JP2010245320A - Solar power generation facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently explore an optimum operation point where a maximum electric power of an array assembly is generated, and to effectively utilize energy of solar power generation. <P>SOLUTION: A power conditioner 12 varies a voltage of its array assembly 11 in a region different from other adjacent array assemblies 11, and explores the operation point where the output electric power of its array assembly 11 reaches a maximum power point, and a comparing means 22 computes output electric powers at operation points explored by power conditioners 12 of the plurality of adjacent array assemblies 11, and compares the output electric powers including the current output electric power. A voltage determination means 23 extracts a voltage corresponding to a maximum electric power among the output electric powers compared by the comparing means 22 and determines it as an operation point voltage, and a voltage control means 24 outputs the operation point voltage determined by the voltage determining means 23 as a voltage command to the power conditioner 12 of the respective adjacent array assemblies 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photovoltaic power generation facility provided with a plurality of array assemblies formed by connecting arrays of a plurality of solar cell modules in parallel.

  Generally, a solar power generation system forms a solar cell module by connecting solar cells that photoelectrically convert sunlight into a solar cell module, converts DC power generated by the solar cell module into AC power by a power conditioner, and an electric power system. In this way, AC power is supplied to the power system.

  In large-scale photovoltaic power generation facilities, multiple solar cell modules are combined to form multiple arrays, and multiple arrays are connected in parallel to form multiple array assemblies, and each array assembly is powered. A conditioner is provided, and the DC power generated by each array assembly is converted to AC power by each power conditioner and connected to the power system to supply AC power to the power system.

  Because solar cells have different operating points that generate maximum power depending on solar radiation intensity and temperature, it is important to follow the optimal operating point that changes every moment in order to effectively use the power generated by solar cells. It becomes.

  FIG. 5 is a graph of an example of the V-I characteristic showing the relationship between the output voltage V and the output current I of the solar cell and the V-P characteristic showing the relationship between the output voltage V and the output power P of the solar cell. is there. The VI characteristic curve and VP characteristic curve which made the solar radiation intensity at the time of making the temperature of a solar cell constant the parameter are shown. The VI characteristic curve C1 is a characteristic curve when the solar radiation intensity is high, the VI characteristic curve C2 is a characteristic curve when the solar radiation intensity is intermediate, and the VI characteristic curve C3 is a characteristic curve when the solar radiation intensity is low. .

  When the solar radiation intensity is high, it is the optimum operating point at which the output power becomes maximum at the coordinates C11 (V1, I1) on the VI characteristic curve C1, and the VP characteristic curve P1 becomes the maximum power P1max. . When the solar radiation intensity is intermediate, the coordinate C22 (V2, I2) on the VI characteristic curve C2 is the optimum operating point at which the output power is maximum, and the VP characteristic curve P2 is the maximum power P2max. Become. Similarly, when the solar radiation intensity is low, the coordinates C33 (V3, I3) on the VI characteristic curve C3 are the optimum operating points at which the output power is maximum, and the VP characteristic curve P3 is the maximum power P3max. Become.

  In order to obtain such an optimal operating point for extracting the maximum power, maximum power tracking control {MPPT (Maximum Power Point Tracking) control} for tracking control to the optimal operating point at which the output of the solar cell is maximum is used. For example, the output power obtained at the current operating point is compared with the output power obtained at the operating point slightly moved from the current operating point to determine the direction to the optimal operating point, and to the optimal operating point. The hill-climbing method to follow is used.

  To determine the optimal operating point, the direction of the next operating voltage is determined based on the difference between the initial or previous operating voltage and the current operating voltage, and the direction is determined at multiple points within a fixed period. In the power generation situation where the final direction is determined and the maximum output point is followed, the influence of a single disturbance is alleviated, the direction is always stable, and the conventional MPPT method may make a wrong determination. However, there is one that can effectively extract solar cell power without impairing the generated power opportunity (see, for example, Patent Document 1).

  In addition, there is one that can follow the maximum power even when a part of the panel of the solar cell is shaded and a plurality of maximum values are generated in the output of the solar cell (for example, patent document) 2).

JP 2004-295688 A JP 2006-59126 A

  However, the thing of patent document 1 carries out maximum electric power tracking control individually with a grid connection inverter, and does not carry out maximum power tracking control in cooperation with the grid connection inverter of a plurality of solar cells. Moreover, although the thing of patent document 2 can follow to a maximum electric power even if it is a case where several local maximum values generate | occur | produce in the output of a solar cell, the calculation which calculates | requires an optimal operating point becomes complicated.

  Even in a photovoltaic power generation facility having a plurality of array assemblies, a power conditioner is provided for each array assembly, and each power conditioner individually controls maximum power tracking. The optimal operating point that generates the maximum power of the body could not be explored efficiently. If the search for the optimum operating point is delayed, the optimum operating point that follows the change in solar radiation intensity is lost, so that the energy of solar power generation cannot be utilized to the maximum.

  An object of the present invention is to provide a solar power generation facility that can efficiently search for an optimum operating point that generates the maximum power of an array assembly and that can effectively utilize the energy of solar power generation.

  According to a first aspect of the present invention, there is provided a photovoltaic power generation facility comprising: a plurality of array assemblies formed by connecting arrays of a plurality of solar cell modules in parallel; and maximum power following of the array assembly provided in each array assembly. In a photovoltaic power generation facility having a power conditioner for controlling and linking the array assembly to a power system, the voltage of its own array assembly is changed in a region different from that of another adjacent array assembly. The power conditioner that searches for the operating point where the output power of the array assembly becomes the maximum power point, and the output power at the operating point searched for by the power conditioner of a plurality of adjacent array assemblies are calculated and the current output power is calculated. A comparison means for comparing each of them, and a voltage at which the output power compared by the comparison means is the maximum power is extracted and the voltage is adjusted. Voltage determining means for determining a point voltage; and voltage control means for outputting the operating point voltage determined by the voltage determining means to the power conditioner of each adjacent array assembly as a voltage command. To do.

  According to the present invention, the operating point at which the output power of the array assembly is changed to the maximum power point by changing the voltage of the array assembly in a region different from that of the other adjacent array assembly is searched. The output power at the explored operating point of the array aggregate and the current output power of each array aggregate are compared, and the maximum power is used as the operating point voltage of multiple adjacent array aggregates, so the maximum power of the array aggregate is generated. The optimum operating point to be searched can be quickly searched. In addition, when the number of adjacent array aggregates is increased, the range of searching for the maximum power point is widened, so that even when a plurality of maximum values occur in the output power of the array aggregate, the maximum power can be tracked. It becomes possible. Therefore, the optimum operating point that generates the maximum power of the array assembly can be efficiently searched, and the energy of solar power generation can be effectively utilized.

  Further, the voltage of the array assembly is changed in a region different from other adjacent array assemblies within a predetermined range that is expected to include the maximum power point of the array assembly. The optimum operating point that generates the maximum power of the aggregate can be searched more efficiently.

The block diagram of an example of the solar power generation facility concerning the 1st Embodiment of this invention. The graph which shows an example of the characteristic curve of the output voltage and output power of the array aggregate | assembly of the solar power generation facility concerning the 1st Embodiment of this invention. The block diagram of an example of the solar power generation facility concerning the 2nd Embodiment of this invention. The graph which shows an example of the characteristic curve of the output voltage and output power of the array aggregate | assembly of the solar power generation equipment concerning the 2nd Embodiment of this invention. The graph of an example of the VP characteristic which showed the VI characteristic which showed the relationship between the output voltage V of a solar cell, and the output current I, and the output voltage V of the solar cell, and the output electric power P.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of an example of a photovoltaic power generation facility according to the first embodiment of the present invention. FIG. 1 shows a case where two array aggregates 11 are coordinated and controlled when a plurality of adjacent array aggregates 11 are coordinated.

  The solar power generation facility is provided with a plurality of array aggregates 11, and a power conditioner 12 is connected to each array aggregate 11. The array assembly 11 is configured by connecting a plurality of arrays 13 in parallel, and FIG. 1 shows a case where three arrays 13 are connected in parallel. The array is configured by series-parallel connection of solar cell modules formed by connecting solar cells in series.

  The power conditioner 12 includes a power converter that converts DC power generated by the array assembly 11 into AC power, and a grid interconnection device that links the power converter to the power system. Power follow-up control is performed to convert the DC power generated by the array assembly 11 into AC power and output it to the bus 15 via the circuit breaker 14. Then, AC power is supplied from the bus 15 to the power system 18 via the transformer 16 and the main circuit breaker 17.

  In addition, a control device 19 is provided as a pair of two array aggregates 11 adjacent to each other, and the pair of two array aggregates 11 are cooperatively controlled by the control device 19. That is, the control device 19 outputs a voltage command to the power conditioner 12 of the pair of two array assemblies 11 to cooperatively control the pair of two array assemblies 11.

  The power conditioner 12 changes the voltage of its own array aggregate in a region different from the other adjacent array aggregates among a pair of two array aggregates that are cooperatively controlled, and the output power of its own array aggregate Is searched for the operating point at which the maximum power point becomes, and the voltage of its own array assembly 11 is changed to the optimal operating point based on the voltage command from the control device 19.

  At the output end of each array assembly 11, a current detector 20 that detects the output current of each array assembly 11 and a voltage detector 21 that detects the output voltage are provided. Then, the conditioner 12 inputs the output current and output voltage of the array assembly 11 at the operating point when the maximum power point is searched for to the comparison means 22 of the control device 19. The comparison unit 22 calculates the output power of the pair of adjacent array aggregates 11 at the operating point when the maximum power point is searched based on the output current and output voltage of the pair of adjacent array aggregates 11, The output power and the current output power are compared, and the comparison result is output to the voltage determining means 23.

  The voltage determination means 23 determines the maximum power as the operating point voltage from the comparison result of the comparison means 22 and outputs it to the voltage control means 24. The voltage control unit 24 outputs a voltage command to each power conditioner 12 of the pair of adjacent array assemblies 11 so that the operating point voltage determined by the voltage determination unit 24 is obtained. Thereby, the power conditioner 12 of a pair of adjacent array aggregates 11 controls the output voltage of each array aggregate 11 so that the operating point voltage determined by the voltage determining means 24 is obtained.

  Next, the operation of the photovoltaic power generation facility according to the first embodiment of the present invention will be described. FIG. 2 is a graph showing an example of a characteristic curve between the output voltage and the output power of the array assembly of the photovoltaic power generation facility according to the first embodiment of the present invention.

  Here, each array assembly 11 of the photovoltaic power generation equipment has the same specification, and in particular, since the adjacent array assembly 11 is considered to have an error range in terms of solar radiation intensity and temperature, the characteristics are almost the same. It is thought that it has. That is, it is premised that the output voltage / output power characteristic curves P of the adjacent array aggregates 11 are the same. Strictly speaking, the output voltage / output power characteristic curves P of the adjacent array aggregates 11 may not be the same, and therefore the output voltage V of the adjacent array aggregate 11 under the same solar radiation intensity and temperature conditions. The VI characteristic indicating the relationship between the output current I and the output current I is tracked in advance, and the output voltage / output power characteristic curve P of the adjacent array assembly 11 is corrected based on the VI characteristic. It may be.

  Now, it is assumed that the pair of array aggregates is operating at the operating point eb of the output voltage Vb. In order to obtain an operating point in the next cycle, one power conditioner 12 of the pair of array aggregates 11 follows the voltage increasing direction, and the other power conditioner 12 follows the voltage decreasing direction. That is, one power conditioner 12 has an operating point ea of the voltage Va obtained by moving the output voltage Vb by −ΔV from the operating point eb of the output voltage Vb, and the other power conditioner 12 has an operating voltage eb from the operating point eb of the output voltage Vb. Is an operating point ec of the voltage Vc moved by + ΔV.

  The control device 19 of FIG. 1 inputs the output current and output voltage of the array assembly 11 at the operating point ea to calculate the output power Pa at the operating point ea, and outputs the output current and the array assembly 11 at the operating point ec. The output power Pc at the operating point ec is calculated by inputting the output voltage. Then, the current output power Pb, the output power Pa at the operating point ea, and the output power Pc at the operating point ec are compared, and the maximum power is extracted. In this case, since Pc> Pb> Pa, since the output power Pc at the operating point ec is the maximum power, the control device 19 supplies the voltage that becomes the output power Pc to both power conditioners 12 of the adjacent array assemblies 11. Command Vc is output. Thereby, in the next period, it is possible to quickly control to the optimum operating point ec that generates the maximum power of the pair of array aggregates.

  Similarly, when the operating point at the next cycle is obtained while operating at the operating point ec of the output voltage Vc, one power conditioner 12 obtains the output voltage Vc from the operating point ec of the output voltage Vc. The operating point eb of the voltage Vb moved by −ΔV is set as the operating point eb of the voltage Vd obtained by moving the output voltage Vc by + ΔV from the operating point ec of the output voltage Vc.

  The control device 19 inputs the output current and output voltage of the array assembly 11 at the operating point eb, calculates the output power Pb of the operating point eb, and calculates the output current and output voltage of the array assembly 11 at the operating point ed. The output power Pd at the operating point ed is input and calculated. And these are compared including the present output electric power Pc, and the maximum electric power is taken out. In this case, since Pd> Pc> Pb, since the output power Pd at the operating point ed is the maximum power, the control device 19 supplies the voltage that becomes the output power Pd to both power conditioners 12 of the adjacent array aggregate 11. Command Vd is output. As a result, in the next cycle, it is possible to quickly control to the optimum operating point ed that generates the maximum power of the pair of array aggregates.

  In addition, when operating at the operating point ed of the output voltage Vd and obtaining an operating point in the next cycle, one power conditioner 12 changes the output voltage Vc from the operating point ed of the output voltage Vd to -ΔV. The operating condition ec of the voltage Vc that has been shifted by a certain amount, and the other power conditioner 12 has an operating point ee of the voltage Ve that has been shifted by + ΔV from the operating point ed of the output voltage Vd.

  The control device 19 inputs the output current and output voltage of the array assembly 11 at the operating point ec, calculates the output power Pc at the operating point ec, and calculates the output current and output voltage of the array assembly 11 at the operating point ee. The input power Pe is calculated at the operating point ee. And these are compared including the present output electric power Pd, and the maximum electric power is taken out. In this case, since Pd> Pc> Pe, the output power Pd at the operating point ed is the maximum power. Therefore, the control device 19 supplies the voltage that becomes the output power Pd to both power conditioners 12 of the adjacent array assembly 11. Command Vd is output. As a result, even in the next cycle, it is possible to quickly control to the optimum operating point ed that generates the maximum power of the pair of array aggregates.

  As described above, in the conventional search for the optimum operating point, each power conditioner 12 individually searches for the operating point in both the voltage increasing direction and the voltage decreasing direction from the current operating point eb. In the first embodiment, since one power conditioner 12 searches in the voltage rising direction and the other power conditioner 12 searches in the voltage falling direction, the optimum operating point that generates the maximum power of the array assembly can be quickly searched. It can follow quickly even if the solar radiation intensity changes.

  Next, a second embodiment of the present invention will be described. FIG. 3 is a configuration diagram of an example of a photovoltaic power generation facility according to the second embodiment of the present invention. In the second embodiment, when the plurality of adjacent array aggregates 11 are cooperatively controlled, the two array aggregates 11 are coordinated and controlled as a pair with respect to the first embodiment shown in FIG. Instead, the two array aggregates 11 are coordinated and controlled as a pair. The same elements as those in FIG.

  As shown in FIG. 3, a control device 19 is provided as a set of three adjacent array aggregates 11, and one set of three array aggregates 11 is cooperatively controlled by the control device 19. That is, the control device 19 outputs a voltage command to the power conditioner 12 of the three array assemblies 11 to cooperatively control the three array assemblies 11.

  The power conditioner 12 changes the voltage of its own array assembly in a region different from the other two adjacent array assemblies among the three array assemblies to be coordinated, and outputs the output of its own array assembly. The operating point at which the power reaches the maximum power point is searched, and the voltage of its own array assembly 11 is changed to the optimum operating point based on the voltage command from the control device 19.

  At the output end of each array assembly 11, a current detector 20 that detects the output current of each array assembly 11 and a voltage detector 21 that detects the output voltage are provided. Then, the conditioner 12 inputs the output current and output voltage of the array assembly 11 at the operating point when the maximum power point is searched for to the comparison means 22 of the control device 19. The comparison means 22 calculates the output power of the three adjacent array aggregates 11 at the operating point when the maximum power point is searched based on the output current and output voltage of the pair of adjacent array aggregates 11. Then, the output power is compared with the current output power, and the comparison result is output to the voltage determining means 23.

  The voltage determination means 23 determines the maximum power as the operating point voltage from the comparison result of the comparison means 22 and outputs it to the voltage control means 24. The voltage control unit 24 outputs a voltage command to the power conditioners 12 of the three adjacent array assemblies 11 so that the operating point voltage determined by the voltage determination unit 23 is obtained. As a result, the power conditioners 12 of the three adjacent array assemblies 11 control the output voltage of each array assembly 11 so that the operating point voltage determined by the voltage determining means 23 is obtained.

  Next, the operation of the photovoltaic power generation facility according to the second embodiment of the present invention will be described. FIG. 4 is a graph showing an example of a characteristic curve between the output voltage and the output power of the array assembly of the photovoltaic power generation facility according to the second embodiment of the present invention. Also in the second embodiment, it is assumed that the VP characteristic curves P of the three adjacent array aggregates 11 are the same.

  It is assumed that the operation is performed at the operating point eb of the output voltage Vb. In order to obtain the operating point in the next cycle, the first power conditioner 12 sets the operating point ea of the voltage Va obtained by moving the output voltage Vb by −ΔV from the operating point eb of the output voltage Vb to the second power conditioner. Reference numeral 12 denotes an operating point ec of the voltage Vc obtained by moving the output voltage Vb by + ΔV from the operating point eb of the output voltage Vb. The third power conditioner 12 moves the output voltage Vb from the operating point eb of the output voltage Vb by + 2ΔV. The operating point ed of the voltage Vd is assumed.

  The control device 19 inputs the output current and output voltage of the array assembly 11 at the operating point ea, calculates the output power Pa of the operating point ea, and inputs the output current and output voltage of the array assembly 11 at the operating point ec. Then, the output power Pc at the operating point ec is calculated, the output current and the output voltage of the array assembly 11 at the operating point ed are input, and the output power Pd at the operating point ed is calculated.

  The current output power Pb, the output power Pa at the operating point ea, the output power Pc at the operating point ec, and the output power Pd at the operating point ed are compared, and the maximum power is extracted. In this case, since Pd> Pb> Pc> Pa, since the output power Pd at the operating point ed is the maximum power, the control device 19 supplies the output power Pd to the power conditioners 12 of the three adjacent array assemblies 11. The voltage command Vd is output. Thereby, in the next period, it is possible to quickly control to the optimum operating point ed that generates the maximum power of the array assembly.

  Similarly, when the operating point at the next cycle is obtained while operating at the operating point ed of the output voltage Vd, the first power conditioner 12 determines the output voltage from the operating point ed of the output voltage Vd. Vd is the operating point ec of the voltage Vc moved by −ΔV, and the second power conditioner 12 is the operating point ee of the voltage Ve obtained by moving the output voltage Vd by + ΔV from the operating point ed of the output voltage Vd. In this case, the power conditioner 12 has an operating point ef of the voltage Vd obtained by moving the output voltage Vd by + 2ΔV from the operating point ed of the output voltage Vd.

  The control device 19 inputs the output current and output voltage of the array assembly 11 at the operating point ec, calculates the output power Pc of the operating point ec, and inputs the output current and output voltage of the array assembly 11 at the operating point ee. Then, the output power Pc at the operating point ee is calculated, the output current and the output voltage of the array assembly 11 at the operating point ef are input, and the output power Pf at the operating point ef is calculated.

  Then, the current output power Pd, the output power Pc at the operating point ec, the output power Pe at the operating point ee, and the output power Pf at the operating point ef are compared to extract the maximum power. In this case, since Pf> Pe> Pd> Pc, since the output power Pf at the operating point ef is the maximum power, the control device 19 supplies the output power Pf to the power conditioners 12 of the three adjacent array assemblies 11. Is output as a voltage command Vf. Thereby, in the next period, it is possible to quickly control the optimum operating point ef that generates the maximum power of the array assembly.

  In addition, since the three adjacent array aggregates 11 are cooperatively controlled, the range for searching for the maximum power point is widened, and even when there are a plurality of maximum values in the output power, the maximum maximum value is obtained. It becomes possible to drive at. That is, although the operating points eb and ef are maximum values, the operation at the operating point ef having the maximum maximum value is possible without stopping at the operating point eb.

  In the above description, the case where there are two adjacent array aggregates 11 is three, but it may be four or more. As described above, according to the embodiment of the present invention, it is assumed that the characteristic curves P of the output voltage / output power of the plurality of adjacent array aggregates 11 are the same. Is preferably about 2 to 5. This is because if it exceeds that, the solar radiation intensity may not be the same due to the influence of shade by clouds and trees.

  Further, since the maximum operating point of each array aggregate is within the range of the maximum solar radiation intensity to the minimum solar radiation intensity, the margin value dV is expected in the range of the output voltages V1 to V3 shown in FIG. The voltage of its own array assembly is changed within a range of −dV <V <V1 + dV) and in a region different from other adjacent array assemblies. As a result, the optimum operating point that generates the maximum power of the array assembly 11 can be searched more efficiently.

  As described above, according to the embodiment of the present invention, the search range of the operating point can be expanded and the search can be performed quickly, so that the optimal operating point that generates the maximum power of the array aggregate can be efficiently searched. Can be used effectively.

DESCRIPTION OF SYMBOLS 11 ... Array assembly, 12 ... Power conditioner, 13 ... Array, 14 ... Circuit breaker, 15 ... Busbar, 16 ... Transformer, 17 ... Main circuit breaker, 18 ... Power system, 19 ... Control device, 20 ... Current detector , 21 ... voltage detector, 22 ... comparison means, 23 ... voltage determination means, 24 ... voltage control means

Claims (2)

A plurality of array assemblies formed by connecting arrays of solar cell modules in parallel, and a maximum power tracking control of the array assemblies provided in each array assembly, and the array assemblies are connected to a power system. In a photovoltaic power generation facility equipped with a power conditioner
A power conditioner that searches for an operating point at which the output power of its own array assembly is changed to a maximum power point by changing the voltage of its own array assembly in a different area from the other adjacent array assembly;
Comparing means for calculating the output power at the operating point searched by the power conditioner of a plurality of adjacent array aggregates and comparing each including the current output power;
Voltage determining means for taking out a voltage at which the output power compared by the comparing means is the maximum power, and determining the voltage as an operating point voltage;
A photovoltaic power generation facility comprising: voltage control means for outputting the operating point voltage determined by the voltage determination means as a voltage command to the power conditioner of each adjacent array assembly.   The power conditioner changes the voltage of its own array assembly in a region different from that of other adjacent array assemblies within a predetermined range that is expected to include the maximum power point of its own array assembly. The solar power generation facility according to claim 1.

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