JP4814058B2 - Gas engine control device - Google Patents

Description

  The present invention relates to a gas engine that drives a generator that can be connected to and disconnected from a power transmission system from an electric power company with a gas engine, and controls gas supply to the gas engine to control its output. TECHNICAL FIELD The present invention relates to an engine control device, and more particularly to a gas engine control device capable of performing stable operation by reducing the amount of knocking of the gas engine as much as possible to prevent the electric power from exceeding a set load during operation. is there.

  In a factory or the like, a system that uses power transmitted from an electric power company and power obtained by driving a generator with a gas engine in the factory in some cases may be employed. In this way, in the output control of the gas engine that drives the generator that can be connected to the system, if an ordinary electronic governor that feedback-controls the engine speed is used, the engine speed is pulled by the system, so the electronic governor Even if the output of is changed, it does not change and fuel adjustment cannot be performed as it is.

  For example, when the target rotation speed is 1000 rotations and the actual rotation speed is 1001 rotations, the electronic governor decreases the fuel adjustment output in an attempt to decrease the rotation speed, but the engine is linked to a generator linked to a system with a constant frequency. Since the engine speed will not change, the output will eventually be 0% and the engine output will also be 0%. Conversely, the generator will become a motor and the engine will be powered by the grid power (power supplied by the power company). This will result in rotation.

  Therefore, in the case of output control of a gas engine that drives a generator that can be connected to the grid, conventionally, droop control based on the rotational speed has been often performed. This control method is feedback control based on the rotational speed, and controls the target rotational speed to decrease as the engine output increases, and the power generated by the generator includes a predetermined power including the target power. In this case, the speed increase signal or the speed decrease signal is output when the dead zone is deviated to increase or decrease the rotation, respectively.

  FIG. 5 is a digital signal showing a waveform of a signal used in the conventional output control of the gas engine for driving the generator, and FIG. 5A shows the time of the rotation speed of the gas engine (engine speed). FIG. 4B shows the change over time of the power (indicated by the load factor) output from the generator.

  However, the frequency of the power supplied from the grid (bus frequency) is not strictly constant, and some variation is unavoidable. For example, in the Kanto region, the frequency of electricity supplied from an electric power company is 50 Hz, but there is actually a fluctuation of about ± 0.1 Hz. Therefore, as shown in FIG. 5 (a), the engine speed is unavoidably changed with a change in the bus frequency.

  Further, as shown in FIG. 5B, in the conventional control described above, the dead zone, which is a reference range for outputting a speed increase signal or a speed decrease signal, is wider than the power generated by the generator. If the load factor fluctuates due to fluctuations in the engine speed that accompany changes in the bus frequency, the speed reduction signal may not be in time, resulting in overloading of the rated output. May exceed 103%, and the engine sometimes knocks at this time.

  If the dead zone is set narrow to avoid the occurrence of the overload condition, a speed increase signal or a speed decrease signal will be output more frequently, resulting in the occurrence of an event where the load increases beyond the dead zone. The probability is rather larger than when the dead zone is wide.

  In order to avoid the above problems, it may be possible to control only the electric power. In this case, the gas engine and the generator are separated from the system and operated (for example, the system reaches the rated operation and the system is operated). At the time of start-up before linking to the power supply, etc.), if the rotation control is not performed, the rotation speed corresponding to the electric power frequency of the electric power company cannot be maintained, so that control of only such electric power cannot be adopted.

As described above, in the conventional output control of the gas engine that drives the generator that can be connected to the grid, there is a problem of knocking due to the occurrence of an overload due to the fluctuation of the bus frequency and the wide dead band in the control. However, there is a problem that the efficiency of the engine is lowered because adjustments such as reducing the knocking region by reducing P _max (the maximum combustion pressure in the cylinder) so that knocking does not occur even in an overload state. It was.

  The present invention solves the above problems, and in the output control of the gas engine that drives the generator that can be connected to the grid, it can be controlled so that the generated power does not exceed the set load during rated load operation, As a result, the object is to reduce the occurrence of knocking and enable stable operation.

A control device for a gas engine according to claim 1 is provided.
In a control device for a gas engine that drives a generator that can be connected to and disconnected from a power transmission system from an electric power company ,
A droop control unit that performs rotation speed control by droop, a power control unit that performs power control using a maximum load ratio at which knocking occurs in the gas engine as a target value, a first control signal from the droop control unit, and the power control A comparison unit that receives a second control signal from the unit and selects a lower value and outputs it as a control signal. When connected to the power transmission system, the driver controls the fuel of the gas engine. An electronic governor that outputs a control signal is provided.

The control device for a gas engine according to claim 2 is the control device for a gas engine according to claim 1,
Before Symbol comparison unit, if the load of the gas engine does not reach the maximum load factor, the pre-Symbol first control signal that will be output from the loop control unit and the control signal, the load of the gas engine maximum load When the rate is exceeded, the second control signal having a relatively lower value than the first control signal output from the power control unit is used as the control signal .

A control device for a gas engine according to claim 3 is provided.
In a control device for controlling a gas supply valve of a gas engine that drives a generator that can be connected to and disconnected from a power transmission system from an electric power company ,
A power transducer that converts the voltage and current waveform of the generator into a power signal and outputs the power signal;
A power controller for inputting a voltage current waveform of the generator and a target generated power, and outputting a speed increase signal or a speed decrease signal when the power generated by the generator is out of a predetermined dead band including the target generated power. When,
A rotational speed detection means for detecting the rotational speed of the gas engine and outputting a rotational pulse signal;
A storage means in which a target electric power and a droop rate corresponding to a rotation speed initial value and a maximum load rate at which knocking occurs in the gas engine are set;
First target rotational speed setting means for calculating a first target rotational speed based on an initial rotational speed value obtained from the storage means and a speed increase signal or a speed decrease signal from the power controller; a power signal from the power transducer; A second target rotational speed is calculated by changing the first target rotational speed from the first target rotational speed setting means based on the droop rate from the storage means and the rotational pulse signal from the rotational speed detection means. A droop control unit that performs a droop speed control by outputting the second target revolution speed as a first control signal;
A power control unit that outputs a second control signal for power control based on a target power obtained from the storage means and a power signal from the power transducer;
A comparison unit that compares the first control signal from the droop control unit and the second control signal from the power control unit when connected to the power transmission system and outputs the lower value as a control signal;
A driver that receives the control signal from the comparison unit and applies a drive signal to the gas supply valve of the gas engine to control the supply of gas fuel to the gas engine.

  According to the control device for a gas engine according to the present invention, if the maximum load factor at which knocking occurs in the gas engine is set as the target value of the load factor, the rotation that outputs a relatively low control signal at a load factor equal to or lower than the target value. Control is performed, and power control is performed to output a relatively low control signal at a load factor equal to or higher than the target value. In power control, since it is not affected by the bus frequency of the system, the load factor is stabilized. As a result, knocking due to overload can be avoided, and efficiency-priority adjustment can be performed, thereby improving efficiency.

The best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a control device for a gas engine according to this example.
In the gas engine 1, each cylinder 2 is provided with a gas supply electromagnetic valve 3, and each gas supply electromagnetic valve 3 is controlled by a driver 4. The generator 5 linked to the gas engine 1 can be freely connected to and disconnected from the system.

  The electric voltage / current waveform generated by the generator 5 is applied to the power transducer 6 and converted into a power signal to be output.

  An electric voltage / current waveform generated by the generator 5 and a target generated power set by the engine control panel 8 are input to the power controller 7, and the power generated by the generator 5 is converted into the target power generation. When a predetermined dead zone including electric power is deviated, a speed increasing signal (when the lower limit of the dead zone is exceeded) or a speed decreasing signal (when the upper limit of the dead zone is exceeded) is output and given to the electronic governor 10 described later. It is configured.

  In the vicinity of the link gear 9 of the gas engine 1, there is provided a magnet pickup 11 as a rotation speed detecting means for detecting the rotation speed and outputting a rotation pulse signal. This rotation pulse signal is an electronic governor described later. 10 is used for controlling the number of revolutions.

  The electronic governor 10 that is a main part of the control device includes a droop control unit 12 that is a first control unit, a power control unit 13 that is a second control unit, and a storage unit that stores control data. 14 and a comparison unit 15 for determining which control signal of the droop control unit 12 or the power control unit 13 is to be selected.

  First, the electronic governor 10 is provided with storage means 14 for storing control data. In this storage means 14, the rotation speed initial value 16 of the gas engine 1 and the generator 5 are to generate power. A target power 17 (corresponding to a set load factor serving as a reference for control, which is fixed and set to a maximum load factor of 100% in this example) and a droop rate 18 are set. Although the details will be described later, the droop rate indicates the percentage at which the target rotational speed changes with respect to the change of the load factor of 100% in the droop control for controlling the target rotational speed to decrease as the engine output increases. Is.

Next, the electronic governor 10 has a droop control unit 12 as a first control unit. The droop control unit 12 includes first target rotation speed setting means 20 and second target rotation speed setting means 21.
The first target rotational speed setting means 20 uses the rotational speed initial value 16 obtained from the storage means 14 and the speed increase signal (pulse) or speed decrease signal (pulse) from the power controller 7 to generate the first target rotational speed. Is calculated.

  The second target rotational speed setting means 21 is configured to output the first target rotational speed from the first target rotational speed setting means 20 based on the power signal from the power transducer 6 and the droop rate 18 from the storage means 14. The second target rotational speed is calculated by changing the number.

  The rotation control unit 22 generates a first control signal for performing rotation speed control by droop based on the second target rotation speed from the second target rotation speed setting means 21 and the rotation pulse signal from the magnet pickup 11. Output.

The droop control by the droop control unit 12 will be described with reference to FIG. First, as described above, the droop control unit 12 has two target rotational speeds. The first target rotational speed is the initial rotational speed value 16 set in the storage means 14 (for example, 1000 min ⁻¹ (rotational speed per minute) in this example) and the power of the generator 5 that is actually generating power. It is increased or decreased by a speed increase / decrease signal generated and output by the power controller 7 based on the difference from the target generated power. On the other hand, the second target rotational speed is a target rotational speed obtained by correcting the first target rotational speed with the load factor corresponding to the power signal from the power transducer 6 and the droop rate 18 of the storage means 14. If the bus frequency is 50 Hz, it becomes 1000 min ⁻¹ , and the actual feedback control is performed so as to achieve this rotational speed.

FIG. 2 shows an example in which the rated rotational speed (the rotational speed when connected to the grid) is 1000 min ⁻¹ and the droop rate is 4%. The droop rate of 4% means that the first target rotation speed changes by 4% of the rated rotation speed with respect to a change of the load ratio of 100%.

For example, when the first target rotational speed is 1000 min ⁻¹ , the load factor is 0%. Here, when the load due to operation increases, since the rotation speed is not changed at 1000min ^-1 to that system and interconnection, the first target rotational speed is changed, when it rises to 1040Min ^-1, If the bus frequency is 50 Hz, the second target rotational speed is 1000 min ⁻¹ , so the load factor is 100%.

Also, for example, if the load factor is 50% in actual operation, the second target rotational speed does not change from the rated rotational speed at 1000 min ⁻¹ because it is connected to the grid, so the first target rotational speed is 1020 min ⁻¹ .

In the state as in these examples, when the bus frequency fluctuates (see “change in second target value” in FIG. 2), the load factor changes by 2.5% with respect to the change in the rotational speed 1 min ^−1. Will be. This is the output fluctuation due to the bus frequency fluctuation.

Next, the electronic governor 10 has a power control unit 13 as a second control unit.
The power control unit 13 outputs a second control signal for power control based on the target power 17 obtained from the storage unit 14 and the power signal from the power transducer 6.

  Next, the electronic governor 10 compares the first control signal from the droop control unit 12 and the second control signal from the power control unit 13 when connected to the system, and determines the control signal having the lower value as the control signal. As a comparison unit 15 for outputting.

  In this example, assuming that the maximum load factor at which knocking occurs in the gas engine 1 is the target value of the load factor (corresponding to the target power 17), a rotation that outputs a relatively low control signal at a load factor below the target value. The first control signal is output as a control signal from the comparison unit 15, power control is performed to output a relatively low control signal at a load factor equal to or higher than the target value, and the second control signal is controlled from the comparison unit 15. Output as a signal. In power control, since it is not affected by the bus frequency of the system, the load factor is stabilized. As a result, knocking due to overload can be avoided, and efficiency-priority adjustment can be performed, thereby improving efficiency.

  A control signal from the comparison unit 15 is given to the driver 4, and each driver 4 gives a drive current to the gas supply electromagnetic valve 3 of the gas engine 1 to control the supply of gas fuel to each cylinder 3 of the gas engine 1.

The effect | action by the above structure is demonstrated.
The graph shown in the upper part of FIG. 3 is a waveform indicating the time change of the load factor inputted through the power transducer 6 and digitized by the electronic governor 10, and the graph shown in the lower part is the comparison unit 15 of the electronic governor 10. 6 is a waveform representing a control signal as a governor output, which is a result of the comparison operation in FIG. In this example, the maximum load factor 100% at which the gas engine 1 starts to knock is set as the set load factor, and is input and stored as the target power 17 in the storage unit 14 in advance.

  At time 0 to t1 in FIG. 3, the load factor of the gas engine 1 is lower than the set load, and when the bus frequency increases, the output is decreased so that the target rotation speed becomes a load factor corresponding to the bus frequency when the bus frequency increases. However, in the power control, the output is increased in order to increase the load that has decreased below the target. For this reason, the rotation speed control is prioritized at a load factor equal to or less than the target value.

  From time t1 to time t2 in FIG. 3, when the load factor of the gas engine 1 is higher than the set load and the bus frequency is lowered, the output is increased so that the target rpm becomes a load factor corresponding to the bus frequency when the bus frequency is lowered. On the other hand, in the power control, the output is reduced in order to reduce the load that has risen above the target. For this reason, power control is prioritized at a load factor equal to or higher than the target value.

  Accordingly, the rotation speed control is selected because the load factor is less than or equal to the target value at times 0 to t1 and t2 in FIG. 3, and the load factor is greater than or equal to the target value at times t1 to t2 in FIG. Power control is selected for this purpose. Thus, in this device, the electronic governor 10 does not determine whether the load is greater than or less than the set load, and the maximum load factor is set as the load factor target value (corresponding to the target power 17). As a result of comparing and selecting the lower one of the first and second control signals, the rotation control outputs a relatively low control signal at a load factor lower than the target value, and relatively at a load factor higher than the target value. Switching to power control for outputting a low control signal is performed. For this reason, in areas where the load factor is higher than the target value, it is possible to operate at a stable load factor without being affected by the bus frequency of the system by power control, and knocking due to overload is avoided, and efficiency priority adjustment is performed. Can improve efficiency.

  FIG. 4 is a digital signal showing the waveform of the signal used in this example. FIG. 4A shows the time change of the rotation pulse signal (corresponding to the engine speed) from the magnet pickup 11, and FIG. (B) has shown the time change of the electric power (it shows with a load factor) which the generator 5 outputs. According to this example, a change appears in the rotation speed of the gas engine 1 with a change in the bus frequency. However, the control of the power control and the rotation speed control as described above causes a change in the bus frequency. Since it becomes difficult to be affected, the load factor is stable as shown in FIG.

  Further, according to the control device of this example, both power control and rotational speed control are used together, and both are switched and used without a signal from the outside, so that the connection between the generator 5 and the system is instantaneous. Even if the gas engine 1 itself has to maintain the rotational speed after the shut-off, since the rotational speed depends on the bus frequency before the shut-off, the engine is automatically turned off when the load factor falls below the target value. Since switching to rotation control is performed, the number of rotations can be controlled even after the system is shut off to maintain proper operation. On the other hand, when only the power control is performed, the rotation speed cannot be maintained after the system is disconnected from the system, so that proper operation cannot be continued.

  As described above, according to the control apparatus for a gas engine according to the present invention that drives a generator that can be connected to and disconnected from the system, the control signal is limited to a limiter limit in a relatively low load region. The droop speed control is performed without using the power control with a high value, and the droop speed control uses the power control in which the value of the control signal decreases only in a high load region where knocking occurs. For this reason, it becomes possible to operate the gas engine 1 in a state where the overload does not exceed a load factor of 100%, which is a knocking occurrence condition.

FIG. 1 is a block diagram illustrating a configuration of a control device for a gas engine according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the relationship between the rotation speed and the load factor for explaining the droop control. FIG. 3 is a schematic diagram of the control waveform in the embodiment of the present invention, and the upper graph is a waveform diagram showing the time change of the load factor input through the power transducer and digitized by the electronic governor. FIG. 6 is a waveform diagram showing a control signal as a governor output, which is a result of comparison operation performed by a comparison unit of the electronic governor. FIG. 4 is a digital signal showing a control waveform in the embodiment of the present invention, and FIG. 4A is a diagram showing a time change of the rotation pulse signal (corresponding to the engine speed) from the magnet pickup. FIG. (B) is a diagram showing the time change of the electric power (indicated by the load factor) output from the generator. FIG. 5 is a digital signal showing a waveform of a signal used in conventional output control of a gas engine that drives a generator. FIG. 5 (a) shows the change over time in the rotational speed of the gas engine (engine rotational speed). FIG. 4B is a diagram showing the change over time of the power (indicated by the load factor) output from the generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas engine 4 Driver 5 Generator 6 Electric power transducer 7 Electric power controller 10 Electronic governor 11 Magnet pick-up as rotation speed detection means 12 Droop control part 13 Power control part 14 Storage means 15 Comparison part 16 Initial value of rotation speed 17 Target power 18 Droop Rate 20 First target rotational speed setting means 21 Second target rotational speed setting means 22 Rotation control unit

Claims (3)

In a control device for a gas engine that drives a generator that can be connected to and disconnected from a power transmission system from an electric power company ,
A droop control unit that performs rotation speed control by droop, a power control unit that performs power control using a maximum load ratio at which knocking occurs in the gas engine as a target value, a first control signal from the droop control unit, and the power control A comparison unit that receives a second control signal from the unit and selects a lower value and outputs it as a control signal. When connected to the power transmission system, the driver controls the fuel of the gas engine. A gas engine control device comprising an electronic governor for outputting a control signal. Before Symbol comparison unit, if the load of the gas engine does not reach the maximum load factor, the pre-Symbol first control signal that will be output from the loop control unit and the control signal, the load of the gas engine maximum load 2. The control signal according to claim 1, wherein when the rate is exceeded, the second control signal having a relatively lower value than the first control signal output from the power control unit is used as the control signal. The control apparatus of the described gas engine. In a control device for controlling a gas supply valve of a gas engine that drives a generator that can be connected to and disconnected from a power transmission system from an electric power company ,
A power transducer that converts the voltage and current waveform of the generator into a power signal and outputs the power signal;
A power controller for inputting a voltage current waveform of the generator and a target generated power, and outputting a speed increase signal or a speed decrease signal when the power generated by the generator is out of a predetermined dead band including the target generated power. When,
A rotational speed detection means for detecting the rotational speed of the gas engine and outputting a rotational pulse signal;
A storage means in which a target electric power and a droop rate corresponding to a rotation speed initial value and a maximum load rate at which knocking occurs in the gas engine are set;
First target rotational speed setting means for calculating a first target rotational speed based on an initial rotational speed value obtained from the storage means and a speed increase signal or a speed decrease signal from the power controller; a power signal from the power transducer; A second target rotational speed is calculated by changing the first target rotational speed from the first target rotational speed setting means based on the droop rate from the storage means and the rotational pulse signal from the rotational speed detection means. A droop control unit that performs a droop speed control by outputting the second target revolution speed as a first control signal;
A power control unit that outputs a second control signal for power control based on a target power obtained from the storage means and a power signal from the power transducer;
A comparison unit that compares the first control signal from the droop control unit and the second control signal from the power control unit when connected to the power transmission system and outputs the lower value as a control signal;
A driver that is supplied with the control signal from the comparison unit and that supplies a drive signal to the gas supply valve of the gas engine to control the supply of gas fuel to the gas engine;
A control device for a gas engine, comprising:

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