JP2010178495A - Power conversion apparatus and power conversion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion apparatus capable of carrying out maintenance of a storage battery, while keeping its original functions as the power conversion apparatus, and to provide a power conversion system that uses the power conversion apparatus. <P>SOLUTION: The power conversion apparatus includes power converters 4a, 4b, and 4c and an overall control unit 3. The power converters 4a, 4b, and 4c each have a battery pack 91 and a PWM converter 8. When there is no need for maintenance of the battery pack 91, the overall control unit 3 executes a regular process of causing each PWM converter 8 of each power converter 4, to adjust an amount of power input/output to/from a transmission line Lu. When a need for maintenance of any one of the battery packs 91 of each power converter 4 arises, the overall control unit executes a maintenance process of causing the PWM converters 8 of the power converters 4, other than the power converter 4, including the battery pack 91 that needs maintenance work, to adjust the amount of power input/output to/from the transmission line Lu. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power conversion device that adjusts power supply to a load using a storage battery, and a power conversion system using the same.

  In a distribution system to which many inductive loads are connected, a delay power factor results, so that reactive power flows through the distribution system and the system voltage becomes unstable. In the future, it is expected that the introduction of distributed power sources will be actively promoted in various forms, and voltage fluctuations in the distribution system accompanying this may be a major problem. On the other hand, a reactive power compensator has been proposed as a measure for improving the stability and power factor of the distribution system. Among these, the self-excited reactive power compensator is capable of continuous reactive power control from the late phase to the advanced phase and has an advantage that it is difficult to generate harmonics (see, for example, Non-Patent Document 1). .

  From the viewpoint of environmental consideration, power generation using natural energy such as wind power generation and solar power generation is attracting attention. However, these power generation amounts vary irregularly depending on wind speed and sunshine hours because natural energy is used. Therefore, in order to supply stable power to the distribution system, a technique for leveling the fluctuating power by installing a distributed power supply in the vicinity is known (for example, see Non-Patent Document 2).

  Such a reactive power compensator and a distributed power source that performs fluctuation power leveling are provided with a plurality of storage batteries for storing electric power, and the reactive power can be compensated by controlling charging and discharging of the storage batteries. , Or power leveling. Since charging / discharging to / from the storage battery is performed with direct current, such reactive power compensator and distributed power source are configured using a power conversion device that mutually converts alternating current power and direct current power.

In addition, such a storage battery is generally configured as an assembled battery in which a plurality of secondary batteries are connected in series in order to output a voltage required by the power system.
"6.6 kV Transformerless Cascade PWM STATCOM Three-phase 200V 10kVA Mini Model Operation Verification", 2007 IEEJ Transaction D, P781-788 “Wind Farm Output Averaging Technology-Technology Development for Wind Power Generation System Stabilization,” The Institute of Electrical Engineers of Japan, VOL125, NO, 11, NOV2005, pp. 708-711

  However, in the power conversion device described above, when a variation in capacity or a failure occurs between a plurality of secondary batteries constituting the assembled battery, an equalization process for aligning the terminal voltages of the secondary batteries is performed. In order to perform maintenance such as replacement of assembled batteries, it is necessary to stop the power converter once, and it is necessary to stop the operation for the purpose of reactive power compensation and power leveling, which are the original purpose. was there.

  The objective of this invention is providing the power converter device which can perform the maintenance of a storage battery, and a power conversion system using the same, maintaining the original function of a power converter device.

  A power converter according to the present invention includes a plurality of power converters connected in series between phases of a power transmission line that transmits AC power, and an amount of power input / output between each power converter and the power transmission line. Each of the power converters mutually converts the storage battery, AC power input / output from / to the power transmission line, and power charged / discharged by the storage battery, and A converter that adjusts the amount of electric power input / output between the electric wire and the storage battery, and the power control unit is configured so that each storage battery of each power converter has no need for maintenance. Each converter of the converter performs normal processing for adjusting the amount of power input / output to / from the power transmission line, and maintenance is required for one of the storage batteries of each power converter. If the maintenance By each conversion unit of the power converter remaining except the power converter including a storage battery principal occurs, executes the maintenance processing for adjusting respectively the amount of power input and output to and from the transmission line.

  According to this structure, the some power converter provided with the storage battery is connected in series between the phases of the transmission line which transmits alternating current power. If any of the storage batteries needs to be maintained, the converters of the remaining power converters other than the power converter including the storage battery that requires the maintenance need to be connected to the transmission line. Maintenance processing is performed to adjust the amount of power output, so even if the power adjustment operation by the power converter that requires maintenance is stopped for maintenance, the other power converters As a result of being able to adjust the amount of power input / output between the two, the maintenance of the storage battery can be performed while maintaining the original function of the power conversion device.

  Further, in the normal process, the power control unit is configured so that the total amount of power input / output to / from the power transmission line by each conversion unit of each power converter becomes a predetermined target power amount. The amount of power input / output to / from the power transmission line is adjusted by each conversion unit, and in the maintenance process, the total amount of power input / output to / from the power transmission line by each conversion unit is The amount of power input / output to / from the transmission line by each conversion unit of the remaining power converter excluding the power converter including the storage battery in which the maintenance is required is set so that the target power amount is reached. It is preferable to adjust.

  According to this configuration, in the maintenance process, the storage battery in which maintenance is required so that the total amount of power input / output to / from the transmission line by each conversion unit becomes the same target power amount as that in the normal process The remaining converters, including power converters, each adjust the amount of power input to and output from the transmission line, so power adjustment operations by power converters that require maintenance are maintained for maintenance. Even if it is stopped, the amount of power input / output to / from the transmission line by other power converters can be adjusted to the same target power amount as during normal processing. While maintaining the function, the storage battery can be maintained.

  Further, the storage battery is an assembled battery including a plurality of secondary batteries, and each power converter detects an imbalance in the terminal voltage of each secondary battery and detects the imbalance, An imbalance detection unit that notifies the power control unit that the imbalance has been detected is provided, and when the power control unit is notified by the imbalance detection unit that the imbalance has been detected, the imbalance is detected. It is preferable to determine that the maintenance needs have occurred in the detected storage battery.

  According to this configuration, when the imbalance detection unit detects a terminal voltage imbalance in the plurality of secondary batteries included in each power converter, the power control unit performs maintenance on the storage battery in which the imbalance is detected. The amount of power input / output to / from the transmission line is adjusted by each conversion unit of the remaining power converter excluding the power converter including the storage battery in which the imbalance is detected. Therefore, even if the power adjustment operation by the power converter in which an imbalance has occurred is stopped for maintenance, the amount of power input / output to / from the transmission line by another power converter As a result, the storage battery in which an imbalance has occurred can be maintained while maintaining the original function of the power conversion device.

  Moreover, you may make it the said electric power control part determine with the said need for the maintenance having arisen for every set time set beforehand about each of these storage batteries.

  According to this configuration, the power control unit determines that maintenance is required for each of the plurality of storage batteries every preset time. And the maintenance process which adjusts each electric energy inputted / outputted with a power transmission line by each conversion part of the remaining power converters except the power converter containing the storage battery judged that the need of the maintenance concerned arises, respectively Therefore, even if the power adjustment operation by the power converter is periodically stopped for maintenance, the amount of power input / output to / from the transmission line can be adjusted by another power converter. As a result, the storage battery can be regularly maintained while maintaining the original function of the power conversion device.

  In addition, during the execution period of the maintenance process, a set current preset to a value suitable for charging the storage battery is supplied to the storage battery by a conversion unit in a power converter including the storage battery in which the maintenance is required. It is preferable to further include a maintenance charge control unit for charging.

  According to this configuration, power that is input / output to / from the transmission line by each conversion unit of the remaining power converter excluding the power converter including the storage battery in which maintenance is required during the maintenance process. In parallel with each adjustment of the amount, a setting current preset to a value suitable for charging the storage battery is supplied to the storage battery by the conversion unit in the power converter including the storage battery in which maintenance is required, Each secondary battery in which the terminal voltage imbalance is detected is charged. And when all the secondary batteries are fully charged until they are fully charged, the Neumann charging reaction causes the terminal voltage of each secondary battery to be aligned with the substantially full charge voltage. The terminal voltage imbalance can be reduced while maintaining the function.

  In the maintenance process, the power control unit includes an amount of power for supplying the set current by a conversion unit in a power converter including a storage battery in which the maintenance is required, and a storage battery in which the maintenance is required. The maintenance needs to occur so that the total amount of power input / output to / from the transmission line by each conversion unit of the remaining power converters excluding power converters including the power converter becomes the target power amount. It is preferable that the amount of power input / output to / from the power transmission line is adjusted by each conversion unit of the remaining power converter excluding the power converter including the storage battery.

  According to this configuration, the power amount input / output to / from the transmission line by each power converter, including the power for supplying the set current to the storage battery in which maintenance is required, matches the target power amount. Can be made.

  The plurality of secondary batteries are preferably alkaline secondary batteries.

  An alkaline secondary battery is suitable as the secondary battery because it generates a Neumann charging reaction.

  Further, an SOC detection unit for detecting the SOC of the storage battery in each power converter, and an average SOC of the SOC of each storage battery detected by the SOC detection unit without the need for maintenance In accordance with the difference between the SOC average unit calculated as, the average SOC calculated by the SOC average unit in the normal process and the maintenance process, and the SOC of each storage battery detected by the SOC detection unit, If the SOC of the storage battery is smaller than the average SOC, the storage battery having a larger difference is larger if the SOC of each storage battery is larger than the average SOC so that the storage battery having a larger difference has a larger charge power amount and a smaller discharge power amount. Adjustment of the amount of power by the power control unit so that the amount of charging power is small and the amount of discharging power is large. It is preferable to further comprising a SOC control unit to perform.

  According to this configuration, the SOC detection unit detects the SOC of the storage battery in each power converter, and the average value of the SOC of the storage battery that does not require maintenance out of the SOC of each storage battery detected by the SOC detection unit is The average SOC is calculated by the SOC average unit. Then, according to the difference between the average SOC and the SOC of each storage battery, if the SOC of each storage battery is smaller than the average SOC, the storage battery with a larger difference will have a larger amount of charging power and a smaller amount of discharging power. If the SOC of each storage battery is larger than the average SOC, the amount of power input / output between the transmission line and the storage battery is adjusted so that the storage battery with the larger difference has a smaller charge power amount and a larger discharge power amount. The

  If it does so, as for the storage battery in which SOC is smaller than average SOC, charge power will increase at the time of charge, and charge power will decrease at the time of discharge. On the other hand, a storage battery with an SOC greater than the average SOC has a reduced charge power during charging and an increased charge power during discharge. As a result, the SOC of each storage battery is brought close to the average SOC, so that variation in SOC among the storage batteries is reduced.

  Further, in the power conversion system according to the present invention, the AC power is multiphase AC power, and the power conversion system includes a plurality of the power conversion devices described above corresponding to the respective phases in the multiphase AC power. An SOC detection unit that detects the SOC of the storage battery in each power converter of the device, and an average value of the SOC of the storage battery that does not require maintenance among the SOCs of each storage battery detected by the SOC detection unit, An SOC average unit that calculates an average SOC for each conversion device, and an overall SOC average unit that calculates an SOC average value of the storage battery that is included in the plurality of power conversion devices and that does not require maintenance, as an SOC target value; In the normal process and the maintenance process, the SOC target value calculated by the overall SOC average part and the SOC average part If the average SOC is smaller than the SOC target value according to the difference from the average SOC calculated for each power converter, the power converter having a larger difference has a larger charge power and a smaller discharge power. As such, if the average SOC is larger than the SOC target value, the power control unit adjusts the power amount so that the power converter having a larger difference has a smaller charge power amount and a larger discharge power amount. And an overall SOC control unit.

  According to this configuration, the SOC of the storage battery in each power converter is detected by the SOC detection unit, and the SOC of each storage battery that does not require maintenance is averaged for each power converter by the SOC averaging unit. An average SOC for each device is calculated. Moreover, the average value of the SOC of each storage battery that does not require maintenance included in the plurality of power conversion devices is calculated as the SOC target value by the overall SOC averaging unit. Then, according to the difference between the SOC target value and the average SOC for each power converter, if the average SOC is smaller than the SOC target value, the power converter having a larger difference has a larger charge power amount and a higher discharge power amount. If the average SOC is larger than the SOC target value so as to decrease, the power conversion device with a larger difference will be input / output between the transmission line and the storage battery so that the amount of charging power is smaller and the amount of discharging power is larger. The amount of power is adjusted.

  If it does so, each storage battery of a power converter device whose average SOC is smaller than a SOC target value will increase charge power at the time of charge, and decrease charge power at the time of discharge. On the other hand, each storage battery of the power conversion device whose average SOC is larger than the SOC target value is reduced in charging power during charging and increased in charging power. As a result, the average SOC of each power converter is brought close to the SOC target value, and as a result, variation in the average SOC among the power converters is reduced.

  Moreover, it is preferable that the said power transmission line is Y-connected three-phase alternating current wiring, and each said power converter device is interposed between each phase and neutral point in the said three-phase alternating current.

  According to this configuration, the storage battery can be maintained while maintaining the original function of the power conversion device that performs power adjustment in the Y-connected three-phase AC power supply system.

  The power transmission line may be a Δ-connected three-phase AC wiring, and the power conversion device may be interposed between the phases in the three-phase AC.

  According to this configuration, the storage battery can be maintained while maintaining the original function of the power conversion device that performs power adjustment in the Δ-connected three-phase AC power supply system.

  In the power conversion device having such a configuration, a plurality of power converters including storage batteries are connected in series between phases of a transmission line that transmits AC power. If any of the storage batteries needs to be maintained, the converters of the remaining power converters other than the power converter including the storage battery that requires the maintenance need to be connected to the transmission line. Maintenance processing is performed to adjust the amount of output power, so even if the power adjustment operation by the power converter that requires maintenance is stopped for maintenance, the power transmission line is As a result of adjusting the amount of power input / output between the storage battery and the battery, maintenance of the storage battery can be performed while maintaining the original function of the power conversion device.

  Further, in the power conversion system having such a configuration, the SOC detection unit detects the SOC of each storage battery in each power converter, and the SOC averaging unit calculates the SOC of each storage battery that does not require maintenance for each power conversion device. To calculate the average SOC for each power converter. Moreover, the average value of the SOC of each storage battery that does not require maintenance included in the plurality of power conversion devices is calculated as the SOC target value by the overall SOC averaging unit. Then, according to the difference between the SOC target value and the average SOC for each power converter, if the average SOC is smaller than the SOC target value, the power converter having a larger difference has a larger charge power amount and a higher discharge power amount. If the average SOC is larger than the SOC target value so as to decrease, the power conversion device with a larger difference will be input / output between the transmission line and the storage battery so that the amount of charging power is smaller and the amount of discharging power is larger. The amount of power is adjusted.

  If it does so, each storage battery of a power converter device whose average SOC is smaller than a SOC target value will increase charge power at the time of charge, and decrease charge power at the time of discharge. On the other hand, each storage battery of the power conversion device whose average SOC is larger than the SOC target value is reduced in charging power during charging and increased in charging power. As a result, the average SOC of each power converter is brought close to the SOC target value, and as a result, variation in the average SOC among the power converters is reduced.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a block diagram illustrating an example of a configuration of a power system including a power conversion system according to an embodiment of the present invention.

  The power system 100 illustrated in FIG. 1 includes a power generation device 101 and a load device 102 in which three-phase AC transmission lines Lu, Lv. Lw, for example, Y-connected power transmission lines Lu, Lv. The power conversion system 1 is connected between Lw.

  The power conversion system 1 includes power conversion clusters 2u, 2v, and 2w and an overall control unit 3 (power control unit). The power conversion cluster 2u is connected between the U-phase transmission line Lu and the three-phase neutral point P0, and the power conversion cluster 2v is connected between the V-phase transmission line Lv and the neutral point P0. The power conversion cluster 2w is connected between the W-phase power transmission line Lw and the neutral point P0.

  That is, power conversion clusters 2u and 2v are connected between the U phase and the V phase, power conversion clusters 2v and 2w are connected between the V phase and the W phase, and power is supplied between the V phase and the U phase. Conversion clusters 2w and 2u are connected.

  The power generation apparatus 101 outputs information indicating the generated power to the overall control unit 3 as a power generation amount Pg (power supply amount). In addition, the load device 102 outputs information indicating power consumption to the overall control unit 3 as power consumption Pc (power consumption).

  The overall control unit 3 then determines the power conversion clusters 2u, 2v, 2w and the power transmission lines Lu, Lv., In accordance with the power generation amount Pg, the power consumption Pc, and the signals obtained from the power conversion clusters 2u, 2v, 2w. Controls the amount of power input to and output from Lw. Further, when it is determined by at least one of the imbalance detection units 922 described below that an imbalance has occurred, the overall control unit 3 performs a maintenance process to reduce the imbalance.

  In this case, the power conversion cluster 2u and the overall control unit 3, the power conversion cluster 2v and the overall control unit 3, and the power conversion cluster 2w and the overall control unit 3 respectively correspond to examples of the power conversion device in the claims. . A part of the overall control unit 3 may be incorporated in the power conversion clusters 2u, 2v, 2w to constitute a power conversion device.

  FIG. 2 is a block diagram illustrating an example of the configuration of the power conversion system 1 and the power conversion cluster 2u illustrated in FIG. The power conversion cluster 2u illustrated in FIG. 2 includes a current detector 5, a reactor 6, a voltage detector 7, and power converters 4a, 4b, and 4c. And it is connected from the power transmission line Lu to the neutral point P0 through the current detector 5, the reactor 6, and the power converters 4a, 4b, 4c.

  The power conversion clusters 2v and 2w are both configured in the same manner as the power conversion cluster 2u, and thus detailed description thereof is omitted.

  The power converters 4a, 4b, and 4c are configured similarly to each other, and each include a single-phase full-bridge voltage source PWM converter 8 (converter), a battery pack 9, a capacitor 10, and a DC voltage detector 11. Has been. In FIG. 2, only the configuration of the power converter 4 a is illustrated, and the internal configuration of the power converters 4 b and 4 c is the same as that of the power converter 4 a and is not illustrated.

  In the following description, when the power conversion clusters 2u, 2v, 2w are generically referred to, the subscript is omitted and described as the power conversion cluster 2, and when referring to an individual configuration, a reference numeral with a subscript is added. It shows with. In addition, when referring to the power converters 4a, 4b, and 4c included in the power conversion clusters 2u, 2v, and 2w, the subscripts are omitted and described as the power converter 4, and when referring to individual configurations, they are appended. It is indicated by a reference sign with a letter.

  The single-phase full-bridge voltage source PWM converter 8 is configured by connecting a series circuit of switching elements Q1 and Q2 and a series circuit of switching elements Q3 and Q4 in parallel in a bridge shape. The connection point P1 of the switching elements Q1 and Q2 and the connection point P2 of the switching elements Q3 and Q4 are used as an AC side input / output terminal of the single-phase full-bridge voltage source PWM converter 8, that is, an input / output terminal of the power converter 4. .

  Further, a parallel circuit of the capacitor 10, the DC voltage detection unit 11, and the battery pack 9 is connected between the connection point P3 of the switching elements Q1 and Q3 and the connection point P4 of the switching elements Q2 and Q4. In this case, the connection points P3 and P4 are the DC side input / output terminals of the single-phase full-bridge voltage source PWM converter 8.

  As the switching elements Q1, Q2, Q3, and Q4, for example, semiconductor switching elements such as IGBTs (Insulated Gate Bipolar Transistors) are used.

  And the connection point P1 of the power converter 4a is connected to the transmission line Lu via the reactor 6 and the current detector 5 without a transformer, and the connection point P2 of the power converter 4a is connected to the connection point P1 of the power converter 4b. The connection point P2 of the power converter 4b is connected to the connection point P1 of the power converter 4c, and the connection point P2 of the power converter 4c is connected to the neutral point P0, so that the power converters 4a and 4b are connected. , 4c are connected in cascade to each other in the single-phase full-bridge voltage source PWM converter 8, and power converters 4a, 4b, 4c are connected in series. In this way, the power converters 4a, 4b, 4c connected in series are connected to the power transmission line Lu via the current detector 5 and the reactor 6.

  A voltage detector 7 is connected in parallel with the series circuit of the current detector 5, the reactor 6, and the power converters 4a, 4b, and 4c. The voltage detector 7 is configured using, for example, a voltage dividing resistor. The voltage detector 7 detects, for example, by dividing the U-phase voltage (voltage between the transmission line Lu and the neutral point P0), and the divided voltage is a voltage indicating the U-phase instantaneous voltage value. The value Vu is output to the overall control unit 3.

  Similarly, the voltage detector 7 in the power conversion cluster 2v detects the V-phase voltage and outputs the voltage value Vv to the overall control unit 3. The voltage detector 7 in the power conversion cluster 2w And the voltage value Vw is output to the overall control unit 3.

  Each current detector 5 in each of the power conversion clusters 2u, 2v, 2w detects a current input / output to / from each power conversion cluster and, for example, controls the current values Iu, Iv, Iw whose instantaneous values are indicated by analog signals. Output to part 3.

  FIG. 3 is a block diagram showing an example of the detailed configuration of the battery pack 9 shown in FIG. The battery pack 9 shown in FIG. 3 includes an assembled battery 91, a battery control unit 92, a battery voltage detection unit 93, and a battery current detector 94.

  The assembled battery 91 is configured, for example, by connecting a plurality of battery blocks 911, 912, 913, 914, and 915 in series. Further, each of the battery blocks 911, 912, 913, 914, and 915 is configured by connecting, for example, Ni-MH batteries (nickel metal hydride secondary batteries) 20 cells, series, parallel, or a combination of series and parallel. ing.

  The unit cells constituting the battery blocks 911, 912, 913, 914, and 915 are not limited to nickel hydride secondary batteries, and various secondary batteries can be used, and the number of unit cells is not limited to 20 cells. Further, the number of battery blocks is not limited to five. For example, each of the battery blocks 911, 912, 913, 914, and 915 may be composed of one unit cell.

  When alkaline secondary batteries such as nickel metal hydride secondary batteries and nickel cadmium secondary batteries are used, the dispersion of terminal voltage between the secondary batteries is reduced by using the Neumann charging reaction described later. Easy to do.

  The assembled battery 91 corresponds to an example of a storage battery in the claims, and the battery blocks 911, 912, 913, 914, and 915 correspond to an example of a secondary battery in the claims.

  The battery current detector 94 includes, for example, a current detecting shunt resistor, a current transformer, and an analog-digital converter. Then, the battery current detector 94 outputs, for example, a signal indicating the charging current of the assembled battery 91 with a positive current value Ib and the discharging current with a negative current value Ib to the battery control unit 92.

  The battery voltage detection unit 93 includes, for example, block voltage detectors 931, 932, 933, 934, and 935 that detect terminal voltages of the battery blocks 911, 912, 913, 914, and 915. Each of the block voltage detectors 931, 932, 933, 934, and 935 includes a voltage dividing circuit that divides the terminal voltage of the corresponding battery block, an analog-digital converter, and the like.

  The block voltage detectors 931, 932, 933, 934, 935 send signals representing the terminal voltages Vb1, Vb2, Vb3, Vb4, Vb5 of the battery blocks 911, 912, 913, 914, 915 to the battery control unit 92. Output.

  The battery voltage detector 93 and the battery current detector 94 may not include an analog-digital converter, and the battery controller 92 may include an analog-digital converter. In addition, a filter circuit or an insulating circuit may be provided between the battery voltage detector 93 or the battery current detector 94 and the battery controller 92.

  The positive electrode of the assembled battery 91 (positive electrode of the battery block 911) is connected to the connection point P3 via the battery current detector 94, and the negative electrode of the assembled battery 91 (negative electrode of the battery block 915) is connected to the connection point P4. Yes.

  The battery control unit 92 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a nonvolatile ROM (Read Only Memory) in which a predetermined control program is stored, and a RAM (temporarily storing data). Random Access Memory), a communication unit 923, a peripheral circuit thereof, and the like. The battery control unit 92 functions as the SOC detection unit 921 and the imbalance detection unit 922 by executing a control program stored in the ROM, for example.

  The SOC detection unit 921 detects SOC (State Of Charge), which is the ratio of the charge amount to the full charge capacity of the assembled battery 91, and sends a signal SOC (u1) indicating the value of the SOC via the communication unit 923. Output to the overall control unit 3. As the SOC detection method, the current value Ib detected by the battery current detector 94 is integrated, or the SOC is estimated from the terminal voltages Vb1, Vb2, Vb3, Vb4, Vb5 detected by the battery voltage detector 93. A method or the like is used.

  Similarly, SOC detection unit 921 in power converter 4b outputs signal SOC (u2) to overall control unit 3, and SOC detection unit 921 in power converter 4c provides signal SOC (u3) to overall control unit 3. Output.

  The imbalance detection unit 922 determines the degree of variation (unbalance) of each terminal voltage based on the terminal voltages Vb1, Vb2, Vb3, Vb4, and Vb5 detected by the battery voltage detection unit 93. Specifically, the imbalance detection unit 922 is configured such that the terminal voltage Vb1, Vb2, Vb3, Vb4, Vb5 has a variance value or a voltage difference between arbitrary terminal voltages, for example, the maximum of the terminal voltages Vb1, Vb2, Vb3, Vb4, Vb5. The difference between the value and the minimum value is measured, and if the difference is equal to or greater than a predetermined determination value, it is determined that an imbalance of the terminal voltage has occurred and a maintenance process by the overall control unit 3 is requested. Determination result information Mu1 to Mu3, Mv1 to Mv3, Mw1 to Mw3 indicating that an imbalance has occurred is output to the overall control unit 3 via the communication unit 923.

  In this case, the occurrence of imbalance means that maintenance is necessary.

  The communication unit 923 is, for example, a serial or parallel communication interface circuit, and the SOC of the assembled battery 91 obtained by the SOC detection unit 921 and the imbalance determination results Mu1 to Mu3 and Mv1 to Mv3 by the imbalance detection unit 922. Information such as Mw1 to Mw3 is output to the overall control unit 3.

  Single-phase full-bridge voltage source PWM converter 8 mutually converts AC power input / output from / to power transmission line Lu and DC power charged / discharged by assembled battery 91. Specifically, when charging the assembled battery 91, the single-phase full-bridge voltage source PWM converter 8 switches the switching element Q1 with a duty ratio according to, for example, a PWM (Pulse Width Modulation) control signal from the overall controller 3. , Q2, Q3, and Q4 are turned on and off to full-wave rectify and output to the capacitor 10 while chopping the AC voltage supplied from the transmission line Lu.

  Then, the full-wave rectified voltage chopped by the single-phase full-bridge voltage source PWM converter 8 is smoothed by the capacitor 10 and converted into a DC voltage. Then, the DC voltage is applied to the assembled battery 91, whereby charging DC power is supplied to the assembled battery 91.

  Note that the capacitor 10 is not necessarily provided. Since the full-wave rectified voltage chopped in accordance with the PWM control signal can be regarded as a pseudo DC voltage, applying the pseudo DC voltage thus obtained to the assembled battery 91 allows Pseudo DC power can be supplied to the battery 91.

  On the other hand, when discharging the assembled battery 91 and outputting electric power to the transmission line Lu, the single-phase full-bridge voltage source PWM converter 8 is switched at a duty ratio corresponding to the PWM control signal from the Lu overall control unit 3, for example. By turning on and off the elements Q1, Q2, Q3, and Q4, the DC output voltage of the assembled battery 91 is chopped and converted to a pseudo AC voltage, and is output from the connection points P1 and P2 to the transmission line Lu.

  The overall control unit 3 adjusts the amount of power input / output between the transmission line Lu and the assembled battery 91 by PWM control for controlling the duty ratio and timing for turning on and off the switching elements Q1, Q2, Q3, and Q4. Or compensation for active power and reactive power in the transmission line Lu is performed.

  Each DC voltage detector 11 in the power converters 4a, 4b, and 4c included in the power conversion cluster 2u detects the voltage between the connection points P3 and P4, that is, the terminal voltage of the assembled battery 91, and the battery voltage values VBU1, VBU2, and so on. Output to the overall control unit 3 as VBU3.

  The power conversion cluster 2v is connected to the transmission line Lv instead of the transmission line Lu in the power conversion cluster 2u, and the power conversion cluster 2w is connected to the transmission line Lw instead of the transmission line Lu in the power conversion cluster 2u. Yes.

  Then, each SOC detection unit 921 of the power converters 4a, 4b, and 4c in the power conversion cluster 2v outputs the signals SOC (v1), SOC (v2), and SOC (v3) to the overall control unit 3, and the power conversion cluster Each SOC detection unit 921 at 2w outputs signals SOC (w1), SOC (w2), and SOC (w3) to the overall control unit 3.

  Similarly, each DC voltage detection unit 11 in the power converters 4a, 4b, and 4c included in the power conversion cluster 2v outputs the battery voltage values VBV1, VBV2, and VBV3 to the overall control unit 3, and the power provided in the power conversion cluster 2w Each DC voltage detector 11 in converters 4 a, 4 b, 4 c outputs battery voltage values VBW 1, VBW 2, VBW 3 to overall controller 3.

  FIG. 4 is a block diagram for explaining the control of power converter 4 shown in FIG. The overall control unit 3 includes, for example, a PLL (Phase Locked Loop) circuit 31, A / D converters 32 and 33, a PWM signal generator 34, and a DSP (Digital Signal Processor) 35.

  The battery voltage values VBU1, VBU2, VBU3, VBV1, VBV2, VBV3, VBW1, VBW2, and VBW3 output from the DC voltage detection unit 11 in each power converter 4 are converted into digital values by the A / D converter 33. Are output to the DSP 35.

  The current values Iu, Iv, Iw output from the current detector 5 and the voltage values Vu, Vv, Vw output from the voltage detector 7 are converted into digital values by the A / D converter 32, and It is output to the DSP 35.

  The PLL circuit 31 multiplies the analog signal waveform indicating the voltage values Vu, Vv, and Vw output from the voltage detector 7, thereby voltage phase information Vsu, Vsv, and Vsw indicating the phases of the voltage values Vu, Vv, and Vw. Is transmitted to the DSP 32. For example, when a clock signal obtained by multiplying an analog signal waveform indicating the voltage values Vu, Vv, and Vw by 360 is generated, one clock indicates one phase.

  The PWM signal generator 34 is a voltage instruction signal S (u1), S (u2), S (u3), S (v1), S (v2), S (v3), from the DSP 35 to each power converter 4. Switching in each single-phase full-bridge voltage source PWM converter 8 so that a voltage corresponding to S (w1), S (w2), S (w3) is generated between the connection points P1, P2 of each power converter 4. A PWM control signal for controlling on / off of the elements Q1, Q2, Q3, Q4 is generated.

  The PWM signal generator 34 is configured by, for example, an FPGA (Field Programmable Gate Array). Since there are a total of 36 semiconductor switching elements in nine single-phase full-bridge voltage source PWM converters 8 in each power converter 4, the PWM signal generator 34 includes these 36 semiconductor switching elements. A total of 36 types of PWM control signals for switching control are generated.

  Specifically, when charging the assembled battery 91, the PWM signal generator 34 turns off the switching elements Q1, Q4 while the switching elements Q2, Q3 are turned off when the AC voltage of each phase is positive. When the AC voltage of each phase is negative, the rectification is performed by turning on and off the switching elements Q2 and Q3 with the switching elements Q1 and Q4 turned off. Then, the PWM control signal is generated so that the on-duty of the switching elements Q1, Q4 or the switching elements Q2, Q3 increases as the voltage indicated by the voltage instruction signal from the DSP 35 increases. Thus, a voltage corresponding to the voltage instruction signal S from the DSP 35 is generated between the connection points P1 and P2 of each power converter 4.

  Since the power charged in the assembled battery 91 is the product of the current values Iu, Iv, Iw of the currents flowing through each power conversion cluster 2 and the voltage between the connection points P1, P2, the DSP 35 receives the voltage instruction signal S. By instructing the voltage between the connection points P1 and P2 by (u1) or the like, the charging power to the assembled battery 91 can be controlled.

  On the other hand, when discharging the assembled battery 91, the PWM signal generator 34 turns on and off the switching elements Q1 and Q4 with the switching elements Q2 and Q3 turned off when the AC voltage of each phase is positive. When the AC voltage of each phase is a negative phase, the DC voltage output of the assembled battery 91 is converted to AC by turning the switching elements Q2 and Q3 on and off while the switching elements Q1 and Q4 are turned off.

  Then, the PWM control signal is generated so that the on-duty of the switching elements Q1, Q4 or the switching elements Q2, Q3 increases as the voltage indicated by the voltage instruction signal from the DSP 35 increases. Thus, a pseudo AC voltage corresponding to the voltage instruction signal S from the DSP 35 is generated between the connection points P1 and P2 of each power converter 4.

  Since the electric power discharged from the assembled battery 91 to the power transmission line is the product of the current values Iu, Iv, Iw of the current flowing through each power conversion cluster 2 and the voltage between the connection points P1, P2, the DSP 35 By instructing the voltage between the connection points P1 and P2 with the instruction signal S (u1) or the like, the discharge power of the assembled battery 91 can be controlled.

  Further, when any of the determination result information Mu1 to Mu3, Mv1 to Mv3, Mw1 to Mw3 output from each imbalance detection unit 922 indicates the occurrence of an imbalance, the PWM signal generator 34 performs the maintenance process. The single-phase full-bridge voltage so that the current for power adjustment flowing through the power-conversion cluster 2 in which the imbalance has occurred bypasses the single-phase full-bridge voltage source PWM converter 8 of the power converter 4 in which the imbalance has occurred. The switching operation of the switching elements Q1, Q2, Q3, Q4 in the PWM converter 8 is controlled.

  Note that the number of power converters 4 in each power conversion cluster 2 is three, the single-phase power converter is a single-phase full-bridge voltage-type PWM converter, and the IGBT is used as a semiconductor switching element. It is an example, and the configuration of the present invention is not limited. Other stages, other converters, and other semiconductor switching elements may be used.

  Further, for example, as shown in FIG. 5, the power conversion system 1 a may include power conversion clusters 2 u, 2 v, 2 w that are Δ-connected. In addition, although a 200 V system is assumed as the system voltage, a 6.6 kV system can be realized with the same configuration. Moreover, although it was set as the alternating current of three phases, a single phase may be sufficient. Further, although the connection destination is a system voltage, it may be used as a part of a device that stores AC power such as UPS and outputs an alternating current. Further, the number of blocks of the assembled battery and the number of cells in one block are 5 blocks and 20 cells, but this is an example, and other numbers of blocks and cells may be used.

  FIG. 6 is a principle block diagram for explaining the operation of the DSP 35 shown in FIG. The DSP 35 shown in FIG. 6 includes a target power setting unit 351, a dq conversion unit 352, a phase voltage target value setting unit 353, an overall SOC averaging unit 354, and assembled battery SOC control blocks 355u, 355v, and 355w. .

  The dq converter 352 is based on the current values Iu, Iv, Iw output from the A / D converter 32, the voltage values Vu, Vv, Vw, and the voltage phase information Vsu, Vsv, Vsw output from the PLL circuit 31. Then, for each of the U, V, and W phases, the d-axis current value i (d) that is the active current and the q-axis current value i (q) that is the reactive current are calculated, and the assembled battery SOC control of the corresponding phase is performed. Output to block 355.

  The d-axis current value i (d) and the q-axis current value i (q) are, for example, known techniques known as dq conversion (for example, published by Ohm Publishing Co., Ltd., IEEJ / Semiconductor Power Conversion System Research Special Committee) Power electronics circuit).

  The target power setting unit 351 sets the difference (Pg−Pc) between the power generation amount Pg output from the power generation device 101 and the power consumption Pc output from the load device 102 corresponding to the U, V, and W phases. The electric energy is calculated as Pref (u), Pref (v), Pref (w) and output to the phase voltage target value setting unit 353. Since Pref (u), Pref (v), and Pref (w) are generally substantially equal, the target power amounts Pref (u), Pref (v), and Pref (w) are hereinafter collectively referred to as target power amount Pref. To do.

  The phase voltage target value setting unit 353 receives the target power amount Pref output from the target power setting unit 351, the d-axis current value i (d) of each phase output from the dq conversion unit 352, and the A / D converter 32. Based on the output current values Iu, Iv, Iw, the voltage values Vu, Vv, Vw, and the voltage phase information Vsu, Vsv, Vsw output from the PLL circuit 31, output from the power conversion clusters 2u, 2v, 2w, respectively. Voltage target values Vtu, Vtv, Vtw (instantaneous values) to be set are set.

  Specifically, for example, the phase voltage target value setting unit 353 calculates the voltage value by dividing the target power amount Pref for each phase by the d-axis current value i (d) of each phase, and the voltage phase information Vsu, By adjusting the phase of the voltage value based on Vsv, Vsw, current values Iu, Iv, Iw, and voltage values Vu, Vv, Vw, voltage target values Vtu, Vtv, Vtw for each phase are set. Here, the current values Iu, Iv, and Iw of the input and output currents to the power conversion clusters 2u, 2v, and 2w are Iu = Pref / Vu, Iv = Pref / Vv, and Iw = Pref / Vw.

  The total SOC averaging unit 354 includes all the SOC (u1), SOC (u2), SOC (u3), SOC (v1), and SOC that are continuously sent from the battery control unit 92 of each power converter 4 to the DSP 32. Among SOCs (v2), SOC (v3), SOC (w1), SOC (w2), and SOC (w3), the average SOC value of the assembled battery 91 in which no imbalance has occurred is calculated as the SOC target value (ref). And output to the assembled battery SOC control blocks 355u, 355v, 355w.

  At this time, the total SOC averaging unit 354 determines whether or not each assembled battery 91 is unbalanced based on the determination result information Mu1 to Mu3, Mv1 to Mv3, and Mw1 to Mw3 output from each unbalance detection unit 922. .

  FIG. 7 is a block diagram showing an example of the configuration of the assembled battery SOC control block 355u shown in FIG. FIG. 8 is a block diagram showing an example of the configuration of the assembled battery SOC control block 355v shown in FIG. FIG. 9 is a block diagram showing an example of the configuration of the assembled battery SOC control block 355w shown in FIG.

  The assembled battery SOC control blocks 355v and 355w shown in FIGS. 8 and 9 are configured in the same manner as the assembled battery SOC control block 355u shown in FIG. 7, and only the signal names input to and output from each block are different.

  The assembled battery SOC control blocks 355u, 355v, and 355w shown in FIGS. 7, 8, and 9 include an intra-cluster SOC control unit 551, 552, 553 (an SOC control unit), an intra-cluster SOC average unit 554 (an SOC average unit), An intercluster SOC control unit 555 (overall SOC control unit), adders 561, 562, 563, maintenance charge control units 571, 572, 573, and selectors 581, 582, 583 are provided.

  The in-cluster SOC averaging unit 554 in the assembled battery SOC control block 355u indicates that the determination result information Mu1, Mu2, Mu3 indicates that no imbalance has occurred. (U2) and the average value of the SOC (u3) are calculated as the average intra-cluster SOC (uave) by the following formula (1), and the intra-cluster SOC control units 551, 552, 553, and the inter-cluster SOC control unit 555 are calculated. Output to.

SOC (uave) = {SOC (u1) + SOC (u2) + SOC (u3)} / 3 (1)
On the other hand, when the in-cluster SOC averaging unit 554 in the assembled battery SOC control block 355u indicates that any one of the determination result information Mu1, Mu2, and Mu3 has an imbalance, the imbalance in the assembled battery SOC control block 355u is detected. The average value of the SOC of the assembled battery 91 in the remaining power converter 4 except for the generated power converter 4 is calculated as SOC (uave), and the intra-cluster SOC control units 551, 552, 553, and inter-cluster SOC control are calculated. Output to the unit 555.

  For example, when the determination result information Mu1 indicates that an imbalance has occurred, the intra-cluster SOC averaging unit 554 calculates the intra-cluster average SOC (uave) based on the following equation (1) ′.

SOC (uave) = {SOC (u2) + SOC (u3)} / 2 (1) ′
Similarly, the in-cluster SOC averaging unit 554 in the assembled battery SOC control block 355v indicates that any of the determination result information Mv1, Mv2, and Mv3 indicates that an imbalance has not occurred. Based on (2), the average SOC (vave) within the cluster is calculated, and if any of the determination result information Mv1, Mv2, Mv3 indicates that an imbalance has occurred, the assembled battery SOC to perform the maintenance process The average SOC value of the assembled battery 91 in the remaining power converters 4 except for the power converter 4 in which an imbalance has occurred in the control block 355v is calculated as the intra-cluster average SOC (vave).

SOC (vave) = {SOC (v1) + SOC (v2) + SOC (v3)} / 3 (2)
In addition, the in-cluster SOC average unit 554 in the assembled battery SOC control block 355w indicates that none of the determination result information Mw1, Mw2, and Mw3 has an imbalance, and the following formula ( Based on 3), the average SOC (wave) in the cluster is calculated, and when any of the determination result information Mw1, Mw2, Mw3 indicates that an imbalance has occurred, the assembled battery SOC control is performed so as to execute the maintenance process. The average value of the SOC of the assembled battery 91 in the remaining power converter 4 except the power converter 4 in which an imbalance has occurred in the block 355w is calculated as an intra-cluster average SOC (wave).

SOC (wave) = {SOC (w1) + SOC (w2) + SOC (w3)} / 3 (3)
The inter-cluster SOC control units 555 in the assembled battery SOC control blocks 355u, 355v, and 355w are respectively the average SOC in the cluster that is the average SOC of each assembled battery 91 in the own cluster, and each of the entire power conversion system 1 (all clusters). The voltage target values Vtu, Vtv, and Vtw output from the phase voltage target value setting unit 353 are supplied to each power converter 4 so as to reduce the difference from the SOC target value (ref) that is the average value of the SOC of the assembled battery 91. Control signals S (Au1), S (Au2), S (Au3), S (Av1), S (Av2), for controlling the AC side terminal voltage (voltage between connection points P1 and P2) to be distributed, S (Av3), S (Aw1), S (Aw2), and S (Aw3) are generated and output to the adders 561, 562, and 563 in each assembled battery SOC control block 355. To.

  Hereinafter, the control signals S (Au1), S (Au2), and S (Au3) are collectively referred to as a control signal S (Au), and the control signals S (Av1), S (Av2), and S (Av3) are collectively referred to. Control signal S (Av), and control signals S (Aw1), (Aw2), S (Aw3) are collectively referred to as control signal S (Aw).

  The control signals S (Au), S (Av), and S (Aw) indicate instantaneous voltage values and are represented by digital values that change in real time.

  Specifically, when each assembled battery 91 is charged, each inter-cluster SOC control unit 555 increases the AC-side terminal voltage as the difference between the cluster average SOC is smaller than the SOC target value (ref). In other words, the control signals S (Au), S (Av), and S (Aw) are adjusted by adjusting the voltage target values Vtu, Vtv, and Vtw so that the charging power (current) supplied to the assembled battery 91 is increased. If the average intra-cluster SOC is larger than the SOC target value (ref), the AC side terminal voltage is decreased as the difference is larger, that is, the charging power (current) supplied to the assembled battery 91 is decreased. The control signals S (Au), S (Av), and S (Aw) are set by adjusting the voltage target values Vtu, Vtv, and Vtw.

  On the other hand, when each cluster battery 91 is discharged, each inter-cluster SOC control unit 555 reduces the AC-side terminal voltage as the difference between the cluster average SOC is smaller than the SOC target value (ref). That is, the control signals S (Au), S (Av), and S (Aw) are set by adjusting the voltage target values Vtu, Vtv, and Vtw so that the electric power (current) discharged from the assembled battery 91 decreases. If the inner average SOC is larger than the SOC target value (ref), the larger the difference is, the higher the AC terminal voltage is increased, that is, the power (current) discharged from the assembled battery 91 is increased. Control signals S (Au), S (Av), and S (Aw) are set by adjusting Vtv and Vtw.

  As a result, the average SOC of each assembled battery 91 in the power conversion clusters 2u, 2v, and 2w is brought close to the SOC target value (ref). As a result, the variation in SOC between the power conversion clusters 2u, 2v, and 2w is reduced. It has become so.

  Further, each inter-cluster SOC control unit 555 controls the phase and voltage of the control signals S (Au), S (Av), and S (Aw) so as to compensate the reactive power based on the q-axis current value i (q). The value is adjusted.

  Further, the inter-cluster SOC control unit 555 in the assembled battery SOC control block 355u indicates that all the power conversions in the cluster are performed in order to perform normal processing when the determination result information Mu1, Mu2, Mu3 indicates that no imbalance has occurred. The control signals S (Au1), S (Au2), and S (Au3) that have been adjusted based on the above-mentioned average intra-cluster SOC after distributing the voltage target value Vtu to the devices 4a, 4b, and 4c are added to the adder 561. , 562, 563.

  Since the voltage target value Vtu is set by the phase voltage target value setting unit 353 so as to obtain the target power amount Pref, each assembled battery SOC control block 355 controls the control signal S (Au1) as described above. , S (Au2), S (Au3) are generated, and power is input / output to / from the transmission line Lu by each single-phase full-bridge voltage source PWM converter 8 of each power converter 4 in normal processing. The amount of power input / output to / from the transmission line Lu is adjusted by the power converters 4a, 4b, and 4c so that the total amount becomes the target power amount Pref.

  On the other hand, when the inter-cluster SOC control unit 555 in the assembled battery SOC control block 355u indicates that any of the determination result information Mu1, Mu2, and Mu3 is imbalanced, the imbalance is determined in order to perform maintenance processing. The control signals S (Au1) and S (Au2) that have been adjusted based on the intra-cluster average SOC described above after the voltage target value Vtu is allocated to the remaining power converters 4 excluding the power converter 4 that generates , S (Au3) are output to the adders 561, 562, and 563.

  For example, when the determination result information Mu1 indicates that an imbalance has occurred, a voltage instruction signal S (u1) instructing the output voltage of the power converter 4a causing the imbalance is a maintenance charge control unit described later. 571 is generated to maintain the power converter 4a. The inter-cluster SOC control unit 555 then subtracts the value obtained by subtracting the command voltage of the voltage command signal S (u1) from the voltage target value Vtu, and the remaining power converter 4b excluding the power converter 4a causing the imbalance. , 4c, the control signals S (Au2) and S (Au3) are adjusted based on the above intra-cluster average SOC and output to the adders 561, 562, and 563.

  The control signals S (Au1), S (Au2), and S (Au3) are generated in this way by each assembled battery SOC control block 355, so that the assembled battery 91 that needs maintenance in the maintenance process is displayed. The amount of power input / output to / from the transmission line Lu by each single-phase full-bridge voltage source PWM converter 8 of each of the remaining power converters 4 excluding the power converter 4 included, and the assembled battery 91 in need of maintenance Power so that the sum of the amount of power used to maintain the power converter 4 including the power (that is, the amount of power required to supply the set current Is to the assembled battery 91) becomes the target power amount Pref. The converters 4a, 4b, and 4c adjust the amounts of electric power that are input to and output from the power transmission line Lu, respectively.

  In the case where equalization charging is not performed at the time of maintenance, for example, when the assembled battery 91 is replaced by maintenance, maintenance charging control units 571, 572, and 573, which will be described later, are unnecessary, and power conversion in which an imbalance has occurred Since the electric power used in the unit 4 is zero, each of the remaining power converters 4 excluding the power converter 4 including the assembled battery 91 in which maintenance is required is performed by the assembled battery SOC control block 355 in the maintenance process. The amount of power input / output to / from the transmission line Lu by each single-phase full-bridge voltage source PWM converter 8 and the amount of power used to maintain the power converter 4 including the assembled battery 91 in which maintenance is required. Between the transmission line Lu and the power converters 4a, 4b, and 4c so that the total power becomes the target power amount Pref. Amount of power output is adjusted respectively.

Similarly to the inter-cluster SOC control unit 555 in the assembled battery SOC control block 355u, the inter-cluster SOC control unit 555 in the assembled battery SOC control blocks 355v and 355w is controlled by the control signals S (Av1), S (Av2), S (Av3) and control signals S (Aw1), (Aw2), and S (Aw3) are generated.

  The control signals S (Au), S (Av), and S (Aw) may be generated by detecting each phase current on the AC side of each power converter 4 and applying an appropriate gain thereto. .

  The intra-cluster SOC control units 551, 552, and 553 in the assembled battery SOC control block 355u include the SOC (u1), SOC (u2), and SOC (u3) of each assembled battery 91 in the power conversion cluster 2u, and the power conversion cluster 2u. Control signals S (Bu1), S (Bu2), and S (Bu3) are generated so as to reduce the difference from the average SOC (uave) in the cluster that is the average SOC of each assembled battery 91, and adders 561 and 562 , 563.

  The control signals S (Bu1), S (Bu2), and S (Bu3) indicate instantaneous voltage values and are represented by digital values that change in real time.

  Specifically, the in-cluster SOC control units 551, 552, and 553 charge SOC (u1), SOC (u2), and SOC (u3) from the in-cluster average SOC (uave) when charging each assembled battery 91. If the difference is smaller, the control signals S (Bu1), S (Bu2), and S (Bu3) are increased as the difference is larger, and the SOC (u1), SOC (u2), and SOC (u3) are higher than the intra-cluster average SOC (uave). If it is larger, the control signals S (Bu1), S (Bu2), S (Bu3) are set to negative values, and the absolute value is increased as the difference is larger.

  On the other hand, the intra-cluster SOC control units 551, 552, and 553 control the discharge of each assembled battery 91 if the SOC (u1), SOC (u2), and SOC (u3) are smaller than the intra-cluster average SOC (uave). The signals S (Bu1), S (Bu2), and S (Bu3) are set to negative values, and the absolute value is increased as the difference increases, so that SOC (u1), SOC (u2), and SOC (u3) are obtained. The control signal S (Bu1), S (Bu2), S (Bu3) is increased as the difference is larger than the intra-cluster average SOC (uave).

  The control signals S (Bu1), S (Bu2), and S (Bu3) generated in this way are added to the control signal S (Au) by the adders 561, 562, and 563, and the added value is The voltage instruction signals S (u1), S (u2), and S (u3) are output to the PWM signal generator 34 via the selectors 581, 582, and 583.

  As a result, the voltage instruction signal S of the power converter 4 including the assembled battery 91 whose SOC is smaller than the intra-cluster average SOC (uave) is increased when the control signal S (Au) is increased at the time of charging, and is controlled at the time of discharging. The signal S (Au) is lowered and the charging power is reduced.

  On the other hand, the voltage instruction signal S of the power converter 4 including the assembled battery 91 whose SOC is larger than the in-cluster average SOC (uave) is reduced when the control signal S (Au) is reduced during charging and the charging power is reduced, and is controlled during discharging. The signal S (Au) is increased and the charging power is increased.

  As a result, the SOC of each assembled battery 91 of the power converters 4a, 4b, 4c in the power conversion cluster 2u is brought close to the intra-cluster average SOC (uave). As a result, the SOC of the power converters 4a, 4b, 4c is reduced. Variations are reduced.

  The in-cluster SOC control units 551, 552, and 553 in the assembled battery SOC control blocks 355v and 355w also operate in the same manner as the in-cluster SOC control units 551, 552, and 553 in the assembled battery SOC control block 355u. S (v1), S (v2), S (v3) and voltage instruction signals S (w1), S (w2), S (w3) are generated and output to the PWM signal generator 34, thereby converting power. The variation of the SOC of each assembled battery 91 between the power converters 4a, 4b, and 4c in the clusters 2v and 2w is reduced.

  The maintenance charge control units 571, 572, and 573 use the single-phase full-bridge voltage source PWM converter 8 to set the preset current Is set to a current value suitable for charging of the assembled battery 91, in particular, Neumann-type charging reaction. A voltage instruction signal S to be supplied to 91 is generated and output to selectors 581, 582 and 583.

  Specifically, the maintenance charge control unit 571 of the assembled battery SOC control block 355u, for example, the current value Iu output from the A / D converter 32, VBU1 output from the A / D converter 33, and From the set current Is set, a voltage instruction signal S (u1) is generated based on the following equation (4).

S (u1) = Is × VBU1 / Iu (4)
As the set current Is, for example, a current value of about 1 A can be used.

  Similarly, each maintenance charge control unit in each assembled battery SOC control block 355 is based on the following formulas (5) to (12), and voltage instruction signals S (u2), S (u3), S (v1), S (v2), S (v3), S (w1), S (w2), and S (w3) are generated.

S (u2) = Is × VBU2 / Iu (5)
S (u3) = Is × VBU3 / Iu (6)
S (v1) = Is × VBV1 / Iv (7)
S (v2) = Is × VBV2 / Iv (8)
S (v3) = Is × VBV3 / Iv (9)
S (w1) = Is × VBW1 / Iw (10)
S (w2) = Is × VBW2 / Iw (11)
S (w3) = Is × VBW3 / Iw (12).

  The selectors 581, 582, and 583 in the assembled battery SOC control block 355 u indicate that when the determination result information Mu 1, Mu 2, Mu 3 indicates that an imbalance has not occurred, the adders 561, 562, and 563 perform normal processing. The output signal is output to the PWM signal generator 34 as voltage instruction signals S (u1), S (u2), S (u3), while the determination result information Mu1, Mu2, Mu3 indicates that an imbalance has occurred. In this case, the voltage instruction signals S (u1), S (u2), and S (u3) output from the maintenance charge control units 571, 572, and 573 are output to the PWM signal generator 34 to execute the maintenance process.

  Similarly to the selectors 581, 582, 583 in the assembled battery SOC control block 355u, the determination result information Mv1, Mv2, Mv3, and the determination result information Mw1, Mw2 in the assembled battery SOC control blocks 355v, 355w are the same. , Mw3, one of the output signals of the adders 561, 562, 563 and the maintenance charge control units 571, 572, 573 is selected, and the voltage instruction signals S (v1), S (v2), S ( v3) and voltage instruction signals S (w1), S (w2), and S (w3) are output to the PWM signal generator 34.

  Next, the operation of the power conversion system 1 configured as described above will be described. First, the SOC detection unit 921 of each power converter 4 detects the SOC of each assembled battery 91, and signals SOC (u1), SOC (u2), SOC (u3), and SOC (v1) indicating the values of the SOCs. , SOC (v2), SOC (v3), and SOC (w1), SOC (w2), and SOC (w3) are output to the overall control unit 3.

  Further, the degree of variation (unbalance) of each terminal voltage based on the terminal voltages Vb1, Vb2, Vb3, Vb4, Vb5 detected by each battery voltage detection unit 93 by the imbalance detection unit 922 of each power converter 4. Is determined. Then, the determination result information Mu1 to Mu3, Mv1 to Mv3, Mw1 to Mw3 indicating whether or not the terminal voltage is imbalanced in each assembled battery 91, that is, whether maintenance is necessary, by each imbalance detection unit 922. Is output to the overall control unit 3.

  On the other hand, in the overall control unit 3, the difference (Pg−Pc) between the power generation amount Pg output from the power generation device 101 and the power consumption Pc output from the load device 102 by the target power setting unit 351 is the target power amount. It is calculated as Pref and output to the phase voltage target value setting unit 353.

  In addition, the dq conversion unit 352 is an effective current for each of the U, V, and W phases based on the current values Iu, Iv, Iw, the voltage values Vu, Vv, Vw, and the voltage phase information Vsu, Vsv, Vsw. The d-axis current value i (d) and the q-axis current value i (q), which is a reactive current, are calculated and output to the assembled battery SOC control blocks 355u, 355v, 355w of the corresponding phases.

  Next, the target voltage Pref, the d-axis current value i (d), the current values Iu, Iv, Iw, the voltage values Vu, Vv, Vw, and the voltage phase information Vsu, Vsv, Based on Vsw, voltage target values Vtu, Vtv, Vtw (instantaneous values) to be output from the power conversion clusters 2u, 2v, 2w are set and output to the assembled battery SOC control blocks 355u, 355v, 355w.

  In addition, the entire SOC averaging unit 354 provides SOC (u1), SOC (u2), SOC (u3), SOC (v1), SOC (v2), SOC (v3), SOC (w1), SOC (w2), SOC Among (w3), the average SOC value of the assembled battery 91 in which no imbalance has occurred is calculated as the SOC target value (ref) and output to the assembled battery SOC control blocks 355u, 355v, and 355w.

  Since the assembled battery SOC control blocks 355u, 355v, and 355w operate in the same manner, the operation of the assembled battery SOC control block 355u shown in FIG. 7 will be described below.

  First, when none of the determination result information Mu1, Mu2, and Mu3 indicates that an imbalance has occurred, the intra-cluster SOC averaging unit 554 performs SOC (u1), SOC (u2), and The average value of the SOC (u3) is calculated as the intra-cluster average SOC (uave), and is output to the intra-cluster SOC control units 551, 552, 553, and the inter-cluster SOC control unit 555.

  On the other hand, in the case where any of the determination result information Mu1, Mu2, Mu3 indicates that an imbalance has occurred, the remaining power converter 4 except the power converter 4 in which the imbalance has occurred in order to execute the maintenance process. The average SOC value of the assembled battery 91 is calculated by the intra-cluster SOC average unit 554 as the intra-cluster average SOC (ave), and is output to the intra-cluster SOC control units 551, 552, 553, and the inter-cluster SOC control unit 555. The

  As a result, an intra-cluster average SOC (uave) is calculated for the remaining power converters 4 excluding the power converter 4 that cannot be used for power adjustment of the transmission line due to maintenance, and this intra-cluster average Based on the SOC (uave), generation of the control signals S (Au1), S (Au2), S (Au3) by the inter-cluster SOC control unit 555, and the control signal S (by the intra-cluster SOC control units 551, 552, 553) Bu1), S (Bu2), and S (Bu3) are generated.

  Thereby, about any one of power converter 4a, 4b, 4c, the power converter 4 for maintenance cannot be used for maintenance, such as reducing the imbalance of the terminal voltage of each battery block in the assembled battery 91 In other power converters 4 that are normally operable, the input / output power is distributed to each power conversion cluster so as to reduce the variation in the SOC of the assembled battery 91 between the power conversion clusters 2u, 2v, 2w, It becomes possible to distribute input / output power to each power converter 4 so as to reduce the variation in SOC between the power converters 4 that can normally operate in the power conversion cluster 2.

  Next, the inter-cluster SOC control unit 555 causes the voltage target value Vtu to be unbalanced in the determination result information Mu1, Mu2, and Mu3 so as to reduce the difference between the intra-cluster average SOC and the SOC target value (ref). Control signals S (Au1), S (Au2), and S (Au3) are generated and output to the adders 561, 562, and 563.

  As a result, the average SOC of each assembled battery 91 in the power conversion cluster 2u is brought close to the SOC target value (ref). Similarly, the average SOC of each assembled battery 91 in the power conversion clusters 2v and 2w is also brought close to the SOC target value (ref), so that the variation in SOC between the power conversion clusters 2u, 2v and 2w is reduced. .

  Further, the SOC (u1), SOC (u2), SOC (u3) and average intra-cluster SOC of each assembled battery 91 in the power conversion cluster 2u are obtained by the in-cluster SOC control units 551, 552, and 553 in the assembled battery SOC control block 355u. Control signals S (Bu1), S (Bu2), and S (Bu3) are generated so as to reduce the difference from (uave), and are output to the adders 561, 562, and 563.

  The control signals S (Bu1), S (Bu2), and S (Bu3) are added to the control signals S (Au1), S (Au2), and S (Au3) by the adders 561, 562, and 563, and the addition is performed. The value is output to selectors 581 582 583.

  If the determination result information Mu1, Mu2, Mu3 indicates that no imbalance has occurred, that is, no maintenance is required, this added value is used as the selectors 581, 582, 583 to execute normal processing. Is output to the PWM signal generator 34 as voltage instruction signals S (u1), S (u2), and S (u3).

  Then, PWM control signals corresponding to the voltage instruction signals S (u1), S (u2), and S (u3) are output to the power converters 4a, 4b, and 4c, and are output by the single-phase full-bridge voltage source PWM converters 8. As a result of the charging / discharging power of each assembled battery 91 being adjusted, the SOC of each assembled battery 91 of the power converters 4a, 4b, 4c in the power conversion cluster 2u is brought closer to the intra-cluster average SOC (uave). In the processing, variation in SOC between the power converters 4a, 4b, and 4c is reduced.

  Further, voltage instruction signals S (u 1), S (u 2), S (for allowing the set current Is to be supplied to the assembled battery 91 by the single-phase full-bridge voltage source PWM converter 8 by the maintenance charge control units 571, 572, 573. u3) is generated and output to the selectors 581, 582 and 583.

  In the selectors 581, 582, 583, if the determination result information Mu1, Mu2, Mu3 indicates that an imbalance has occurred, that is, that maintenance is necessary, for example, only the determination result information Mu1 has an imbalance. , The selector 581 outputs the voltage instruction signal S (u1) output from the maintenance charge control unit 571 to the PWM signal generator 34.

  Then, the set current Is is supplied to the assembled battery 91 by the single-phase full-bridge voltage source PWM converter 8 in the power converter 4a, and the battery blocks 911, 912, 913, 914, and 915 are charged with the set current Is.

  Here, since the determination result information Mu1 indicates the occurrence of an imbalance, an imbalance has occurred in the terminal voltages Vb1, Vb2, Vb3, Vb4, and Vb5 of the battery blocks 911, 912, 913, 914, and 915. Since there is a correlation between the terminal voltages Vb1, Vb2, Vb3, Vb4, Vb5 and the SOCs of the battery blocks 911, 912, 913, 914, 915, each SOC of the battery blocks 911, 912, 913, 914, 915 There is also an imbalance between them.

  Then, when the battery blocks 911, 912, 913, 914, and 915 are charged with the set current Is, the battery block having a large SOC (high terminal voltage) is more than the battery block having a small SOC (low terminal voltage). When the battery is fully charged first and further charged, the battery block that has been fully charged first is charged in an overcharged state.

  Here, in the case of an alkaline battery such as a nickel metal hydride secondary battery or a nickel cadmium secondary battery, when the battery is overcharged, oxygen is generated from the positive electrode and moves to the negative electrode, and oxygen is reduced at the negative electrode (Neumann method). Since the movement of oxygen is equivalent to the discharge of the charged charge, the terminal voltage of the fully charged battery block does not increase any more even if charging continues in an overcharged state. It becomes a constant voltage.

  If charging is continued until all the battery blocks 911, 912, 913, 914, and 915 are fully charged in such a state, the terminal voltages Vb1, Vb2, Vb3, Vb4, and Vb5 become substantially equal. The imbalance of Vb2, Vb3, Vb4, Vb5 can be eliminated.

  On the other hand, since the determination result information Mu2 and Mu3 indicate that no imbalance has occurred, the added values of the adders 562 and 563 are converted into voltage instruction signals S (u2) and S (u3) as a PWM signal generator. 34. Then, PWM control signals corresponding to the voltage instruction signals S (u2) and S (u3) are output to the power converters 4b and 4c, and are output by the single-phase full-bridge voltage source PWM converters 8 of the power converters 4b and 4c. The charge / discharge power of the assembled battery 91 in which no imbalance has occurred is adjusted.

  Thereby, in parallel with the execution of the maintenance of the power converter 4a, the power converter 4b, 4c can adjust the power in the transmission line Lu, so that the original function of the power conversion cluster 2u is maintained, Maintenance of the assembled battery 91 in the power converter 4a can be performed.

  Although an example has been shown in which the imbalance detection unit 922 is provided to determine whether or not maintenance is necessary by detecting an imbalance in the terminal voltage of each battery block in the assembled battery 91, the maintenance is performed by other methods. You may make it determine the necessity. For example, using a timer, it may be determined that maintenance is necessary every preset time, for example, every month.

  Further, as an example of using the Neumann charging reaction as a method for reducing the imbalance of each battery block in the assembled battery 91, for example, only a battery block having a large SOC is forcibly discharged or a battery having a small SOC. You may make it reduce the imbalance of each battery block by charging only a block.

  Further, the type of maintenance is not limited to reducing the terminal voltage imbalance of each battery block in the assembled battery 91. Moreover, although the structure which controls the SOC state of a battery was shown, you may use the method of controlling a battery voltage directly.

  The power conversion device and the power conversion system according to the present invention are a power conversion device that adjusts power supply to a load using a storage battery and a power conversion system in various power generation systems such as wind power generation and solar power generation. It can be used suitably.

FIG. 1 is a block diagram illustrating an example of a configuration of a power system including a power conversion system according to an embodiment of the present invention. It is a block diagram which shows an example of a structure of the power conversion system shown in FIG. 1, and a power conversion cluster. FIG. 3 is a block diagram showing an example of details of the configuration of the battery pack shown in FIG. 2. It is a block diagram for demonstrating control of the power converter shown in FIG. It is a block diagram which shows the modification of the power conversion system shown in FIG. FIG. 5 is a principle block diagram for explaining the operation of the DSP shown in FIG. 4. It is a block diagram which shows an example of a structure of the assembled battery SOC control block shown in FIG. It is a block diagram which shows an example of a structure of the assembled battery SOC control block shown in FIG. It is a block diagram which shows an example of a structure of the assembled battery SOC control block shown in FIG.

DESCRIPTION OF SYMBOLS 1,1a Power conversion system 2,2u, 2v, 2w Power conversion cluster 3 Overall control part 4,4a, 4b, 4c Power converter 5 Current detector 6 Reactor 7 Voltage detector 8 Single phase full bridge voltage type PWM converter 9 Battery pack 10 Capacitor 11 DC voltage detection unit 31 PLL circuit 32, 33 A / D converter 34 PWM signal generator 35 DSP
91 assembled battery 92 battery control unit 93 battery voltage detection unit 94 battery current detector 100 power system 101 power generation device 102 load device 351 target power setting unit 352 dq conversion unit 353 phase voltage target value setting unit 354 overall SOC average unit 355, 355u , 355v, 355w assembled battery SOC control block 551 intra-cluster SOC control unit 554 intra-cluster SOC average unit 555 inter-cluster SOC control unit 561, 562, 563 adder 571, 572, 573 maintenance charge control unit 581 582 582 selector 911 , 912, 913, 914, 915 Battery block 921 SOC detection unit 922 Unbalance detection unit 923 Communication unit 931, 932, 933, 934, 935 Block voltage detector Ib, Iu, Iv, Iw Current value Is Set current Lu Lv, Lw Transmission lines Mu1 to Mu3, Mv1 to Mv3, Mw1 to Mw3 Determination result information P0 Neutral point P1, P2, P3, P4 Connection point Pc Power consumption Pg Power generation amount Pref Target power amount VBU1 to VBU3, VBV1 to VBV3 VBW1 to VBW3 Battery voltage value Vb1, Vb2, Vb3, Vb4, Vb5 Terminal voltage Vsu, Vsv, Vsw Voltage phase information Vtu, Vtv, Vtw Voltage target value Vu, Vv, Vw Voltage value

Claims (11)

A plurality of power converters connected in series between phases of a transmission line transmitting AC power;
A power control unit that controls the amount of power input and output between each power converter and the transmission line;
Each power converter is
A storage battery,
A converter for mutually converting AC power input and output from the power transmission line and power charged and discharged by the storage battery, and adjusting an amount of power input and output between the power transmission line and the storage battery; With
The power control unit
When there is no need for maintenance for each storage battery of each power converter, each converter of each power converter executes a normal process for adjusting the amount of power input / output to / from the power transmission line. When any of the storage batteries of each of the power converters requires maintenance, the converters of the remaining power converters except for the power converter including the storage battery in which the maintenance is necessary, A power conversion device that performs a maintenance process for adjusting an amount of electric power input / output to / from a power transmission line. The power control unit
In the normal processing, the converters cause the transmission power so that the total amount of power input to and output from the power transmission line by the converters of the power converters becomes a predetermined target power amount. The amount of electric power input / output to / from the electric wire is adjusted, and in the maintenance process, the total amount of electric power input / output to / from the power transmission line by each of the conversion units becomes the target electric energy. Further, the amount of power input / output to / from the power transmission line is adjusted by each conversion unit of the remaining power converter excluding the power converter including the storage battery in which the maintenance is required. Item 4. The power conversion device according to Item 1. The storage battery is
An assembled battery including a plurality of secondary batteries,
Each power converter is
An imbalance detection unit that detects an imbalance in the terminal voltage of each secondary battery and notifies the power control unit that the imbalance has been detected when the imbalance is detected.
The power control unit
3. The power conversion according to claim 1, wherein when the imbalance detection unit is notified that the imbalance has been detected, it is determined that the maintenance is required for the storage battery in which the imbalance is detected. apparatus. The power control unit
The power conversion device according to claim 1, wherein for each of the plurality of storage batteries, it is determined that the need for maintenance has occurred for each preset time. During the execution period of the maintenance process, the conversion unit in the power converter including the storage battery in which the maintenance is necessary causes the storage battery to be supplied with a set current preset to a value suitable for charging the storage battery. The power conversion device according to claim 3, further comprising a maintenance charge control unit for charging. The power control unit
In the maintenance process, the amount of power for supplying the set current by the conversion unit in the power converter including the storage battery in which the maintenance is required, and the remainder excluding the power converter including the storage battery in which the maintenance is required A power converter including a storage battery in which the maintenance is required so that the total amount of power input to and output from the power transmission line by each conversion unit of the power converter becomes the target power amount The power converter according to claim 5, wherein an amount of electric power input / output to / from the power transmission line is adjusted by each converter of the remaining power converter except the above. The plurality of secondary batteries are:
The power converter according to claim 5 or 6, wherein the power converter is an alkaline secondary battery. An SOC detector for detecting the SOC of the storage battery in each of the power converters;
An SOC average unit that calculates an average value of the SOCs of the storage batteries that do not require maintenance among the SOCs of the storage batteries detected by the SOC detection unit, as an average SOC;
In the normal process and the maintenance process, according to the difference between the average SOC calculated by the SOC average unit and the SOC of each storage battery detected by the SOC detection unit, the SOC of each storage battery is greater than the average SOC. If the SOC of each storage battery is larger than the average SOC, the smaller the storage battery, the lower the charging power amount and the lower the discharge power amount. The power conversion device according to claim 1, further comprising: an SOC control unit that adjusts the amount of power by the power control unit so as to increase the power. The AC power is multiphase AC power,
A plurality of the power conversion devices according to any one of claims 1 to 8 are provided corresponding to each phase in the multiphase AC power,
An SOC detector for detecting the SOC of the storage battery in each power converter of each power converter;
An SOC average unit that calculates an average value of the SOC of each storage battery that does not require maintenance among the SOCs of each storage battery detected by the SOC detection unit, as an average SOC for each power converter;
An overall SOC average unit that calculates an SOC average value of the storage battery that does not require maintenance included in the plurality of power conversion devices as an SOC target value;
In the normal process and the maintenance process, the average SOC is calculated according to a difference between the SOC target value calculated by the overall SOC average unit and the average SOC for each power converter calculated by the SOC average unit. If the average SOC is larger than the SOC target value, the power conversion device having a larger difference is charged so that the power conversion device having a larger difference has a larger charge power amount and the discharge power amount is smaller if the SOC is smaller than the SOC target value. A power conversion system, further comprising: an overall SOC control unit that adjusts the power amount by the power control unit so that the power amount is small and the discharge power amount is large. The transmission line is
Y-connected three-phase AC wiring
The power conversion system according to claim 9, wherein the power conversion device is interposed between each phase and a neutral point in the three-phase alternating current. The transmission line is
△ Three-phase AC wiring connected,
The power conversion system according to claim 9, wherein the power conversion device is interposed between the phases of the three-phase alternating current.

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