TWI665841B - Control method for natural energy power generation system, ineffective power controller, or natural energy power generation system - Google Patents

Abstract

[Questions] The purpose is to provide a natural energy power generation system, a reactive power controller, and a control method for a natural energy power generation system, which suppresses voltage fluctuations at an interconnection point caused by an invalid power loss of an interconnection transformer. [Solutions] Equipped with: a power generation device (12), which generates electricity by receiving natural energy; a power converter (13), which is electrically connected to the power generation device (12) and the power system (4); an interconnecting transformer (2) ), Which is arranged between the power converter (13) and the power system (4); and an invalid power controller (16), which generates an invalid power instruction output by the power converter (13); an invalid power controller (16) is to make the sum of the variation components caused by the effective power in the interconnection point voltage of the power converter (13) and the power system (4) and the variation components caused by the invalid electricity in the interconnection point voltage be Roughly fixed, and decided the invalid power instruction.

Description

Control method for natural energy power generation system, ineffective power controller, or natural energy power generation system

[0001] The present invention relates to a control method for a natural energy power generation system, an ineffective power controller, or a natural energy power generation system that supplies electric power generated using natural energy such as wind or sunlight to a power system.

[0002] Considering the cause of global warming, reduction of carbon dioxide emission is a major issue. As a means to reduce the amount of carbon dioxide emissions, the introduction of natural energy power generation such as photovoltaic power generation or wind power generation is popular. These natural energy power generation are mostly used to interconnect with the power system, but because of changes in the amount of sunlight or wind speed, the output of power generation changes, and there is a fear of adversely affecting the voltage of the interconnected system. [0003] As a method for suppressing voltage fluctuations, it is proposed to use reactive power. As a method of suppressing voltage fluctuation at an interconnection point when a wind power generator is interconnected to a power system through a power converter, there are Patent Documents 1 to 3. [0004] Patent Document 1 discloses a method of detecting an output of a power converter and controlling the power converter so as to compensate for a voltage variation at an interconnection point resulting from an effective power output of the power converter. Specifically, the system parameter α = R _L / X _{L is} estimated from the effective power output P _CON of the power converter and the voltage change ΔV _PCC of the interconnection point of the power converter generated by this, so that Q _CON =- The reactive power Q _CON obtained by αP _CON is output to the power converter. Here, R _L and X _L are a resistance component and a reactance component respectively representing the impedance of the interconnection line. [0005] Patent Document 2 discloses a method of using a power factor correction amount that sets a specific power factor command value PF = P / √ (P ² + Q ² ) in an interconnection point for each wind power generation system. Method, a method of determining a power factor command value of each wind power generation system. Here, P and Q represent the effective power output and the invalid power output of the wind power generation system, respectively. Furthermore, the power factor correction amount is determined based on the reactance component existing between each wind power generation system and the interconnection point. [0006] Patent Document 3 discloses that a voltage target value or a power factor target value is obtained from a reactive power measurement value, a voltage measurement value, or a power factor measurement value at an interconnection point. In order to achieve these target values, Method for outputting necessary reactive power from a wind power system. [Prior Art Literature] [Patent Literature] [0007] [Patent Literature 1] Japanese Patent Laid-Open No. 2007-124779 [Patent Literature 2] WO2009 / 078076 Patent Publication [Patent Literature 3] WO2013 / 128986

[Problems to be Solved by the Invention] [0008] Regarding the technique of Patent Document 1, the suppression of the voltage fluctuation at the interconnection point due to the effective power output of the power converter is targeted, and it cannot be suppressed due to the connection power conversion The voltage change at the interconnection point of the ineffective electrical loss consumed by the interconnection transformer of the transformer and the interconnection line. [0009] Regarding the technology of Patent Document 2, the reactive power output is controlled by the power factor command, and the reactive power output changes in proportion to the valid power output. In order to compensate the reactive power loss of the interconnecting transformer which also has the subject of Patent Document 1, it is necessary to control the reactive power output so as to be proportional to the square of the valid power output (or current output). For this reason, in the power factor command, it is impossible to suppress the voltage fluctuation of the interconnection point caused by the invalid electric loss of the interconnection transformer. [0010] Regarding the technology of Patent Document 3, in consideration of the loss of reactive power consumed by the interconnecting transformer, the reactive power directive of each wind power generation system has not yet been determined, and the reactive power at the interconnection point cannot be made consistent with the target value. [0011] In the present invention, it is an object of the present invention to provide a control method for a natural energy power generation system, a reactive power controller, or a natural energy power generation system, which suppresses a voltage change at an interconnection point due to an invalid power loss of an interconnection transformer. . [Means to Solve the Problem] [0012] In order to achieve the aforementioned object, the natural energy power generation system of the present invention includes: a power generation device that generates power by receiving natural energy; and a power converter that is electrically connected to the power generation device and the power System; interconnecting transformer, which is arranged between the aforementioned power converter and the aforementioned power system; and reactive power controller, which generates a reactive power command output by the aforementioned power converter; The sum of the variation component caused by the effective power in the interconnection point voltage of the power converter and the power system and the variation component caused by the reactive power in the interconnection point voltage are approximately constant, and the aforementioned invalid power instruction is determined. [0013] Further, the ineffective power controller of the present invention includes a calculation device that is an interconnection point between a power generation device that generates electricity to receive natural energy and a power converter electrically connected to the power system and the power system. The sum of the variation components caused by the effective power in the voltage and the variation components caused by the invalid power in the interconnection point voltage is approximately constant, and the invalid power command output by the power converter is generated. [0014] Still further, a control method of a natural energy power generation system according to the present invention includes: a power generation device that generates power by receiving natural energy; and a power converter that is electrically connected to the power generation device and Power system; interconnecting transformer, which is arranged between the power converter and the power system; and reactive power controller, which generates a reactive power command output by the power converter; characterized by: The sum of the fluctuation component caused by the effective power in the interconnection point voltage of the converter and the aforementioned power system and the fluctuation component caused by the reactive power in the interconnection point voltage are approximately constant, and the aforementioned invalid electricity instruction is determined. [Effects of the Invention] [0015] According to the present invention, it is possible to provide a natural energy power generation system, a reactive power controller, or a control method for a natural energy power generation system that suppresses an interconnection point caused by an invalid power loss of an interconnection transformer. Voltage fluctuation.

[0017] The modes for implementing the invention will be described in detail with reference to the drawings as appropriate. [Embodiment 1] [0018] FIG. 1 is a diagram showing the overall configuration of a natural energy power generation system, that is, a wind power generation system in a first embodiment. The wind power generation system 1 is interconnected with the power system 4 through an interconnection transformer 2 and an interconnection line 3. The resistance component of the impedance of the interconnection line 3 is R _L , and the reactance component is X _L. The point where the interconnection transformer 2 and the interconnection line 3 are connected is taken as the interconnection point 5. [0019] Each part constituting the wind power generation system 1 will be described. The wind power generation system 1 is structured as follows: a wind turbine 11, a wind turbine 11 and a generator 12 connected through a main shaft (and further a speed increaser, etc. if necessary); A power converter 13 that adjusts the power generated by the generator 11 for the opposite side, a sensor 14 provided between the power converter 13 and the interconnecting transformer 2, an active power controller 15, and a reactive power controller 16. The wind energy received by the wind turbine 11 is converted into electrical energy by the generator 12 and sent to the power converter 13. The effective power controller 15 is a pitch angle or a wind speed of the wind turbine 11. The generator 12 determines an effective power command value P _REF that can be generated, and sends the effective power command value P _REF to the power converter 13. The reactive power controller 16 determines the reactive power command value Q _REF from the effective power output P _CON and the current output I _CON of the power converter 13 measured by the sensor 14 to suppress the voltage variation at the interconnection point 5. The invalid power command value Q _{REF is} transmitted to the power converter 13. The power converter 13 controls the effective power output P _CON and the reactive power output Q _{CON in} order to follow the effective power command value P _REF and the invalid power command value Q _REF . FIG. 2 is a configuration diagram of the reactive power controller 16. The reactive power controller 16 obtains the effective power output P _CON and the current output I _CON of the power converter 13 measured by the sensor 14 through the receiving unit 161. The reactive power instruction determination section 162 is composed of the effective power output P _CON , the current output I _CON , the resistance R _L and the reactance X _L stored in the impedance of the interconnection 3 in the interconnection parameter storage section 163, and stored in The primary-side X _TR1 and secondary-side X _TR2 and winding number ratio α _TR of the reactance of the interconnect transformer parameter memory section 164 are used to obtain the reactive power command Q _REF . The reactive power command Q _REF is output to the power converter 13 through the transmitting unit 165. [0021] The invalid power command Q _REF is determined to suppress the variation of the voltage V _PCC at the interconnection point 5 shown in FIG. 1 (which is ΔV _PCC ). The calculation of the reactive power command Q _REF is performed by the following formula (8). Before explaining the specific calculation method of the invalid power command Q _REF , the generation principle of the voltage variation ΔV _PCC will be described. [0022] The generation principle of the voltage change ΔV _PCC is expressed by a mathematical formula. As shown in FIG. 1, when the effective power P _PCC and the reactive power Q _PCC flow from the interconnection transformer 2 to the interconnection point 5, a variation component ΔV caused by the effective power P _PCC in the voltage V _PCC at the interconnection point 5. _PCC 1, and the variation component ΔV _PCC 2 caused by the reactive power Q _PCC are expressed by equations (1) and (2), respectively. Regarding the positive and negative values of the reactive power, it is assumed that the reactive power flow from the power converter 13 to the interconnection transformer 2 is positive. [0023] [0024] [0025] Here, R _L and X _L are impedance components and reactance components of the impedance of the interconnection line 5, respectively. [0026] The effective power P _PCC and the reactive power Q _PCC at the interconnection point 5 are respectively the effective power output P _CON and the reactive power output Q _{CON of the} power converter 13 minus the effective power loss consumed by the interconnection transformer 2 The values of P _LOSS and reactive power loss Q _{LOSS are} expressed by equations (3) and (4). Yet, with respect to the active power output P _CON, active power loss P _LOSS is the sufficiently small, the power loss can be omitted effective P _LOSS. [0027] [0028] [0029] Here, I _CON is the current output of the power converter 13, and R _TR1 and R _TR2 are the _primary side (close to the wind power system 1) and the secondary side (close to the interconnection point 5) of the interconnection transformer 2 respectively. The impedance components of the impedance, X _TR1 and X _TR2 are the reactance components of the _primary and secondary impedances of the interconnection transformer 2 respectively, and α _TR is the winding number ratio of the interconnection transformer 2. [0030] Substituting equation (3) into equation (1) and bringing equation (4) into equation (2), respectively, to obtain equations (5) and (6). [0031] [0032] [0033] Next, from the expressions (5) and (6), the voltage change ΔV _{PCC of the} interconnection point 5 is expressed as (7). [0034] [0035] An example of the timing waveform of the voltage change ΔV _PCC in the formula (7) is shown in FIG. 3. In the formula (7), the variable that varies according to the fluctuation of the wind speed of the natural energy is the effective power output P _CON and the current output I _CON of the power converter 13. Here, an example when the effective power output P _CON and the current output I _CON fluctuate is shown in FIG. 3. The reactive power Q _CON is 0V _ar and is constant. [0036] Here, R _L varies to some extent due to temperature changes, but the impedance value determined by the type and length of the interconnection line is approximately constant, and V _PCC usually also needs to suppress the voltage variation to Changes within a few percent will still take into account the approximately constant. Therefore, from FIGS. 3 (A), (D), and (5), the voltage fluctuation component ΔV _PCC 1 has a waveform that is approximately proportional to the effective power output P _CON . [0037] The winding number ratio α _TR is a positive constant determined by the interconnection transformer 2. The impedance component R _L of the impedance of the interconnection 5 is a positive constant, and the reactance component X _{L is} based on the inductance. For the sake of sex, it is a positive constant. In other _words , the reactance components X _TR1 and X _TR2 of the impedance of the interconnect transformer 2 are positive constants because the inductance component is dominant. Next, Q _CON = 0 in Equation (6), and I _PCC is represented by the waveform in FIG. 3 (B). Therefore, via Equations 3 (B), (C), (D), and (6), The voltage fluctuation component ΔV _PCC 2 is a waveform obtained by quadraticizing the current output I _CON and inverting the phase (inverting the upper and lower waveforms). [0038] Next, from FIG. 3 (D) and (7) regarding the voltage change, the voltage change ΔV _PCC is a waveform in which the voltage change components ΔV _PCC 1 and ΔV _PCC 2 are combined. [0039] Next, a specific method for determining the invalid power command value Q _REF by the invalid power command determination unit 162 operating as a calculation device will be described. By calculating the invalid power command value Q _REF that allows the following relation to be established, it is possible to suppress the voltage change ΔV _{PCC at} the interconnection point 5 shown in FIGS. 3 (D) and (7). In this embodiment, particularly, as a suitable example, the case where the voltage variation ΔV _{PCC of} the interconnection point 5 is approximately zero is described. However, from the viewpoint of so-called variation suppression, it is preferable that ΔV _PCC is substantially constant. ΔV _PCC = ΔV _PCC 1 + ΔV _PCC 2 = Equation (5) + (6) = 0. Specifically, the reactive power command value Q _REF obtained by equation (8) is used to control the power converter 13 It is better to have a reactive power output Q _CON . That is, the reactive power command determination unit 162 shown in FIG. 2 preferably uses the formula (8) to obtain the reactive power command value Q _REF . Moreover, in the formula (8), in a manner that the impedance ratio (R _L / X _L ) of the interconnection 3 is small, and when the first term is sufficiently small compared to the second and third terms, also The first item can be omitted. [0040] [0041] An example of the timing waveform of the reactive power command value Q _REF in Equation (8) is shown in FIG. 4. The effective power output P _CON and the current output I _CON shown in FIGS. 4A and 4B are the same conditions as those in FIG. 3. As shown in FIG. 4 (C), the effective power output P _CON shown in FIG. 4 (A) and a portion of the invalid power command obtained by the first term of the formula (8) are reversed as shown in FIG. 4 (C). Outputs the waveform of the phase of P _CON (inverts the upper limit of the waveform). In addition, a part of the reactive power command obtained by the current output I _CON shown in FIG. 4 (B) and the second and third terms of the formula (8) becomes a square of the current output I _CON Proportional waveform. Then, the synthesized waveform is the final invalid power command. [0042] Finally, using FIG. 5 and the mathematical formula, the effect of suppressing the voltage change ΔV _PCC of the interconnection point 5 caused by the reactive power controller 16 in the first embodiment will be described. In FIGS. 5 (A) to (C), the reactive power output Q of the power converter 13 under each condition shown in the following formulas (I) to (III) and (9) to (11) is shown The waveforms of the voltage of control _CON , the interconnection point 5 and the voltage variation ΔV _PCC . [0043] (1) A condition that the reactive power Q _CON must be 0 V _ar . [0044] [0045] (II) Conditions to which the reactive power control method of Patent Document 1 is applied. [0046] [0047] (II) The conditions for applying the invalid power control method according to the first embodiment are applied. [0048] [0049] The voltage control amount Y of the interconnection point 5 is obtained by substituting the second term ((X _L / V _PCC ) Q _CON ) of the equation (7) into the equations (9) to (11). Out. The voltage control amount Y under the conditions of (I) to (III) is shown in equations (12) to (13) and FIG. 5 (B). [0050] [0051] [0052] [0053] The voltage change ΔV _PCC suppressed by the voltage control amount Y is to replace the second term ((X _L / V _PCC ) Q _CON ) of the formula (7) to the (12) to (14) ) Formula. The voltage variation ΔV _PCC under the conditions of (I) to (III) is shown in equations (15) to (17) and FIG. 5 (C). [0054] [0055] [0056] [0057] Using the expressions (15) to (17) and FIG. 5 (C), the suppression effect of the voltage change ΔV _PCC caused by the reactive power control method (I) to (III) is compared. After learned with respect to the (I) and (II) of the disabling control power also remains voltage fluctuation ΔV _PCC, in (III) can be suppressed to a voltage fluctuation ΔV _PCC 0V. [0058] According to the first embodiment, in order to suppress the voltage variation of the interconnection point 5, the effective power output and current output of the power converter 13, the impedance ratio of the interconnection line 3, the reactance of the interconnection transformer 2 and The winding ratio method can control the reactive power output of the power converter 13 to an optimum value. As a result, special equipment such as a reactive power compensation device for suppressing a voltage fluctuation at the interconnection point 5 or a transformer with tap changeover becomes unnecessary. In addition, as mentioned above, the impedance ratio of the interconnect 3 is small, and as a result, the first term of the formula (8) is sufficiently small compared to the second and third terms. For the sake of omitting item 1, it is not necessary to consider it. [0059] In addition, the reactive power command value Q _{REF of} the first embodiment may be obtained as follows. [0060] <Modification 1 of Embodiment 1> As represented by the expression (18), the current output I _{CON is} approximated to the reference line voltage V _BASE between the effective power output P _CON and the set point of the sensor 14. [0061] [0062] When the formula (8) is substituted into the formula (18), the formula (19) is obtained. By using the formula (19) to obtain the reactive power command value Q _REF , the current output I _CON can be omitted compared to the formula (8). [0063] [0064] <Modification Example 1 of the Embodiment 2> prior to creating the active power output P _CON correspondence table and the reactive power command value Q _REF, see the table determines the reactive power command value Q _REF. Specifically, as shown in FIG. 6, the reactive power controller 16 a has a configuration in which a reactive power command value table creation unit 166 and a reactive power command value table memory unit 167 are added to the reactive power controller 16. The reactive power command value table preparation unit 166 calculates the reactive power command Q _REF when the valid power output P _{CON is} changed from 0 kW to the maximum output at a specific time using Equation (19). Next, a table corresponding to the effective power output P _CON and the invalid power command Q _{REF is} stored in the invalid power command value table storage unit 167 as shown in FIG. 7. The reactive power command value determination unit 162 determines the reactive power command value Q _{REF by} referring to the table of the reactive power command value table storage unit 167 each time the valid power output P _CON is updated. [Embodiment 2] [0065] FIG. 8 is a configuration diagram of a reactive power controller 16b in a wind power generation system 1 according to Embodiment 2 of the present invention. This embodiment 2 is different from the embodiment 1 in that the wind power generation system 1 (1A, 1B, 1C, 1D) and the interconnection transformer 2 (2I, 2J, 2K) are plural. Furthermore, the reactive power controller 16b differs from the first embodiment in that the reactive power commands Q _REF (Q _{REF_A} , Q _{REF_B} , Q _{REF_C} , and Q _{REF_D} ) of each wind power generation system 1 are determined. In addition, in the following, A, B, C, and D are used as signs to distinguish each wind power generation system 1, and I, J, and K are used as signs to distinguish each interconnected transformer 2. [0066] In this embodiment, the power system side of each power converter of the wind power generation system 1A and the wind power generation system 1B is interconnected. ) Equipped with interconnection transformer 2I. In addition, the power system side interconnections of the power converters of the wind power generation system 1C and the wind power generation system 1D are provided with interconnection transformers after the interconnection (on the power system side than the interconnection points of the two wind power generation systems). 2J. Next, an interconnection transformer 2K is further provided on the power system side of the two interconnection transformers 2I and 2J. The reactive power controller 16b collectively controls the wind power generation systems 1A to 1D. [0067] The configuration of the reactive power controller 16b is different from the reactive power controller 16 of the first embodiment, and has the configuration of FIG. 9. Added to the reactive power controller 16 b are a current collection configuration memory unit 168 that stores a table showing the current collection configuration of the interconnecting transformer 2 and the wind power generation system 1, and a power converter rated output memory that stores the rated output of the power converter 13. The unit 170 and the invalid power allocation determination unit 169 that allocates the invalid power output command Q _REF to the wind power generation system 1. [0068] A method for obtaining the invalid power output command Q _REF of the wind power generation system 1 will be described. [0069] First, a method for determining the total invalid power output command Q _{REF_TOTAL} by the reactive power command determination _{unit 162 b} of the reactive power controller 16 _{b will} be described. As for the determination of the total invalid electric power output instruction Q _{REF_TOTAL} , as shown in the expression (20), the interconnection of the wind power generation system 1 and the plurality of wind power generation systems 1 and the plurality of wind power generation systems 1 corresponding to the expression (8) in the first embodiment is used. Transformer-like function. [0070] [0071] Here, the first term of the formula (20) is the impedance (R _L , X _L ) from the interconnection line 3 and the effective electric power (P _{CON_A} + P _{CON_B} + P) flowing through the interconnection line 3 _{CON_C} + P _{CON_D} ). In addition, items 2 and 3 are the reactances (X _{TR1_I} , X _{TR2_I} ) from the primary and secondary sides of the interconnection transformer 2I, and the current flowing through the primary and secondary sides of the interconnection transformer 2I. (I _{CON_A} + I _{CON_B} , (I _{CON_A} + I _{CON_B} ) / α _I ) Similar to items 2 and 3, items 4 to 7 are the invalid power command values corresponding to the interconnection transformer 2J and the interconnection transformer 2K. Next, the value obtained by adding the reactive power commands obtained in the first to seventh items is the total reactive power output command Q _{REF_TOTAL} . [0072] As in the formula (20), when there are a plurality of wind power generation systems 1 and a plurality of interconnection transformers 2, it is necessary to determine which current of the wind power generation system 1 flows in each interconnection transformer 2. Output I _CON . Here, the reactive power command determination unit 162b of the reactive power controller 16a reads a power collection configuration table showing the power collection configuration of the interconnecting transformer 2 and the wind power generation system 1 from the power collection configuration memory unit 168. An example of the current collector composition table is shown in FIG. 10. In FIG. 10, when a column crossing each of the wind power generation systems 1 and each of the interconnected transformers 2 is indicated by ●, it means that a current output I _{CON of the} wind power generation system 1 flows through the interconnected transformer 2. In this embodiment, the form of interconnection shown in FIG. 8 is adopted, but a different method of interconnection may be used. Also in this case, by referring to the current collector composition table, it can be determined which current output I _{CON of the} wind power generation system 1 flows through each interconnecting transformer 2. [0073] Next, the reactive power allocation determination unit 169 of the reactive power controller 16b shown in FIG. 9 will _explain the reactive power command Q _REF (Q _{REF_A} , Q _{REF_B} , Q _{REF_C} , Q _{REF_D} ) from the total reactive power output command Q _{REF_TOTAL} . Method for distributing to each wind power generation system 1. [0074] The reactive power allocation determination unit 169 is a rated apparent power S _RAT from the power converter 13 of each wind power generation system 1 (1A, 1B, 1C, 1D) stored in the power converter rated output memory unit 170. (S _{RAT_A} , S _{RAT_B} , S _{RAT_C} , S _{RAT_D} ) and the effective power output P _CON (P _{CON_A} , P _{CON_B} , P _{CON_C} , P _{CON_D} ), use Equation (21) to find the power converter of the wind power system 1 The possible amount of reactive power output Q _UL (Q _{UL_A} , Q _{UL_B} , Q _{UL_C} , Q _{UL_D} ). [0075] [0076] Next, in order to make the reactive power command Q _REF ≦ Q _{UL of} each wind power generation system 1, the total reactive power output command Q _{REF_TOTAL is} allocated to each wind power generation system. [0077] According to the second embodiment, in a wind power plant composed of a plurality of wind power generation systems 1 and a plurality of interconnection transformers 2, the effective power output and current output of each wind power generation system are detected, and the interconnection is indicated by using The impedance of line 3, the reactance of individual interconnecting transformers, the collecting configuration of interconnecting transformer 2 and wind power generation system 1 determine the total invalid power output instruction Q _{REF_TOTAL of the} wind power generation system, thereby suppressing the interconnection point. 5 voltage fluctuation. Furthermore, in order to make the total reactive power output command Q _{REF_TOTAL} to each wind power generation system 1 in order to make the reactive power command Q _REF of each wind power generation system 1 below the possible amount of invalid power output Q _UL , it is possible to avoid wind power generation. The capacitance of the power converter 13 of the system 1 is insufficient, and a voltage fluctuation occurs at the interconnection point 5. [Embodiment 3] FIG. 11 is a configuration diagram of a reactive power controller 16c in a wind power plant according to Embodiment 3 of the present invention. The difference between the third embodiment and the second embodiment is the input of the effective power output prediction P _PRE (P _{PRE_A} , P _{PRE_B} , P _{PRE_C} , P _{PRE_D} ) and current output of each wind power generation system 1 output from the power generation output prediction means 6. I _PRE (I _{PRE_A} , I _{PRE_B} , I _{PRE_C} , I _{PRE_D} ) is _predicted to reach the ineffective power controller _{16 c} . [0079] As shown in FIG. 12, the invalid power controller 16c detects the effective power output P _CON and the current output I _{CON of the} wind power generation system 1 when a specific update time (T1 and T2) is reached (FIG. 12 (A), (B)), the reactive power command Q _{REF is} determined from the active power output P _CON and the current output I _CON (FIG. 12 (C)). [0080] With reference to FIG. 12 (C), a description will be given of a case where the reactive power command Q _REF determined at the update time T1 is continued until the next update time T2. The effective power output P _CON and the current output I _{CON of the} wind power generation system 1 change in response to the changing wind speed from time to time. Because of these changes, the ideal reactive power instruction Q _{REF_IDEAL} also changes. The so-called ideal reactive power instruction Q _{REF_IDEAL} is to update the reactive power instruction one by one in _accordance with the changes in the effective power output P _CON and the current output I _CON . For this reason, after the slave update time T1, an alienation occurs between the ideal reactive power command Q _{REF_IDEAL} and the reactive power command Q _REF which continues from the time T1. This alienation reduces the effect of suppressing voltage fluctuations. [0081] Here, in the third embodiment, as shown in FIG. 13, at the update time T1, the future effective power output prediction value P _PRE and the current from the power generation output prediction means 6 to the next update time T2 are obtained. The predicted value I _{PRE is} output. Next, for each of the detected values (P _CON , I _CON ) and predicted values (P _PRE , I _PRE ) of the effective power output and the current output, an invalid power command value Q _{REF is obtained} . In this way, at the update time T1, in order to determine the invalid power command value Q _REF including a future plural time profile, the alienation of the ideal invalid power command Q _{REF_IDEAL} can be reduced. Furthermore, the power generation output prediction means 6 predicts the effective power output prediction value P _PRE and the current output prediction value I _{PRE by} extrapolating linearly from the past detected values of the effective power output P _CON and the current output I _CON . However, the prediction method is not limited to linear extrapolation. [0082] An example of the reactive power command value Q _REF sent from the reactive power controller 16c to each wind power generation system 1 (1A, 1B, 1C, 1D) at time T1 is shown in FIG. 14. In FIG. 14, the invalid power command value Q _REF (30 kVar) at time T1 (0: 00: 00) is obtained from the effective power output P _CON and the current output I _CON detected at time T1. value. Invalid power command value Q _REF (35kVar) for each of time T1.25 (0:02:30), time T1.5 (0:05:00), and time T1.75 (0:07:30) , 40kVar, 45kVar) are values obtained from the effective power output prediction value P _PRE and current output prediction value I _PRE obtained at time T1. [0083] Next, the wind power generation system 1 operates so that the reactive power command value Q _REF and the reactive power output Q _CON at the time shown in FIG. 14 are consistent. For example, it may be the invalid power command value Q _REF for a period from the time later (0: 00:01) to time T1.25 (0:02:29), and the duration T1. (0: 00: 00: 00) The invalid power command value Q _REF (30Var). In addition, the invalid power command value Q _REF (30Var, 35Var) of time T1 (0: 00: 00) and time T1. 25 (0: 02: 30) may be obtained by linearly completing. [0084] In addition, the feature of the third embodiment is that in addition to the detected values of the effective power output and current output of the wind power generation system 1, the future predicted value is used to obtain the invalid power command Q _{REF of} the complex time profile. The method of obtaining the invalid power command value Q _REF at each time profile is the same as that of the first and second embodiments. [0085] According to the third embodiment, compared with the method from updating the invalid power command value until the next update, the output prediction value of the future wind power generation system is used to find the invalidity of the future complex time profile. The power command value method can improve the performance of the voltage fluctuation suppression control. [Embodiment 4] As the first to third embodiments, the wind power generation system 1 related to the natural energy power generation system has been described, but it is not necessarily limited to this. As a fourth embodiment, a case where a natural energy power generation system is used as the solar power generation system 7 will be described using FIGS. 15 to 17. In addition, as a natural energy power generation system, a wind power generation system and a solar power generation system are representative. Although the embodiment is exemplified, it is not limited thereto. 15 is a diagram showing the overall configuration of a photovoltaic power generation system 7 in a fourth embodiment. FIG. 16 is a diagram showing the overall configuration of a solar power plant equipped with a plurality of the photovoltaic power generation systems of FIG. 15 and having a reactive power central controller that determines the reactive power command of each photovoltaic power generation system. FIG. 17 is a diagram showing the overall configuration of the power generation output prediction means added to FIG. 16. [0088] FIG. 15 shows a configuration of a photovoltaic power generation system corresponding to FIG. 1 (Example 1). FIG. 16 shows the configuration of a solar power plant corresponding to FIG. 8 (Example 2). FIG. 17 shows the configuration of a solar power plant corresponding to FIG. 11 (Embodiment 3). [0089] The difference between FIG. 1 and FIG. 15 is the difference between whether the power generation system installed in the natural energy power generation system is a wind power generation system 1 or a solar power generation system 7. The wind turbine 11 and the generator 12 in FIG. 1 are equivalent to the solar cell 71 in FIG. 15. The power converter 12 for a wind turbine in FIG. 1 corresponds to the power converter 72 for a photovoltaic power generation device in FIG. 15. The effective power controller 15 for wind power generation in FIG. 1 corresponds to the effective power controller 74 for solar power generation in FIG. 15. The pitch angle, wind speed, and the like obtained from the wind turbine 11 by the effective power controller 15 for wind power generation in FIG. 1 correspond to the voltage and current generated from the solar cell 71 in FIG. 15. The reactive power controller 16 for wind power generation in FIG. 1 corresponds to the reactive power controller 75 for solar power generation in FIG. 15. The wind power generation sensor 14 in FIG. 1 corresponds to the solar power generation sensor 73 in FIG. 15. Similarly, the difference between FIG. 8 and FIG. 16 and the difference between FIG. 11 and FIG. 17 are also differences between the wind power generation system 1 and the solar power generation system 7. Otherwise, the same reference numerals are assigned to the same elements, and the description will not be made here. [0090] The structure of each of FIGS. 15 to 17 and these functions and effects are the same as those described in the first to third embodiments, and detailed descriptions are omitted, but the first to third embodiments are described. The effect of the wind power generation system of the present invention is also the same in the solar power generation system of this embodiment. [0091] The present invention is not limited to the above-mentioned embodiments 1 to 4, and includes various modifications. For example, the above-mentioned embodiments are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the structures described. In addition, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment, and the configuration of one embodiment may be added to the configuration of another embodiment. In addition, a part of the configuration of each embodiment can be added, deleted, or replaced with another configuration. [0092] In addition, each of the above-mentioned structures, functions, processing units, and processing means may be implemented in hardware by designing a part or all of them by, for example, designing an integrated circuit. In addition, the above-mentioned various structures, functions, etc., can also be implemented by software by means of analyzing and executing a program that implements each function through a processor. Information such as programs, forms, and files that implement various functions can be placed in recording devices such as memory, hard disks, or SSDs (solid-state devices), or recording media such as IC cards, SD cards, and DVDs.

[0093]

1‧‧‧wind power system

2‧‧‧interconnect transformer

3‧‧‧ Interconnect

4‧‧‧ Power System

5‧‧‧ interconnection point

6‧‧‧Prediction methods of power output

7‧‧‧Solar Power Generation System

11‧‧‧wind turbine

12‧‧‧ Generator

13‧‧‧Power Converter

14‧‧‧Sensor

15‧‧‧Effective Power Controller

16‧‧‧Invalid power controller

71‧‧‧solar battery

72‧‧‧ Power converter for solar power generation equipment

73‧‧‧Sensor for solar power generation device

74‧‧‧Effective power controller for solar power generation

75‧‧‧Invalid power controller for solar power

161‧‧‧Receiving Department

162‧‧‧Invalid power instruction decision department

163‧‧‧Interconnection parameter memory

164‧‧‧Interconnect transformer parameter memory

165‧‧‧Department

166‧‧‧ Invalid power instruction value table creation department

167‧‧‧Invalid power instruction value table memory

168‧‧‧ Collector constitutes memory department

169‧‧‧Invalid power allocation decision department

170‧‧‧Power converter rated output memory

[0016] FIG. 1 is a diagram showing an overall configuration of a wind power generation system in Embodiment 1. [Fig. 2] Fig. 2 is a diagram showing a configuration of a reactive power controller in the first embodiment. [Fig. 3] A graph for explaining the voltage change of the interconnection point in Example 1, (A) is a time variation of the effective power of the interconnection point, and (B) is a time variation of the current of the interconnection point, ( C) is the time change of the reactive power output of the power converter, and (D) is the time change of the voltage change of the interconnection point. [Fig. 4] A diagram for explaining a method for determining a reactive power command value in Embodiment 1. (A) is a time change of an effective power output of a power converter, and (B) is a time of a current output of the power converter. Change, (C) is the invalid power command of the power converter. [Fig. 5] A graph for explaining the effect of suppressing the voltage variation of the interconnection point in Example 1, (A) is the time change of the reactive power output of the power converter, and (B) is the power control amount of the interconnection point (C) is the time change of the voltage change of the interconnection point. [Fig. 6] Fig. 6 is a diagram showing a configuration of a reactive power controller in a second modification of the first embodiment. [Fig. 7] Fig. 7 is a diagram showing an example of a table stored in the invalid power command value table storage unit in the second modification of the first embodiment. [Fig. 8] A diagram showing the overall configuration of a wind power plant in Example 2. [Fig. 9] Fig. 9 is a diagram showing a configuration of a reactive power central controller in the second embodiment. [Fig. 10] Fig. 10 is a diagram showing an example of a table of a current storage configuration memory unit stored in the second embodiment. [Fig. 11] A diagram showing the overall configuration of a wind power plant equipped with the power generation output prediction means in the third embodiment. [Fig. 12] A graph for explaining the problem of the invalid power instruction in Example 3. (A) is a time change of effective power output of the power converter, (B) is a time change of current output of the power converter, (C ) Is the time change of the reactive power command value of the power converter. [Fig. 13] A diagram for explaining a method for determining an invalid power command value in Embodiment 3. (A) is a change in effective power output time of the power converter, and (B) is a change in current output time of the power converter. (C) is the time change of the reactive power command value of the power converter. [Fig. 14] is a table for explaining an invalid power command in the third embodiment. [Fig. 15] Fig. 15 is a diagram showing the overall configuration of a photovoltaic power generation system in Embodiment 4. [Fig. 16] A diagram showing the overall configuration of a solar power plant in Example 4. [Fig. [Fig. 17] Fig. 17 is a diagram showing the overall configuration of a solar power plant equipped with a power generation output prediction method in Embodiment 4.

Claims (10)

A natural energy power generation system includes: a power generation device that generates electricity by receiving natural energy; a power converter that is electrically connected to the power generation device and the power system; an interconnecting transformer that is disposed between the power converter and the foregoing Between power systems; and a reactive power controller that generates a reactive power instruction output from the power converter; the reactive power controller includes a reactive power instruction determination unit that is configured using the At least one of the reactance of the interconnection transformer between the power converter and the power system, and the current or effective power output by the power converter, in order to make the voltage of the interconnection point between the power converter and the power system The sum of the variation component caused by the effective power in the above and the variation component caused by the invalid power in the foregoing interconnection point voltage is constant, and the foregoing invalid power instruction is determined. For example, in the natural energy power generation system according to claim 1, wherein the invalid power controller further uses the impedance ratio of the interconnection line between the power converter and the power system to determine the invalid power instruction. For example, the natural energy power generation system according to item 2 of the present invention includes: a control table creation unit that generates at least one of the current or the effective power from the effective power, the reactance, and the impedance ratio, and invalidates A control table for establishing a corresponding power command value; and a control table memory section that stores the foregoing control table; the invalid power command determination section uses at least one of the control table and the current or the valid power to determine the invalid power Instruction value. For example, the natural energy power generation system according to item 2 or item 3, comprising: a plurality of the aforementioned power generating devices, a plurality of the aforementioned power converters, and a plurality of the aforementioned interconnecting transformers; and the aforementioned ineffective power controller, comprising: The current collection configuration table memory unit is a table representing the current collection structure of the interconnecting transformer and the power converter; the invalid power instruction determining unit uses at least one of the current or the valid power, and the mutual power. The reactance of the transformer, the impedance ratio of the interconnection lines, and the current collector composition table are used to determine the invalid power command value. The natural energy power generation system according to claim 4, wherein the reactive power controller includes a reactive power output allocation determining unit that calculates the power conversion from the maximum apparent power of the power converter and the valid power. The possible amount of reactive power output of the generator is to determine the allocation of the invalid power command value to the plurality of power converters, so that the value of the invalid power command is equal to or less than the possible amount of invalid power output. In the natural energy power generation system according to any one of claims 1 to 3, wherein the invalid power controller includes: obtaining at least one of the predicted current value of the power converter or the predicted effective power value; Means; the invalid electric power command determining unit determines the invalid electric power command value of a plurality of time profiles from the effective electric power predicted value. The natural energy power generation system according to any one of the items 1 to 3, wherein the aforementioned power generation device is a wind power generation device. The natural energy power generation system according to any one of claims 1 to 3, wherein the aforementioned power generation device is a solar power generation device. An invalid power controller is provided with a calculation device which is caused by effective power in an interconnection point voltage of a power converter electrically connected to a power system and a power converter electrically connected to the power system in order to receive natural energy. The sum of the fluctuation component and the fluctuation component caused by the reactive power in the voltage at the interconnection point is constant, and the reactive power command output by the power converter is generated; and the reactive power instruction determination unit uses the power At least one of the reactance of the interconnecting transformer between the converter and the power system, and the current or effective power output by the power converter determines the invalid power command. A control method for a natural energy power generation system. The natural energy power generation system includes: a power generation device that generates power by receiving natural energy; a power converter that is electrically connected to the power generation device and the power system; an interconnecting transformer that Disposed between the power converter and the power system; and a reactive power controller that generates a reactive power command output by the power converter; and is characterized by using the power converter disposed between the power converter and the power system At least one of the reactance of the interconnection transformer, the current output by the power converter, or the effective power, in order to make the variation component caused by the effective power in the voltage at the interconnection point between the power converter and the power system The sum of the fluctuation components caused by the reactive power in the aforementioned interconnection point voltage is constant, and the aforementioned reactive power instruction is determined.