JP2005076566A - Overheating prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overheating prevention device for a line-connected engine-driven generator capable of ensuring a predetermined reliability while permitting use of an existing apparatus. <P>SOLUTION: The overheating prevention device is provided with a cooling water temperature switch 52 which operates when the cooling water temperature of an engine E exceeds a predetermined overheat temperature, a correction value computing portion 24 for computing as a correction value based on the difference between a cooling temperature detected by a water temperature sensor 51 at the time of the operation of the cooling water temperature switch due to an increase in the cooling water temperature of the engine E and the predetermined overheat temperature, a cooling water temperature data computing portion 26 for computing as cooling water temperature data the sum of the detected cooling water temperature and the correction value, and an inverter control means 30 for controlling an output power of an inverter device IV. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an overheat prevention device for an engine-driven generator capable of grid interconnection (hereinafter referred to as “system interconnection engine-driven generator”).

The grid-connected engine-driven generator is a highly efficient power generator that always operates at rated output when the customer's load exceeds the generator power, but it is not a cogeneration system that uses exhaust heat. In the grid-connected engine-driven generator, the engine must be cooled by a cooling device such as a radiator. At this time, if the maintenance interval is extended and the grid-connected engine-driven generator continues to operate, the cooling device will become dirty or clogged, resulting in a decrease in cooling efficiency. Failure to do so may cause the cooling system to malfunction and cause the engine to overheat. In this case, maintenance work for the cooling device is necessary, and personnel expenses are incurred by calling a service person. On the other hand, when a grid-connected engine-driven generator equipped with a large cooling device for preventing overheating is used, the price becomes high.
In order to prevent overheating, a technique for controlling the output when a high water temperature (overheat temperature) is detected by a temperature sensor has been proposed (see Patent Document 1).
Japanese Patent Application No. 8-168103 ([0025]-[0029], FIGS. 1-2)

However, in the above technique, it is necessary to use an expensive temperature sensor with high accuracy in order to perform appropriate control.
On the other hand, overheating occurs temporarily due to specific conditions such as sunshine conditions in summer, and the probability of occurrence is low in the long run.Therefore, overheating is an expensive temperature only for the purpose of preventing the overheating. The use of the sensor is inconvenient from the viewpoint of reducing manufacturing costs.

  The present invention has been made in order to solve the above-mentioned problems, and it is possible to use an existing apparatus and to overheat a grid-connected engine-driven generator capable of ensuring a predetermined reliability. An object is to provide a prevention device.

  In order to solve the above-mentioned problems, the present invention rectifies the output of a generator driven by an engine by rectifying means, converts the rectified output into AC power having a specified voltage and a specified frequency by an inverter device, and outputs the AC power An overheat prevention device for an engine drive generator for interconnection, a water temperature switch that operates when a cooling water temperature of the engine is equal to or higher than an overheat set temperature, and a cooling water temperature detection means for detecting the cooling water temperature; Current detecting means for detecting an output current of the inverter device; and for stopping the engine in at least one of a case where the water temperature switch is operated and a case where the cooling water temperature detecting means is equal to or higher than the overheat set temperature. The engine governor control means and the cooling water temperature of the engine rise and the water temperature switch operates. A correction value calculating means for calculating a difference between the detected cooling water temperature detected by the cooling water temperature detecting means when the water temperature switch is operated and the overheat set temperature as a correction value; and storing the correction value. A cooling water temperature for calculating a sum of correction values stored in the correction value storage means, the detected cooling water temperature detected by the cooling water temperature detection means, and the correction values stored in the correction value storage means as cooling water temperature data When the cooling water temperature data calculated by the data calculating means and the cooling water temperature data calculating means is lower than the overheat set temperature, the output current of the inverter device is controlled based on the detected current detected by the current detecting means. And an inverter control means, wherein the inverter control means determines in advance below the overheat set temperature. For each of a plurality of predetermined cooling water temperature ranges, a limit current value is set stepwise so that the cooling water temperature range decreases as the temperature increases. Accordingly, the control unit is configured to be able to perform control to reduce the output current of the inverter device step by step so that the limit current value is maintained accordingly.

  Further, the present invention rectifies the output of a generator driven by an engine by a rectifying means, converts the rectified output into AC power having a specified voltage and a specified frequency by an inverter device, and outputs the AC power for grid interconnection. An overheat prevention device in a machine, wherein a water temperature switch that operates when a cooling water temperature of the engine is equal to or higher than an overheat setting temperature, a cooling water temperature detecting means for detecting the cooling water temperature, and an output of the inverter device Current detection means for detecting current, voltage detection means for detecting output voltage of the inverter device, at least one of the case where the water temperature switch is operated and the case where the cooling water temperature detection means is equal to or higher than the overheat set temperature Engine governor control means for stopping the engine and cooling water temperature of the engine When the water temperature switch rises and the water temperature switch operates, a correction value that calculates, as a correction value, the difference between the detected cooling water temperature detected by the cooling water temperature detection means when the water temperature switch operates and the overheat set temperature The sum of the calculation means, the correction value storage means for storing the correction value, the detected cooling water temperature data detected by the cooling water temperature detection means, and the correction value stored in the correction value storage means Cooling water temperature data calculating means for calculating the cooling water temperature, and the detected current detected by the current detecting means when the cooling water temperature data calculated by the cooling water temperature data calculating means is less than the overheat set temperature, and the Inverter control means for controlling the output power of the inverter device based on the detection voltage detected by the voltage detection means; In the inverter control means, the power limit value is set so that the cooling water temperature range decreases as the cooling water temperature range increases for each of a plurality of predetermined cooling water temperature ranges below the overheat set temperature. It is set in a stepwise manner, and it is possible to perform a control for reducing the output power of the inverter device in a stepwise manner so that the limit power value is maintained in accordance with an increase in the coolant temperature data. It is characterized by being configured.

  In the present invention, the difference between the overheat set temperature of the water temperature switch and the detected cooling water temperature detected by the cooling water temperature detecting means when the water temperature switch is operated is calculated as a correction value, and the detected cooling water temperature and the correction are calculated. The output control of the inverter device is performed based on the coolant temperature data calculated by the sum of the values. Therefore, even when the output control of the inverter device is performed using the measured value of the cooling water temperature detecting means that is less reliable than the water temperature switch, it is possible to reliably prevent overheating.

  Further, in the inverter control means, for each of a plurality of predetermined cooling water temperature ranges that are less than the overheat set temperature, a limit current value so that the cooling water temperature range decreases as the temperature increases, or The limit power value is set in a stepwise manner, and the limit current value or the limit power value is maintained as the cooling water temperature increases, based on the detection current or the detection current and the detection voltage. Thus, since control can be performed to reduce the output current or output power of the inverter device, overheating can be reliably prevented even when the cooling efficiency of the engine is reduced.

  A best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings.

[Constitution]
(1) Engine interconnection generator for grid interconnection As shown in FIG. 1, a grid interconnection engine drive generator 1 having an overheat prevention device of the present invention includes a generator G driven by an engine E, and the power generation Rectifying means REC that rectifies the AC output voltage of the machine G and outputs a DC voltage, inverter device IV that converts the DC voltage into AC power having a specified voltage and a specified frequency, an engine control means 20, an inverter The control means 30, the current detector 41 (current detection means), and the voltage detector 42 (voltage detection means) are provided.
The grid-connected engine-driven generator 1 is connected in parallel with the commercial power source 2 via the first circuit breaker CB1 and the second circuit breaker CB2, both of which are loaded via the third circuit breaker CB3. It is connected to the device 3.

(2) Overheat prevention device The overheat prevention device comprises an engine control means 20, an inverter control means 30 for controlling the output of the inverter device IV, a current detector 41, a voltage detector 42, and a water temperature sensor 51 (cooling). The water temperature detecting means) and the water temperature switch 52 are the main parts.

A radiator R is connected to the engine E, and the water temperature sensor 51 for detecting the cooling water temperature of the radiator R is turned on when the cooling water temperature is equal to or higher than the overheat set temperature (105 degrees in this embodiment). A water temperature switch 52 is provided that turns off when the temperature is lower than the overheat set temperature.
The water temperature sensor 51 can output a voltage proportional to the detected coolant temperature to an A / D (analog / digital) converter 23 of a microcomputer 22 (hereinafter referred to as “microcomputer”) in the engine control means 20.
The water temperature switch 52 is a commonly used water temperature switch and is a device with higher measurement accuracy than the water temperature sensor 51.

The engine control means 20 has an engine governor control circuit 21 and a microcomputer 22 for controlling the engine governor control circuit 21.
The engine governor control circuit 21 outputs a start signal to the engine starter S based on a start command signal of the engine E issued from the microcomputer 22 to start the engine E, and outputs an engine stop signal to output an engine governor solenoid power source ( The engine E is stopped by turning off the engine E by turning off the water temperature switch 52 and detecting the one of the case where the water temperature sensor 51 is equal to or higher than the overheat set temperature described later. In addition, it is a circuit for controlling various operations for controlling the engine speed and operating and stopping the engine E.

The microcomputer 22 includes an A / D converter 23, a correction value calculation unit 24 (correction value calculation unit), a correction value storage unit 25 (correction value storage unit), and a cooling water temperature data calculation unit 26 (cooling water temperature). Data calculation means).
The A / D converter 23 is a means for converting the input detected cooling water temperature data into a digital value (hereinafter referred to as “detected cooling water temperature data”). The detected cooling water temperature data is converted into a correction value calculation unit 24; It can be output to the coolant temperature data calculation unit 26.
The correction value calculation unit 24 is a means for calculating a difference between the overheat set temperature and the detected coolant temperature data when the water temperature switch 52 is operated as a correction value, and the correction value data is stored in the correction value storage unit. 25 can be output.

The correction value storage unit 25 is a means for storing the correction value data calculated by the correction value calculation unit 24. The initial value of the correction value data stored in the correction value storage unit 25 is 0 degree.
The cooling water temperature data calculation unit 26 is a means for calculating the cooling water temperature data by adding correction value data to the detected cooling water temperature data. The coolant temperature data is output to the inverter control means 30.

The inverter device IV is configured as an IGBT (insulated gate bipolar transistor) 6 including a gate circuit 7. This inverter device IV can output AC power to the load device 3 by performing on / off control of the IGBT 6 by the gate circuit 7 in accordance with the gate signal transmitted from the inverter control means 30. In addition, code | symbol MC is an electromagnetic contactor.
Further, the current detector 41 and the voltage detector 42 are devices for detecting the output current and output voltage of the inverter device IV, respectively, and a voltage proportional to the detected output current and output voltage is the inverter control means 30 described later. Are output to the A / D converters 31 and 32.

The inverter control means 30 is constituted by a microcomputer, and sequentially reads and executes a program stored in a storage means (not shown), thereby performing a series of operations from setting of a limited power setting value, which will be described later, to ON / OFF of the IGBT 6. It is a means for executing control and controlling the output of the inverter device IV step by step.
The inverter control means 30 includes A / D converters 31 and 32 for converting the detected output current and the detected output voltage into digital values (hereinafter referred to as “detected current data” and “detected voltage data”, respectively). A cooling water temperature data receiving unit 33, an output power calculating unit 34, a limited power value storage unit 35, a limited power value setting unit 36, an output power determining unit 37, and a gate signal transmitting unit 38. Yes.

The cooling water temperature data receiving unit 33 is a unit for receiving the cooling water temperature data transferred from the engine control unit 20 and outputting it to the limit power value setting unit 36.
The output power calculation unit 34 is a means for calculating an actual output value of the inverter device IV from the detected current data and the detected voltage data output from the A / D converters 31 and 32.

In the limit power value storage unit 35, the data of the cooling water temperature ranges of a plurality of predetermined categories determined in advance below the overheat set temperature (105 degrees) and the limit power set corresponding to each category Value data is stored in association with each other. In this embodiment, the grid-connected engine-driven generator 1 with a rated output of 10 kW is targeted, and two categories of cooling water temperature ranges (103 to 104 degrees, 104 to 105 degrees) are set. For each cooling water temperature range, the limit power values of 9 kW and 8 kW are set so that the limit power value gradually decreases as the temperature increases.
Note that the output power setting value of 10 kW, which is the total output, is set for the cooling water temperature range in which the cooling water temperature data is less than 103 degrees.

  When the cooling water temperature data is lower than the overheat set temperature, the limited power value setting unit 36 receives data from the plurality of limited power values stored in the limited power value storage unit 35 from the cooling water temperature data reception unit 33. The data of the limit power value corresponding to the coolant temperature range to which the output coolant temperature data belongs is extracted, and the limit power value (hereinafter, the extracted limit power value is referred to as “limit power set value” to be distinguished). As output to the output power determination unit 37.

  The output power determination unit 37 compares the limit power set value extracted by the limit power value setting unit 36 with the actual output power value so that the actual output power value of the inverter device IV matches the limit power set value. Whether or not the output power measured value is larger or smaller than the limit power set value when they do not coincide with each other.

The gate signal transmission unit 38 is a unit for generating an appropriate gate signal for performing predetermined on / off control on the IGBT 6 based on the determination result of the output power determination unit 37 and transmitting it to the gate circuit 7. .
That is, when the actual output power value matches the limit power setting value, the gate signal transmission unit 38 continues the output of the inverter device IV as it is, and the actual output power value is the limit power setting value. When the output power is larger than the value, the output power of the inverter device IV is reduced, and when the actual output power value is smaller than the limit power setting value, a gate signal for increasing the output power of the inverter device IV is generated, It can be transmitted to the circuit 7.

[Operation]
Hereinafter, the operation of the overheat prevention apparatus will be described mainly with reference to FIG. At this stage, it is assumed that the water temperature switch 52 has not been operated and the correction value data is set to 0 degrees.

<Before operation of water temperature switch>
First, the second circuit breaker CB2 is turned on and the third circuit breaker CB3 is turned on.
Subsequently, the first circuit breaker CB1 is turned on, the engine E of the grid-connected engine drive generator 1 is started (S1), the synchronization with the commercial power source 2 is confirmed, and the electromagnetic contactor MC is turned on. To start interconnection.
The water temperature sensor 51 detects the detected cooling water temperature data (S2), the cooling water temperature data calculation unit 26 calculates the cooling water temperature data (S3), and the calculated cooling water temperature data is transmitted to the inverter control means 30. Then, it is received by the cooling water temperature data receiving unit 33 (S4). On the other hand, the engine control means 20 determines whether or not the coolant temperature data is 105 degrees or higher (S6) and whether or not the water temperature switch 52 is off (S10), and the coolant temperature data is less than 105 degrees (No in S6). If the water temperature switch 52 is off (Yes in S10), the inverter device IV is controlled as follows according to the value of the cooling water temperature data determined by the inverter control means 30.
At this stage, since the initial value of the correction value is set to 0 degrees, the cooling water temperature data coincides with the detected cooling water temperature data.

(1) When the cooling water temperature data is less than 103 degrees In the case of the above condition (No in S17 and No in S18), the output power set value is set to 10 kW (S18 ″).
On the other hand, from the detected current data and detected voltage data detected by the current detector 41 and the voltage detector 42, the output power calculation unit 34 calculates the actual output power value of the inverter device IV.
Then, the output power determination unit 37 compares the actual output power value with the output power setting value (10 kW), and if the actual output power value matches the output power setting value (Yes in S19), A gate signal is transmitted from the gate signal transmission unit 38 so as to continue the operation as it is, and the output of the inverter device IV is controlled. On the other hand, when the actual output power value is smaller than the set output power value (No in S19 and No in S20), the output of the inverter device IV is controlled so as to increase the output power of the inverter device IV (S20 ″).

(2) When the cooling water temperature data is not less than 103 degrees and less than 104 degrees In the case of the above condition (No in S17 and Yes in S18), the limit power value setting unit 36 stores it in the limit power value storage unit 35. The limit power set value is set to 9 kW by extracting the limit power value data corresponding to the cooling water temperature range from the plurality of limit power value data that are present (S18 ′).
When the actual output power value of the inverter device IV matches the limit power set value (9 kW) (Yes in S19), the output of the inverter device IV is controlled so that the operation is continued as it is. To do.
On the other hand, when the actual output power value is larger than the limit power set value (No in S19 and Yes in S20), the output power of the inverter device IV is lowered (S20 ′), and the actual output power value is smaller than the limit power set value. In the case (No in S19 and No in S20), the output of the inverter IV is controlled so as to increase the output power of the inverter IV (S20 '').

(3) When the cooling water temperature data is not less than 104 degrees and less than 105 degrees In the case of the above condition (Yes in S17), the limit power set value is set to 8 kW by the same procedure as described above (S17 ').
When the actual output power value of the inverter device IV matches the limit power setting value (8 kW) (Yes in S19), the output of the inverter device IV is controlled so that the operation is continued as it is. To do.
On the other hand, when the actual output power value is larger than the limit power set value (No in S19 and Yes in S20), the output voltage of the inverter device IV is lowered (S20 ′), and the actual output power value is smaller than the limit power set value. In the case (No in S19 and No in S20), the output of the inverter IV is controlled so as to increase the output power of the inverter IV (S20 '').

(4) When the cooling water temperature data is 105 degrees or more In the case of the above condition (Yes in S6), the engine governor control circuit 21 outputs an engine stop signal (S7) and the engine governor solenoid power is turned off. (S8) The engine E is stopped and a predetermined abnormality signal is displayed (S9).

<When water temperature switch is activated>
(Cooling water temperature data is less than 105 degrees)
In the case of the above conditions (No in S6 and No in S10), due to the measurement error of the water temperature sensor 51, the detected cooling water temperature data detected by the water temperature sensor 51 becomes lower than the actual cooling water temperature value. Yes. In this case, the water temperature switch 52 is turned on, and an engine stop signal is output by the engine governor control circuit 21 (S11), the engine governor solenoid power is turned off (S12), and the engine E is stopped. Abnormal signal display is performed (S13).
Then, the correction value calculation unit 24 calculates a correction value from the difference between the detected cooling water temperature data when the water temperature switch 52 is operated and the overheat set temperature (105 degrees) of the water temperature switch 52 (S14). The correction value data is stored in the value storage unit 25 (S15).

<After operation of water temperature switch>
The engine E of the grid interconnection engine drive generator 1 is started again (S1), the synchronization with the commercial power source 2 is confirmed, and the electromagnetic contactor MC is turned on to start the interconnection operation. Then, based on the value of the coolant temperature data calculated using the correction value calculated by the above method, the grid interconnection engine drive generator 1 is controlled by the same method as described above.

  In this case, compared with the overheat set temperature of the water temperature switch 52, the detected cooling water temperature data detected by the water temperature sensor 51 can be corrected at a lower temperature, so that overheating can be prevented more reliably. it can.

  As described above, according to the overheat prevention device of the present invention, the difference between the water temperature switch 52 operating at the overheat set temperature or higher and the detected cooling water temperature is calculated as a correction value, and the detected cooling water temperature and the correction value are calculated. The output control of the inverter device IV is performed based on the cooling water temperature data calculated by the sum. Therefore, even when the output control of the inverter device IV is performed using the measured value of the water temperature sensor 51 which is inferior in comparison with the water temperature switch 52, overheating can be reliably prevented.

  In addition, the limit power value is set stepwise so that the cooling water temperature range decreases as the temperature rises for each of a plurality of predetermined predetermined cooling water temperature ranges below the overheat set value. Since the limit power value is maintained according to the rise in the cooling water temperature data, it is possible to control the output power of the inverter device IV in a stepwise manner. Furthermore, overheating can be reliably prevented.

  In the embodiment, the inverter control means 30 is based on the actual output power value calculated from the detected current detected by the current detector 41 and the detected voltage detected by the voltage detector 42. The output is controlled. However, based on only the detected current detected by the current detector 41, the inverter control means 30 determines the cooling water temperature range for each of a plurality of predetermined cooling water temperature ranges above the set temperature. You may control the output of the inverter apparatus IV so that the limiting current value set so that it may increase as it becomes high temperature may be maintained.

As mentioned above, although an example about a suitable embodiment was explained about the present invention, the present invention is not restricted to the embodiment concerned, and a design change is possible suitably in the range which does not deviate from the meaning of the present invention. In particular, it is needless to say that the overheat set temperature, the cooling water temperature range and the number of divisions thereof, and each limit power value (limit current value) are appropriately determined according to the rated output of the grid-connected engine drive generator. Yes.
Further, the inverter control means is configured to be controlled by a microcomputer, but may be controlled by other methods.

It is a block diagram of the engine drive generator for grid connection. It is a flowchart which shows operation | movement of an overheat prevention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine drive generator for grid connection 20 Engine control means 21 Engine governor control circuit 22 Microcomputer (microcomputer)
24 Correction value calculation unit (correction value calculation means)
25 Correction value storage unit (correction value storage means)
26 Cooling water temperature data calculation unit (cooling water temperature data calculation means)
30 Inverter control means 34 Output power calculation section 35 Limit power value storage section 36 Limit power value setting section 37 Output power determination section 38 Gate signal transmission section 41 Current detector (current detection means)
42 Voltage detector (voltage detection means)
51 Water temperature sensor (cooling water temperature detection means)
52 Water temperature switch E Engine G Generator IV Inverter REC Rectification means

Claims (2)

An overheat prevention device in a grid-connected engine-driven generator that rectifies the output of a generator driven by an engine by a rectifier and converts the rectified output into AC power of a specified voltage and a specified frequency by an inverter device. There,
A water temperature switch that operates when the engine coolant temperature is equal to or higher than the overheat set temperature;
Cooling water temperature detecting means for detecting the cooling water temperature;
Current detecting means for detecting an output current of the inverter device;
Engine governor control means for stopping the engine when at least one of the case where the water temperature switch is operated and the case where the cooling water temperature detection means is equal to or higher than the overheat set temperature;
When the cooling water temperature of the engine rises and the water temperature switch operates, a difference between the detected cooling water temperature detected by the cooling water temperature detection means when the water temperature switch operates and the overheat set temperature is calculated. Correction value calculation means for calculating as a correction value;
Correction value storage means for storing the correction value;
Cooling water temperature data calculating means for calculating, as cooling water temperature data, the sum of the detected cooling water temperature detected by the cooling water temperature detecting means and the correction value stored in the correction value storage means;
Inverter control means for controlling the output current of the inverter device based on the detection current detected by the current detection means when the cooling water temperature data calculated by the cooling water temperature data calculation means is less than the overheat set temperature; With
In the inverter control means,
For each of a plurality of predetermined cooling water temperature ranges that are set in advance below the overheat set temperature, the limiting current value is set stepwise so that the cooling water temperature range decreases as the temperature increases.
It is configured to be able to perform control to reduce the output current of the inverter device in a stepwise manner so that the limit current value is maintained according to the rise in the cooling water temperature data. An overheat prevention device. An overheat prevention device in a grid-connected engine-driven generator that rectifies the output of a generator driven by an engine by a rectifier and converts the rectified output into AC power of a specified voltage and a specified frequency by an inverter device. There,
A water temperature switch that operates when the engine coolant temperature is equal to or higher than the overheat set temperature;
Cooling water temperature detecting means for detecting the cooling water temperature;
Current detecting means for detecting an output current of the inverter device;
Voltage detection means for detecting an output voltage of the inverter device;
Engine governor control means for stopping the engine when at least one of the case where the water temperature switch is operated and the case where the cooling water temperature detection means is equal to or higher than the overheat set temperature;
When the cooling water temperature of the engine rises and the water temperature switch operates, a difference between the detected cooling water temperature detected by the cooling water temperature detection means when the water temperature switch operates and the overheat set temperature is calculated. Correction value calculation means for calculating as a correction value;
Correction value storage means for storing the correction value;
Cooling water temperature data calculating means for calculating a sum of the detected cooling water temperature data detected by the cooling water temperature detecting means and the correction value stored in the correction value storage means as a cooling water temperature;
Based on the detection current detected by the current detection means and the detection voltage detected by the voltage detection means when the cooling water temperature data calculated by the cooling water temperature data calculation means is less than the overheat set temperature, Inverter control means for controlling the output power of the inverter device,
In the inverter control means,
The limit power value is set stepwise so that the cooling water temperature range decreases as the cooling water temperature range becomes higher for each of a plurality of predetermined predetermined cooling water temperature ranges below the overheat set temperature.
It is configured to be able to perform control to reduce the output power of the inverter device in a stepwise manner so that the limit power value is maintained according to the rise in the cooling water temperature data. An overheat prevention device.

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