JP2006050691A - Generator and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply power stably in consideration of a start transition time of an auxiliary generation means, without employing a capacitor device, in a generator which mainly uses a generation means utilizing natural energy and auxiliarily uses the above generation means utilizing fuel. <P>SOLUTION: This generator monitors the generated power of a solar cell (S2-S4), and predicts the generated power of the solar cell after a specified time (S5), and when the predicted value of the generated power falls under a specified value (S7-S8), instructs the auxiliary generation means to be started (S9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power generation device and a control method thereof, for example, a hybrid power generation device in which a power generation device using natural energy is a main power generation device and a power generation device using fuel is an auxiliary power generation device.

  In recent years, interests in environmental protection, energy saving, and stable securing and supply of energy have increased worldwide. Under such circumstances, solar cells using inexhaustible solar energy are highly expected as energy sources that are easy to maintain, have no moving parts, and are quiet and clean. In recent years, solar cells have been installed on the roofs of ordinary houses or installed as solar power generators using solar cells on remote islands, etc., and are also referred to as commercial AC power systems (hereinafter simply referred to as “power systems”). ) And distributed power sources are becoming widespread.

  In addition, to cover the power of isolated islands and mountainous areas separated from the main commercial power distribution network, solar power generators and wind power generators that use natural energy, and power generators that use fuel (for example, diesel generators) A power generation system combined with a device is used. A power generator using fuel usually includes a plurality of generators, and controls the operation (start and stop) of each generator based on a power supply and demand plan that is planned in consideration of past load fluctuations.

  However, the diesel power generator consumes a large amount of fossil fuel, and the power generation cost is extremely high. If electric power can be supplied only by the solar power generation device or the wind power generation device, the diesel power generation device should be stopped as much as possible. However, the outputs of solar power generation devices and wind power generation devices that depend on solar radiation and wind power are unstable. In order to supply stable power, it is necessary to appropriately control the operation of both power generation devices.

  Many configuration methods and control methods of a power generation system combining a solar power generation device and a power generation device using fuel have been proposed. For example, Japanese Patent Laid-Open No. 2001-136681 discloses a power generation system that activates a diesel power generator when the output of the solar power generator or the wind power generator is insufficient by combining the solar power generator or the wind power generator with the diesel power generator. Is disclosed. In order to solve the problems that cannot be dealt with immediately when the output of a solar power generator or wind power generator fluctuates greatly due to solar radiation or wind fluctuation, it takes time to start up the diesel power generator. A technique for supplementing the electric power of the period with the energy stored in the capacitor is described.

  However, the method of supplementing the power during the startup transition period of the diesel power generation device using the capacitor as the power storage device generally requires a large-capacity and large power storage device, increasing the initial cost of the power generation system, There is a problem of increasing the installation area.

JP 2001-136681

  The present invention solves the above-mentioned problems individually or collectively, and mainly uses a power generator that uses natural energy, and a power generator that uses a fuel as an auxiliary power without using a power storage device. An object of the present invention is to supply power stably in consideration of the startup transition period of the auxiliary power generator.

  The present invention has the following configuration as one means for achieving the above object.

  According to the present invention, in a power generation apparatus having a first power generation means that uses natural energy and a second power generation means that uses fuel, the power generated by the first power generation means is monitored, The generated power of one power generation means is predicted, and when the predicted value of the generated power is equal to or lower than a first predetermined value, the activation of the second power generation means is instructed.

  Further, in a power generation apparatus having a first power generation unit that uses a plurality of solar cell subarrays and a second power generation unit that uses fuel, the generated power of each of the solar cell subarrays is monitored, Predicting the generated power of each of the battery sub-arrays, and instructing the start of the second power generation means when the solar battery sub-arrays whose predicted power generation values are equal to or less than the first predetermined value are adjacent to each other by the first predetermined number. And

  According to the present invention, in a power generation device mainly using a power generation device that uses natural energy and assisting a power generation device that uses fuel, the start-up transient period of the auxiliary power generation device is considered without using the power storage device. Power can be supplied stably. Therefore, for example, a solar power generation device and a cogeneration system such as a diesel generator can be combined to supply power stably and inexpensively.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, a solar power generation device will be described as an example of a power generation device that uses natural energy, but a wind power generation device can also be used instead of the solar power generation device.

[Configuration of power generation system]
FIG. 1 is a block diagram illustrating a configuration example of the power generation system according to the first embodiment.

  The power generation system shown in FIG. 1 is a hybrid power generation system in which a main power generation device 4 of a solar power generation device and an auxiliary power generation device 7 having a diesel generator are combined.

  The main power generator 4 collects the DC power output from the solar cell 1 at the junction box 2 and supplies it to the solar inverter 3. The power converted from DC to AC by the solar inverter 3 is supplied to a load 12 such as a power system. Supply.

  The detection unit 5 detects the output (output voltage and output current) of the solar cell 1. The detection unit 5 acquires, for example, the voltage divided by the voltage dividing resistors 14 and 15 connected between the positive and negative electrodes at the output end of the junction box 2 (see FIG. 2), and the voltage dividing ratio of the voltage dividing resistor Based on the above, the output voltage value of the solar cell 1 is calculated.

  The detection unit 5 also obtains the output voltage of the clamp ammeter 16 arranged in one current path between the junction box 2 and the solar inverter 3 (see FIG. 2), and based on the current proportionality factor of the clamp ammeter The output current value of the solar cell 1 is calculated.

  Note that there is no limitation on the detection method of the output voltage and output current of the solar cell 1, and the output voltage of the solar cell 1 may be obtained directly without using a voltage dividing resistor, or instead of the clamp ammeter 16. A shunt resistor may be connected to and the output current value may be calculated from the voltage across the shunt resistor.

  The control unit 6 controls the operation of the auxiliary power generator 7 based on the detection result of the detection unit 5.

  The auxiliary power generator 7 drives an AC generator (synchronous generator) 10 with a diesel engine 8 to generate AC power. The control unit 9 of the auxiliary power generator 7 controls the operation of the diesel engine 8 and the opening / closing of the switch 11 that electrically connects the AC generator 10 and the load 12 based on a control signal input from the control unit 6. .

  The detection unit 5 includes an acquisition unit that acquires a voltage value at a predetermined interval, an A / D converter that converts an analog signal into a digital signal, a memory that stores a voltage division ratio and a current proportionality coefficient, and an acquired voltage value (digital signal ) Multiplied by a voltage division ratio and a current proportionality coefficient, and an interface for outputting a digital signal. For example, a digital voltmeter having an interface that measures a voltage at a programmed interval and outputs the measurement result as a digital signal can be used as the detection unit 5.

  The control units 6 and 9 include a memory for storing a program for performing computation, processing and control, which will be described later, a CPU for executing the program, a work memory for the CPU, and an interface or I / O for inputting and outputting digital signals. Provide a port. For example, a one-chip microprocessor storing the above program in a ROM, a personal computer storing the above program in a hard disk, or the like can be used as the control units 6 and 9.

[Prediction of power generated by solar cells]
Detection unit 5, the measurement interval T _B set in advance, acquires the output voltage and output current of the solar cell 1, it calculates the solar cell 1 of the output power (generated power) (measurement) to. Then, the control unit 6 calculates the generated power P3 of the solar cell 1 at the timing to be predicted according to the equation (1).
P3 = P1-{(P1-P2) / C} × F… (1)
Where C is the rate of change calculation interval (seconds)
P1 is the measured power (C) before C seconds
P2 is the current measured power (W)
F is the time (seconds) from the current time to the predicted timing

  In the description of the above formula (1) and the following description, it is expressed as “current time” for simplicity, but more accurately, it is the immediately preceding measurement timing.

Here, the measurement interval T _B is too large, leading to decrease sharply in the generated power of the solar cell 1, there is a miss detection of decrease in the power generated by fast-moving clouds. Measurement interval T _B is preferably set to 1/10 to 1/100 of the starting time Ts of the diesel generator. Further, F is preferably set to be slightly longer than the activation time Ts in order to allow a margin for the activation of the diesel generator. For example, if the starting time Ts is 10 seconds, T _B is about 1 second 0.1 seconds, F is preferably set to about 15 seconds 10 seconds.

[Control of auxiliary power generator]
The control unit 6 calculates the power generation rate R3 and the current power generation rate R2 of the predicted generated power P3 after F seconds using the equations (2) and (3).
R3 = P3 / Pr (2)
R2 = P2 / Pr (3)
Where Pr is the rated power generation of the solar power generation device

  When the auxiliary power generation device 7 is in a stopped state and the power generation rate R3 after F seconds is equal to or less than the preset start reference value D of the auxiliary power generation device 7, the control unit 6 sends a start signal to the control unit 9 of the auxiliary power generation device 7. To start the power generation by the AC generator 10. Upon receiving the start signal, the control unit 9 starts the diesel engine 8, and when the diesel engine 8 reaches a predetermined rotational speed, the power generation of the AC generator 10 is stabilized and synchronized with the system, the switch 11 is closed and the AC is switched. The power generated by the generator 10 is supplied to the load 12.

[Concrete example]
In the following, this embodiment is applied to a solar power generation device, and from the change in the generated power of the solar cell 1, the sudden decrease or recovery of the generated power due to the shade of the sun due to bad weather or clouds is detected. A specific example of a system for starting the auxiliary power generation device 7 before the generated power becomes insufficient will be described.

The resistance values of the voltage dividing resistors 14 and 15 shown in FIG. 2 are 1000 kΩ and 10 kΩ, respectively (voltage dividing ratio 0.99%). For example, when the operating voltage of the solar cell 1 is 300 V, a voltage of about 2.97 V is obtained across the resistor 15. The clamp ammeter 16 outputs 2V at 200A (current proportionality factor 100A / V). That is, the voltage V1 across the voltage dividing resistor 15 and the output voltage V2 of the clamp ammeter 16 have the following relationship.
V1 = Vo × {R15 / (R14 + R15)}… (4)
V2 = Io / k (5)
Where Vo is the operating voltage of solar cell 1
R14 is the resistance value of voltage divider resistor 14 (1000kΩ)
R15 is the resistance value of voltage divider resistor 15 (10kΩ)
Io is the operating current of solar cell 1
k is the current proportionality factor (100A / V)

Therefore, the operating voltage Vo and the operating current Io of the solar cell 1 are expressed by the following equations.
Vo = V1 / d = V1 × {(10 + 1000) / 10} = 101 ・ V1… (6)
Io = k × V2 = 100 ・ V2 (7)

  FIG. 3 is a flowchart for explaining start / stop control of the auxiliary power generator 7 by the control unit 6.

When activated, the control unit 6 sets data stored in a nonvolatile memory such as a ROM as a default value in a memory such as a RAM (S1). The following is an example of the initial value.
(1) Rated power generation of solar cell 1 A = 100kW
(2) Startup time of auxiliary power generator 7 Ts = 10 seconds
(3) Measurement interval T _B = 0.1 sec
(4) Change rate calculation interval C = 0.5 seconds
(5) Start reference value D = 50%
(6) Stop reference value E = 60%
(7) Time from the present time to the timing to be predicted F = Ts + 3 seconds
(8) Reciprocal of voltage division ratio 1 / d = 101
(9) Current proportional coefficient k = 100

  The starting time Ts of the auxiliary power generator 7 is the control unit 9 that has received the start signal, starts the diesel engine 8, the diesel engine 8 reaches a predetermined rotational speed, and the power generation of the AC generator 10 is stabilized, This is the time until the switch 11 can be closed in synchronization with the grid, and is set appropriately according to the auxiliary power generator 7.

  Next, it is determined whether or not the measurement interval has been reached (S2), and if it has reached, the operating voltage signal and the operating current signal of the solar cell 1 are received from the detection unit 5 (S3), and the received operating voltage signal and The generated power P2 of the solar cell 1 is calculated from the operating current signal and stored in a memory such as a RAM (S4).

Next, the generated power P3 of F seconds is calculated (predicted) from the generated power P1 stored in the memory C seconds before and after the increase / decrease calculation interval and the generated power P2 calculated in step S4 by Equation (1) (S5). In this embodiment, since C = 0.5 seconds and T _B = 0.1 seconds, the generated power value at the five previous measurement timings is P1. In the case of the present embodiment, for the same reason, it is sufficient to store in the memory up to at least five generation power values at the previous measurement timing.

For example, when the latest generated power P2 of the solar cell 1 is 84 kW and the generated power P1 0.5 seconds before is 85 kW, the generated power P3 and the power generation rate R after F = 13 seconds are as follows.
P3 = 85-{(85-84) /0.5} × 13 = 59kW… (8)
R3 = 59/100 = 59%… (9)
R2 = 84/100 = 84%… (10)

  Next, it is determined whether the auxiliary power generator 7 is stopped or in operation (S6) .If the auxiliary power generator 7 is stopped, the power generation rate R3 is calculated by equation (2) (S7), and it is determined whether R3 ≦ D. (S8), if R3 ≦ D, the above-described activation signal is output (S9). Further, if the auxiliary power generation device 7 is in operation, the power generation rate R2 is calculated by the equation (3) (S10), it is determined whether R2 ≧ E (S11), and if R2 ≧ E, the stop signal described above Is output (S12). Thereafter, the process returns to step S2, and the above-described start / stop control is repeated.

  Thus, according to the present embodiment, the power generation rate R3 after F seconds and the start reference value D, or the current power generation rate R2 and the stop reference value E are compared, and the power generation rate R3 is equal to the start reference value D. This is a mechanism for starting or stopping the auxiliary power generation device 7 when the power generation rate R2 is lower or when the power generation rate R2 exceeds the stop reference value E.

  In the case of the present embodiment, since the activation reference value D is 50%, when it is predicted that the power generation rate R3 will be less than 50% after E = 13 seconds, an activation signal is output and the auxiliary power generator 7 is activated. Since the start-up time Ts of the diesel generator is 10 seconds, the power supply from the auxiliary power generator 7 to the grid is ensured by the start-up about 13 seconds before the power generation rate R of the solar cell 1 falls below 50%. Can start.

  Then, when the auxiliary power generation device 7 is in operation, the generated power of the solar cell 1 recovers due to the recovery of the weather, and when the current power generation rate R2 exceeds the stop reference value E (60% in this embodiment), the auxiliary power generation device 7 is stopped, and power is supplied again only by the main power generator 4.

  Therefore, in a power generation system that mainly uses a solar power generator and uses a diesel generator as a secondary (auxiliary), it can stably supply power in consideration of the startup transient period of the diesel generator without using a power storage device such as a capacitor. Can be supplied.

  Hereinafter, the power generation system of Example 2 according to the present invention will be described. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.

[Application to large-scale photovoltaic power generation equipment]
In the case of a solar cell 1 having a large number of solar cell sub-arrays 17 as shown in FIG. 4 for a large-scale photovoltaic power generation apparatus, the power generation of each sub-array 17 is performed by the detection unit 5 and the control unit 6 provided for each sub-array 17. The amount is monitored, and the subarray 17 in which the power generation rate R3 after F seconds becomes equal to or less than the activation reference value D is detected by the above-described prediction method. Then, for example, when the subarray 17 in the first row and the first column becomes R3 ≦ D, and then the adjacent subarray 17 in the first row and the second column becomes R3 ≦ D, the solar cell 1 is arranged such that the cloud spreads. It can be determined that the solar radiation in the vicinity of the place is starting to be shaded. Therefore, for example, when the adjacent G sub-arrays 17 satisfy R3 ≦ D (for example, this corresponds to a case where three consecutive sub-arrays 17 from the first row to the first column to the first row and third column satisfy R3 ≦ D). The auxiliary power generation device 7 is activated by outputting the activation signal described above. If N rows and M columns (N, M ≧ 2) subarrays 17 are arranged over a wide area, the cloud position, moving direction, and moving speed are determined from the change in power generation rate R2 or R3 and the arrangement of subarrays 17. You can also know.

[Concrete example]
Example 2 detects the sudden drop / recovery of the generated power due to the shade of sunlight due to bad weather or clouds from the change in the generated power of the solar cell sub-array arranged outside the solar cell 1, and It is a power generation system that starts the auxiliary power generation device 7 before the power generation is insufficient, but in particular, the cloud approaches the solar power generation device 4 due to the increase or decrease of the power generation of the subarray 17 arranged at the outermost part of the solar cell 1. Alternatively, the auxiliary power generator 7 is started or stopped quickly as it passes.

  The solar cell 1 shown in FIG. 4 has 25 subarrays 17 in total of five vertically and five horizontally. Out of the 25 subarrays 17, the outermost 16 subarrays 17 are used for starting / stopping control of the auxiliary power generator 7. For this reason, 16 sets of the detection unit 4 and the control unit 6 shown in FIG. 1 are connected to the output ends of the 16 outermost subarrays 17, and the operation voltage Vo of each subarray is determined by the detection method described in the first embodiment. The operating current Io is detected.

  FIG. 5 is a flowchart for explaining start / stop control of the auxiliary power generator 7 by each control unit 6.

When activated, the control unit 6 sets data stored in a nonvolatile memory such as a ROM as a default value in a memory such as a RAM (S21). The following is an example of the initial value.
(1) Rated power generation of subarray A = 4kW
(2) Startup time of auxiliary power generator 7 Ts = 10 seconds
(3) Measurement interval T _B = 0.1 sec
(4) Change rate calculation interval C = 0.5 seconds
(5) Start reference value D = 30%
(6) Stop reference value E = 40%
(7) Time from the present time to the timing to be predicted F = Ts + 3 seconds
(8) Reciprocal of voltage division ratio 1 / d = 101
(9) Current proportional coefficient k = 100
(10) Adjacent number G = 3

  The processing of steps S22 to S26 is the same as steps S2 to S6 shown in FIG. 3 of the first embodiment, except that the generated power of the solar cell 1 becomes the generated power of the subarray 17. Therefore, detailed description thereof is omitted.

  Next, if the auxiliary power generation device 7 is stopped, the power generation rate R3 of the subarray 17 is calculated by equation (2) (S27), and G subarrays 17 of R3 ≦ D are adjacent to each other (three in the second embodiment). It is determined whether or not there is (S28), and if so, the above-described activation signal is output (S29). Further, if the auxiliary power generator 7 is in operation, the power generation rate R2 of the subarray 17 is calculated by the equation (3) (S30), and (16-G) subarrays 17 with R2 ≧ E (13 in the second embodiment). It is determined whether or not there is more (S31), and if so, the stop signal described above is output (S32). Thereafter, the process returns to step S22, and the above-described start / stop control is repeated.

  Here, the processing of steps S28 and S31 includes determination and output of the control signal by each control unit 6, and 16 AND gates 31 to 46 for inputting the control signal of each control unit 6 shown in FIG. This is realized by an OR gate 47 that logically sums the outputs of these AND gates. Each AND gate inputs and logically ANDs the control signals of the control unit 6 corresponding to adjacent G (three in FIG. 6) subarrays 17. Alternatively, one of the 16 control units 6 may receive a control signal from another control unit and output a start signal or a stop signal from the state of the control signal corresponding to the adjacent G subarrays. Good.

For example, if the latest generated power P2 of the subarray 17 is 2640 W and the generated power P1 0.5 seconds before is 2700 W, the generated power P3 and the power generation rate R after F = 13 seconds are as follows.
P3 = 2700-{(2700-2640) /0.5} × 13 = 1140W… (11)
R3 = 1140/4000 = 28.5%… (12)
R2 = 2640/4000 = 66%… (13)

  Accordingly, in step S18, if there are, for example, three sub-arrays 17 whose power generation rate R3 has decreased in the same manner adjacent to 25, an activation signal is output and the auxiliary power generation device 7 is activated. If the power generation rate R3 of one, two adjacent or non-adjacent subarrays 17 has decreased, but the power generation rate R3 of three adjacent subarrays 17 does not fall below the activation reference value D, the cloud will spread. It is determined that there is no need to start the auxiliary power generator 7.

  Then, while the auxiliary power generation device 7 is in operation, the generated power of the subarray 17 is recovered due to the recovery of the weather, etc., and the subarray 17 whose current power generation rate R2 exceeds the stop reference value E (40% in this embodiment) G) If there are more (13 in the second embodiment), a stop signal is output, the auxiliary power generator 7 stops, and power is supplied only by the main power generator 4 again.

[Other embodiments]
An object of the present invention is to supply a storage medium (or recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus. Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. Needless to say, the CPU of the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

Block diagram showing a configuration example of the power generation system of Example 1, Block diagram explaining the connection of the detector, A flowchart for explaining the start / stop control of the auxiliary power generator by the control unit, The figure explaining the solar cell which has many solar cell subarrays, Flowchart explaining the start / stop control of the auxiliary power generator by each control unit of Example 2, FIG. 6 is a block diagram showing a configuration example for realizing the processes of steps S28 and S31 of FIG.

Claims (11)

A first power generation means using natural energy;
A second power generation means using fuel;
Predicting means for monitoring the generated power of the first power generating means and predicting the generated power of the first power generating means after a predetermined time;
And a control unit for instructing activation of the second power generation unit when a predicted value of the generated power by the prediction unit is equal to or less than a first predetermined value.   2. The control unit according to claim 1, wherein when the second power generation unit is operating, the control unit instructs the second power generation unit to stop when the predicted value is equal to or greater than a second predetermined value. The power generator described in 1.   The predicting means calculates a fluctuation of the generated power per unit time from the generated power of the first power generating means acquired at a predetermined time interval, and predicts the generated power after the predetermined time. The power generation device according to claim 1 or claim 2. A first power generation means using a plurality of solar cell sub-arrays;
A second power generation means using fuel;
Predicting means for monitoring the generated power of each of the solar cell sub-arrays and predicting the generated power of each of the solar cell sub-arrays after a predetermined time;
Control means for instructing activation of the second power generation means when a first predetermined number of solar cell sub-arrays whose predicted values of power generated by the prediction means are equal to or less than a first predetermined value are adjacent to each other. A power generator.   When the number of solar cell subarrays having the predicted value equal to or greater than a second predetermined value is equal to or greater than a second predetermined number when the second power generation means is operating, the control means 5. The power generation device according to claim 4, wherein a stop of the means is instructed.   6. The power generation device according to claim 1, wherein the predetermined time is set according to a startup time of the first power generation means.   7. The power generation apparatus according to claim 1, wherein the first power generation unit is a solar power generation apparatus. A method for controlling a power generation apparatus having a first power generation means using natural energy and a second power generation means using fuel,
Monitor the generated power of the first power generation means, predict the generated power of the first power generation means after a predetermined time,
When the predicted value of the generated power is equal to or less than a first predetermined value, the control method is characterized by instructing activation of the second power generation means. A control method of a power generation apparatus having a first power generation means using a plurality of solar cell subarrays and a second power generation means using fuel,
Monitoring the generated power of each of the solar cell sub-arrays to predict the generated power of each of the solar cell sub-arrays after a predetermined time;
A control method characterized by instructing activation of the second power generation means when a first predetermined number of solar cell sub-arrays whose predicted values of generated power are equal to or less than a first predetermined value are adjacent to each other.   10. A program for controlling a power generator to execute the control described in claim 8 or claim 9.   11. A recording medium on which the program according to claim 10 is recorded.

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