JP4721015B2 - Generator frequency control device - Google Patents

Description

  The present invention relates to a frequency control device for a generator that provides a load device instead of a governor mechanism and controls the frequency by consuming electric power in the load device.

  As a generator frequency control device, a load device is provided instead of a governor mechanism, and the frequency is controlled by consuming electric power in this load device (Patent Document 1).

  This type of generator frequency control device has a configuration as shown in FIG. In FIG. 10, 1 is an internal combustion engine, 2 is an exhaust passage, 3 and 9 are valves, 4 is a turbine, 5 is a clutch, 6 is a generator, 7 is a circuit breaker, 8 is a load, 10 is a rectifier, 11 is a capacitor, Reference numeral 12 is a diode, 13 is a dummy resistance load, 14 is an IGBT, 15 is a frequency detector, 16 is a subtractor, 17 is an amplifier, 18 is a PWM circuit, and 19 is a gate drive circuit.

  With such a configuration, exhaust gas is sent from the internal combustion engine 1 through the exhaust passage 2. When power generation is performed, the valve 3 is opened, the valve 9 is closed, the exhaust gas is sent to the turbine 4, and the turbine 4 is driven by the thermal energy of the exhaust gas. The generator 6 is connected to the shaft of the turbine 4 via the clutch 5 and generates power by the rotation of the turbine. Further, a load 8 is connected to the generator 6 via a circuit breaker 7, and the generator 6 supplies power to the load 8. Here, since the valve 3 can only be in the “open” state or the “closed” state, the flow rate of the exhaust gas cannot be adjusted, and the rotational speed of the turbine 4 cannot be controlled.

Here, when the rotational speed of the turbine 4 is ω, the moment of inertia is J, the torque that exhaust gas drives the turbine 4 is TE, and the load torque applied to the generator 6 is TG, the relationship of the following equation (1) is established.
dω / dt = (TE−TG) / J (1)

  In a state where TE and TG are balanced, dω / dt = 0 and there is no rotation speed fluctuation. When the flow rate of the exhaust gas changes, the drive torque TE changes, and when the load 8 changes, the load torque TG applied to the generator 6 changes. Then, the balance between TE and TG is lost, and if TE> TG, the rotational speed of the turbine 4 increases and the output frequency of the generator 6 also increases. In such a case, if TE and TG are balanced by increasing the power consumed by the dummy resistance load 13, the frequency can be controlled to a desired value.

The power consumption by the dummy resistance load 13 is performed by once converting the output of the generator 6 into direct current by the rectifier 10 and the capacitor 11 and turning on the IGBT 14. The IGBT 14 is switched as follows. That is, first, the frequency detector 15 detects the frequency of the output voltage of the generator 6. The subtracter 16 subtracts the frequency reference f ^* from the output voltage frequency of the generator 6 and outputs a frequency deviation Δf. The amplifier 17 amplifies the frequency deviation Δf and outputs a power consumption command that is consumed by the dummy resistance load 13. The PWM circuit 18 outputs a pulse having a pulse width proportional to the power consumption command, drives the IGBT 14 with the gate drive circuit 19, and causes a current to flow through the dummy resistance load 13. As a result, the electric power flowing through the dummy resistance load 13 can be adjusted, and the frequency of the generator 6 can be controlled to a desired frequency.
JP 7-217526 A

  In the conventional frequency control device for a generator described above, the input current of the rectifier 10 includes many harmonics, so that there is a problem that the output voltage waveform of the generator 6 is distorted. In addition, switching noise is generated from the IGBT 14 and may adversely affect other devices. If a noise filter is connected to the input part of the rectifier 10, noise can be reduced. However, there is a drawback that an expensive noise filter needs to be installed.

  The present invention has been made in view of the above circumstances, and a generator frequency control device capable of controlling the output frequency of a generator by consuming power in a dummy load device without generating harmonics and switching noise. The purpose is to provide.

In the invention corresponding to claim 1, a generator is driven by a prime mover not equipped with a governor mechanism, and the capacity of the generator is P × 2 ^(k−1) (where P is a predetermined load capacity, k = 1, 2... N) A generator in which a plurality of dummy load devices each having a resistive load and a semiconductor switch are connected, and the frequency of the generator is controlled by controlling the power consumption of the load device. A frequency detection device for detecting the frequency of the output voltage of the generator, comparing the frequency detected by the frequency detection device with a predetermined frequency setting value, and the resistance load Power consumption determining means for determining a power consumption value to be consumed; load selection means for selecting a load device to be energized from among the N load devices based on the power consumption value determined by the power consumption determining means; , The generator output power With the zero-crossing detecting means for detecting a zero-cross timing of the AC cycle, and a gate signal generating means for providing a gate signal to the semiconductor switch of the selected load device with a zero cross timing output from the zero crossing detecting means, wherein Among the plurality of load devices, a load device having a capacity P corresponding to k = 1 and a load device having a capacity 2P corresponding to k = 2 are integrated to form an integrated load device, and the integrated load device is used as a load resistance for three phases. When the load device selected by the load selection means corresponds to a part or all of the integrated load device, the phase to be energized by the three-phase integrated load device The energization phase determining means for matching the number with the selected load device gives a gate signal to the semiconductor switch, and And controlling the.

  ADVANTAGE OF THE INVENTION According to this invention, the frequency control apparatus of the generator which can control the output frequency of a generator by consuming electric power to a dummy load apparatus, without generating a harmonic and switching noise can be provided.

(First embodiment)
As shown in FIG. 1, the frequency control device for the generator according to the first embodiment of the present invention includes a frequency detector 15, a subtracter 16, an amplifier 17, a divider 20, a limiter 27, a binary number converter 21, a zero cross. A detector 22, AND circuits 23A, 23B, and 23C, gate drive circuits 24A, 24B, and 24C, and dummy load devices 25A, 25B, and 25C are provided.

The frequency detector 15 is used as a frequency detection means, and a power consumption determining means for deriving a power consumption value by amplifying a deviation Δf between the output frequency of the generator and the frequency reference f ^* by an amplifier 17 is further configured. A load selection means for selecting a dummy load device to be used by dividing by the capacity P and passing through the limiter 27 and the binary converter 21 is configured, and the zero cross detector 22 operates as the zero cross detection means, and the AND circuits 23A, 23B. , 23C and the gate drive circuits 24A, 24B, 24C constitute a gate signal generating means, so that when the generator output frequency fluctuates, the power consumed by the dummy load device is adjusted to adjust the generator output frequency. Control.

The load capacities of the load devices 25A, 25B and 25C are respectively P × 2 ^(k−1) (P is a predetermined load capacity, k = 1 to 3), and P [kW], 2P [kW], 4P [ kW], and the inside of the load device has a configuration in which resistive loads 32A, 32B, 32C and thyristors 31A to 31F are combined as shown in FIG. The thyristors 31A and 31B are connected to energize the resistive load 32A by applying a UV line voltage, and the thyristors 31C and 31D are connected to energize the resistive load 32B by applying a VW line voltage. The thyristors 31E and 31F are connected to apply a WU line voltage to the resistance load 32C to energize it. In FIG. 2, the total capacity of the resistive loads 32A, 32B, and 32C is the capacity of the load device. If the load device is 25A, it is P [kW]. The interiors of the load devices 25B and 25C have the same configuration, but are loads with a load capacity of 2P [kW] and 4P [kW]. Thus, the total load capacity of the load device is an integral multiple of P.

Hereinafter, the operation of the generator frequency control device of the present embodiment will be described.
An amplifier 17 amplifies the frequency deviation Δf obtained by subtracting the frequency reference f ^* from the output frequency of the generator detected by the frequency detector 15 by the subtractor 16 is an index of the power value to be consumed. The divider 20 divides the output from the amplifier 17 by the base power P [kW], outputs a quotient, and limits the sum of the load capacities of the load devices 25A, 25B, and 25C by P. The coefficient L (power consumption value = L × P) corresponding to the power consumption value actually consumed by the load devices 25A, 25B, and 25C is determined. When the coefficient L is converted into a binary number by the binary number converter 21, a signal for selecting a load device to be energized is output. A signal from the binary converter 21 is input to the AND circuits 23A, 23B, and 23C, and a zero-cross timing signal of the line voltage of the generator 6 detected by the zero-cross detector 22 is also input to the AND circuits 23A, 23B, and 23C. Thus, signals are sent from the AND circuits 23A, 23B, and 23C to the gate drive circuits 24A, 24B, and 24C. At this time, when the signal from the binary converter 21 is 1, the gate drive circuit 24A operates.

  FIG. 3 is a diagram for explaining the gate drive state from the gate drive circuit, and the resistance load 32A and thyristors 31A and 31B in FIG. 2 are described as an example. When selected as a load device to be energized, the zero cross timing signal of the line voltage between UV is detected by the zero cross detector 22, and the gate signal is sent to the thyristors 31A and 31B at the zero cross timing as shown in FIG. It is done. By energizing the resistance load 32A in this way, the load current becomes substantially sinusoidal, and the distortion can be reduced and the switching noise can be reduced. The same applies to the other resistive loads 32B and 32C.

  Since the load capacities of the load devices 25A, 25B, and 25C are set to P [kW], 2P [kW], and 4P [kW], respectively, the sum of the load capacities is 7P [kW]. The coefficient L takes an integer value between 0 and the maximum value 7. The power consumption can be adjusted in a P [kW] step from 0 to 7 P [kW] from a combination of selecting whether to drive each load device 25A, 25B, 25C.

  As described above, according to the generator frequency control device of the present embodiment, the generator output in the form of controlling the frequency by consuming electric power in the load device instead of the normal governor mechanism, The load devices 25A, 25B, and 25C are energized by turning on and off the thyristors 31A to 31F at the voltage zero-cross timing, so that power is consumed without generating harmonics and switching noise. Thus, a generator frequency control device capable of controlling the output frequency of the generator can be provided.

In this embodiment, three sets of dummy load devices are used. However, the value of P is as small as possible in P × 2 ^(k−1) (P is a predetermined load capacity, k = 1 to N). If the number of dummy load devices is increased and the capacity of each load device is selected, the frequency can be finely adjusted by increasing the adjustable steps. In addition to the exhaust gas of the internal combustion engine 1 shown in FIG. 1, the power source for driving the generator 6 may be ordinary hydraulic power, thermal power, or a gas turbine.

(Second Embodiment)
FIG. 4 is a diagram showing the configuration of the generator frequency control apparatus according to the second embodiment of the present invention. The difference from the generator frequency control device of the first embodiment shown in FIG. 1 is that it includes an on-period setting device 26 and includes load devices 40A, 40B, and 40C instead of the load devices 25A, 25B, and 25C. It is that you are.

The internal configuration of the load devices 40A, 40B, and 40C is the same as that of the load devices 25A, 25B, and 25C shown in FIG. The functions of the load devices 40A, 40B, and 40C are the same as those of the load devices 25A, 25B, and 25C, and power is consumed to control the output frequency of the generator 6. However, the load capacity of the load devices 40A, 40B, and 40C is P × 2 ^(k−1) (P is a predetermined load capacity, k = 1 to N, N = 4), and k = 1. And the load devices corresponding to k = 2 are integrated into a single load device. That is, the load device 40A has a total of 3 P [kW] with P [kW] and 2P [kW]. The load device 40B is 4P [kW] when k = 3, and the load device 40C is 8P [kW] when k = N = 4. The total capacity of the load device is 15 P [kW]. Therefore, the limiter 27 in this embodiment is limited to 15.

  When the output from the limiter 27 is converted into a binary number by the binary number converter 21, a load device to be energized is selected. As described above, the load device 40A has a total of 3P of P [kW] and 2P [kW]. It is set as a load device of [kW], and the load selection signal from the binary converter 21 cannot be directly applied with the load amount corresponding to the load selection signal. Therefore, the load device 40A is controlled via the on period setting device 26.

  In the on period setting device 26, since the load device 40A is an integrated unit of P [kW] and 2P [kW], the number of AC cycles m = 1 + 2 = 3 from the numbers k = 1 and 2 corresponding to the load device 40A. I think. Then, a period for turning on the thyristors 31A to 31F is set in the three AC cycles so as to match the load amount corresponding to the load selection signal from the binary converter 21. FIG. 7 summarizes the processing results inside the on-period setting device 26 and the power consumption at 40A.

  As described above, the power consumption of the load device 40A is an average value in the AC three-cycle period by the action of the on period setting unit 26 that changes the ratio of the on period and the off period of the thyristors 31A to 31F constituting the load apparatus 40A. As a result, the adjustment can be made in 4 stages of P [kW] steps from 0 to 3P [kW]. Note that energization of the load devices 40A, 40B, and 40C is performed in accordance with the zero cross timing of the voltage, as in the first embodiment.

In the present embodiment, in P × 2 ^(k−1) (P is a predetermined load capacity, k = 1 to N), the value of P is made as small as possible and the number of load devices is increased (N is increased). In the case of the configuration, fine adjustment of the frequency is possible, but it is possible to prevent a decrease in reliability of the entire system due to an increase in the number of components and an increase in the cost of the apparatus. That is, even if P is reduced and N is increased, several load devices can be integrated, and the power consumption in the integrated load device can be controlled by the above-described on-period setting device 26. The same effect can be obtained without increasing the number.

  As described above, in the present embodiment, the output frequency of the generator can be controlled without distorting the output voltage of the generator and the occurrence of switching noise can be suppressed, and the reliability of the entire system can be maintained. Also, it is possible to provide a generator frequency control device capable of finely adjusting the frequency while coping with an increase in cost.

(Third embodiment)
FIG. 5 is a diagram showing the configuration of the generator frequency control apparatus according to the third embodiment of the present invention. The difference from the generator frequency control apparatus of the second embodiment shown in FIG. 4 is that an energized phase selector 28 is provided instead of the on period setting device 26. Since the load device 40A is an integration of P [kW] and 2P [kW], the number of AC cycles m = 3 from the numbers k = 1 and 2 corresponding to the load device 40A. Therefore, the phase to be energized is selected in the three AC cycles.

  FIG. 8 summarizes the processing results inside the energized phase selector 28 and the power consumption in the load device 40A. As described above, by selecting the energized phase, the power consumption of the load device 40A can be adjusted to 0 to 3P [kW] in four stages of the P [kW] step as an average value in the AC three-cycle period. . Note that energization of the load devices 40A, 40B, and 40C is performed in accordance with the zero cross timing of the voltage, as in the first embodiment.

  As described above, also in the present embodiment, the output frequency of the generator can be controlled without distorting the output voltage of the generator, and the generation of switching noise can be controlled, and the reliability of the entire system is maintained. Also, it is possible to provide a generator frequency control device capable of finely adjusting the frequency while coping with an increase in cost.

(Fourth embodiment)
In the fourth embodiment of the present invention, the on period setting unit 26 described in the second embodiment (FIGS. 4 and 7) does not turn on / off in units of one cycle of AC, but in units of half cycles. Is set to turn on / off. The processing results inside the on-period setting device 26 in this case and the power consumption in the load device 40A are summarized in FIG. Even if it carries out like FIG. 9, the power consumption of 40 A of load apparatuses is adjusted by the ON period setting device 26 in four steps of P [kW] step by 0-3P [kW] as an average value in AC 3 cycle period. Is possible.

  As described above, also in the present embodiment, the output frequency of the generator can be controlled without distorting the output voltage of the generator, and the generation of switching noise can be controlled, and the reliability of the entire system is maintained. Also, it is possible to provide a generator frequency control device capable of finely adjusting the frequency while coping with an increase in cost.

(Fifth embodiment)
In the fifth embodiment of the present invention, the thyristors 31A to 31A provided in the load devices 25A, 25B, 25C, 40A, 40B, and 40C provided in the generator frequency control device of the first to fourth embodiments. This relates to failure detection of 31F. FIG. 6 is a diagram illustrating a circuit (for one phase) that detects a thyristor failure. In this figure, the components necessary for explaining one phase are extracted from FIGS. 1 and 2, and a voltage detector 50, a phase delay circuit 51, and a comparison circuit 52 are added.

  The voltage detector 50 detects the voltage across the thyristors 31A and 31B. A gate signal to the thyristor is input to the phase delay circuit 51, and is output after being delayed to a timing at which the UV line voltage observed by the voltage detector 50 is substantially peaked when the thyristors 31A and 31B are non-conductive. The comparison circuit 52 compares the voltage across the thyristor detected by the voltage detector 50 with the signal from the phase delay circuit 51. When the following condition a or b is satisfied, it is determined that the operation is abnormal and a failure signal is output.

Condition a: The signal from the phase delay circuit 51 is high, and the voltage across the thyristor> predetermined value Condition b: The signal from the phase delay circuit 51 is low, and the voltage across the thyristor <predetermined value In this embodiment, the thyristor Since a failure can be detected, when a failure signal is output, it is possible to take measures such as stopping the system (closing the valve 3 and opening the valve 9 to stop the turbine 4 and the generator 6).

The circuit diagram which shows the structure of the frequency control apparatus of the generator of the 1st Embodiment of this invention. The circuit diagram which shows the structure of the load apparatus with which the frequency control apparatus of the generator of the 1st Embodiment of this invention is equipped. The wave form diagram explaining operation | movement of the load apparatus with which the frequency control apparatus of the generator of the 1st Embodiment of this invention is equipped. The circuit diagram which shows the structure of the frequency control apparatus of the generator of the 2nd and 4th embodiment of this invention. The circuit diagram which shows the structure of the frequency control apparatus of the generator of the 3rd Embodiment of this invention. The circuit diagram which shows the structure of the frequency control apparatus of the generator of the 5th Embodiment of this invention. The table | surface explaining operation | movement of the frequency control apparatus of the generator of the 2nd Embodiment of this invention. The table | surface explaining operation | movement of the frequency control apparatus of the generator of the 3rd Embodiment of this invention. The table | surface explaining operation | movement of the frequency control apparatus of the generator of the 4th Embodiment of this invention. The circuit diagram which shows the structure of the conventional frequency control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Exhaust passage, 3, 9 ... Valve, 4 ... Turbine, 5 ... Clutch, 6 ... Generator, 7 ... Circuit breaker, 8 ... Load, 10 ... Rectifier, 11 ... Capacitor, 12 ... Diode, DESCRIPTION OF SYMBOLS 13 ... Dummy resistance load, 14 ... IGBT, 15 ... Frequency detector, 16 ... Subtractor, 17 ... Amplifier, 18 ... PWM circuit, 19 ... Gate drive circuit, 20 ... Divider, 21 ... Binary converter, 22 ... Zero cross detector, 23A, 23B, 23C ... AND circuit, 24A, 24B, 24C ... gate drive circuit, 25A, 25B, 25C ... load device, 26 ... on period setting device, 27 ... limiter, 28 ... energized phase selector, 31A, 31B, 31C, 31D, 31E, 31F ... Thyristor, 32A, 32B, 32C ... Resistive load, 40A, 40B, 40C ... Load device, 50 ... Voltage detector, 51 ... Phase lag , 52 ... comparison circuit.

Claims (1)

The generator is driven by a prime mover not equipped with a governor mechanism, and the generator has a capacity of P × 2 ^(k−1) (where P is a predetermined load capacity, k = 1, 2,..., N) A generator frequency control device, wherein a plurality of dummy load devices including a load and a semiconductor switch are connected, and the frequency of the generator is controlled by controlling power consumption of the load device,
The frequency detection means for detecting the frequency of the output voltage of the generator, the frequency detected by the frequency detection means and a predetermined frequency set value are compared, and the power consumption value consumed by the resistive load is determined. Power consumption determining means; load selecting means for selecting a load device to be energized from among the N load devices based on the power consumption value determined by the power consumption determining means; and AC of the generator output voltage Zero cross detection means for detecting the zero cross timing of the cycle, and gate signal generation means for giving a gate signal to the semiconductor switch in the selected load device at the zero cross timing output from the zero cross detection means,
Among the plurality of load devices, a load device having a capacity P corresponding to k = 1 and a load device having a capacity 2P corresponding to k = 2 are integrated into an integrated load device, and the integrated load device is a load for three phases. When the load device selected by the load selection means corresponds to a part or all of the integrated load device, the three-phase integrated load device is energized. A generator frequency control device characterized in that a gate signal is given to the semiconductor switch to control power consumption of the load device by means of energized phase determining means for matching the number of phases with the selected load device.

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