JP2014152727A - Power generating system and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generating system and its control method showing superior responsibility and efficiency by combining a power generator having a rotational power source with charger/discharger devices.SOLUTION: This power generating system comprises a power generating unit comprising a power source and a power generator; a generated power processing unit for charging a part or all of the generated power to a charger/discharger device comprising an electric double layer capacitor and a storage battery or discharging electricity from the charger/discharger device and adding it to the generated power; an invertor unit; and a control unit. The control unit has a storage device storing in advance a cooperative relation between the number of rotation of the power source and a demand power, means for setting the number of rotation of the power source, when an increasing of the demand power more than a prescribed variation range of the demand power is detected, to the number of rotation at a prescribed incremental value more than the number of rotation corresponding to the demand power after its increasing and increasing it, and means for more preferentially discharging the electric double layer capacitor than the storage battery until the number of rotation of the power source reaches the number of rotation corresponding to the demand power.

Description

  The present invention relates to a power generation system including a generator having a power source such as an engine, an electric double layer capacitor (EDLC), and a storage battery, and a control method thereof.

  2. Description of the Related Art Conventionally, a power generation system that generates power by transmitting rotational power of a power source such as an engine generator to a power generator is known. For example, there are Patent Documents 1 and 2.

JP 2000-328956 A JP 2002-309953 A

  In the conventional power generation system equipped with a power source and a generator, the AC frequency is generated by the generator, so the power generation system is mainly a generator regardless of the operating conditions such as the fuel efficiency and rotation efficiency of the power source. . Therefore, the main control method is to maintain the rotational speed that matches the output AC frequency, and if the rotational speed of the power is lower than the AC frequency, the AC frequency can be maintained at 1500 rpm / 1800 rpm that can maintain 50/60 Hz. It was generating electricity together. For example, in a gas turbine engine, it rotates at tens of thousands of revolutions, but the high revolution is reduced (decelerated) with a gear and is operated near the number of revolutions of the generator to generate power. Further, when the control range of the power source is narrow and the fluctuation of the power is large, the device is similarly devised to reduce the fluctuation change by using reduction. However, since the gear is interposed, there is energy that the gear takes. In addition, since fluctuation suppression is performed with kinetic energy, for example, sudden fluctuations are lost due to energy conversion other than electrical energy such as braking (kinetic energy thermal energy conversion). Furthermore, it is difficult to follow a rapid fluctuation in demand power.

  In view of the above-described situation, the present invention provides a power generation system including a power source and a generator, and a control method thereof, which can quickly follow rapid fluctuations in power demand and can achieve a fuel consumption rate as low as possible. It aims at enabling control to drive a power source efficiently.

  In order to achieve the above object, the present invention provides the following configurations. The numbers in parentheses are reference numerals in the drawings described later, and are given for reference.

  An aspect of the present invention provides a power generation unit (1) including a power source and a generator that outputs generated power by the rotational power of the power source, and a charge / discharge device including an electric double layer capacitor and a storage battery. A generated power processing unit (2) that performs a process of charging a part or all of it or discharging from the charging / discharging device to add to the generated power, and converting the supplied power output from the generated power processing unit (2) into alternating current And an inverter unit (3) that outputs to the load, and a control unit (4) that controls the operation of the power generation unit (1), the generated power processing unit (2), and the inverter unit (3). In the power generation system provided, the control unit (4) stores in advance a correspondence relationship between the rotational speed of the power source and the demand power of the load when there is no charge / discharge from the charge / discharge device ( 4G) and during operation of the power source When an increase of the demand power in the load over a predetermined fluctuation range is detected, the storage device (4G) is referred to, and the rotational speed of the power source exceeds the rotational speed corresponding to the demand power after the increase. Means for increasing the rotational speed by setting the rotational speed, until the rotational speed of the power source reaches the rotational speed corresponding to the increased power demand, and discharging from the charging / discharging device, and in the discharge Means for preferentially discharging the electric double layer capacitor over the storage battery.

  In one embodiment, the control unit (4) stores the correspondence relationship between the rotational speed of the power source and the fuel consumption rate in the storage device in advance, and within a predetermined time when the power source is stable. Means for calculating the fluctuation range and average value of demand power, and referring to the storage device, obtaining the fluctuation range and average value of the rotational speed of the power source corresponding to the calculated fluctuation range and average value of demand power; Means for setting the rotational speed of the power source to a rotational speed that is equal to or greater than an average value and has a minimum fuel consumption rate within the obtained fluctuation range of the rotational speed of the power source.

  In one embodiment, the control unit (4) refers to the storage device when starting the power source, and sets the rotational speed of the power source to a predetermined value exceeding the rotational speed corresponding to the standby demand power. A means for setting and increasing the demand standby rotational speed, and until the rotational speed of the power source reaches the rotational speed corresponding to the standby demand power, discharging from the charge / discharge device, and in discharging Means for preferentially discharging the electric double layer capacitor over the storage battery.

  In one Example, when the said control part (4) detects the fluctuation | variation within the predetermined fluctuation range of the demand electric power in load during operation of the said power source, when a demand electric power exceeds a generated electric power, it is a surplus part. The charging / discharging device is charged at the same time, and in charging, the electric double layer capacitor is preferentially charged over the storage battery, and when the demand power is lower than the generated power, the shortage is charged from the charging / discharging device. And a means for discharging the electric double layer capacitor preferentially over the storage battery in discharging.

  In one embodiment, the control unit (4) is configured to reduce the power source by setting the rotational speed of the power source to zero when the power source is stopped, and the rotational speed of the power source reaches zero. Until the charging / discharging device is charged, and in the charging, the storage battery is preferentially charged over the electric double layer capacitor.

  In one embodiment, the control unit (4) has means for detecting fluctuations in the demand power of the load by increasing or decreasing the load frequency.

  In one embodiment, when the control unit (4) is connected to the grid, the control unit (4) acquires a reference frequency and a reference voltage from the grid, and an AC frequency output from the inverter unit to the acquired reference frequency and reference voltage. And a means for controlling the inverter unit to match the voltages.

  Another aspect of the present invention provides power generation for a power generation unit (1) including a power source and a generator that outputs generated power by the rotational power of the power source, and a charge / discharge device including an electric double layer capacitor and a storage battery. The generated power processing unit (2) that performs a process of charging a part or all of the power or discharging the charging / discharging device to add to the generated power, and the supply power output from the generated power processing unit (2) are exchanged A control method for controlling a power generation system provided with an inverter unit (3) that converts the power source into a load and outputs the load to the load, and the rotational speed of the power source when there is no charge / discharge from the charge / discharge device; The step of storing the correspondence relationship with the demand power of the load in the storage device (4G) in advance, and when the increase of the demand power in the load over a predetermined fluctuation range is detected during the operation of the power source, the storage Equipment (4G) The step of increasing the rotational speed of the power source by setting the rotational speed of the power source to a predetermined rotational speed exceeding the rotational speed corresponding to the increased power demand, and the power demand after the rotational speed of the power source is increased. Until the rotational speed corresponding to is reached, discharging from the charging / discharging device, and discharging the electric double layer capacitor preferentially over the storage battery.

  In one embodiment, the correspondence relationship between the rotational speed of the power source and the fuel consumption rate is stored in the storage device in advance, and the fluctuation range of the demand power within a predetermined time when the power source is stable, and A step of calculating an average value, referring to the storage device, obtaining a fluctuation range and average value of the rotational speed of the power source corresponding to the calculated fluctuation range and average value of demand power, and the rotational speed of the power source Is set to a rotational speed at which the fuel consumption rate is the minimum and within the average value within the obtained fluctuation range of the rotational speed of the power source.

  In one embodiment, when the power source is started, the storage device is referred to, and the rotational speed of the power source is set to a predetermined demand standby rotational speed that exceeds the rotational speed corresponding to the standby demand power. And increasing the number of revolutions of the power source until the number of revolutions of the power source reaches the number of revolutions corresponding to standby demand power, and discharging the electric double layer capacitor from the storage battery in discharging. And preferentially discharging.

  In one embodiment, when the fluctuation within the predetermined fluctuation range of the demand power in the load is detected during operation of the power source, if the demand power exceeds the generated power, the charging / discharging device is charged with a surplus. And in charging, the step of charging the electric double layer capacitor with priority over the storage battery, and when the demand power is lower than the generated power, the shortage is discharged from the charging / discharging device, and in discharging Discharging the electric double layer capacitor preferentially over the storage battery.

  In one embodiment, when the power source is stopped, the charge / discharge device is configured to reduce the rotational speed of the power source by setting it to zero and until the rotational speed of the power source reaches zero. And charging the storage battery more preferentially than the electric double layer capacitor in charging.

  In one embodiment, the method includes a step of detecting a change in power demand of the load by increasing or decreasing the load frequency.

  In one embodiment, in the case of grid connection, the step of acquiring a reference frequency and a reference voltage from the system, and the inverter for matching the acquired reference frequency and reference voltage with the AC frequency and voltage output from the inverter unit. Controlling the unit.

 In the power generation system and the control method thereof according to the present invention, a correspondence relationship between the rotational speed of the power source (that is, corresponding to the generated power) and the demand power is set in advance, and when the demand power varies, the rotational speed of the power source In the transitional period until the generated power reaches the value of the demand power after fluctuation, the electric double layer capacitor (EDLC) and the storage battery, which are charge / discharge devices, are charged and discharged to reduce the generated power. adjust. Thereby, when there is a fluctuation in demand power, supply power corresponding to the demand power can be quickly supplied to the load. As for fluctuations in power demand, we expect the output density capability of electric double layer capacitors, and realize response speed within nanoseconds. Therefore, in charge / discharge, the electric double layer capacitor is basically prioritized over the storage battery. In the case where the corresponding range of the electric double layer capacitor is exceeded, the storage battery is supplementarily supported. However, at the time of stop, the storage battery is preferentially charged with electric power for a time (tens of seconds to several minutes) until the power source stops from high speed rotation. As a result, at the time of starting the next power source, the shortage of discharge of the electric double layer capacitor can be compensated sufficiently by the storage battery, and by adding the discharged power to the generated power, the supply power can be quickly obtained after the start. Can respond.

  The fluctuation of the demand power is detected by the fluctuation of the load frequency, and the rotational speed of the power source is controlled according to the fluctuation amount of the demand power. As a result, it is possible to accurately grasp fluctuations in demand power.

  In the case of grid connection, the frequency and voltage of the power supplied to the load are synchronized with the grid by detecting the reference frequency and the reference voltage from the grid and driving the inverter. Thereby, grid connection is realized.

FIG. 1 is a configuration diagram schematically and schematically showing an embodiment of a power generation system according to the present invention. FIG. 2 shows the same power generation system of the present invention as FIG. 1, and is a configuration diagram showing in detail the inverter unit and the control unit. FIG. 3 is a graph showing the relationship between the power source rotation speed in the engine generator and the power source output, that is, the generated power G, the fuel consumption rate, and the demand power. FIG. 4 is a diagram showing an example of a change in power source output, that is, generated power, and a change in actual demand power in this system. FIG. 5 is a schematic flowchart showing an example of a control flow at the time of starting. FIG. 6 is a flowchart schematically showing an example of a control flow during driving of the inverter unit. FIG. 7 is a schematic flowchart showing an example of a control flow during demand standby. FIG. 8 is a schematic flowchart showing an example of a control flow when the generated power is increased in the normal demand power range. FIG. 9A is a schematic flowchart illustrating an example of a control flow when the generated power is stable. FIG. 9B is a schematic flowchart showing an example of a control flow (continuation of FIG. 9A) when the generated power is stable. FIG. 10 is a schematic flowchart showing an example of a control flow when the generated power is reduced. FIG. 11 is a schematic flowchart showing an example of a control flow at the time of increasing the maximum generated power. FIG. 12 is a schematic flowchart showing an example of a control flow at the time of maximum generated power. FIG. 13 is a schematic flowchart illustrating an example of a control flow at the time of stopping.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings showing an example.
FIG. 1 is a configuration diagram schematically and schematically showing an embodiment of a power generation system according to the present invention. Black arrows indicate the flow of power, and white arrows indicate the flow of detection signals, measurement signals, or control signals.

  The power generation system includes a power generation unit 1, a generated power processing unit 2, an inverter unit 3, and a control unit 4 as main components.

  The power generation unit 1 includes a power source 1A, a generator 1B, and a power control unit 1C. The power source 1A is preferably an engine that consumes fuel such as light oil or gasoline and outputs rotational power. The rotational power of the power source 1A is transmitted to the generator 1B, and the turbine power generator 1B rotates to output AC generated power. A power control unit 1 </ b> C including a CPU controls the start and stop of the power source 1 </ b> A and the rotation speed based on the control of the control unit 4. In this system, the rotational speed of the power source 1A is controlled in response to fluctuations in power demand of the load 5.

The generated power processing unit 2 receives the generated power output from the power generating unit 1 and processes the generated power. There are the following as processing of generated power.
(I) A process of supplying a part or all of the generated power to the inverter unit 3 as it is through the output converter 2C.
(Ii) A process of charging a part or all of the generated power to the electric double layer capacitor (EDLC) 2F or the storage battery 2I.
(Iii) A process of discharging from the electric double layer capacitor 2F or the storage battery 2I and supplying it to the inverter unit 3 through the output converter 2C together with the generated power.

  The rectifying unit 2A rectifies the generated power that is alternating current and converts it into direct current.

  The generated power measuring unit 2 </ b> B measures the voltage and current of the generated power converted into direct current, and transmits the measured value to the control unit 4. In addition, the generated power measuring unit 2B switches connection or disconnection between the generated power (the output of the rectifying unit 2A) and the output converter 2C based on the control of the control unit 4, and the generated power and the electric double layer capacitor A function of switching connection or disconnection between 2F or the storage battery 2I is also provided.

  The output converter 2C includes a step-up circuit and a step-down circuit configured by a DC-DC converter. Based on the control of the control unit 4, the voltage of the electric power sent from the generated power measurement unit 2 </ b> B is boosted or lowered to an appropriate voltage and output to the inverter unit 3. The selection of the step-up or step-down and the value of step-up or step-down are performed by transmitting a PWM signal from the control unit 4 to the switching element of the DC-DC converter (the same applies to the following DC-DC converters). The booster circuit and the step-down circuit by PWM control are well-known techniques (the same applies to the following step-up / step-down circuits).

  The EDLC charge / discharge converter 2D includes a step-up circuit and a step-down circuit constituted by a DC-DC converter, and works in both directions of charging and discharging of the electric double layer capacitor 2F, and is appropriate in each case of charging power and discharging power. Adjust to the correct voltage and current. This adjustment is performed under the control of the control unit 4.

  The EDLC current / voltage measuring unit 2 </ b> E measures the voltage and current in charging and discharging of the electric double layer capacitor 2 </ b> F, and transmits the measured value to the control unit 4. Further, the EDLC current / voltage measuring unit 2E measures the output voltage and output current of the electric double layer capacitor 2F by cutting off the connection with the EDLC charge / discharge converter 2D, and transmits the measured value to the control unit 4.

  The storage battery charging / discharging converter 2G includes a step-up circuit and a step-down circuit configured by a DC-DC converter, and operates in both directions of charging and discharging of the storage battery 2I. Adjust to current. This adjustment is performed under the control of the control unit 4.

  The storage battery current / voltage measuring unit 2 </ b> H measures the voltage and current in charging and discharging of the storage battery 2 </ b> I, and transmits the measured value to the control unit 4. Further, the storage battery current / voltage measuring unit 2H measures the output voltage and output current of the storage battery 2I by cutting off the connection with the storage battery charging / discharging converter 2G, and transmits the measured value to the control unit 4.

  The electric double layer capacitor 2F selects an appropriate capacity in consideration of the range of generated power and demand power of the system. The storage battery 2I is a secondary battery, such as a lead storage battery or a lithium ion battery. The electric double layer capacitor 2F that accumulates electric energy by dielectric polarization is much more responsive and has a higher output density than the storage battery 2I by chemical reaction, and can therefore respond to rapid charge / discharge due to a large current. The charge / discharge efficiency is also high, and an output efficiency of 95% or more can be obtained even at an output density of 1 kW / kg. In this system, the electric double layer capacitor 2F is preferentially discharged when the generated power is insufficient with respect to the demand power of the load 5, and the electric double layer capacitor 2F is preferentially charged when the generated power is surplus. Therefore, it can respond quickly to fluctuations in demand. The storage battery 2I in this system basically plays an auxiliary role for the electric double layer capacitor 2F.

  In the present specification, the electric double layer capacitor 2F and the storage battery 2I are collectively referred to as a “charge / discharge device”.

  In this system, two countermeasures are provided for fluctuations in power demand of the load 5. As a first countermeasure, the power supplied to the load is adjusted by increasing / decreasing the rotational speed of the power source 1A to increase / decrease the generated power. As a second countermeasure, a part or all of the generated power is charged in the electric double layer capacitor 2F or the storage battery 2I, or discharged from these and added to the generated power to adjust the power supplied to the load. This system adjusts the rotation speed of the power source and the charging / discharging of the charging / discharging device so that the supplied power can quickly follow the fluctuation of the demand power of the load by combining these two countermeasures.

  The inverter unit 3 receives DC power from the output converter 2 </ b> C of the generated power processing unit 2. The inverter unit 3 converts the input DC power into AC power having a predetermined voltage and frequency based on the control of the control unit 4, and outputs it as supply power to the load 5.

  The power demand of the load 5 is basically covered by the power supplied by this system. On the other hand, the present system of the embodiment is linked to the grid 6, and power is supplied from the grid 6 when the supply power of this system can no longer cover the demand power of the load 5.

  In this embodiment, the voltage and frequency of power supplied to the load 5 are synchronized with the system 6. In order to realize this, in this system, the control unit 4 samples the system power of the system 6 and acquires the system frequency and system voltage. The control unit 4 sets the system frequency and the system voltage as the reference frequency and the reference voltage, respectively, and controls the inverter 3 so as to be synchronized therewith. Hereinafter, an embodiment in the case of grid interconnection will be described. However, when grid interconnection is not performed as in the case of an independent power supply, the reference frequency and the reference voltage may be set independently.

  Further, in the present system, the frequency at the load 5 is sampled in order to detect fluctuations in demand power at the load 5. When the demand power in the load 5 increases and the supply power is insufficient, the frequency of the load 5 is lower than the reference frequency. On the other hand, when the demand power in the load 5 decreases and the supplied power becomes excessive, the frequency of the load 5 rises above the reference frequency. When the load frequency falls below the reference frequency, the load frequency is returned to the reference frequency by increasing the power supply by increasing the rotational speed of the power source and / or discharging the charge / discharge device. On the other hand, when the load frequency rises above the reference frequency, the load frequency is returned to the reference frequency by reducing the power supply by reducing the rotational speed of the power source and / or charging the charge / discharge device. In this way, a decrease or increase in the load frequency is detected, the amount of change in demand power is calculated based on the amount of decrease or increase, and the power supplied by the rotational speed control of the power source and / or the charge / discharge control of the charge / discharge device. Adjust.

  FIG. 2 shows the same power generation system of the present invention as in FIG. 1, and in particular, a configuration diagram showing the inverter unit 3 and the control unit 4 in detail.

  The supplied power input to the inverter unit 3 is only generated power when the charging / discharging device is not charging / discharging. When the charging / discharging device is discharged, the supplied power is the generated power plus the discharged power. On the other hand, when the charging / discharging device is charged, the supplied power is obtained by subtracting the charging power from the generated power.

  The control unit 4 includes a CPU 4A, a digital signal processor (DSP) 4B, a comparator 4C, a logic circuit 4D, and a drive circuit 4E as main components. The CPU 4A receives a load frequency detection signal from the load 5 and a reference frequency and reference voltage detection signal from the system 6 (usually, the detection signal here means sampling, and the actual frequency and voltage analysis is performed by the CPU. To do). Further, the CPU 4 </ b> A receives each measurement value described above from the generated power processing unit 2. Further, the CPU 4 </ b> A performs control of the rotational speed of the power source of the power generation unit 1, charge / discharge control of the charge / discharge device of the generated power processing unit 2, and drive control of the inverter unit 3.

  The CPU 4A can be configured by, for example, a PIC (Peripheral interface controller) that is a one-chip microprocessor. Based on the detected reference frequency and reference voltage of the system, the CPU 4A causes the DSP 4B to generate a target sine wave Vref having the same frequency and a modulated wave (harmonic) Vt for generating the same voltage. The target sine wave Vref and the modulation wave (harmonic wave) Vt are input to the comparator 4C, and the comparator 4C outputs a PWM waveform. The logic circuit 4D outputs a control signal to a drive circuit that drives the gates of the switching elements TR1, TR2, TR3, and TR4 of the inverter unit 3 based on the PWM waveform. There are drive circuits for positive half cycle and negative half cycle. Such PWM control itself is a well-known technique.

  The CPU 4 has a storage device 4G for storing information necessary for control in advance. The storage device 4G is an external storage device such as a semiconductor memory.

  The inverter unit 3 includes two pairs of switching elements for positive half cycle and negative half cycle and an LC smoothing circuit. As the switching elements TR1, TR2, TR3, TR4 of the inverter unit 3, transistors such as MOS-FETs or IGBTs are used. As an example, it is preferable to provide a plurality of inverter units 3 in parallel so as to withstand the voltage of the supplied power input from the generated power processing unit 2. When multiple inverter units 3 are provided in parallel, a single inverter circuit uses SIC-SBD (silicon carbide diode) as a switching element, and is configured to have a current amount within 60% of the designed output power, providing high-speed response. It is more preferable that the circuit has a high withstand voltage performance. It is preferable to simultaneously control the plurality of inverter circuits 3 provided in parallel and drive and adjust the necessary number of inverter circuits 3 so as to cope with high-efficiency supply power.

  The thick dotted line in the graph of FIG. 3 is a curve showing the relationship between the power source rotational speed R (horizontal axis) and the power source output, that is, the generated power G (left vertical axis). In addition, the correspondence relationship between the power source rotational speed R and the demand power D (right outer vertical axis) is also shown. The correspondence relationship between the power source rotational speed R and the demand power D is a correspondence relationship when there is no charging / discharging by the charging / discharging device shown in FIG. That is, the demand power D on the right vertical axis is the power demand when the generated power G on the left vertical axis is supplied to the load as the supplied power as it is and is demanded by the load.

  The correspondence relationship between the power source rotational speed R and the demand power D when there is no charge / discharge power is stored in advance in the storage device 4G of the control unit 4 shown in FIG. For example, the point of power source rotational speed R (s0) corresponds to the point of demand power D (s0), and the point of power source rotational speed R (max) corresponds to the point of demand power D (max). Yes. Thus, in the graph of FIG. 3, the straight line extending upward from a predetermined point of the power source rotational speed R on the horizontal axis and the straight line extending horizontally from the point where the curve of the generated power G intersects the demand power D on the vertical axis. The intersecting point is the corresponding point of demand power D.

  Further, for use in control, a demand power range at start, a normal power range, and a high demand power range are set in the range of demand power D, and these ranges are also stored in the storage device 4G in advance.

  The thick solid line in the graph of FIG. 3 is a curve showing the relationship between the power source rotational speed R in the engine generator and the fuel consumption rate F of the engine (right inner vertical axis). The fuel consumption rate refers to the ratio of fuel consumption to mechanical energy generated by the engine, and is generally expressed in units of g / kWh. Within the range of the power source rotational speed R, there is a minimum point of the power source rotational speed R (Fmin) at which the fuel consumption rate F is minimum. The fuel consumption rate F is large in the low speed range and the high speed range. Depending on the type of engine, the power source rotational speed R (Fmin) at which the fuel consumption rate F is minimized is almost determined. In the present invention, the power source rotational speed is controlled in consideration of the existence of the power source rotational speed R (Fmin) at which the fuel consumption rate F is minimized. Details will be described with reference to a flowchart described later.

Each reference numeral in FIG. 3 will be referred to in the description of the flowchart described later.
In the following description, the electric double layer capacitor is referred to as “EDLC”.

FIG. 4 is a diagram showing an example of a change in power source output, that is, generated power G (solid line) and an actual change in demand power D (dotted line) in this system. In this system, the supply power quickly responds to the demand power of the load, so the change in the demand power D is also a change in the supply power. Supply power and generated power G have the following relationship.
(I) When there is no charge / discharge from the charge / discharge device Supply power = Generated power (ii) When discharged from the charge / discharge device Supply power = Generated power + Discharge power (iii) When charging / discharge device is charged Supply power = Power generation Power-Charging power

  The example in FIG. 4 shows a pattern in which the operating status of the system has changed over time, such as when starting, when waiting for demand, when generating normal power, when increasing maximum generated power, when generating maximum power, and when stopping. Yes. During normal power generation, according to fluctuations in demand power, when generated power is increased, when generated power is stabilized, and when generated power is reduced. Of course, the pattern of transition is not limited to this and is diverse.

  Although the generated power at the time of starting increases with an increase in the number of revolutions of the power source, the slope of the increase in the generated power indicated by the solid line cannot follow the rapid increase in demand power (inrush current, etc.) of the load at the time of starting. Therefore, the shortage of generated power is compensated by the discharge from the charging / discharging device. In this system, the discharge from the charging / discharging device gives priority to the EDLC having a quick response, and starts discharging from the storage battery when the EDLC cannot be discharged. Here, since the EDLC is easily self-discharged, the charge amount is usually lowered from the fully charged state at the start. When the EDLC becomes incapable of discharging, it is immediately switched to a storage battery and discharged. Since the storage battery is preferentially charged when the previous operation is stopped (the storage battery is given priority only when the operation is stopped), the storage battery is sufficiently charged at the start. Therefore, at the time of start-up, driving of the inverter is started mainly by the discharge power from the storage battery, and the power supplied to the load is borne.

  When the rotational speed of the power source reaches the rotational speed R (s0) corresponding to the standby power demand, the discharge is stopped. When the rotational speed R (s0) is further exceeded, the charging / discharging device is charged with the surplus generated power. In this system, charge to the charging / discharging device gives priority to EDLC, and when the EDLC becomes fully charged, the storage battery is charged. Thus, the storage battery plays an auxiliary role for EDLC in charging and discharging.

  FIG. 5 is a schematic flowchart showing an example of a control flow at the time of starting. 1 to 4 are also referred to in the description (the same applies to the following flowcharts).

  In step 101, the demand standby rotational speed R (s1) in FIGS. 3 and 4 is set to the target rotational speed, and the rotational speed of the power source is started to increase from zero. The demand standby rotational speed R (s1) is a predetermined rotational speed exceeding the rotational speed R (s0) corresponding to the standby demand power D (s0). The standby time is a state in which the load has not started full-scale power consumption, for example, in an idling state. Here, the standby power demand is referred to as “standby demand power”, and the standby power source rotational speed is referred to as “demand standby rotational speed”. As the rotational speed of the power source increases, the generated power increases.

  In step 102, it is determined whether or not the power supplied to the inverter unit (initially only the generated power, and the generated power + discharge power after the start of discharge) has reached the power that can drive the inverter unit. If not reached, the battery is first discharged from the EDLC in step 103, and if the EDLC becomes undischargeable, the battery is discharged from the storage battery in step 104. As described above, at the time of start-up, the discharge power from the storage battery is mainly used rather than the EDLC. Due to the discharge from the charging / discharging device, the supplied power becomes an amount obtained by adding the discharged power to the generated power. The amount of discharge power is set to compensate for the shortage of generated power. Therefore, control is performed so that the discharge power is reduced as the generated power increases.

  If the supplied power reaches the power that can drive the inverter unit in step 102, the inverter unit starts to be driven in step 105. Thereby, supply electric power is supplied with respect to load. The drive of the inverter unit is continued during the operation period until it is stopped by the control flow at the time of stop shown in FIG. The control of the inverter unit will be described with reference to FIG.

  After driving the inverter unit, in step 106, it is determined whether the generated power has reached the demand power. If not reached, the discharge from the storage battery is continued in step 107. If so, the discharge is stopped at step 108. The rotational speed of the power source at this time is R (s0) in FIG. 3, which is the rotational speed corresponding to the standby demand power. On the other hand, since the set demand standby rotational speed R (s1) is higher than R (s0), the rotational speed of the power source further increases, the generated power increases, and a surplus is generated.

  In step 109, the EDLC is first charged with the surplus of generated power, and if there is a surplus, the storage battery is charged in step 110.

  In step 111, it is determined whether or not the rotational speed of the power source has reached the demand standby rotational speed R (s1). If the rotational speed of the power source has not reached the demand standby rotational speed R (s1), charging is continued. If the rotational speed has reached, the rotational speed of the power source is maintained at the demand standby rotational speed R (s1) in step 112. . Thereafter, the process proceeds to the control flow during demand standby in FIG.

FIG. 6 is a flowchart schematically showing an example of a control flow during driving of the inverter unit.
In step 201, system power is sampled. In step 202, the frequency and voltage of the sampled system power are acquired as a reference frequency and a reference voltage. In step 203, a sine wave having a reference frequency and a modulated wave based on a reference voltage are generated, and a PWM waveform is generated therefrom. In step 204, the switching element is driven by the PWM waveform, and the same frequency and voltage as the reference frequency and reference voltage are output from the inverter unit. By repeating this control flow, supply power is always supplied to the load at the same frequency and voltage as the reference frequency and reference voltage.

FIG. 7 is a schematic flowchart showing an example of a control flow during demand standby.
In step 301, the rotation of the power source is continuously maintained at the demand standby point R (s1). In step 302, it is determined whether the load frequency detected from the load matches the reference frequency of the system. Demand power is always changing even if the amount of fluctuation is large, so here, if the fluctuation width within a certain time is within the predetermined fluctuation width, the load frequency and the reference frequency match. It is considered to be.

  If the load frequency matches the reference frequency, it is determined in step 303 whether the generated power exceeds the demand power. If the generated power exceeds the demand power, in steps 304 and 305, the EDLC and the storage battery are charged with the surplus power. If the generated power does not exceed the demand power, the process returns to step 302. In this example, it is assumed that the demand standby rotation speed R (s1) is set above the rotation speed R (s0) corresponding to the standby demand power, so that the generated power hardly falls below the demand power. ing.

  If the load frequency does not match the reference frequency in step 302 (assuming an increase in demand power in this example), in step 306, the increased demand power is calculated from the amount of decrease in the load frequency. In step 307, it is determined whether the calculated demand power after the increase is in the normal demand power range or the high demand power range. This determination is made with reference to the setting of each range of demand power stored in advance in the storage device. If it is within the normal demand power range, the process proceeds to the control flow at the time of power generation increase in the normal demand power range of FIG. In the case of the high demand power range, the process proceeds to the control flow at the time of maximum power generation increase in FIG.

  FIG. 8 is a schematic flowchart showing an example of a control flow when the generated power is increased in the normal demand power range.

  In step 401, an increase in the rotational speed is started with a target of a predetermined rotational speed that exceeds the rotational speed corresponding to the increased power demand. The generated power increases as the number of revolutions of the power source increases.

  In step 402, it is determined whether the generated power has reached the demand power. If not reached, the battery is first discharged from the EDLC in step 403. If the EDLC becomes undischargeable, the battery is discharged in step 404. Due to the rapid discharge from the EDLC, the supplied power can immediately respond to the demand power. If the generated power reaches the demanded power after the increase in step 402, the discharge is stopped in step 405. Since the set predetermined rotation speed is higher than the rotation speed corresponding to the increased demand power, the rotation speed of the power source further increases, the generated power increases, and a surplus is generated.

  In step 406, the EDLC is first charged with the surplus of generated power, and if there is a surplus, the storage battery is charged in step 407.

  In step 408, it is determined whether or not the rotational speed of the power source has reached a predetermined rotational speed that has been set. If the rotational speed of the power source does not reach the predetermined rotational speed, charging is continued. If it has reached, the rotational speed of the power source is maintained in step 409. Thereafter, the process proceeds to the control flow when the generated power is stable in FIGS. 9A and 9B.

  9A and 9B are schematic flowcharts showing an example of a control flow when the generated power is stable. In particular, the description will be given with reference to FIG.

  In step 501, a demand power fluctuation range and a demand power average value within a predetermined time are calculated. In FIG. 3, ΔD (A) and ΔD (B) are shown as two examples of the demand power fluctuation range, and D (Aave) and D (Bave) are shown as two examples of the demand power average value. Next, in step 502, the fluctuation range of the power source rotation speed and the average value of the power source rotation speed respectively corresponding to the demand power fluctuation width and the demand power average value are acquired from the storage device. In FIG. 3, ΔR (A) and ΔR (B) are shown as two examples of the fluctuation range of the power source rotational speed, and R (Aave) and R (Bave) are shown as average values of the power source rotational speed.

  Subsequently, in step 503, the power source rotational speed is set. The setting method is a point in which the fuel consumption rate (F in FIG. 3) is the minimum and within the average value of the power source rotational speed within the obtained fluctuation range of the power source rotational speed. By maintaining the power source rotational speed at this point, efficient operation can be performed. In FIG. 3, when the fluctuation range of the power source rotational speed is ΔR (A), the point where the fuel consumption rate F is minimum in the rotational speed range equal to or higher than the average value R (Aave) is the maximum of the fluctuation range ΔR (A). This is the point R (Amax). Therefore, in this case, the power source is set to the rotation speed R (Amax). On the other hand, when the fluctuation range of the power source rotational speed is ΔR (B), the point at which the fuel consumption rate F is minimum in the rotational speed range equal to or higher than the average value R (Bave) is the average value R (Bave). Therefore, in this case, the power source is set to the rotation speed R (Bave).

  In step 504, it is determined whether the load frequency detected from the load matches the reference frequency acquired from the system. Since the demand power is constantly changing even if the amount of change is large, the load frequency and the reference frequency are considered to coincide with each other within a predetermined fluctuation range within a certain time.

  If the load frequency matches the reference frequency, it is determined in step 505 whether the generated power exceeds the demand power. If the generated power exceeds the demand power, in steps 506 and 507, the EDLC and the storage battery are charged with surplus power. If the generated power is lower than the demand power, in steps 508 and 509, the EDLC and the storage battery are discharged to supplement the generated power. By such control, the operation is performed when the generated power is stable.

  If the load frequency does not match the reference frequency in step 504, the process proceeds to step 510 in FIG. 9B. In step 510, the changed demand power is calculated from the change amount of the load frequency. In step 511, it is determined whether the change in power demand is an increase or a decrease. If so, it is determined in step 512 whether the calculated demand power after the rise is within the normal demand power range or the high demand power range. If it is within the normal demand power range, the process proceeds to the control flow at the time of power generation increase in the normal demand power range of FIG. In the case of the high demand power range, the process proceeds to the control flow at the time of maximum power generation increase in FIG. On the other hand, when the change in the demand power is a decrease in step 511, the process proceeds to the control flow for reducing the generated power in FIG.

FIG. 10 is a schematic flowchart showing an example of a control flow when the generated power is reduced.
In step 601, reduction of the rotational speed of the power source is started with a target of a predetermined rotational speed that exceeds the rotational speed corresponding to the calculated reduced demand power. While the number of rotations of the power source is being reduced, the generated power exceeds the demand power. Therefore, in steps 602 and 603, the EDLC and the storage battery are charged with the surplus power. Thereby, as a result of subtracting the charging power from the generated power, the supplied power quickly reaches the demand power. In step 602, it is determined whether or not the rotational speed of the power source has reached the reduced rotational speed. If it has reached, the process proceeds to the control flow of FIG. 9A and FIG. 9B when the generated power is stable.

FIG. 11 is a schematic flowchart showing an example of a control flow at the time of increasing the maximum generated power.
In step 701, the increase of the rotation speed is started with the maximum rotation speed as a target. The generated power increases as the number of revolutions of the power source increases.

  In step 702, it is determined whether the generated power has reached the increased demand power. If not reached, the battery is first discharged from the EDLC in step 703. If the EDLC becomes undischargeable, the battery is discharged from the storage battery in step 704. Due to the rapid discharge from the EDLC, the supplied power can immediately respond to the demand power. If in step 702 the generated power reaches the increased demand power, the discharge is stopped in step 705. Since the set maximum rotational speed is higher than the rotational speed corresponding to the increased demand power (if the rotational speed corresponding to the demand power is the maximum rotational speed, the process proceeds to step 709), the rotational speed of the power source Will further increase, generating power will increase, and surplus will be generated.

  In step 706, the EDLC is first charged with the surplus of generated power, and if there is a surplus, the storage battery is charged in step 707.

  In step 708, it is determined whether the rotational speed of the power source has reached the maximum rotational speed. If the rotational speed of the power source has not reached the maximum rotational speed, charging is continued. If the rotational speed has been reached, the rotational speed of the power source is maintained at the maximum rotational speed in step 709. Thereafter, the process proceeds to the control flow at the maximum generated power in FIG.

FIG. 12 is a schematic flowchart showing an example of a control flow at the time of maximum generated power.
In step 801, the rotation of the power source is continuously maintained at the maximum output point R (max). In step 802, it is determined whether the load frequency detected from the load matches the reference frequency of the system. If it is within a predetermined fluctuation range within a certain time, it is considered that the load frequency and the reference frequency coincide with each other.

  If the load frequency matches the reference frequency, in step 803, the EDLC and the storage battery are charged with the surplus generated power (however, if the demand power is the maximum generated power, there is no surplus and charging is not performed). ).

  In step 802, when the load frequency does not match the reference frequency, the demand power is decreased and the load frequency is increased, so the process proceeds to the control flow when the generated power is reduced in FIG. To the control flow).

FIG. 13 is a schematic flowchart illustrating an example of a control flow at the time of stopping.
In step 901, the reduction of the rotational speed of the power source is started with the target of the rotational speed of zero. In step 901, driving of the inverter unit is stopped, and supply of power to the load is stopped. Thereby, all of generated electric power can be directed to charge of a charging / discharging apparatus. Prioritize charging the storage battery when stopping. This is because the storage battery is easy to maintain the charged state even during the stop period until the next start. In step 903, the storage battery is charged. When the storage battery is in a fully charged state and there is generated power, the EDLC is charged in step 904.

  In step 905, it is determined whether the rotational speed of the power source has become zero. If it is not zero, continue charging. When it reaches zero, it ends.

  The power generation system including the engine generator using the engine as a power source has been described above as an example. However, the power source may be other than the engine generator as long as it generates rotational power.

DESCRIPTION OF SYMBOLS 1 Power generation part 1A Power source 1B Generator 1C Power control part 2 Power generation process part 2A Rectification part 2B Power generation measurement part 2C Output converter 2D EDLC charge / discharge converter 2E EDLC current voltage measurement part 2F Electric double layer capacitor (EDLC)
2G storage battery charge / discharge converter 2H storage battery current / voltage measurement unit 2I storage battery 3 inverter unit TR1, TR2, TR3, TR4 switching element L induction element C capacitive element 4 control unit 4A CPU
4B Digital signal processor (DSP)
4C comparator 4D logic circuit 4E drive circuit 4G storage device 5 load 6 system

Claims (14)

A power generation unit (1) comprising a power source and a generator that outputs generated power by the rotational power of the power source;
A generated power processing unit (2) that performs a process of charging a part or all of the generated power with respect to the charge / discharge device including the electric double layer capacitor and the storage battery or discharging the charge / discharge device from the charge / discharge device and adding the generated power to the generated power,
An inverter unit (3) that converts supply power output from the generated power processing unit (2) into alternating current and outputs it to a load;
A control unit (4) for controlling the operation of the power generation unit (1), the generated power processing unit (2) and the inverter unit (3),
The control unit (4)
A storage device (4G) that stores in advance the correspondence between the rotational speed of the power source and the demand power of the load when there is no charge / discharge from the charge / discharge device;
While the power source is in operation, when the increase in demand power in the load is detected to be greater than a predetermined fluctuation range, the storage device (4G) is referred to and the rotational speed of the power source corresponds to the increased power demand Means for setting and increasing a predetermined number of revolutions at an increase exceeding the number of revolutions to be performed;
The charge / discharge device is discharged until the rotation speed of the power source reaches the rotation speed corresponding to the increased power demand, and the electric double layer capacitor is given priority over the storage battery in discharging. A power generation system comprising: means for discharging. The control unit (4)
The correspondence relationship between the rotational speed of the power source and the fuel consumption rate is stored in advance in the storage device,
Means for calculating a fluctuation range and an average value of power demand within a predetermined time when the power source is stable;
Referring to the storage device, obtain the fluctuation range and average value of the rotational speed of the power source corresponding to the calculated fluctuation range and average value of demand power, and determine the rotational speed of the power source of the acquired power source. 2. The power generation system according to claim 1, further comprising: a rotation speed that is equal to or higher than an average value and has a minimum fuel consumption rate within a fluctuation range of the rotation speed. The control unit (4)
Means for increasing the rotational speed of the power source by setting the rotational speed of the power source to a predetermined demand standby rotational speed exceeding the rotational speed corresponding to the standby power demand at the time of starting the power source;
The charging / discharging device is discharged until the rotational speed of the power source reaches the rotational speed corresponding to the standby demand power, and the electric double layer capacitor is preferentially discharged over the storage battery in discharging. The power generation system according to claim 1, further comprising: When the control unit (4) detects a fluctuation within a predetermined fluctuation width of the demand power in the load during operation of the power source,
When the demand power exceeds the generated power, the charging / discharging device is charged with a surplus, and in charging, the electric double layer capacitor is charged with priority over the storage battery,
Means for discharging the shortage from the charging / discharging device when the demand power is lower than the generated power, and discharging the electric double layer capacitor preferentially over the storage battery in discharging. The power generation system according to any one of claims 1 to 3. The control unit (4)
Means for reducing the rotational speed of the power source by setting it to zero when the power source is stopped;
Means for charging the charging / discharging device until the rotational speed of the power source reaches zero, and charging the storage battery more preferentially than the electric double layer capacitor in charging. The power generation system according to any one of claims 1 to 4. The control unit (4)
The power generation system according to any one of claims 1 to 5, further comprising means for detecting fluctuations in demand power of the load by increasing or decreasing the load frequency. The control unit (4)
In the case of grid interconnection, means for obtaining a reference frequency and a reference voltage from the grid,
The means for controlling the inverter unit so as to make the frequency and voltage of the alternating current output from the inverter unit coincide with the acquired reference frequency and reference voltage, according to any one of claims 1 to 6. Power generation system. Charging part or all of generated power to a power generation unit (1) including a power source and a generator that outputs generated power by the rotational power of the power source, and a charge / discharge device including an electric double layer capacitor and a storage battery Or the generated power processing unit (2) that performs the process of discharging from the charging / discharging device and adding the generated power to the generated power, and the supply power output from the generated power processing unit (2) is converted into an alternating current to the load A control method for controlling a power generation system including an inverter unit (3) for output,
Storing the correspondence relationship between the rotational speed of the power source and the demand power of the load when there is no charge / discharge from the charge / discharge device in advance in the storage device (4G);
While the power source is in operation, when the increase in demand power in the load is detected to be greater than a predetermined fluctuation range, the storage device (4G) is referred to and the rotational speed of the power source corresponds to the increased power demand A step of setting a predetermined number of rotations to increase and exceeding the number of rotations to increase; and
The charge / discharge device is discharged until the rotation speed of the power source reaches the rotation speed corresponding to the increased power demand, and the electric double layer capacitor is given priority over the storage battery in discharging. And a step of discharging the power generation system. Storing the correspondence relationship between the rotational speed of the power source and the fuel consumption rate in the storage device in advance;
When the power source is stable, calculating a fluctuation range and an average value of demand power within a predetermined time; and
Referring to the storage device, obtain the fluctuation range and average value of the rotational speed of the power source corresponding to the calculated fluctuation range and average value of demand power, and determine the rotational speed of the power source of the acquired power source. The method for controlling the power generation system according to claim 8, further comprising a step of setting the rotation speed to be equal to or higher than an average value and having a minimum fuel consumption rate within a fluctuation range of the rotation speed. At the time of starting the power source, referring to the storage device, and increasing the rotational speed of the power source by setting it to a predetermined demand standby rotational speed exceeding the rotational speed corresponding to the standby demand power; and
The charging / discharging device is discharged until the rotational speed of the power source reaches the rotational speed corresponding to the standby demand power, and the electric double layer capacitor is preferentially discharged over the storage battery in discharging. The method of controlling a power generation system according to claim 8 or 9, further comprising: During operation of the power source, when detecting a fluctuation within a predetermined fluctuation range of demand power in the load,
If the demand power exceeds the generated power, the charging / discharging device is charged with a surplus, and in charging, the electric double layer capacitor is preferentially charged over the storage battery; and
Discharging power from the charging / discharging device when demand power is lower than generated power, and discharging the electric double layer capacitor preferentially over the storage battery in discharging. The control method of the electric power generation system in any one of Claims 8-10. At the time of stopping the power source, setting the rotational speed of the power source to zero and reducing;
Charging the charging / discharging device until the rotational speed of the power source reaches zero, and charging the storage battery more preferentially than the electric double layer capacitor in charging. The control method of the electric power generation system in any one of Claims 8-11 characterized by the above-mentioned. The method for controlling a power generation system according to any one of claims 8 to 12, further comprising a step of detecting a change in demand power of the load by an increase or decrease in load frequency. In case of grid connection, obtaining a reference frequency and a reference voltage from the grid;
14. The step of controlling the inverter unit so as to make the AC frequency and voltage output from the inverter unit coincide with the acquired reference frequency and reference voltage. 14. Control method of power generation system.

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