can notify the user by displaying on the control panel 83 that the gas engine 9 has failed.
If the engine stall is less than 5 times in 40 minutes, the first control unit 51 determines that a temporary abnormality has occurred in the gas engine 9 (S121 in FIG. 3), and temporarily turns off the gas engine 9. It stops (FIG. 3 S123). Thereafter, the first control unit 51 instructs reactivation (S101 in FIG. 3).

  If it is determined in step S111 that the engine speed N exceeds the reference speed Ns, the process proceeds to step S113, and further, it is determined whether or not the generator 7 has failed.

  The first control unit 51 determines whether Vdc is less than N / c (Vdc <N / c) using the output voltage Vdc and the engine speed N (S113 in FIG. 3). The purpose of this step S113 is to determine whether or not the generator 7 has failed. Since it is determined in step S111 whether or not the gas engine 9 has failed, the determination in step S113 is based on the premise that there is no failure in the gas engine 9.

  As described above, the output voltage Vdc increases or decreases in proportion to the rotational speed of the generator 7 (equal to the engine rotational speed N). Assuming that the generator 7 is normal, the output voltage Vdc can be obtained virtually by the product of the measured engine speed N and a predetermined coefficient. This coefficient is 1 / c. However, if the generator 7 is out of order, only an output voltage Vdc that does not match the engine speed N can be obtained. Therefore, by comparing the output voltage Vdc and N / c, it can be determined whether or not the generator 7 is generating power corresponding to the engine speed N. Considering that the rotation speed of the normal gas engine 9 fluctuates, if 1 / c is set so that the generator 7 is clearly in a broken state and a determination of Vdc <N / c is made, power generation The failure of the machine 7 can be detected with high accuracy.

  The coefficient 1 / c can be appropriately determined according to the specifications of the generator 7 and the gas engine 9. For example, if the rated rotational speed of the gas engine 9 is 1600 rpm, for example, c (1 / c) can be set in a range of 5.5 to 6.5 (1 / 5.5 to 1 / 6.5).

  In step S113, if Vdc <N / c, it is assumed that there is a high possibility that the generator 7 has failed, and the process proceeds to step S115 to determine whether or not there is a final failure. On the other hand, if Vdc ≧ N / c in step S113, it is determined that the generator 7 has not failed (step S118 in FIG. 3), and the process returns to step S107.

Even if a state of Vdc <N / c is detected instantaneously, it is assumed that it is based on a decrease in the rotational speed due to misfire of the gas engine 9. Therefore, in the present embodiment, it is determined whether the state of Vdc <N / c continues for 1 second (S115 in FIG. 3). If the state of Vdc <N / c continues for 1 second, the first control unit 51 determines that the generator 7 has failed, stops the operation of the gas engine 9, and causes the generator 7 to fail. Can be displayed on the control panel 83 to notify the user.
If the duration of Vdc <N / c is less than 1 second, the first control unit 51 determines that the generator 7 has not failed and returns to step S107.

As described above, the present embodiment is based on the viewpoint of whether the generator 7 generates electricity corresponding to the engine speed N, and the output voltage Vdc and N (engine speed) × 1 / c (coefficient). (S113 in FIG. 3), the failure of the generator 7 can be detected with higher accuracy. Therefore, it can be avoided that the decrease in the output voltage Vdc due to the misfire of the gas engine 9 is mistaken as a failure of the generator 7.
In the present embodiment, a failure of the gas engine 9 is detected by determining whether or not the rotational speed N of the gas engine 9 exceeds the reference rotational speed Ns (S111 in FIG. 3), and then the output voltages Vdc and N Since (engine speed) × 1 / c (coefficient) is compared, a failure of the generator 7 can be detected with higher accuracy.

  In this embodiment, the output voltage Vdc of the AC / DC converter 37 is adopted as the voltage Vo, but the output voltage of the DC / AC inverter 41 and the voltage detected by the voltmeter provided in the generator 7 are used as the voltage Vo. It can also be used. In the present embodiment, the DC voltage Vdc information is sent from the second control unit 53 to the first control unit 51, and the first control unit 51 determines a failure. On the contrary, the engine speed N It is also possible to realize this by a method in which information regarding the above is sent from the first control unit 51 to the second control unit 53 and the second control unit 53 determines a failure. In addition, although a simple method of comparing the DC voltage Vdc and the failure occurrence reference value N / c is adopted for the determination of failure, the failure occurrence reference value is converted into a calculation formula or data table value obtained from load current, temperature, etc. It can also be realized by a method in which the value is compared with the DC voltage Vdc. Other than this, as long as the gist of the present invention is not deviated, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Cogeneration system, 7 ... Generator, 9 ... Gas engine, 51 ... 1st control part, 53 ... 2nd control part, 63 ... Failure detection means

Claims (4)

An engine that outputs rotational force;
A permanent magnet synchronous generator that outputs electric power by being driven by the rotational force output by the engine;
A failure detection means for determining a failure of the generator,
The engine speed is N [rpm],
When the voltage based on the electric power output from the generator is Vo [V],
The failure detection means includes
Determining whether the engine speed N exceeds a reference engine speed Ns at which it is determined that the engine has not failed;
If the engine speed N exceeds the reference speed Ns,
The generator has failed when the voltage Vo is lower than a failure occurrence reference value (N / c) determined by the product of the engine speed N and the coefficient 1 / c (c is a positive number). An engine power generator characterized by being judged. The failure detection means includes
The engine power generator according to claim 1, wherein when the state where the voltage Vo is lower than the failure occurrence reference value continues for a predetermined time, it is determined that the generator has failed. The engine power generator includes an AC / DC converter that converts alternating current power output from the generator into direct current,
The engine power generator according to claim 1 or 2 , wherein an output voltage of the AC / DC converter is used as the voltage Vo. The engine power generator includes a DC / AC inverter that converts direct current power output from the AC / DC converter into alternating current,
The engine power generator according to claim 3 , wherein an output voltage of the DC / AC inverter is used as the voltage Vo.

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