JP2009292187A - Power storage type regenerated power absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein an energy equivalent to an amount of voltage drop determined by a discharge current and an internal resistance at a point of time reaching the end, remains in a capacitance when discharge is stopped at the point of time when a capacitor voltage reaches a discharge end voltage in a regenerated power absorber for an electric railway. <P>SOLUTION: A charge/discharge current command Ic* computed by conventional control and the internal resistance 5 of the capacitor are multiplied by a multiplier 19, thereby calculating the amount of the voltage drop ΔVr by the internal resistance 5. This ΔVr is added to the discharge end voltage V2, thereby calculating a new discharge end voltage setting value V2'. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention connects a power charging / discharging circuit composed of a power conversion device and a power storage device such as a secondary battery or a large-capacity capacitor in parallel to a power source, such as a regenerative power absorbing device for electric railways, The present invention relates to a system that once absorbs electric power regenerated to the side and discharges the absorbed electric power as needed.

In FIG. 5, the structure of the electric power storage type | mold regenerative electric power absorption apparatus proposed by patent document 1 is shown. A DC substation system for electric railways provided at a substation that supplies DC power from an AC power source 1 to an electric railway load (wire railway vehicle with power regeneration function) 7 via a rectifier 2, The power storage device 4 that can be charged / discharged via the power converter 3 is connected to the electric wire voltage), and the regenerative power generated by the railway load 7 is stored and the power of the rectifier 2 is smoothed by the charge / discharge of the power storage device 4 To do. In addition, it has been proposed to apply a large-capacity capacitor such as an electric double layer capacitor as a power storage device.
Moreover, in patent document 2, in the apparatus shown in patent document 1, the feeder voltage is monitored, and when the feeder voltage is equal to or higher than the charging control setting voltage, the power storage device is charged from the feeder line side. There has been proposed a control method for a power storage device such that when the voltage is equal to or lower than the discharge control set voltage, the power storage device discharges to the feeder line side.
FIG. 6 is a control block diagram (outline) showing the above contents. The feeder voltage Vf is detected and input to the charge / discharge control amount calculation circuit 10. The charge / discharge control amount calculation circuit 10 calculates the charge control amount according to the voltage value when the feeder voltage Vf is equal to or higher than the set voltage Vb-ch of the charge voltage setter 12, and the feeder voltage Vf is discharged. When the voltage is less than or equal to the set voltage Vb-dis of the voltage setter 11, the discharge control amount Idch is calculated according to the voltage value. Further, the charge / discharge control amount Idch calculated by the subsequent charge / discharge current calculation circuit 15 is converted into a current command value Ic * of the conversion circuit 3.

On the other hand, the capacitor voltage Vb is detected, the discrimination process between the full charge voltage V1 of the capacitor and the discharge end voltage V2 of the capacitor is performed, and this discrimination result is input to the limit processing circuit 16 together with the charge / discharge control amount. In the limit processing circuit 16, if the capacitor voltage Vb is within the range of the full charge voltage V1 and the discharge end voltage V2 in the discrimination process, the current is limited by the capacitor characteristics, and the full charge or discharge end is performed in the discrimination process. In the case of, limit processing for reducing the charge / discharge current to zero is performed. The power converter 3 performs charge / discharge control based on the current command subjected to the limit process.
Patent Document 3 proposes a method for performing average discharge from the power storage device based on train operation information data as a charge / discharge control method.
JP-A-11-91415 JP 2001-260719 A JP 2005-162076 A

When actually charging / discharging in the system proposed in Patent Documents 1 to 3, since the internal storage device 5 exists in the power storage device 4 to be applied, a voltage drop corresponding to the charging / discharging current occurs. As a result, the observed capacitor voltage is an added value of the capacitance voltage value depending on the remaining capacity and the drop voltage value generated by the discharge current. Therefore, when the discharge is stopped when the capacitor voltage reaches the discharge end voltage, energy corresponding to the voltage drop determined by the discharge current and the internal resistance 5 at the end of the end remains in the capacitance 6. As the internal resistance 5 increases, the remaining amount increases, which causes a decrease in the subsequent absorbable energy.
As countermeasures, there are a method of selecting a capacitor having a small internal resistance 5 and a method of decreasing the internal resistance 5 by increasing the number of parallel connections. In the former, as the internal resistance 5 decreases, the capacitance 6 also decreases accordingly, so that the parallel number increases in order to obtain the capacitance 6 that is originally required for energy absorption. Either method increases the size of the capacitor group.

In order to solve the above-described problem, in the first invention, a power charging / discharging circuit including a power conversion device and a power storage device is connected in parallel to a power source, and power regenerated from a motor load or the like to the power source side is generated. In the system that absorbs the power by the power storage device and releases the absorbed power to the power supply as needed, when the control is performed to release the absorbed energy to the discharge completion voltage level of the power storage device, The voltage drop caused by the internal resistance of the electricity storage device is estimated, and the discharge completion voltage level is adjusted according to the estimated value of the voltage drop.
In the second invention, a power charging / discharging circuit composed of a power conversion device and a power storage device is connected in parallel to the power source, and the power regenerated from the motor load or the like to the power source side is absorbed by the power storage device and absorbed. In a system that discharges electric power to the power supply as needed, when the control is performed to release the absorbed energy to the discharge completion voltage level, the energy discharge amount of the power storage device becomes zero when the discharge completion voltage level is reached. The emission energy is gradually reduced.
In the third invention, a power charging / discharging circuit composed of a power conversion device and a power storage device is connected in parallel to the power source, and the power regenerated from the motor load or the like to the power source side is absorbed by the power storage device and absorbed. In the system for discharging electric power to the power supply as needed, a first discharge completion voltage level and a second discharge completion voltage level are provided in the control for releasing the absorbed energy to the discharge completion voltage level. When the discharge completion voltage level is reached, the remaining energy of the electricity storage device in the case of discharging to the second discharge completion voltage level is estimated in consideration of the voltage drop caused by the internal resistance of the electricity storage device. A current pattern for releasing the remaining energy is calculated within a time period of time, and energy is released based on the current pattern.

In the first invention, the remaining capacity stored in the capacitance 6 can be discharged to zero by correcting the voltage drop caused by the internal resistance 5 downward from the original discharge end level.
In the second and third inventions, by reducing the discharge current to zero as the capacitor voltage approaches the discharge end level, the voltage drop due to the internal resistance 5 becomes zero when the discharge end level is reached, and the capacitance 6 The stored remaining capacity can be made zero.
As described above, the capacitors can be efficiently used, and the capacitor group can be downsized.

  The main point of the present invention is that, in discharging a power storage device such as a capacitor, the discharge completion voltage is determined in consideration of the voltage drop due to the internal resistance, or the current at the time of discharge completion is controlled to be zero. The remaining capacity is made zero without being affected by the resistance.

FIG. 1 shows a first embodiment of the present invention, and FIG. 2 shows an operation example thereof. Here, the arithmetic processing indicated by the broken line in FIG. 2 is added to the conventional control shown in FIG. As shown in FIG. 1, the charge / discharge current command Ic * calculated in the conventional control and the internal resistance 5 of the capacitor are multiplied by a multiplier 19 to calculate a voltage drop ΔVr due to the internal resistance 5. This ΔVr and the discharge end voltage V2 are added to calculate a new discharge end voltage set value V2 ′. Based on the calculated V2 ′, the state of charge of the capacitor is determined, and the subsequent discharge operation is performed.
FIG. 2 shows waveforms of discharge voltage and current when the discharge end state is determined by conventional control (a) and when the proposed additional processing is performed (b).
In the conventional control, the capacitor voltage Vb reaches the discharge end voltage V2, the capacitor current Ic becomes zero, and at the same time, the voltage is shifted by ΔVr. This value is a voltage determined by the residual energy of the capacitance of the capacitor, and energy indicated by ΔJ below remains with respect to the energy at the discharge end voltage V2 set to zero by design.

On the other hand, when the calculation process is added, as shown in FIG. 2 (b), the discharge operation is continued until the new discharge end voltage V2 ', and the capacitor voltage Vb after the end of discharge becomes the conventional set value V2 and discharges to zero. can do.

FIG. 3 shows a second embodiment of the present invention, and FIG. 4 shows an operation example thereof. By attenuating the capacitor current to zero when the end-of-discharge voltage is reached, the voltage drop ΔVr due to the internal resistance 5 becomes as close to zero as possible, and the residual energy at the end-of-discharge determination time is obtained by setting the capacitance voltage Vc = capacitor voltage Vb Is zero.
First, the determination circuit 21 compares the capacitor voltage Vb with a determination voltage Vx having a set value higher than the discharge end voltage level. When it is determined that the capacitor voltage Vb has reached the determination voltage Vx, the discharge current pattern calculation circuit 22 calculates a current pattern for discharging from the determination voltage Vx to the discharge end voltage V2.
In the embodiment shown in FIG. 3, the time until the discharge is completed is set as T, and a current pattern that linearly decays to zero is calculated from the capacitor current I0 at the time of Vx. Here, the capacitance voltage Vc is first calculated from the capacitor voltage Vb, the capacitor current Ic, and the internal resistance R by the following equation.

Next, ΔV is calculated by subtracting the discharge end voltage V2 (Vend) from the calculation result Vc.

Thus, the initial capacitor current I0 is calculated, and the current pattern I (t) is calculated by the following equation.

A current command is calculated by the discharge current command calculation circuit 24 using the current pattern and a timer 25 that starts after reaching Vx, and is set as a capacitor current command Ic * after reaching Vx.
FIG. 4 shows the capacitor voltage Vb and the current waveform Ic when the current pattern is set. The current command value after reaching Vx is attenuated by the current pattern, and the current command after T time reaching the discharge end voltage V2 becomes zero. As a result, the amount of voltage drop due to the internal resistance when V2 is reached is also zero, and the residual energy of the capacitance is zero.
According to the above embodiment, the remaining energy of the capacitor can be set to zero at the end of discharge determination. As a result, it is possible to take measures against a decrease in the amount of energy that can be absorbed, which is a problem in the conventional method, and the capacitor can be used effectively.
In the above-described embodiment, an example in which the voltage V2 ′ before the end of discharge is one stage is shown. Further, the discharge current pattern may be any system that discharges the capacitor energy to zero when the discharge is completed, and various patterns can be applied.

  The present invention is a control method for effectively utilizing a large-capacity power storage device, and can be applied to a power load leveling device, an electric vehicle, and the like in addition to a regenerative power absorbing device for electric railways.

1 is a block diagram of a control circuit showing a first embodiment of the present invention. The operation diagram when FIG. 1 is applied is shown. The control circuit block diagram which shows the 2nd Example of this invention is shown. The operation | movement figure when FIG. 3 is applied is shown. The structural example of an electric power storage type regenerative electric power absorber is shown. The conventional control circuit block diagram is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... Rectifier circuit 3 ... DC-DC converter 4 ... Large capacity capacitor 5 ... Internal resistance 6 ... Electrostatic capacity 7 ... Electric wire with a power regeneration function Railcar 8 ... feeder 9 ... rail 10 ... charge / discharge control amount calculation circuit 11 ... discharge voltage setter 12 ... charge voltage setter 13 ... full charge voltage setter 14. ··· End-of-discharge voltage setting device 15 ··· Charging / discharging current calculation circuit 16 ··· Limiter processing circuit 17 ··· Charging state determination circuit 18 ··· Internal resistance setting device 19 · · · 21 ... Voltage setting device before discharge end 22 ... Discharge current pattern calculation circuit 23 ... Current command switching circuit 24 ... Discharge current command calculation circuit 25 ... Timer

Claims (3)

  A power charging / discharging circuit composed of a power conversion device and a power storage device is connected in parallel to a power source, power regenerated from the motor load or the like to the power source side is absorbed by the power storage device, and the absorbed power is In the system that releases to the power source, when controlling the released energy to the discharge completion voltage level of the electricity storage device, estimate the voltage drop caused by the energy released from the electricity storage device and the internal resistance of the electricity storage device. A power storage type regenerative power absorbing device, wherein a completion voltage level is adjusted according to an estimated value of the voltage drop.   A power charging / discharging circuit composed of a power conversion device and a power storage device is connected in parallel to a power source, power regenerated from the motor load or the like to the power source side is absorbed by the power storage device, and the absorbed power is In a system for releasing to a power source, when controlling the released energy to the discharge completion voltage level, the emission energy is sequentially reduced so that the amount of energy released from the electricity storage device reaches zero when reaching the discharge completion voltage level. A power storage type regenerative power absorbing device characterized by that. A power charging / discharging circuit composed of a power conversion device and a power storage device is connected in parallel to a power source, power regenerated from the motor load or the like to the power source side is absorbed by the power storage device, and the absorbed power is In a system for discharging to a power source, a first discharge completion voltage level and a second discharge completion voltage level are provided in the control for releasing the absorbed energy to the discharge completion voltage level, and the first discharge completion voltage level is reached. The remaining energy of the electricity storage device when discharging to the second discharge completion voltage level is estimated in consideration of the voltage drop caused by the internal resistance of the electricity storage device, and the remaining energy within a predetermined time. A power storage type regenerative power absorption device characterized by calculating a current pattern for discharging the energy and discharging energy based on the current pattern .

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