JP2011188556A - Apparatus and method for controlling charging/discharging of storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive method and apparatus for instantaneously and stably controlling charging/discharging currents on a stage-by-stage basis just by changing control software in multiplexed PCS configured by connecting multiple storage battery modules in series. <P>SOLUTION: (1) A quantity of control Q for controlling an overall active power is determined from a deviation in the overall active power P (=I<SB>dc1</SB>×V<SB>dc1</SB>+I<SB>dc2</SB>×V<SB>dc2</SB>+...+I<SB>dcN</SB>×V<SB>dcN</SB>). (2) The allocation correction α<SB>n</SB>of each stage is determined from the deviation in the direct current of each stage. (3) The quantity of control of each stage is determined from Q and α<SB>n</SB>and Q+α<SB>n</SB>or Q×(1+α<SB>n</SB>) is taken as the quantity of control of the nth stage. The deviation in the overall active power P is inputted to a PI controller and its output Q is corrected with the output α<SB>n</SB>of the PI controller of the direct control system of each stage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a storage battery charge / discharge control device and method, and more specifically, a storage battery charge / discharge control that individually controls a DC side charge / discharge current in an AC / DC converter (PCS) in which a plurality of storage battery modules are connected in series in multiple stages. The present invention relates to an apparatus and a method.

  In nickel-metal hydride batteries and lead-acid batteries, overcharging rarely causes quality degradation. However, in metal salt batteries such as NAS batteries and lithium batteries, the active material decomposes and generates corrosive gas when overcharged. However, quality degradation occurs. Therefore, in order to prevent overcharging due to overvoltage at the end of charging, precise control such as charging while reducing the voltage is required.

  Furthermore, when storage battery modules are connected in series, individual current / voltage control is required at each stage.

  In a conventional charge control system that enables individual stage charging rate (SOC) control when storage battery modules are connected in series, all SOCs can be made constant over a long period of time. Therefore, when charging is performed in a short period, the deviation from the control target value may increase and a residual deviation may occur (see Non-Patent Document 1).

  In addition, in a system in which lithium cells are connected in series, another method for accurately controlling the end of charging for each cell requires the provision of a regulator for controlling charging for each cell, which may be expensive. Yes (see Patent Document 1).

Therefore, it is considered that the SOC control for each stage is realized only by changing the control software without requiring additional hardware. First, FIG. 1A shows a main circuit configuration that is generally used as DC side current control, and FIG. 1B shows a control circuit configuration for controlling an inverter. The deviation between the measured value I _{dc of} DC current and its target value (I _dc ^* ) is input to the PI controller, and the AC side current i _s and AC voltage v _s are obtained from the value obtained by multiplying the output of the PI controller by a sine wave. Subtract and add respectively.

FIG. 2 (a) shows a main circuit configuration in which conventional DC side current control is applied to a storage battery module multiplexed PCS, and FIG. 2 (b) shows a control circuit configuration for controlling two inverters independently. Each stage is controlled independently, and the first stage performs PI control using only I _dc1 as the controlled _variable and the second stage uses only I _dc2 as the controlled _variable . In this specification, this control method is called direct control.

JP 2001-178010 A

"6.6kV transformerless power storage system using cascaded PWM converter and secondary battery", D. 129, No. 1, 2009

  However, when such direct control that controls each stage independently is used, the discharge operation can be controlled, but the charging operation cannot be controlled.

  FIG. 3 shows a simulation result when the two inverters of the storage battery module multiplexed PCS are directly and independently controlled. FIGS. 3A and 3B show the state during charging, and FIGS. 3C and 3D show the state during discharging. The discharge side can follow the target value correctly and can be controlled stably, but the charging side vibrates and is unstable and cannot follow the target value.

Figure 4 ^{_{(a) I dc1 * = 1A}} , I dc2 * = control deviation at direct current and PI controller just before the case of controlling the 1A shows simulation results, (b) is, I _dc1 ^* = 1A, A simulation result of the direct current and the control deviation immediately before the PI controller when controlled with I _dc2 ^* = 1.5 A is shown. FIG. 5 shows a simulation result of the direct current and the control deviation immediately before the PI controller when I _dc1 ^* = − 1 A and I _dc2 ^* = − 1 _A. FIG. 5B shows I _dc1 ^* = −. A simulation result of a direct current and a control deviation immediately before the PI controller when controlled as 1 A, I _dc2 ^* = − 1.5 A is shown.

  During the discharge operation shown in FIG. 4, the control deviation converges to zero. On the other hand, during the charging operation shown in FIG. 5, the control deviation does not converge to zero and is unstable.

  The present invention has been made in view of such a problem, and an object of the present invention is to individually charge / discharge current in each stage by changing control software in a multiplexed PCS in which a plurality of storage battery modules are connected in series. It is to provide an inexpensive control method and control device for instantaneously and stably controlling the control.

In order to solve the above-mentioned problem, the invention according to claim 1 is a battery charge control that individually controls the DC side charge / discharge current in each AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages. In the discharge control device, the inverter of the storage battery module of the i-th stage (1 ≦ i ≦ N) has a control amount Q for performing feedback control on the DC side active power of the plurality of storage battery modules as a whole at least during charging. The i-th storage battery module is controlled based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current of the storage battery module.

The invention according to claim 2 is a storage battery charge / discharge control device that individually controls the DC side charge / discharge current in each stage in an AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages. The inverter of the storage battery module of the first (1 ≦ i ≦ N) has at least one control amount α _j (1 ≦ j ≦ N) for performing feedback control of the direct current of the storage battery module at the other stage at least during charging. The control amount Q is controlled based on the control amount Q _i obtained by correcting the control amount α _i for feedback control of the direct current of the i-th storage battery module.

According to a third aspect of the present invention, in the storage battery charge / discharge control device according to the first or second aspect, the corrected control amount Q _i is defined as Q _i = Q + α _i .

According to a fourth aspect of the present invention, in the storage battery charge / discharge control device according to the first or second aspect, the corrected control amount Q _i is defined as Q _i = Q (1 + α _i ). .

According to a fifth aspect of the present invention, in the storage battery charge / discharge control device according to any of the first to fourth aspects, the control amounts Q and α _i are each PI-controlled.

The invention according to claim 6 is a storage battery charge / discharge control method for individually controlling the DC side charge / discharge current in each stage in an AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages. The inverter of the storage battery module of the first (1 ≦ i ≦ N) has a control amount Q for feedback control of the DC side active power of the whole of the plurality of storage battery modules at least during charging, and the inverter of the i-th storage battery module Control is performed based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current.

The invention described in claim 7 is a storage battery charge / discharge control method for individually controlling the DC side charge / discharge current in each stage in an AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages. The inverter of the storage battery module of the first (1 ≦ i ≦ N) has at least one control amount α _j (1 ≦ j ≦ N) for performing feedback control of the direct current of the storage battery module at the other stage at least during charging. The control amount Q is controlled based on the control amount Q _i obtained by correcting the control amount α _i for feedback control of the direct current of the i-th storage battery module.

The invention according to claim 8 is the storage battery charge / discharge control method according to claim 6 or 7, wherein the corrected control amount Q _i is defined as Q _i = Q + α _i .

The invention according to claim 9 is the storage battery charge / discharge control method according to claim 6 or 7, wherein the corrected control amount Q _i is defined as Q _i = Q (1 + α _i ). .

A tenth aspect of the present invention is the storage battery charge / discharge control method according to any of the sixth to ninth aspects, wherein the control amounts Q and α _i are each PI-controlled.

  INDUSTRIAL APPLICABILITY The present invention has an effect that in a multiplexed PCS in which a plurality of storage battery modules are connected in series, the charge / discharge current can be instantaneously and stably controlled for each stage only by changing control software.

(A) is a figure which shows the main circuit structure generally used as DC side current control, (b) is a figure which shows the control circuit structure for controlling an inverter. (A) is a figure which shows the main circuit structure which applied the conventional direct current side current control to storage battery module multiplexing PCS, (b) is a figure which shows the control circuit structure which directly controls two inverters independently, respectively. It is. It is a figure which shows the simulation result at the time of controlling directly two inverters of a storage battery module multiplexing PCS each independently, (a) is a graph at the time of controlling as _Idc1 ^* = 1A, _Idc2 ^* = 1A, (B) is a graph when controlling as I _dc1 ^* = 1A and I _dc2 ^* = 1.5 A, and (c) is a graph when controlling as I _dc1 ^* = − 1A and I _dc2 ^* = − 1A. Yes, (d) is a graph when control is performed with I _dc1 ^* = − 1A and I _dc2 ^* = − 1.5 A. (A) is a graph showing a simulation result of direct current and control deviation immediately before the PI controller when I _dc1 ^* = 1A and I _dc2 ^* = 1A, and (b) is a graph showing I _dc1 ^* = 1A, It is a graph which shows the simulation result of the control deviation just before a direct-current current and PI controller at the time of controlling by _Idc2 ^* = 1.5A. (A) is a graph showing a simulation result of a direct current and a control deviation immediately before the PI controller when I _dc1 ^* = − 1A and I _dc2 ^* = − 1 A, and (b) is a graph showing I _dc1 ^* = -1A, is a graph showing a simulation result of the control deviation of the DC current and the PI controller just before the case of controlling the I _dc2 ^* = -1.5A. It is a figure which shows the equivalent circuit of the main circuit of storage battery module multiplexing PCS. It is a figure which shows the 1st control circuit structure of the storage battery module multiplexing PCS which concerns on Embodiment 1 of this invention. It is a figure which shows the 2nd control circuit structure of the storage battery module multiplexing PCS which concerns on Embodiment 1 of this invention. It is a figure which shows the simulation result by the 1st control method which concerns on Embodiment 1 of this invention. It is a figure which shows the simulation result by the 2nd control method which concerns on Embodiment 1 of this invention. The experimental result by the prototype using the 1st control method concerning Embodiment 1 of this invention is shown. It is a figure which shows the 3rd control circuit structure of the storage battery module multiplexing PCS which concerns on Embodiment 2 of this invention. It is a figure which shows the 4th control circuit structure of the storage battery module multiplexing PCS which concerns on Embodiment 2 of this invention. The experimental result by the prototype using the 3rd control method concerning Embodiment 2 of this invention is shown. The experimental result by the prototype using the 4th control method concerning Embodiment 2 of this invention is shown.

  The causes of control instability on the charging side described in the problem to be solved by the invention are considered as follows.

  FIG. 6 shows an equivalent circuit of the main circuit of the storage battery module multiplexed PCS. A first stage including the inverter 102a and a DC power source connected thereto is referred to as an AC power source 105a, and a second stage including the inverter 102b and a DC power source connected thereto is referred to as an AC power source 105b.

The direct control circuit performs the following operation during discharging.
Insufficient | I _dc1 | → Increase | v _c1 | → | v _s | Increase | v _c1 + v _c2 | → | i _s | Increase → Inverter− The output of the active power from 102b (| v _c1 | × | i _s |) increases → | I _dc1 | increases → | I _dc1 | deficiency is resolved. Therefore, in the case of discharge, negative feedback is applied and control is stable. To do.

On the other hand, the control circuit for direct control performs the following operation during charging.
| I _dc1 | is insufficient → in order to increase the input of active power to inverter 102a | v _c1 | is increased → | v _s | is increased | v _c1 + v _c2 | is increased → | i _s | is decreased → inverter− The input of the active power (| v _c1 | × | i _s |) to 102b decreases → | I _dc1 | decreases → | I _dc1 | is further insufficient. Therefore, in this case, the feedback becomes positive and the control becomes unstable. Conceivable. Also, instead of decreasing | i _s |, | v _c2 | may be decreased by an increase of | v _c1 |. In such a case, the following operation is performed.
| I _dc1 | is insufficient → in order to increase the input of active power to inverter 102a | v _c1 | is increased → | v _c1 + v _c2 | is constant at | v _s |, so | v _c2 | is decreased → | I _dc2 | Decreases → In order to increase the input of active power to inverter 102b, | v _c2 | increases → | v _c1 + v _c2 | is constant at | v _s |, so | v _c1 | decreases → | I _dc1 | Thus, it is considered that an attempt to increase I _dc1 causes a decrease in I _dc2 , which also causes a negative cycle that causes a decrease in I _dc1 , resulting in unstable control.

From the above, in the case of discharging, the inverter AC side voltage and the DC current increase as they increase, and the steady state deviation can be made zero by PI control when feedback control is performed, but in the case of charging operation, the AC side voltage and DC are increased. Since the relationship with the current decreases as the relationship with the current increases, it is thought that when feedback control is applied, the deviation increases. Further, there is a correlation between I _dc1 and I _dc2, and it is considered that the operation of increasing one acts to decrease the other.

  Therefore, when these phenomena occur in combination, it is considered that in the storage battery module multiplexed PCS, when direct current control is performed independently at each stage, the control does not converge during the charging operation.

  As a countermeasure against this, the present invention feedback-controls the charge / discharge power of the entire converter in which storage battery module converters are connected in series, and then individually controls the DC current of each stage for the storage battery module converter of each stage. Provided is a method of correcting and controlling by value.

  Hereinafter, embodiments of the present invention will be described in detail.

According to this method, individual control of each stage is possible by the following procedure.
(1) A control amount Q for controlling the overall active power P is determined by a deviation of the overall active power P (= I _dc1 × V _dc1 + I _dc2 × V _dc2 +... + I _dcN × V _dcN ). .
(2) The distribution correction α _n of each stage is determined by the deviation of the DC current of each stage.
(3) The control amount of each stage is determined by Q and α _n .
(4) As a method for determining the control amount of each stage, there are the following methods.
(I) n-th stage control amount = Q + α _n ... Control method 1
(Ii) n-th stage control amount = Q × (1 + α _n )... Control method 2
Here, it is important that the control target value of the direct current at each stage is set to one of the control target values at the other stages. For this reason, the control amount Q does not necessarily have to control the entire active power P, and may be any as long as it includes the control target value of another stage.

  These methods have the following characteristics. The controlled object is a scalar quantity of active power and direct current. Therefore, it is possible to use a proportional integration operation for feedback control, and the steady-state deviation of the direct current can be set to “0”.

  Further, since this method can be realized only by changing the control software, no additional hardware such as a special auxiliary control unit is required, so that there is no particular increase in cost.

(Embodiment 1)
FIG. 7 shows a control circuit configuration based on method 1 of the storage battery module multiplexed PCS according to the first embodiment of the present invention. In the first control method shown in FIG. 7, the deviation of the total active power P is input to the PI controller, and the output Q is added to the outputs α ₁ and α ₂ of the PI controllers of the direct control systems of the respective stages. To do. In the first control method, since the slope of the open loop characteristic is inverted depending on whether the control target value is positive or negative, it is necessary to convert the sign of the feedback value depending on whether the control target value is positive or negative. Therefore the control deviation I _dc1, I _dc2 is, I _dc1 ^* Before entering the IP controller, to convert the positive and negative depending on the sign of the I _dc2 ^*.

FIG. 8 shows a control circuit configuration based on method 2 of the storage battery module multiplexed PCS according to the first embodiment of the present invention. In the second control method shown in FIG. 8, the deviation of the total active power P is input to the PI controller, and its output Q is multiplied by the outputs α ₁ and α ₂ of the PI controllers of the direct control systems of the respective stages. To do. Then, the output Q is further added to the multiplied value. As a result, each inverter behaves so as to converge the DC current of its own stage to the target value and simultaneously converge the DC current of other stages to the target value of each stage.

FIG. 9 shows a simulation result by the first control method, and FIG. 10 shows a simulation result by the second control method. For the purpose of comparing the transient response, the control responsiveness was compared when the target value of the direct current was “I _dc1 ^* = − 1 A, I _dc2 ^* = − 1.5 A”. In any control method, stable control characteristics without overshooting are obtained.

FIG. 11 shows the results of experiments using a prototype using the first control method. The control target values of I _dc1 and I _dc2 were changed every minute, and the followability of each stage was confirmed by experiments. From this experimental result, it was confirmed that each of I _dc1 and I _dc2 was stably controlled to follow the control target value.

  The above is an example in the case of a two-stage configuration. However, even when the storage battery module has an N-stage configuration, the control amount for each stage is based on the change in the direct current of each stage. By correcting, the same effect can be exhibited.

(Embodiment 2)
FIG. 12 shows a control circuit configuration based on method 1 of the storage battery module multiplexed PCS according to the second embodiment of the present invention. In the third control method shown in FIG. 12, instead of correcting the entire active power P by the value subjected to PI control, the value subjected to PI control in the first stage is added to the value subjected to PI control in the second stage. . For the same reason as in the first embodiment, before inputting the control deviation of I _dc2 to the IP controller, the sign is changed according to the sign of I _dc1 ^* .

  In FIG. 13, the control circuit structure based on the method 2 of the storage battery module multiplexing PCS which concerns on Embodiment 2 of this invention is shown. In the fourth control method shown in FIG. 13, instead of performing correction based on the deviation of the overall active power P, the PI-controlled value of the second-stage DC current is multiplied by the PI-controlled value of the second-stage DC current. The multiplied value and the value subjected to PI control at the first stage are added.

  In the present embodiment, the first stage is not directly corrected, but is indirectly corrected by the second stage correction.

  FIG. 14 shows the experimental results of the prototype using the third control method, and FIG. 15 shows the experimental results of the prototype using the fourth control method. In either case, the charge / discharge current can be controlled stably at each stage.

  In the second embodiment, for convenience, the storage battery module has a two-stage configuration. What is important here is that the inverter of at least one of the N-stage storage battery modules has a control amount of the DC current of the other stage. In other words, the control is performed with a control amount obtained by correcting the control amount of the direct current in its own stage. Therefore, the same effect can be exhibited even when the storage battery module has an N-stage configuration.

101, 105a, 105b AC power supply 102, 102a, 102b Inverter 103 Control system 104 DC power supply

Claims (10)

A storage battery charge / discharge control device that individually controls the DC side charge / discharge current in each AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages,
The inverter of the i-th storage battery module of the i-th stage (1 ≦ i ≦ N) has a control amount Q for performing feedback control of the DC side active power of the whole of the plurality of storage battery modules at least during charging, and the i-th storage battery module A storage battery charge / discharge control apparatus, wherein the control is performed based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current of the module. A storage battery charge / discharge control device that individually controls the DC side charge / discharge current in each AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages,
The inverter of the storage battery module of the i-th stage (1 ≦ i ≦ N) has at least a control amount α _j (1 ≦ j ≦ N) for performing feedback control of the direct current of the storage battery module of the other stage at least during charging. The storage battery charge / discharge is controlled based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current of the i-th storage battery module with a control amount Q including one Control device. The storage battery charge / discharge control device according to claim 1, wherein the corrected control amount Q _i is defined as Q _i = Q + α _i . The storage battery charge / discharge control device according to claim 1, wherein the corrected control amount Q _i is defined as Q _i = Q (1 + α _i ). The storage battery charge / discharge control apparatus according to claim 1, wherein the control amounts Q and α _i are each PI-controlled. In the AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages, there is a storage battery charge / discharge control method for controlling the DC side charge / discharge current individually for each stage,
The inverter of the i-th storage battery module of the i-th stage (1 ≦ i ≦ N) has a control amount Q for performing feedback control of the DC side active power of the whole of the plurality of storage battery modules at least during charging, and the i-th storage battery module A storage battery charge / discharge control method, wherein control is performed based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current of the module. In the AC / DC converter (PCS) in which N storage battery modules are connected in series in multiple stages, there is a storage battery charge / discharge control method for controlling the DC side charge / discharge current individually for each stage,
The inverter of the storage battery module of the i-th stage (1 ≦ i ≦ N) has at least a control amount α _j (1 ≦ j ≦ N) for performing feedback control of the direct current of the storage battery module of the other stage at least during charging. The storage battery charge / discharge is controlled based on a control amount Q _i obtained by correcting a control amount α _i for feedback control of a direct current of the i-th storage battery module with a control amount Q including one Control method. The storage battery charge / discharge control method according to claim 6 or 7, wherein the corrected control amount Q _i is defined as Q _i = Q + α _i . The storage battery charge / discharge control method according to claim 6 or 7, wherein the corrected control amount Q _i is defined as Q _i = Q (1 + α _i ). The storage battery charge / discharge control method according to claim 6, wherein the control amounts Q and α _i are each subjected to PI control.

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