Patent Application
20090133735
The present invention relates to an input power supply necessary for the completion test of a solar photovoltaic power generation inverter. More specifically, the present invention relates to a solar photovoltaic power generation simulator power supply which artificially reproduces and outputs the output characteristic of a solar photovoltaic power generation module.
The trend of a solar photovoltaic power generation system is toward larger capacitance. For instance, in a 1,000 kVA inverter completion test, in place of permanently installing a 1,200 kW class-solar battery panel, an artificial power-supply apparatus, as a testing power supply, which is lower in installation cost and is easier to handle has been required. The artificial power-supply apparatus is a power-supply apparatus which is connected to the input side of the solar photovoltaic power generation inverter and artificially generates the output current/voltage characteristic of the solar battery. The technical disclosure which can be referred as a characteristic value of the power supply satisfying the requirements is described in Patent Citation 1.
A necessary number of solar battery modules are connected in series. The output thereof is connected to the input side of an inverter tested. The output characteristic (output voltage, current, and power) of the inverter connected to a fluctuating load and the inverter input voltage and current are then measured to calculate the characteristic of the efficiency of the inverter. However, in natural light irradiation, the output of the solar battery module is always fluctuated, which is unsuitable for measuring the characteristic test. The power supply is desired to artificially generate and reproduce a state that solar irradiation during measurement is stable so that the inverter input voltage and current values are stabilized to a predetermined value.
Patent Citation 1 discloses information on a power supply applicable to a simple and small load. A power supply having a large output current causes much internal power loss, which is not applicable to practical use. Patent Citation 1 (paragraph 0014) has the following description. “An example of a power-supply apparatus according to the present invention is illustrated in
Patent Citation 1: Patent 6-195140 Title: “POWER-SUPPLY APPARATUS”
The power loss consumed in the large-capacitance power-supply apparatus generates much heat, thereby having the minus effect on the social requirement. Therefore, there are provided a method for artificially generating the output characteristic of a solar photovoltaic power generation module with the internal power loss reduced, and a power-supply apparatus which artificially generates and outputs the output characteristic.
A solar photovoltaic power generation artificial-power generating method which includes the steps of feedforward controlling a semiconductor switching element for power control based on an input current, and feedback controlling the semiconductor switching element for power control based on an output current, includes: reading particular current/voltage values relation curve (designated IV curve) from among the output characteristics of a solar battery generated based on the annual fluctuation in the amount of solar irradiation and stored in a storing means; generating a control signal such that an output characteristic value of a direct-current power controlling unit satisfies the current/voltage relation on the IV pattern; and supplying the control signal to the semiconductor switching element for power control to control the output characteristic of the direct-current power controlling unit so as to coincide with the designated current/voltage values relation curve of the solar battery.
The solar photovoltaic power generation artificial characteristic will be described by illustrating an example. The current/voltage values relation curve from among the output characteristics of solar photovoltaic power generations will be described by illustrating only points necessary for describing the present invention in
A voltage value Vs on the curve A1 standard temperature is shifted to Vss in the IV characteristic curve B1 at low temperature. When both the curves are stored, Vss at low temperature is stored. There fore, the artificial characteristic can be outputted corresponding to temperature change. The designated IV curve is read to designate at which current value in the curve power is supplied to the load inverter. The corresponding voltage is thus read to control the voltage value so as to be held.
With claim 2, the solar photovoltaic power generation artificial-power generating method according to claim 1 is characterized in that in the generation of the control signal, when a current point Y=I1 on one IV curve designated from among the stored IV patterns is instruction set, a voltage X=V1 corresponding to P1 on the designated IV curve is read and Y=I1 and X=V1 are automatically set and controlled so as to be a control target set value.
With claim 3, the solar photovoltaic power generation artificial-power generating method according to claim 2 is characterized in that in the generation of the control signal, when a load is fluctuated after the current point Y=I1 on the designated IV curve is instruction set, a voltage X=V2 associated with a fluctuated current point Y=I2 is read, Y=I2 and X=V2 are automatically set so as to be a new control target set value, and the output of the direct-current power is controlled so as to trace the designated IV curve.
With claim 4, a solar photovoltaic power generation simulator power-supply apparatus includes: a power conversion main circuit having an input terminal, a converter circuit which changes an alternating current to a direct current, a smoothening capacitor sequentially connected to the output side of the converter circuit, an input current detecting unit, a chopper which performs switching control by a semiconductor switching element, an output voltage detector, an output current detector, and an output terminal; and a control signal circuit which controls the output voltage/output current of the power conversion main circuit. The control signal circuit has a feedforward control circuit and a feedback control circuit. The feedforward control circuit feedforward controls the power control chopper based on an input current obtained from the input current detecting unit. The feedback control circuit is a circuit which feedback controls the power control chopper based on an output voltage and an output obtained from the output voltage detecting unit and the output current detecting unit. The control signal circuit has an IV storing means for storing, as IV curves, a current/voltage values relation curve which coincides with the output characteristic of a solar battery, an IV curve reading means, a selecting and designating means for selecting and designating one IV curve from among the read IV curves, and a control target value setting means for outputting the current/voltage values characteristic of the designated IV curve.
With claim 5, the solar photovoltaic power generation simulator power-supply apparatus according to claim 4 is characterized in that the control target value setting means is a target value setting means including an IV reading means for designating and reading one IV curve from among the stored IV curves, and means, when an instructing person instruction sets an instruction current point Y=I1, for reading a voltage X=V1 associated with a current I1 on the designated IV curve and automatically setting Y=I1 and X=V1 automatically set to the same so as to be a control target value.
With claim 6, the solar photovoltaic power generation simulator power-supply apparatus according to claims 4 to 5 is characterized in that the generation of the control signal is a target value setting means including means, when a load is fluctuated after the current point Y=I1 on the designated IV curve is instruction set, for reading a voltage X=V2 associated with a fluctuated current point Y=I2 and automatically resetting Y=I2 and X=V2 so as to be a new control target set value.
With claim 8, the solar photovoltaic power generation simulator power-supply apparatus according to claims 4 to 6 is characterized in that the control signal circuit generates a PWM control signal from a modulation signal and outputs the PWM control signal to the control pole of the semiconductor switching element for power control by the power conversion main circuit, and the modulation signal is a modulation signal generated by adding a signal S1 obtained by amplifying the difference between a direct-current output voltage detection signal and a reference voltage V1 and a signal S2 obtained by amplifying the difference between a direct-current input current and a reference voltage V2.
The solar photovoltaic power generation simulator has the means for storing, as IV curves, the voltage/current characteristics of solar photovoltaic power generations generated based on the annual fluctuation in the amount of solar irradiation and setting, as the automatic control output target value, the read particular IV characteristic. The solar photovoltaic power generation simulator has the control signal circuit which generates the control signal which holds a voltage value V associated with a current value I on the particular IV curve, supplies the control signal to the semiconductor switching element which controls the power by the power conversion main circuit including the chopper, and controls the power so as to trace the designated IV curve; and the power conversion main circuit from which series resistors have been eliminated. Therefore, the solar photovoltaic power generation simulator can be a power supply which cannot cause large power loss except for in the semiconductor switching element.
The current/voltage values relation curve from among the output characteristics of the solar battery will be described by illustrating only points necessary for describing the present invention in
The voltage value Vs on the curve A1 at standard temperature is shifted to Vss in the IV characteristic curve B1 at low temperature. When both the curves are stored, Vss at low temperature is stored. Therefore, the artificial characteristic can be outputted corresponding to temperature change.
With claim 9, a method for setting an output target value for a feed back control circuit in a solar photovoltaic power generation simulator includes a power conversion circuit which generates a solar photovoltaic power generation artificial-power, a feedforward control circuit which feedforward controls the power conversion circuit based on an input current of the power conversion circuit, and a feedback control circuit which feedback controls the power conversion circuit based on the output current/voltage of the power conversion circuit. The method includes the following steps:
selecting one IV curve from among a plurality of IV curves generated based on the annual fluctuation in the amount of solar irradiation; and
setting an output target value to the feedback control circuit in order for the feedback control circuit to control the power conversion circuit such that the output characteristic of power control satisfies the selected IV curve.
In the method, the optimal IV curve can be selected from among the plurality of previously prepared IV curves and the output characteristic of power control is controlled so as to coincide with the IV curve.
With claim 10, the method for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator according to claim 9 is characterized in that the setting step includes the following steps:
designating a current value on the IV curve selected in the selecting step;
reading a voltage value associated with the current value; and
setting, as the output target value, the current value and the voltage value to the control circuit.
In the method, the voltage value associated with the current value is read so that both of the current value and the voltage value become the output target value, thereby allowing automatic control.
With claim 11, the method for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator according to claim 10, the designating step designates the current value which coincides with the output current value.
A computer program according to claim 12 includes an instruction for allowing a computer to execute the method according to any one of claims 9 to 11.
The solar photovoltaic power generation simulator according to claim 13 includes the computer program according to claim 12.
With claim 14, a device for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator includes a power conversion circuit which generates a solar photovoltaic power generation artificial-power, a feedforward control circuit which feedforward controls the power conversion circuit based on the input current of the power conversion circuit, and a feedback control circuit which feedback controls the power conversion circuit based on the output current/voltage of the power conversion circuit. The device includes: a memory which stores a plurality of IV curves; a reading unit which reads one IV curve from among the plurality of IV curves; and a setting unit which sets an output target value to the feedback control circuit in order for the feedback control circuit to control the power conversion circuit such that the output characteristic of power control satisfies the selected IV curve.
In the device, the reading unit reads one IV curve from the memory, and then, the setting unit sets the output target value for the feedback control circuit. The feedback control circuit controls the power conversion circuit such that the output characteristic of power control satisfies the selected IV curve.
With claim 15, the device for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator according to claim 14 further includes an IV curve designating unit which designates an IV curve to be read by the reading unit.
In the device, the IV curve designating unit designates the IV curve, and then, the reading unit reads the designated IV curve.
With claim 16, the device for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator according to claim 14 or 15 further includes a current value designating unit which designates a current value on the selected IV curve; and a voltage value reading unit which reads a voltage value associated with the current value.
In the device, the voltage value associated with the current value is read so that both of the voltage value and the current value become the output target value, thereby allowing automatic control.
With claim 17, the device for setting an output target value for a feedback control circuit in a solar photovoltaic power generation simulator according to claim 16 further includes an operation instructing unit which detects an output current value fluctuated with load fluctuation to provide the current value to the current value designating unit.
With claim 18, a solar photovoltaic power generation simulator includes: a power conversion circuit which generates a solar photovoltaic power generation artificial-power; a feedforward control circuit which feedback controls the power conversion circuit based on the input current of the power conversion circuit; a feedback control circuit which feedback controls the power conversion circuit based on the output current/voltage of the power conversion circuit; and the output target value setting device according to any one of claims 14 to 17.
The output of the solar battery is always fluctuated during the characteristic test of the inverter. The solar battery is thus unsuitable to be used for the input power supply of the inverter as the load. However, the solar battery characteristic can be reproduced in the state that the voltage/current values are stabilized to a desired value.
An embodiment according to the present invention is illustrated by a block wiring diagram in
The control signal circuit 15 has a feedback control circuit 50 and a feedforward control circuit 51. Control target value setting means 16 and target value generating means 17 form a control reference value in the feedback control circuit 50. The target value generating means 17 obtains designations of Y=I and X=V on a designated IV curve by signals from an IV storing means 18, a first IV reading means 19, a second IV reading means 20, and an IV curve number designating means 30 to generate a control target value P1 (
In the feedback control circuit 50, the output signals of the output voltage detecting unit 11 and the output current detecting unit 12 are received as instruction inputs via a switching means 28. The output signal of a first error amplifier 21 which is different from the output signal of the first reference value generator 23 is supplied to a modulation signal generating circuit 25. A drive signal is generated by the PWM control signal generating circuit 26 and is then provided to the control pole of the semiconductor device.
The IV storing means 18 is means for storing a table of the numerical values of the current/voltage values relation curves (IV curves) of the output characteristics of the solar battery. The first IV reading means 19 designates one IV curve designated by the IV curve number designating means 30 from among the stored IV curves. The second IV reading means 20 reads the relation characteristic of a current value and a voltage value on the IV curve to output it to the target value generating means 17. The control target value generating means 17 generates a control target value from the current and voltage values associated with a current value I1 on the designated IV curve to provide and set it to the control target value setting means 16. A practical use example including abnormality during operation will be described.
The feedforward control circuit 51 will be described below. During the actual operation of the solar photovoltaic power generation simulator, when a large current is flowed due to abnormal occurrence, the feedforward control circuit 51 can prevent and suppress a significant sudden drop in output voltage. The feedforward control circuit 51 receives an instruction input from the input current detecting unit 13. The output of a second error amplifier 22 which is different from a second reference value generator 24 is supplied to the modulation signal generating circuit 25. The PWM control signal generating circuit 26 generates a drive signal by a modulation signal. The large current is positively fed back so as to stop the sudden drop in voltage. Therefore, the output voltage is switched from lowering to rise to prevent the significant sudden drop in voltage. The feedback control circuit 50 detects the value of the lowered voltage to provide the drive signal to the control pole of the semiconductor device for control. The response is thus slightly delayed. The large current is positively fed back from the initial stage of rise ahead of this to quickly lessen voltage instantaneous lowering.
The voltage characteristics of solar photovoltaic power generations of assistance in explaining an embodiment according to the present invention will be described by illustrating it in a curve diagram of
The voltage characteristics of solar photovoltaic power generations of assistance in explaining an embodiment according to the present invention will be described by illustrating it in a curve diagram of
During operation of the power-supply apparatus to which the current point Y=I1 on the designated IV curve C1 is instruction set, when a load (inverter current) is fluctuated, a voltage X=V2 on C1 associated with a fluctuated current point Y=I2 is read, and Y=12 and X=V2 are automatically set and controlled so as to be a new control target set value. During operation, when the load (inverter current) is further fluctuated, a voltage X=V3 on C1 associated with a fluctuated current point Y=13 is read, Y=13 and X=V3 are automatically set so as to be a new control target set value, and the power is controlled so as to trace the designated IV curve. The method for outputting the characteristic of the artificial power supply on the curve C1 corresponding to the load current in which the control target value is fluctuated by the minute is the characteristic technique of the present invention.
The operation of the control signal circuit 15 will be described by the block wiring diagram of
Y=I on the designated IV curve is designated by signals from the second IV reading means 20 and current value designating means 31 on the IV curve. Then, the designation of X=V is obtained to generate the control target value P1. The target value setting means 16 digital sets the numerical value of the first reference value generator 23 so as to coincide with the control target value P1. The output signals of the output voltage detecting unit 11 and the output current detecting unit 12 are received as instruction inputs. The output signal of the first error amplifier 21 which is different from the first reference value generator 23 is supplied to the modulation signal generating circuit 25. The drive signal is generated by the PWM control signal generating circuit 26 and is then provided to the control pole of the semiconductor device. The voltage is controlled so as to be maintained by the signal of the feedback control circuit 50.
The IV storing means 18 is means for storing a table of the numerical values of IV relation curves (IV curves) of the output characteristics of the solar battery. The first IV reading means 19 outputs the relation characteristic of the current value and the voltage value on the IV curve designated by the IV curve number designating means 30 which selects and designates the IV curve from among the stored IV curves. The above control procedure is included in software controlled by operation instructing means 40 including a CPU.
The control target value generating means 17 generates the control target value from the current and voltage values corresponding to the current value I1 on the designated IV curve. The control target value setting means 16 sets a set value to the first reference value generator 23.
The set value that the control target value setting means 16 sets to the first reference value generator 23 is a reference value which is compared with a voltage detection value by the first error amplifier 21 and suppresses voltage fluctuation. This is a value in proportion to the output current value I1 at that point and the voltage value V1 associated with it on the designated IV curve.
With respect to the change in instantaneous load (inverter) current, to give consideration to prevent increase in fluctuation in transient control output voltage, feedforward control is added to feedback control to improve the responding speed.
The above apparatus and controlling method will be described using another representation. The solar photovoltaic power generation simulator illustrated in
The output target value setting device is a device which sets an output target value for the feedback control circuit 50. The device has the IV storing means 18 which stores a plurality of IV curves, the first IV reading means 19 which reads one IV curve from among the plurality of IV curves, and the setting units (16, 17) which set the output target value to the feedback control circuit 50 in order for the feedback control circuit 50 to control the power conversion main circuit 14 such that the output characteristic of power control satisfies the selected IV curve.
In the device, the first IV reading means 19 reads one IV curve from among the IV storing means 18, and then, the setting units (16, 17) set the output target value for the feedback control circuit 50. As a result, the feedback control circuit 50 controls the power conversion main circuit 14 such that the output characteristic of power control satisfies the selected IV curve.
The output target value setting device further has the IV curve number designating means 30 which designates an IV curve to be read by the first IV reading means 19. In the device, the IV curve number designating means 30 designates the IV curve, and then, the first IV reading means 19 reads the designated IV curve.
The output target value setting device further has the current value designating means 31 which designates a current value on the selected IV curve, and the second IV reading means 20 which reads a voltage value associated with the current value. In the device, the voltage value associated with the current value is read so that both of the voltage value and the current value become an output target value, thereby allowing automatic control.
The output target value setting device further has the operation instructing means 40 which detects an output current value fluctuated with load fluctuation to provide the current value to the current value designating means 31.
The operation of the output target value setting device will be described using the flowchart of
In step S1, one IV curve is selected from among a plurality of IV curves. Specifically, the IV curve number designating means 30 designates one IV curve, and then, the first IV reading means 19 reads the IV curve based on it to transmit the information to the control target value generating means 17.
In steps S2 to S4, an output target value is set to the feedback control circuit 50 in order for the feedback control circuit 50 to control the power conversion main circuit 14 such that the output characteristic of power control satisfies the selected IV curve. The optimal IV curve can be selected from among the plurality of prepared IV curves to control the output characteristic of power control so as to coincide with the IV curve.
In step S2, the current value on the IV curve selected in step S1 is designated. Specifically, the operation instructing means 40 measures a load current, and then, the current value designating means 31 designates a current value on the IV curve based on it. The current value which coincides with the output current value is designated.
In step S3, a voltage value associated with the current value is read. Specifically, the second IV reading means 20 reads the voltage value associated with the designated current value on the selected IV curve in the IV storing means 18 to transmit it to the control target value generating means 17.
In step S4, the current value and the voltage value are set, as the output target value, to the feedback control circuit 50. The voltage value associated with the current value is read so that both of the voltage value and the current value become the output target value, thereby allowing automatic control. Specifically, the control target value generating means 17 generates the control target value having the current value and the voltage value to transmit it to the target value setting means 16. The target value setting means 16 sets the control target value to the first reference value generator 23.
In step S5, it is determined whether the IV curve to be selected is changed or not. When it is changed, the routine is returned to step S1. When it is not changed, the routine is returned to step S2. The IV curve to be selected is changed when the operator performs a changing operation in order to generate a solar photovoltaic power generation artificial-power under different solar irradiation conditions.
The above operation can be realized by a computer program as well as hardware such as an electronic circuit. The program includes a command for allowing a computer having a CPU and a memory to execute the above operation.
The power supply according to the present invention artificially generates and outputs the output characteristic of the solar photovoltaic power generation module. Therefore, the stable load test can be conducted without limiting time. The power supply has the output characteristic of the solar battery which can artificially generate an ideal solar irradiation state. The internal power loss of the power-supply apparatus can be reduced, and thus no measures against heat generation are necessary. Large-capacitance storage battery equipment and resource consumption type equipment such as the solar photovoltaic power generation module are eliminated. Accordingly, the present invention can contribute to social resource saving and has a high degree contributing to the industry.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-121443 | Apr 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/055595 | 3/20/2007 | WO | 00 | 10/24/2008 |
