JP2014030301A - Charge and discharge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge and discharge control device capable of achieving safe and stable charge and discharge control according to a use state of a storage battery without causing over-charging and over-discharging .SOLUTION: The charge and discharge control device includes: a charge device 3 that converts system AC power into DC power and supplies the power to a storage battery 2; a discharge device 4 that converts DC power discharged by the storage battery 2 into AC power and supplies the power to a system AC power supply 1; a storage battery use state detection device that detects a use state of the storage battery 2; a charge control device 5 that is included in the charge device 3 and controls charging into the storage battery 2; a discharge control device 6 that is included in the discharge device 4 and controls charging from the storage battery 2; and a response speed changing device that receives an output of the storage battery use state detection device and changes a parameter for determining response speeds of the charge control device 5 and the discharge control device 6 according to the use state of the storage battery 2.

Description

  The present invention relates to a charge / discharge control device for controlling charge / discharge of a storage battery.

  In general, when charging a storage battery, a method of controlling the charging voltage to the storage battery is employed so as not to cause overcharging. However, since the electrical characteristics of the storage battery change according to its use state, a method of changing the control method according to the use state is considered.

  For example, in Patent Document 1, when it is detected that the terminal voltage has reached the inflection point based on the second-order time differential value of the terminal voltage during charging of the battery, the charging current is determined according to the fluctuation range of the voltage between the battery terminals. A technique for performing control to reduce the above is disclosed.

  Patent Document 2 further includes an electric load monitoring unit that detects a load current consumed by the electric load, and a learning unit that determines a deterioration state of the battery based on the load current and the voltage deviation. Discloses a technique for updating the control constant in accordance with the deterioration state of the battery.

Japanese Patent No. 3347808 JP-A-6-197469

  Recently, in order to efficiently use renewable energy obtained from solar power generation and wind power generation, a method of using these renewable energy in a next-generation power network called a smart grid has been considered. The charge control to the storage battery (secondary battery) is an important technology.

  When charging the storage battery or supplying power from the storage battery to the smart grid, power may be taken in and out in a short time. In such cases, it is necessary to shorten the response time (charge / discharge time) as much as possible. is there. However, Patent Documents 1 and 2 do not focus on shortening the response time, and cannot be applied to smart grids.

  The present invention has been made to solve the above-described problems, and provides a charge / discharge control device capable of safe and stable charge / discharge control without overcharge and overdischarge according to the usage state of a storage battery. The purpose is to do.

  The charge / discharge control apparatus according to the present invention is a charge / discharge control apparatus that charges the storage battery with system power of a system AC power supply and discharges the power stored in the storage battery and supplies the power to the system AC power supply. The charging / discharging control device converts the grid AC power into DC power and supplies it to the storage battery, and a discharge device that converts DC power discharged by the storage battery into AC power and supplies the AC power to the grid AC power supply. A storage battery usage state detection device that detects a usage state of the storage battery, a charge control device that is included in the charging device and controls charging of the storage battery, and is included in the discharge device, and controls charging from the storage battery. And a parameter for determining response speeds of the charge control device and the discharge control device according to the use state of the storage battery. And a response speed changing device for changing the.

  According to the charging / discharging control device according to the present invention, the charging / discharging control device includes a response speed changing device that changes a parameter for determining the response speed of the charging control device and the discharging control device according to the usage state of the storage battery. Thus, a charge / discharge control device capable of safe and stable charge / discharge control without overcharge and overdischarge can be obtained.

It is a block diagram which shows the structure of the charging / discharging control apparatus of Embodiment 1 which concerns on this invention. It is a flowchart explaining operation | movement of the charging / discharging control apparatus of Embodiment 1 which concerns on this invention. It is a figure which shows typically the operation | movement which changes a control gain change rate. It is a figure explaining the change of a control gain in case the temperature of a storage battery changes with respect to the accumulation use time of a storage battery. It is a block diagram which shows the structure of the charging / discharging control apparatus of Embodiment 2 which concerns on this invention. It is a flowchart explaining operation | movement of the charging / discharging control apparatus of Embodiment 2 which concerns on this invention. It is a figure which shows typically the operation | movement which changes a control gain change width. It is a figure explaining the change of control gain in case the temperature of a storage battery changes with respect to the accumulation electric energy of a storage battery. It is a block diagram which shows the structure of the charging / discharging control apparatus of Embodiment 3 which concerns on this invention. It is a flowchart explaining operation | movement of the charging / discharging control apparatus of Embodiment 10 which concerns on this invention. It is a figure which shows typically the operation | movement of binary control gain switching. It is a figure explaining the switching characteristic of a control gain in case the temperature of the storage battery 2 changes. It is a figure explaining the effect of the present invention using charge and discharge characteristics.

<Introduction>
A storage battery generally has a very low internal resistance. When a charging voltage is applied to the storage battery without current limitation, the storage battery is limited only by a small internal resistance, and a very large current may flow. When such an overcurrent flows, the function of the storage battery is lost beyond the reversible range of the chemical reaction.

  In order to prevent such an overcurrent at the time of charging, it is a feature of the charge / discharge control apparatus according to the present invention that a current control system is provided so that current control is performed at the rising stage of the charging current.

<Embodiment 1>
A charge / discharge control apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of charge / discharge control apparatus 100 of the first embodiment.

<Device configuration>
As shown in FIG. 1, the charge / discharge control device 100 receives AC power from the system AC power source 1, converts it into DC power, outputs it, and charges the storage battery 2, and DC power discharged from the storage battery 2. The discharge device 4 that receives and converts it into AC power and supplies it to the system AC power source 1, the current measurement device 7 that measures the input / output current to the storage battery 2, and the control gain change device 8 that changes the response speed at the start of charge / discharge And a cumulative usage time calculation device 9 that calculates a cumulative time of power input / output time for the storage battery 2, and a temperature measurement device 10 that measures the temperature (and / or the surrounding temperature) of the storage battery 2.

  The grid AC power source 1 is commercial grid power provided by an electric power company, and is supplied to an electrical load 22 such as an electrical device via a distribution board 21 and is connected to the storage battery 2 via a charge / discharge control device 100. The power is exchanged between the two. In addition, the electrical load 22 is managed by the management system 23. The management system 23 manages the amount of power used by the electrical load 22 and the case where it is more economical to use the discharge power from the storage battery 2 than the system power from the system AC power source 1 or the system AC For example, when power is supplied to the network of the power supply 1, it has a function of controlling the discharge device 4 to discharge the storage battery 2. Moreover, when the system | strain AC power supply 1 has an electric power margin, it has the function which controls the charging device 3 and charges the storage battery 2. FIG.

  Here, when generating AC power by the discharge device 4, it is necessary to generate a voltage tuned to the frequency of the system power, and the discharge device 4 generates AC power tuned to the frequency of the system power from the DC power. . This is an operation called “system linkage operation”. This operation is executed by the discharge control device 6 in the discharge device 4.

  Based on the output of the temperature measuring device 10 that measures the temperature of the storage battery 2 and the output of the current measuring device 7 that measures the charging current to the storage battery 2 or the discharging current from the storage battery 2, the cumulative usage time calculation device 9 The usage time (cumulative usage time) of the storage battery that has been corrected by is calculated. In addition, since the use state of a storage battery is detected using the current measurement device 7, the accumulated use time calculation device 9, and the temperature measurement device 10, these can be referred to as a storage battery use state detection device.

  Here, it is known that the performance deterioration of the storage battery is accelerated by using and storing the storage battery at a temperature outside normal temperature (about 25 degrees Celsius). Therefore, the accumulated usage time calculation device 9 assumes that the deterioration is accelerated when the temperature deviates from the normal temperature, not just the accumulated usage time, and the actual elapsed time varies depending on a predetermined coefficient (depending on the temperature). ) Is accumulated to accumulate the time, and the usage time in consideration of the deterioration degree of the storage battery 2 is obtained in a pseudo manner.

  Specifically, for example, the value obtained by multiplying the absolute value of the deviation from a preset predetermined temperature (normally normal temperature) by a coefficient depending on the temperature is multiplied by the time during which the temperature is maintained. The usage time is increased, and the cumulative usage time in consideration of the deterioration degree of the storage battery 2 is obtained in accordance with the actual usage environment. The acceleration due to the temperature of the cumulative usage time can be expressed by the following mathematical formula (1).

Tsum = Σ (K · | Temp−Temp_org | · Time) (1)
In the above formula (1), K is a temperature-dependent coefficient, Temp is the temperature of the storage battery 2, Temp_org is a predetermined temperature (for example, room temperature), and Time is the time during which Temp is maintained.

  Based on the accumulated use time of the storage battery 2 calculated by the accumulated use time calculation device 9 and the temperature of the storage battery 2 measured by the temperature measurement device 10 as described above, the control gain changing device 8 A charge control gain and a discharge control gain (which may be collectively referred to as a control gain) that determine the response speed are calculated.

  In the calculation processing of the feedback control for the charge control and the discharge control executed by the charge control device 5 and the discharge control device 6 included in the charging device 3 and the discharging device 4, respectively, the charging control gain and the discharging control gain are respectively set. By multiplying, the response speeds of the charge control device 5 and the discharge control device 6 are controlled to prevent overcharge and overdischarge. In this case, the control gain is a parameter (transfer function) that determines the response speeds of the charge control device 5 and the discharge control device 6, and the control gain changing device 8 can be said to be a response speed changing device.

<Operation>
Next, the operation of the charge / discharge control apparatus 100 will be described using the flowchart shown in FIG. 2 with reference to FIG.

  First, in step S1, it is determined whether to charge or discharge the storage battery 2 or not. This determination is made by the charging control device 5 of the charging device 3 and the discharging control device 6 of the discharging device 4 according to the presence or absence of a charging instruction or discharging instruction from the management system 23, respectively. In addition, determination of step S1 is implemented regularly during operation | movement of the charging / discharging control apparatus 100. FIG.

  If it is determined that charging or discharging is to be performed, the process proceeds to step S2. However, if neither charging nor discharging is performed, it is not necessary to change the control gain. Wait for instructions to discharge.

  On the other hand, when charging or discharging is performed, in step S2, in the case of charging, for example, the control gain at the time of the previous charging stored in the memory in the charging control device 5 of the charging device 3 is read, and discharging is performed. In this case, the control gain at the time of the previous discharge stored in the memory in the discharge control device 6 of the discharge device 4 is read.

  Then, charging or discharging is started with the read control gain (step S3). That is, the control gain at the start of charging or discharging is the control gain calculated by the control gain changing device 8 at the end of the previous charging or discharging.

  After the start of charging / discharging, the direction (positive / negative) and the current value of the current input / output to / from the storage battery 2 measured using the current measuring device 7 are measured (step S4), and the current value is expressed as the following formula (2). It is determined whether or not the absolute value | A | is equal to or greater than a predetermined threshold value Ath (step S5).

| A | ≧ Ath (2)
If it is determined in step S5 that the absolute value | A | of the current value is smaller than the threshold value Ath, it is determined that charging / discharging has ended, and the next charging / discharging is performed without executing the following processing. Wait for instructions. This determination is performed by the charging control device 5 of the charging device 3 in the case of charging, and by the discharging control device 6 of the discharging device 4 in the case of discharging.

  On the other hand, when the absolute value | A | of the measured current is equal to or greater than the threshold value Ath, it is determined that charging / discharging has been performed, and the temperature of the storage battery 2 is measured using the temperature measuring device 10 (step) Along with S6), in the case of charging, the control gain at the time of the previous charging stored in the memory in the charging control device 5 of the charging device 3 is read, and in the case of discharging, in the discharging control device 6 of the discharging device 4 The control gain at the time of the previous discharge stored in the memory is read (step S7). Moreover, time measurement is started (step S8).

  The control gain changing device 8 corrects the rate of change of the control gain with respect to the cumulative usage time based on the temperature Tbat of the storage battery 2 measured in step S6, and calculates the current control gain change rate (step S9). Here, the control gain change rate dG is given by the following mathematical formula (3).

dG = f (Tbat) = A / (2π · B · Time · C · (Tbat−Tbat_org)) (3)
In the above formula (3), Tbat is the temperature of the storage battery 2, A is a predetermined coefficient (approximately 1 in this case), Time is the time during which Tbat is maintained, Tbat_org is room temperature (constant), and B is the type of battery. Is a constant determined by, and C is a temperature coefficient.

  The control gain change rate dG is calculated in advance for each temperature, stored as a map in the memory in the control gain changing device 8, and read from the map based on the measured parameters, and the control gain change rate dG May be used as

  Next, the control gain changing device 8 calculates a control gain Gt when the temperature of the storage battery 2 is Tbat based on the following formula (4) (step S10).

Gt = A · (1 / (1 + s · f (Tbat)) (4)
In the above equation (4), A is a predetermined coefficient (approximately 1 in this case) and s is a Laplace operator.

  Here, FIG. 3 schematically shows an operation of changing the control gain change rate according to the measured temperature Tbat of the storage battery 2 (operation of step S9). In FIG. 3, the abscissa indicates the accumulated usage time, the ordinate indicates the control gain, and the control gain change characteristic G1 at room temperature is indicated at the center.

  It shows that the control gain change rate increases as the temperature of the storage battery 2 increases, and the control gain change rate decreases as the temperature of the storage battery 2 decreases, with respect to the control gain change characteristic G1 at normal temperature.

  FIG. 4 shows an example of a change in control gain when the temperature Tbat of the storage battery 2 changes with respect to the cumulative usage time of the storage battery 2. In FIG. 4, the horizontal axis indicates the cumulative usage time, the vertical axis indicates the control gain, and the control gain when the temperature Tbat changes with respect to the control gain change characteristic G1 at room temperature.

  The control gain change characteristic G1 at room temperature is approximated by a single straight line, whereas the control gain change rate increases as the temperature of the storage battery 2 increases, and the control gain change rate decreases as the temperature of the storage battery 2 decreases. It shows that it becomes.

  After obtaining the new control gain based on the current temperature of the storage battery 2 through steps S9 and S10 described above, the previous control gain stored in the memory in the charge control device 5 or the discharge control device 6 is obtained. The new control gain is rewritten and stored (step S11).

  Then, charging / discharging is controlled with a new control gain (step S12), and when charging / discharging ends, the process waits for next charging / discharging instruction.

<Effect>
As described above, in the charge / discharge control device 100 of the first embodiment, the control gain changing device 8 is measured by the cumulative use time and temperature measuring device 10 of the storage battery 2 calculated by the cumulative use time calculation device 9. Based on the temperature of the storage battery 2, a charge control gain and a discharge control gain that determine the current charge / discharge response speed are calculated, and the charge control device 5 of the charging device 3 and the discharge control device 6 of the discharging device 4, respectively. To control the response speed of charging and discharging.

  For this reason, in a system that repeatedly charges or discharges the storage battery 2 in a short time such as a smart grid, even if the electrical characteristics of the storage battery 2 change due to repeated charging and discharging, depending on the usage state of the storage battery 2 Safe and stable charge / discharge control is possible without overcharge and overdischarge.

<Embodiment 2>
A second embodiment of the charge / discharge control device according to the present invention will be described with reference to FIGS. FIG. 5 is a block diagram showing the configuration of the charge / discharge control apparatus 200 of the second embodiment.

<Device configuration>
As shown in FIG. 5, the charging / discharging control device 200 receives AC power from the system AC power source 1, converts it into DC power, outputs the charging device 3 that charges the storage battery 2, and DC power that the storage battery 2 discharges. The discharge device 4 that receives and converts it into AC power and supplies it to the system AC power source 1, the current measurement device 7 that measures the input / output current to the storage battery 2, and the control gain change device 8 that changes the response speed at the start of charge / discharge A voltage measuring device 11 that measures the voltage across the terminals of the storage battery 2, a cumulative power amount calculation device 12 that calculates the cumulative power amount of power input / output to / from the storage battery 2, and a temperature that measures the temperature of the storage battery 2. And a measuring device 10. In addition, the same code | symbol is attached | subjected about the structure same as the charging / discharging control apparatus 100 shown in FIG. 1, and the overlapping description is abbreviate | omitted.

  The accumulated electric energy calculation device 12 includes an output of the temperature measurement device 10 that measures the temperature of the storage battery 2, an output of the voltage measurement device 11 that measures the terminal voltage of the storage battery 2, a charging current to the storage battery 2 or a discharge from the storage battery 2. Based on the output of the current measuring device 7 that measures the current, the accumulated electric energy of the storage battery that has been corrected by the temperature is calculated. In addition, since the use state of a storage battery is detected using the current measurement device 7, the temperature measurement device 10, the voltage measurement device 11, and the cumulative power amount calculation device 12, these can be referred to as a storage battery use state detection device.

  Here, it is known that even if the storage battery has the same electric power, the deterioration degree of the storage battery is different when the temperature is out of the normal temperature. Therefore, in the accumulated power amount calculation device 12, the power obtained by multiplying the actual power amount by a predetermined coefficient (which varies depending on the temperature) based on the temperature when the power is taken in and out, not just the accumulated power amount. Correction is performed by accumulating the amount, and the amount of electric power is obtained in consideration of the degree of deterioration of the storage battery 2 in a pseudo manner. Specifically, the increase in accumulated power amount due to temperature can be expressed by the following mathematical formula (5).

Psum = Σ (K · | Temp−Temp_org | · Power) (5)
In Equation (5), K is a temperature-dependent coefficient, Temp is the temperature of the storage battery 2, Temp_org is a predetermined temperature (for example, room temperature), Power is the measured power, and a predetermined temperature (usually normal) The accumulated electric energy is increased by multiplying the measured electric energy by a value obtained by multiplying the absolute value of the deviation from the normal temperature) by a coefficient depending on the temperature.

  Based on the accumulated power amount of the storage battery 2 calculated by the accumulated power amount calculation device 12 and the temperature of the storage battery 2 measured by the temperature measurement device 10 as described above, the control gain changing device 8 performs the current charging / discharging. A charge control gain and a discharge control gain that determine the response speed are calculated.

  In the calculation processing of the feedback control for the charge control and the discharge control executed by the charge control device 5 and the discharge control device 6 included in the charging device 3 and the discharging device 4, respectively, the charging control gain and the discharging control gain are respectively set. By multiplying, the response speeds of the charge control device 5 and the discharge control device 6 are controlled to prevent overcharge and overdischarge. In this case, the control gain is a parameter (transfer function) that determines the response speeds of the charge control device 5 and the discharge control device 6, and the control gain changing device 8 can be said to be a response speed changing device.

<Operation>
Next, the operation of the charge / discharge control apparatus 200 will be described using the flowchart shown in FIG. 6 with reference to FIG.

  First, in step S <b> 21, it is determined whether to charge or discharge the storage battery 2. This determination is made by the charging control device 5 of the charging device 3 and the discharging control device 6 of the discharging device 4 according to the presence or absence of a charging instruction or discharging instruction from the management system 23, respectively. In addition, determination of step S21 is implemented regularly during the operation of the charge / discharge control apparatus 100.

  If it is determined that charging or discharging is to be performed, the process proceeds to step S22. However, if neither charging nor discharging is performed, it is not necessary to change the control gain. Wait for instructions to discharge.

  On the other hand, when charging or discharging is performed, in step S22, in the case of charging, for example, the control gain at the time of the previous charging stored in the memory in the charging control device 5 of the charging device 3 is read, and the discharging is performed. In this case, the control gain at the time of the previous discharge stored in the memory in the discharge control device 6 of the discharge device 4 is read.

  Then, charging or discharging is started with the read control gain (step S23). That is, the control gain at the start of charging or discharging is the control gain calculated by the control gain changing device 8 at the end of the previous charging or discharging.

  After the start of charging / discharging, the direction (positive / negative) and the current value of the current input / output to / from the storage battery 2 measured using the current measuring device 7 are measured (step S24), and the current value is expressed as the following formula (6). It is determined whether or not the absolute value | A | is equal to or greater than a predetermined threshold value Ath (step S25).

| A | ≧ Ath (6)
If it is determined in step S25 that the absolute value | A | of the current value is smaller than the threshold value Ath, it is determined that charging / discharging has ended, and the next charging / discharging is performed without executing the following processing. Wait for instructions. On the other hand, when the measured absolute value | A | is equal to or greater than the threshold value Ath, it is determined that charging / discharging has been performed. This determination is performed by the charging control device 5 of the charging device 3 in the case of charging, and by the discharging control device 6 of the discharging device 4 in the case of discharging.

  Moreover, the voltage between terminals of the storage battery 2 is measured using the voltage measuring device 11 (step S33), and when it is determined that charging / discharging is performed in step S25, the measured voltage between terminals of the storage battery 2 is measured. Based on V and the input / output current value A measured using the current measuring device 7, the electric power W input / output to / from the storage battery is calculated using the following formula (7) (step S34).

W = V · A (7)
If it is determined in step S25 that charging / discharging is being performed, the temperature of the storage battery 2 is measured using the temperature measuring device 10 (step S26), and in the case of charging, the charging control device of the charging device 3 is measured. 5, the control gain at the time of the previous charge stored in the memory in 5 is read. In the case of discharge, the control gain at the time of the previous discharge stored in the memory in the discharge control device 6 of the discharge device 4 is read. Read (step S27). Moreover, the time (Time) which is performing charging / discharging with the same electric power is measured (step S28).

  Then, based on the electric power W calculated in step S34 and the time (Time) measured in step S28, the electric energy Wh is calculated using the following formula (8) (step S35).

Wh = Σ (W · Time) (8)
In the control gain changing device 8, based on the temperature Tbat of the storage battery 2 measured in step S26, the increase amount of the control gain with respect to the accumulated electric energy is corrected, and the current control gain increase amount is calculated (step S29). Here, the control gain increase width ΔG is given by the following formula (9).

ΔG = f (Tbat) = A / (2π · B · Time · C · (Tbat−Tbat_org)) (9)
In the above formula (9), Tbat is the temperature of the storage battery 2, A is a predetermined coefficient (approximately 1 in this case), Time is the time during which Tbat is maintained, Tbat_org is room temperature (constant), and B is the type of battery. Is a constant determined by, and C is a temperature coefficient.

  The control gain increase width ΔG is calculated in advance for each temperature, stored as a map in the memory in the control gain changing device 8, and read out from the map based on the measured parameters, and the control gain increase width ΔG. May be used as

  Next, the control gain changing device 8 calculates a control gain Gt when the temperature of the storage battery 2 is Tbat based on the following formula (10) (step S30).

Gt = A · (1 / (1 + s · f (Tbat)) (10)
In the above equation (10), A is a predetermined coefficient (approximately 1 in this case), and s is a Laplace operator.

  Here, FIG. 7 schematically shows an operation of changing the control gain increase width according to the measured temperature Tbat of the storage battery 2 (operation of step S29). In FIG. 7, the horizontal axis indicates the accumulated power amount, the vertical axis indicates the control gain, and the control gain change characteristic G11 at room temperature is shown in the center.

  With respect to the change characteristic G11 of the control gain at normal temperature, the increase width of the control gain increases as the temperature of the storage battery 2 increases, and the increase width of the control gain decreases as the temperature of the storage battery 2 decreases. As the accumulated power amount increases, the increase range of the control gain also increases.

  Further, FIG. 8 shows an example of the change in the control gain when the temperature Tbat of the storage battery 2 changes with respect to the accumulated power amount of the storage battery 2. In FIG. 8, the horizontal axis indicates the accumulated power amount, and the vertical axis indicates the control gain. The control gain when the temperature Tbat changes with respect to the control gain change characteristic G11 at room temperature is shown.

  As shown in FIG. 8, when the temperature of the storage battery 2 is high, the increase width (step) of the control gain is larger than when using it at room temperature, but when the temperature of the storage battery 2 is low, it is used at room temperature. Compared to the case, the increase width of the control gain becomes smaller. If the high temperature state continues, a state where the increase width (step) is large is maintained and the control gain increases.

  After obtaining the new control gain based on the current temperature of the storage battery 2 through steps S29 and S30 described above, the previous control gain stored in the memory in the charge control device 5 or the discharge control device 6 is obtained. The new control gain is rewritten and stored (step S31).

  Then, charging / discharging is controlled with a new control gain (step S32). When charging / discharging is completed, the process waits for next charging / discharging instruction.

<Effect>
As described above, in the charge / discharge control device 200 according to the second embodiment, the control gain changing device 8 measures the cumulative power amount and temperature of power input / output to / from the storage battery 2 calculated by the cumulative power amount calculation device 9. Based on the temperature of the storage battery 2 measured by the device 10, a charge control gain and a discharge control gain that determine the current charge / discharge response speed are calculated, and the charge control device 5 and the discharge device 4 of the charging device 3, respectively. The discharge control device 6 is used to control the response speed of charging and discharging.

  For this reason, in a system that repeatedly charges or discharges the storage battery 2 in a short time such as a smart grid, even if the electrical characteristics of the storage battery 2 change due to repeated charging and discharging, depending on the usage state of the storage battery 2 Safe and stable charge / discharge control is possible without overcharge and overdischarge.

<Embodiment 3>
A third embodiment of the charge / discharge control apparatus according to the present invention will be described with reference to FIGS. FIG. 9 is a block diagram showing the configuration of the charge / discharge control apparatus 300 of the third embodiment.

<Device configuration>
As shown in FIG. 9, the charge / discharge control device 300 receives AC power from the system AC power supply 1, converts it into DC power, outputs it, and charges the storage battery 2, and DC power discharged from the storage battery 2. The discharge device 4 that receives and converts it into AC power and supplies it to the system AC power source 1, the current measurement device 7 that measures the input / output current to the storage battery 2, and the control gain change device 8 that changes the response speed at the start of charge / discharge And a voltage measurement device 11 that measures the voltage across the terminals of the storage battery 2 and an internal resistance calculation device 13 that calculates the internal resistance of the storage battery 2. In addition, the same code | symbol is attached | subjected about the structure same as the charging / discharging control apparatus 100 shown in FIG. 1, and the overlapping description is abbreviate | omitted.

  For example, when the internal resistance calculation device 13 senses a change in the electrical load 22, the internal resistance calculation device 13 determines the internal resistance of the storage battery 2 based on the output fluctuation range of the voltage measurement device 11 and the output fluctuation range of the current measurement device 7. Is calculated. In addition, since the use state of a storage battery is detected using the current measurement apparatus 7, the voltage measurement apparatus 11, and the internal resistance calculation apparatus 13, these can be called a storage battery use state detection apparatus.

  Here, the load fluctuation is sensed by a change in electric power discharged from the storage battery 2. For example, if the voltage is the same and the current increases, the load increases. If the voltage is the same and the current decreases, the load is increased. Means less. Therefore, it can be determined that the load has fluctuated if there is a change in the current with almost no change in voltage compared to the current measured before.

  Based on the internal resistance value of the storage battery 2 calculated by the internal resistance calculation device 13, the control gain changing device 8 calculates a charge control gain and a discharge control gain that determine the current charge / discharge response speed.

  In the calculation processing of the feedback control for the charge control and the discharge control executed by the charge control device 5 and the discharge control device 6 included in the charging device 3 and the discharging device 4, respectively, the charging control gain and the discharging control gain are respectively set. By multiplying, the response speeds of the charge control device 5 and the discharge control device 6 are controlled to prevent overcharge and overdischarge. In this case, the control gain is a parameter (transfer function) that determines the response speeds of the charge control device 5 and the discharge control device 6, and the control gain changing device 8 can be said to be a response speed changing device.

<Operation>
Next, the operation of the charge / discharge control apparatus 300 will be described using the flowchart shown in FIG. 10 with reference to FIG.

  First, in step S41, it is determined whether or not to charge the storage battery 2 or discharge from the storage battery 2. This determination is made by the charging control device 5 of the charging device 3 and the discharging control device 6 of the discharging device 4 according to the presence or absence of a charging instruction or discharging instruction from the management system 23, respectively. Note that the determination in step S41 is periodically performed while the charge / discharge control device 100 is in operation.

  If it is determined that charging or discharging is to be performed, the process proceeds to step S42. However, if neither charging nor discharging is performed, it is not necessary to change the control gain. Wait for instructions to discharge.

  On the other hand, when charging or discharging is performed, in step S42, in the case of charging, for example, the control gain at the time of the previous charging stored in the memory in the charging control device 5 of the charging device 3 is read, and discharging is performed. In this case, the control gain at the time of the previous discharge stored in the memory in the discharge control device 6 of the discharge device 4 is read.

  Then, charging or discharging is started with the read control gain (step S43). That is, the control gain at the start of charging or discharging is the control gain calculated by the control gain changing device 8 at the end of the previous charging or discharging.

  After the start of charging / discharging, the direction (positive / negative) of the current input / output to / from the storage battery 2 measured using the current measuring device 7 and the current value A1 at that time are stored in a memory in the internal resistance calculating device 13 (step) In addition, the inter-terminal voltage V1 of the storage battery 2 measured using the voltage measuring device 11 is stored in a memory in the internal resistance calculating device 13 (step S45).

  Then, based on the measured current value A1 and the measured voltage V1, it is determined whether or not a load change has occurred (step S46). This determination is performed by comparing the current value and voltage measured before and stored in the memory in the internal resistance calculation device 13 with the current value A1 and voltage V1 at the present time. If the current is increased and the current is increased, it is determined that the load is increased. If the voltage is the same and the current is decreased, it is determined that the load is decreased.

  Then, when it is determined in step S46 that the load fluctuation has occurred, the following processing is executed. However, when it is determined that the load fluctuation has not occurred, charging / discharging under the same conditions is performed. Wait until the next charge / discharge instruction is issued without executing the following processing. This determination is made by the internal resistance calculation device 13.

  If it is determined in step S46 that a load change has occurred, the current value A2 input / output to / from the storage battery 2 after the load change is measured and stored in the memory in the internal resistance calculation device 13 (step S47). The voltage V2 between the terminals of the storage battery 2 after the load change is measured and stored in the memory in the internal resistance calculation device 13 (step S48).

  Next, based on the voltage V1 and the voltage V2 stored in the memory, the following equation (11) is used to calculate the absolute value ΔV of the fluctuation range of the inter-terminal voltage of the storage battery 2 (step S49).

ΔV = | V1-V2 | (11)
Further, based on the current value A1 and the current value A2 stored in the memory, the following equation (12) is used to calculate the absolute value ΔA of the fluctuation range of the current input to and output from the storage battery 2 (step S50).

ΔA = | A1-A2 | (12)
Then, the internal resistance R of the storage battery 2 is calculated using the following formula (13) based on ΔV and ΔA calculated in step S49 and step S50, respectively (step S51).

R = ΔV / ΔA (13)
Next, the control gain changing device 8 calculates the current control gain change rate based on the internal resistance R of the storage battery 2 calculated in step S51. Here, the control gain change rate dG is given by the following equation (14).

dG = f (Rin) = A / (2π · B · Rin) (14)
In the above formula (14), A is a predetermined coefficient (approximately 1 in this case), B is a constant determined by the type of battery, and Rin is an internal resistance.

  The control gain change rate dG is calculated in advance for each internal resistance, stored as a map in the memory in the control gain changing device 8, and read from the map based on the measured parameters, and the control gain change rate is obtained. It may be used as dG.

  Next, the control gain changing device 8 calculates the control gain Gt based on the following formula (15) (step S52).

Gt = A · (1 / (1 + s · f (Rin)) (15)
In the above equation (15), A is a predetermined coefficient (approximately 1 in this case), and s is a Laplace operator.

  Here, a binary switching operation of comparing the calculated internal resistance R of the storage battery 2 with a preset threshold value and switching the control gain to a small value when the threshold value is exceeded is shown in FIG. Is shown schematically.

  In FIG. 11, the horizontal axis indicates the internal resistance, the vertical axis indicates the control gain, and the control gain switching characteristic G21 at room temperature. As described above, when the internal resistance R exceeds a preset threshold value, an operation for switching the control gain to one of the two values is referred to as a binary switching operation. Further, in FIG. 11, the threshold value set in advance is lower when the temperature of the storage battery 2 is higher than the switching characteristic G21 of the control gain at normal temperature, and the threshold set in advance when the temperature of the storage battery 2 is lower. The value shows that it becomes higher.

  FIG. 12 shows switching characteristics of the control gain when the temperature of the storage battery 2 changes. In FIG. 12, the horizontal axis indicates the internal resistance, and the vertical axis indicates the control gain. The value of the internal resistance that switches the control gain when the temperature of the storage battery 2 is higher than the control gain switching characteristic G21 at room temperature. When the temperature of the storage battery 2 decreases, the value of the internal resistance for switching the control gain increases.

  After obtaining the new control gain based on the current internal resistance of the storage battery 2 through step S52 described above, the previous control gain stored in the memory in the charge control device 5 or the discharge control device 6 is The new control gain is rewritten and stored (step S53).

  Then, charging / discharging is controlled with a new control gain (step S54), and when charging / discharging ends, the process waits until there is a next charging / discharging instruction.

<Effect>
As described above, in the charge / discharge control device 300 of the third embodiment, the control gain changing device 8 is based on the internal resistance of the storage battery 2 calculated by the internal resistance calculation device 13 and the current charge / discharge response. The charge control gain and the discharge control gain that determine the speed are calculated and supplied to the charge control device 5 of the charging device 3 and the discharge control device 6 of the discharging device 4, respectively, thereby controlling the response speed of charging and discharging.

  For this reason, the charge control gain and the discharge control gain can be changed corresponding to the case where the internal resistance has changed due to the deterioration of the storage battery 2.

  In addition, since the internal resistance of the storage battery 2 is measured when there is a load change, the internal resistance is likely to increase rapidly, such as when the storage battery 2 is stored at a high temperature with a large amount of charge stored. It is valid.

  In addition, although the charging / discharging control apparatus of Embodiment 1-3 demonstrated above can also be applied to charging / discharging of the electric power between a stationary storage battery and system | strain AC power supply, it drives electric vehicles, such as an electric vehicle It can also be applied to charge / discharge of power between the storage battery and the system AC power source. In that case, the charge / discharge control device may be mounted on an electric vehicle or may be configured to be installed on a ground facility.

<Description of Effects of the Present Invention Using Charge / Discharge Characteristics>
FIG. 13 is a diagram for explaining the effect of the present invention using charge / discharge characteristics. In part (a) of FIG. 13, the horizontal axis represents time and the vertical axis represents current, and charging characteristics to the storage battery are illustrated.

  In part (a) of FIG. 13, the charging characteristic when the storage battery is charged without performing current control is shown as characteristic T1, and the charging current overshoots due to the electric characteristic of only the internal resistance of the storage battery. It shows the possibility.

  Further, in part (a) of FIG. 13, charging characteristics when current control is performed using a low-pass filter is shown as a characteristic T11, and overshooting of the charging current is suppressed by performing current control. It is shown that.

  In part (b) of FIG. 13, the charging characteristic when current control is performed using a low-pass filter is shown as characteristic T11. Also, current control is not performed and the storage battery becomes old and the internal resistance of the storage battery increases. The charging characteristic in this case is shown as characteristic T21, and the charging characteristic when the storage battery becomes old and the internal resistance of the storage battery becomes large in a state where current control is performed using a low-pass filter is shown as characteristic T22.

  The characteristic T11 is a characteristic when a low-pass filter having a large time constant is used to suppress overshoot when the storage battery is new and the internal resistance is small (corresponding to a case where the control gain is reduced). Thus, when the storage battery becomes old, the internal resistance increases, a state in which double low pass filters are provided, and a long time is required until a specified current flows (charging time becomes long).

  That is, the part (b) of FIG. 13 shows that the time required for the specified current i to flow is t1 in the characteristics T11 and T21, but t3 (t3> t1) in the characteristic T22. .

  Here, it can be seen from the characteristic T21 that when the storage battery is old and the internal resistance of the storage battery is increased, the overcurrent is suppressed only by the internal resistance, and the current control by the low-pass filter is unnecessary.

  In such a case, by reducing the time constant of the low-pass filter (corresponding to increasing the control gain), it is possible to suppress an increase in the time required until a specified current flows.

  In part (c) of FIG. 13, the charging characteristic when using a low-pass filter with a time constant as small as possible is shown as characteristic T31, and current control is not performed, the storage battery becomes old and the internal resistance of the storage battery increases. A charging characteristic when using a low-pass filter in which a time constant is set so as to be close to the characteristic T21 is shown as a characteristic T32.

  As shown in part (c) of FIG. 13, in the characteristic T32, the time required for the specified current i to flow is t2, which is longer than the time t2 in the case of the characteristic T31, but the time t3 (t3 It can be seen that it is shorter than> t2> t1).

  As described above, in the charge / discharge control device according to the present invention, the overcharge and overcharge are adjusted by adjusting the control gain of the current control system and the time constant of the filter in accordance with the use frequency of the storage battery and the internal state (internal resistance). It has the feature that safe and stable charge / discharge control can be performed without discharging.

  The first to third embodiments described above can be freely combined with each other, or can be appropriately modified or omitted. Hereinafter, modifications according to the present invention will be described.

<Modification 1>
In the first embodiment, by adjusting the control gain (transfer function) used in the arithmetic processing executed in the charging control device 5 and the discharging control device 6 included in the charging device 3 and the discharging device 4, respectively. Although the description has been made assuming that the response speeds of charging and discharging are controlled, it may be configured to control the response speeds of charging and discharging by adjusting the time constant of the low-pass filter instead of the control gain.

  That is, a charging low-pass filter (not shown) controlled by the charging control device 5 is provided in the charging device 3 shown in FIG. 1, and a discharging low-pass filter (controlled by the discharging control device 6) is provided in the discharging device 4. The control gain changing device 8 outputs a time constant according to the state of the storage battery instead of the control gain.

  However, the time constant of the low-pass filter is not a simple low-pass filter, but can be changed according to the accumulated usage time or the temperature of the storage battery 2. That is, a resistance element and a capacitance element of a low-pass filter (for example, an RC circuit) configured by an actual electric circuit are configured by variable elements.

  Thus, by changing the time constant of the low-pass filter so as to realize the time constant output from the control gain changing device 8 according to the state of the storage battery, that is, the usage history (new or old) of the storage battery. The time constant can be prevented from becoming unnecessarily large, and the charge / discharge time can be shortened.

  When a low-pass filter is used as the current control system, the control gain Gt described using Equation (4) is expressed by Equation (16) below.

Gt = A · (1 / (1 + s · t)) (16)
In the above equation (16), A is a predetermined coefficient (approximately 1 in this case), t is a time constant of a low-pass filter, and s is a Laplace operator.

  The time constant t of the low-pass filter is given by the following formula (17).

t = Gold + dG · dTime (17)
In the above equation (17), Gold is the control gain at the time of the previous discharging or charging read at step S7, dG is the control gain change rate calculated at step S9, and dTime is the control gain change period. Note that dTime is a time set based on conditions such as temperature, and is determined by the control gain changing device 8 based on, for example, the maximum charging current, the maximum discharging current, and external factors (such as ambient temperature).

  In the above equation (17), Gold can be replaced with the previous low-pass filter cut-off frequency, and dG can be replaced with the rate of change of the cut-off frequency. It shows that it changes to the high frequency side, so that it passes.

<Modification 2>
In the second embodiment, the control gain (transfer function) used in the arithmetic processing executed in the charging control device 5 and the discharging control device 6 included in the charging device 3 and the discharging device 4 is adjusted. Although the description has been made assuming that the response speeds of charging and discharging are controlled, it may be configured to control the response speeds of charging and discharging by adjusting the time constant of the low-pass filter instead of the control gain.

  That is, a charging low-pass filter (not shown) controlled by the charging control device 5 is provided in the charging device 3 shown in FIG. 5, and a discharging low-pass filter (controlled by the discharging control device 6) is provided in the discharging device 4. The control gain changing device 8 outputs a time constant according to the state of the storage battery instead of the control gain.

  However, the time constant of the low-pass filter is not a simple low-pass filter, but can be changed according to the accumulated usage time or the temperature of the storage battery 2. That is, a resistance element and a capacitance element of a low-pass filter (for example, an RC circuit) configured by an actual electric circuit are configured by variable elements.

  Thus, by changing the time constant of the low-pass filter so as to realize the time constant output from the control gain changing device 8 according to the state of the storage battery, that is, the usage history (new or old) of the storage battery. The time constant can be prevented from becoming unnecessarily large, and the charge / discharge time can be shortened.

  When a low-pass filter is used as the current control system, the control gain Gt described using Equation (10) is expressed by Equation (18) below.

Gt = A · (1 / (1 + s · t)) (18)
In the above equation (18), A is a predetermined coefficient (approximately 1 in this case), t is a time constant of a low-pass filter, and s is a Laplace operator.

  The time constant t of the low-pass filter is given by the following mathematical formula (19).

t = Gold + dG · dWh (19)
In Equation (19), Gold is the control gain at the time of the previous discharging or charging read in Step S27, ΔG is the control gain increase width calculated in Step S29, and dWh is the control gain changing period. Note that dWh is the amount of electric power set based on conditions such as temperature, and is determined by the control gain changing device 8 based on, for example, the maximum charging current, the maximum discharging current, and external factors (such as ambient temperature).

  In Equation (19), Gold can be replaced with the previous low-pass filter cut-off frequency, and dG can be replaced with the change rate of the cut-off frequency. In this case, Equation (18) shows that the time constant of the low-pass filter is time It shows that it changes to the high frequency side, so that it passes.

<Modification 3>
In the third embodiment, by adjusting the control gain (transfer function) used in the arithmetic processing executed in the charging control device 5 and the discharging control device 6 included in the charging device 3 and the discharging device 4, respectively. Although the description has been made assuming that the response speeds of charging and discharging are controlled, it may be configured to control the response speeds of charging and discharging by adjusting the time constant of the low-pass filter instead of the control gain.

  That is, a charging low-pass filter (not shown) controlled by the charging control device 5 is provided in the charging device 3 shown in FIG. 9, and a discharging low-pass filter (controlled by the discharging control device 6) is provided in the discharging device 4. The control gain changing device 8 outputs a time constant according to the state of the storage battery instead of the control gain.

  However, the time constant of the low-pass filter is not a simple low-pass filter, but can be changed according to the internal resistance of the storage battery 2. That is, a resistance element and a capacitance element of a low-pass filter (for example, an RC circuit) configured by an actual electric circuit are configured by variable elements.

  Thus, by changing the time constant of the low-pass filter so as to realize the time constant output from the control gain changing device 8 according to the state of the storage battery, that is, the usage history (new or old) of the storage battery. The time constant can be prevented from becoming unnecessarily large, and the charge / discharge time can be shortened.

  When a low-pass filter is used as the current control system, the control gain Gt described using Expression (16) is represented by Expression (20) below.

Gt = A · (1 / (1 + s · t)) (20)
In the above equation (20), A is a predetermined coefficient (approximately 1 in this case), t is a time constant of a low-pass filter, and s is a Laplace operator.

  The time constant t of the low-pass filter is given by the following formula (21).

t = Gold + dG · dR (21)
In the above equation (21), Gold is the control gain at the time of the previous discharging or charging read in step S42, dG is the control gain change rate, and dR is the control gain change cycle. Note that dR is a change width of the internal resistance set based on conditions such as temperature. For example, in the control gain changing device 8 based on the maximum charging current, the maximum discharging current, and external factors (such as ambient temperature). decide.

  In the above equation (21), Gold can be replaced with the cut-off frequency of the previous low-pass filter, and dR can be replaced with the rate of change of the cut-off frequency. It shows that it changes to the high frequency side, so that it passes.

<Modification 4>
In Embodiment 1, the structure which changes the charge control gain and discharge control gain which determine the present charge / discharge response speed based on the accumulation use time of the storage battery 2 and the temperature of the storage battery 2 is shown, and the temperature of the storage battery 2 is shown. The control gain change rate is changed by the above-described configuration. However, the control gain change rate is expressed by a linear function as shown in FIG. As described with reference to FIG. 7 in the second embodiment, this may be one in which the control gain is changed stepwise.

  Further, as described with reference to FIG. 11 in the third embodiment, a method of binary switching using a predetermined threshold may be used.

<Modification 5>
In Embodiment 2, the structure which changes the charge control gain and discharge control gain which determine the present charge / discharge response speed based on the accumulation electric energy of the storage battery 2, and the temperature of the storage battery 2 is shown, and the temperature of the storage battery 2 is shown. However, the control gain may be changed in a linear function as described with reference to FIG. 3 in the first embodiment.

  Further, as described with reference to FIG. 11 in the third embodiment, a method of binary switching using a predetermined threshold may be used.

<Modification 6>
In the third embodiment, a configuration in which the control gain is switched in a binary manner based on the internal resistance of the storage battery 2 has been shown. This is a linear function as described with reference to FIG. 3 in the first embodiment. It is good also as a structure to change automatically.

  Further, as described with reference to FIG. 7 in the second embodiment, the control gain may be changed stepwise.

<Modification 7>
Moreover, in the modification 4, it is good also as a structure which controls the response speed of charge and discharge by adjusting the time constant of a low-pass filter instead of a control gain.

<Modification 8>
Moreover, in the modification 5, it is good also as a structure which controls the response speed of charge and discharge by adjusting the time constant of a low-pass filter instead of a control gain.

<Modification 9>
Moreover, in the modification 6, it is good also as a structure which controls the response speed of charge and discharge by adjusting the time constant of a low-pass filter instead of a control gain.

  2 storage battery, 3 charging device, 4 discharging device, 5 charging control device, 6 discharging control device, 7 current measuring device, 8 control gain changing device, 9 cumulative usage time calculating device, 10 temperature measuring device, 11 voltage measuring device, 12 Cumulative electric energy calculation device, 13 internal resistance calculation device.

Claims (10)

A charging / discharging control device that charges the storage battery with the system power of the system AC power supply and discharges the power stored in the storage battery and supplies the power to the system AC power supply,
The charge / discharge control device comprises:
A charging device that converts alternating current power from the system alternating current power source into direct current power and supplies it to the storage battery;
A discharge device for converting the DC power discharged by the storage battery into AC power and supplying the AC power to the grid AC power supply;
A storage battery use state detection device for detecting a use state of the storage battery;
A charging control device that is included in the charging device and controls charging of the storage battery;
A discharge control device included in the discharge device for controlling charging from the storage battery;
A charge / discharge control device comprising: a response speed changing device that receives an output of the storage battery use state detection device and changes a parameter that determines a response speed of the charge control device and the discharge control device according to a use state of the storage battery. . The charging control device controls charging to the storage battery by feedback control,
The discharge control device controls discharge from the storage battery by feedback control,
The parameter is
A control gain of feedback control in the charge control device and the discharge control device,
The response speed changing device is:
The charge / discharge control device according to claim 1, wherein the control gain is increased and output as the storage battery becomes old based on a detection result of the storage battery use state detection device. The charging device is:
Output charging power through a low-pass filter for charging controlled by the charging control device,
The discharge device
Output discharge power through a low-pass filter for discharge controlled by the discharge control device,
The parameter is
The time constants of the charging low-pass filter and the discharging low-pass filter,
The response speed changing device is:
The charge / discharge control apparatus according to claim 1, wherein the time constant is decreased and output as the storage battery becomes old based on a detection result of the storage battery use state detection apparatus. The storage battery use state detection device is:
The charge / discharge control apparatus according to any one of claims 1 to 3, wherein a use state of the storage battery is detected based on a storage battery cumulative use time that is a total use time from the start of use of the storage battery. The storage battery use state detection device is:
The charging / discharging of any one of Claims 1-3 which detects the use condition of the said storage battery based on the storage battery cumulative input electric energy which is the sum total of the electric energy charged / discharged from the use start time of the said storage battery. Control device. The storage battery use state detection device is:
The charge / discharge control apparatus according to any one of claims 1 to 3, wherein a use state of the storage battery is detected based on an internal resistance of the storage battery. The storage battery use state detection device is:
A voltage measuring device for measuring a voltage between terminals of the storage battery;
A current measuring device for measuring an input / output current to the storage battery,
The charge / discharge control apparatus according to claim 6, wherein the internal resistance is calculated based on the measured voltage and current when it is detected that a load change has occurred from the measured voltage and current fluctuation. The storage battery use state detection device is:
A temperature measuring device for measuring the temperature of the storage battery and / or the temperature around the storage battery;
Based on the measured temperature
The charge / discharge control device according to claim 2, wherein a change rate of the control gain output from the response speed changing device is changed. The storage battery use state detection device is:
A temperature measuring device for measuring the temperature of the storage battery and / or the temperature around the storage battery;
Based on the measured temperature
The charge / discharge control device according to claim 2, wherein a change width of the control gain output from the response speed changing device is changed. The charging low-pass filter and the discharging low-pass filter have variable elements,
The charge / discharge control device according to claim 3, wherein the charge control device and the discharge control device control the variable element so as to realize the time constant output by the response speed changing device.

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