Substation equipped with power storage device, power storage system connected thereto, and charge / discharge control method

Abstract

To provide an electric power substation which can contribute power saving while preventing invalidation of regeneration by the power charging / discharging performed by a power storage device in response to generation of regenerative electric power and power running power in a feeding section of the electric power substation adopted with a rectifier having small voltage fluctuation in output characteristic.SOLUTION: An electric power substation comprises a rectifier converting AC power to DC power, and a power storage device, and supplies power of at least one of the rectifier and the power storage device to a vehicle. The electric power substation includes: a first detector detecting magnitude of a load supplied by the electric power substation; and a second detector detecting feeding voltage. When the magnitude of the load detected by the first detector exceeds a first specified value, the power storage device discharges. When the voltage detected by the second detector exceeds a second specified value, the power storage device is charged. The power storage device discharges at voltage higher than no-load voltage of the rectifier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substation equipped with a power storage device, a power storage system connected thereto, and a charge / discharge control method. [Background technology]

[0002] In order to achieve energy conservation in railways (hereafter abbreviated as "energy conservation"), the effective use of regenerative braking has been attracting attention. Regenerative braking is a deceleration method that secures braking force using the electromotive force of the motor installed in the vehicle (which can also be read as "electric train"). It makes it possible to convert the kinetic energy of the vehicle, which is wasted as heat with conventional friction brakes, into electricity and reuse it. The regenerative power generated by this regenerative braking has been supplied via feeder lines as power for other trains.

[0003] However, because feeder lines are electrically separated into powered sections at predetermined intervals, if there are no vehicles consuming regenerative power in the same powered section, not only will the regenerative power not be utilized, but there is also the risk of the regenerative braking not working, resulting in a state of regeneration failure. For this reason, there is a need for technology that can effectively utilize regenerative power even in situations where there are no powered vehicles in the same powered section.

[0004] In response to this, a technology for effectively utilizing an electric power storage device (hereinafter referred to as "electricity storage device") is known (for example, Patent Document 1). This technology charges the energy storage device with regenerative power and discharges it when a powered vehicle appears, thereby realizing effective utilization of regenerative power even in a situation where there are no powered vehicles in the same feeder section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-150629 Summary of the Invention [Problem to be solved by the invention]

[0006] The energy storage device described in Patent Document 1 observes the voltage that rises and falls in accordance with the characteristics of the rectifier installed in the substation as regenerative power / running power is generated, and controls charging and discharging by charging when the voltage rises and discharging when the voltage drops. For this reason, in the feeding section of a substation that uses a rectifier with output characteristics that have little voltage fluctuation (for example, a thyristor rectifier) ​​and supplies power at a constant voltage, the voltage drop when running power is generated is small, making it difficult to ensure sufficient opportunities for discharging from the energy storage device.

[0007] Furthermore, the inability to secure sufficient discharge opportunities makes it impossible to effectively utilize regenerative power. The present invention has been made in view of the above problems, and an object of the present invention is to provide a substation equipped with a rectifier having output characteristics with little voltage fluctuation and a power storage device, in which the power storage device is charged and discharged in response to the generation of regenerative power and running power, thereby preventing regeneration failure and contributing to power saving. [Means for solving the problem]

[0008] The present invention, which solves the above problem, includes a rectifier that converts AC power to DC power and a storage device, and in a substation that supplies the power of at least one of the rectifier and the storage device to a vehicle via a feeder line, the substation is provided with a first detection unit that detects the magnitude of the load supplied by the substation and a second detection unit that detects the feeding voltage of the feeder line, and when the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the storage device discharges, and when the voltage detected by the second detection unit exceeds a second predetermined value, the storage device is charged. [Effects of the Invention]

[0009] According to the present invention, in a substation that uses a storage device and a rectifier having output characteristics with little voltage fluctuation, the storage device is charged and discharged in accordance with the generation of regenerative power and running power, thereby making it possible to provide a substation that can prevent regeneration failure and contribute to power saving. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a functional block diagram illustrating an outline of a power storage system according to a first embodiment of the present invention. [Figure 2] 2 is a graph illustrating the output characteristics of the thyristor rectifier 10 in FIG. 1. [Figure 3] 2 is a functional block diagram illustrating a control device 30 in FIG. 1. FIG. [Figure 4] 2 is a graph illustrating an example of output characteristics of the power storage device 20 in FIG. [Figure 5] 2 is a graph illustrating an example of an operating waveform of the power storage system of FIG. 1. [Figure 6] 10A and 10B are a functional block diagram illustrating a control device 31 according to a second embodiment of the present invention and an operation explanatory graph. [Figure 7] 7 is a graph illustrating an example of an operational waveform of the control device 31 of FIG. 6. [Figure 8] 7 is a functional block diagram illustrating a control device 32 according to a modified example of the control device 31 of FIG. 6. [Figure 9] FIG. 10 is a functional block diagram illustrating an outline of a power storage system according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a functional block diagram illustrating an outline of a power storage system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiment 1 will be described with reference to Figures 1 to 5, embodiment 2 will be described with reference to Figures 6 and 7, a modified example of embodiment 2 will be described with reference to Figure 8, embodiment 3 will be described with reference to Figure 9, and embodiment 4 will be described with reference to Figure 10. In the following, parts having the same effect will be assigned the same reference numerals to avoid duplication of explanation. [Example]

[0012] A first embodiment of the present invention will be described. Fig. 1 is a functional block diagram illustrating an outline of a power storage system. The power storage system of Fig. 1 is composed of a vehicle 1, a feeder 2, and a substation (hereinafter also referred to as "main substation") 3A equipped with a power storage device. In addition to the main substation 3A of Examples 1 and 2 shown in Fig. 1, a main substation 3B of Example 3 shown in Fig. 9 and a main substation 3C of Example 4 shown in Fig. 10 are also illustrated, but when there is no need to distinguish between them, they will be collectively referred to as the main substation 3.

[0013] This substation 3A includes a rectifier 10, a power storage device 20, and a control device 30. This substation 3A supplies running power to the vehicle 1 via the feeder 2, while also absorbing regenerative power. Cases where this function cannot be performed present a problem, which is solved by the present invention. Note that the power storage device 20 does not necessarily have to be located within the premises of this substation 3A, as long as it is installed somewhere and charging and discharging can be controlled via communications. However, this example illustrates a standard configuration in which the power storage device 20 belongs to this substation 3A.

[0014] The rectifier 10 converts the power received from the power grid 4 into direct current. A feeding current 50 is exchanged between the substation 3A and the vehicle 1. The energy storage device 20 charges and discharges based on control conditions in accordance with the direction and value of the detected feeding current 50. The direction of the feeding current 50 is positive when the traction power is supplied, and negative when the regenerative power is absorbed. Note that the power grid 4 is not necessarily provided solely by electric power companies; railway operators may also own their own power plants. In such cases, public constraints such as power factor improvement obligations may be relaxed.

[0015] The control device 30 prevents regeneration from being invalidated and controls the charging and discharging of the power storage device 20 based on control conditions that contribute to energy saving.

[0016] The power storage system stores regenerative power generated by the braking force of the train 1 in a ground-based power storage device 20 via a feeder 2, and supplies the stored power when the train 1 is powered, repeating this operation to make effective use of power.

[0017] In an actual energy storage system, one of a pair of connection terminals for receiving and sending power on the feeding side, the P side, is connected to the feeder line 2 via a DC high-speed circuit breaker panel (not shown), and the other, the N side, is connected to a rail (not shown) via a disconnecting switch panel (not shown). Such an energy storage system not only has an energy-saving function and a function to prevent regeneration from lapsed, but also a function to supplement the output of this substation 3A in emergencies such as a power outage in the power grid 4.

[0018] However, in the feeding section of this substation 3A, which uses the thyristor rectifier 10 with small voltage fluctuations in its output characteristics, there was a problem that conventional charge / discharge control did not work properly. Therefore, this invention has solved this problem.

[0019] The control device 30 controls charging and discharging by determining a charge / discharge command value 60 for the power storage device 20. The charge / discharge command value 60 is determined based on a substation current (hereinafter referred to as "feeder current" or "load magnitude") 50 and a feeding voltage 40. The feeding current 50 is observed at the connection point between the feeder line 2 and this substation 3A.

[0020] 2 is a graph illustrating the output characteristics of the thyristor rectifier 10 in FIG. 1, with the horizontal axis representing the output current I and the vertical axis representing the output voltage V. When running power is generated, the rectifier 10 supplies current at a no-load voltage V0 up to the rated current Ir, and when the rated current Ir is exceeded, the voltage drops according to the amount of current supplied. Furthermore, when regenerative power is generated, the current is not passed in the reverse direction so as to be absorbed into the power grid 4, and therefore the voltage V on the output side of the rectifier 10 rises.

[0021] Fig. 3 is a functional block diagram illustrating the control device 30 in Fig. 1. The control device 30 includes a target voltage switch 301, voltage regulators 303 and 306, and a switch 308. The target voltage switch 301 compares the feeding current 50 with a threshold current (first predetermined value) It, and appropriately outputs a discharge voltage command value 302.

[0022] Voltage regulator 303 determines discharge power command value 304. Voltage regulator 306 determines charge power command value 307. Switch 308 outputs the appropriate operation mode determined by the determination method shown in Table 1 below as charge / discharge command value 60.

[0023] The control device 30 determines the charge / discharge command value 60 under the following conditions: When the feeding current 50 is equal to or greater than the threshold current It, the control device 30 outputs a voltage VD1 that is greater than the no-load voltage V0 from the target voltage switch 301 as the discharge voltage command value 302.

[0024] When the feeding current 50 is less than the threshold current It, the control device 30 outputs a voltage VD0 that is smaller than the no-load voltage V0 from the target voltage switch 301 as the discharge voltage command value 302.

[0025] Furthermore, voltage regulator 303 determines discharge power command value 304 so that the difference between discharge voltage command 302 and feeding voltage 40 becomes 0. Voltage regulator 306 determines charge power command value 307 so that the difference between charge voltage command value 305 and feeding voltage 40 becomes 0. Switch 308 selects one of discharge, charge, and standby and outputs the determined appropriate operation mode as charge / discharge command value 60.

[0026] When the operation mode is discharging, the switch 308 outputs the discharge power command value 304 as the charge / discharge command value 60. When the operation mode is charging, the switch 308 outputs the charge power command value 307 as the charge / discharge command value 60. When the operation mode is standby, the switch 308 outputs zero as the charge / discharge command value 60. An example of a method for determining the operation mode by the switch 308 is shown in Table 1 below.

[0027] In the control device 30 of FIG. 3, the discharge power command value 304 and the charge power command value 307 are indicators that discharge the power storage device 20 when they are positive and charge the power storage device 20 when they are negative, and therefore the operating mode is determined by the signs of both values.

[0028] Specifically, when the discharge power command value 304 is positive and the charge power command value is positive, discharge occurs; when the charge power command value 307 is negative and the charge power command value is negative, charge occurs; otherwise, standby occurs.

[0029] [Table 1]

[0030] 4 is a graph illustrating the output characteristics of power storage device 20 in FIG. 1, with the horizontal axis representing charge / discharge current D and the vertical axis representing power storage device voltage B. During charging, power storage device 20 is charged so that power storage device voltage B remains constant at a charging upper limit voltage (second predetermined value) VC of power storage device 20, and when charging / discharging current D of power storage device 20 reaches a maximum charging current IC, power storage device voltage B rises above charging upper limit voltage VC.

[0031] During discharge, the power storage device 20 exhibits two types of characteristics according to the feeding current 50. When the feeding current 50 is at a low load below the threshold current It, the power storage device 20 discharges when the power storage device voltage B is equal to or lower than a low voltage VD0, as shown in the first output characteristic 401.

[0032] Furthermore, if charge / discharge current D of power storage device 20 reaches a heavy load of maximum discharge current ID, power storage device voltage B drops below voltage VD0.

[0033] Furthermore, when the feeding current 50 is under a heavy load equal to or greater than the threshold current It, the storage device 20 discharges when the storage device voltage B is equal to or less than the higher voltage VD1, as in the second output characteristic 402. When the charge / discharge current D of the storage device 20 reaches the maximum discharge current ID, the feeding voltage 40 drops below the higher voltage VD1.

[0034] Fig. 5 is a graph illustrating the operating waveforms of the energy storage system of Fig. 1, with the horizontal axis representing time t and the vertical axis representing powering / regenerative current (vehicle current) A, feeding voltage 40, rectifier output current I, energy storage device current D, and feeding current 50. Note that the regenerative current A, powering current A, auxiliary current A (not shown), and vehicle current A, which is a combination of all of these, are all indicated by the common symbol A in Fig. 5.

[0035] Additionally, it is conceivable that auxiliary current A could be used to prevent regeneration lapse by consuming some of the regenerative power, but the optional functions for this would be complicated, so for the sake of convenience, we will simplify the explanation here by assuming that auxiliary current A is either included in powering current A at the same time or is not present. For the same reason, we will assume that there is only one train set 1 on the feeder section of this substation 3A.

[0036] Auxiliary current A and powering current A are supplied from this substation 3A to the feeder 2 to the vehicle 1. Regenerative current A is fed back from the vehicle 1 to the feeder 2 to this substation 3A. Feeder voltage 40 is the voltage at the connection point connecting this substation 3A and the feeder 2.

[0037] For ease of explanation, the feeding voltage 40 is assumed to be a no-load voltage V0 with no powering / regenerative current A, and while it tends to be positive during regeneration, it does not tend to be negative even during powering.

[0038] The rectifier output current I is a current supplied from the rectifier 10 to the feeder 2, and is not fed back in the opposite direction. The rectifier output current I leads to the consumption of power received from the power grid 4, so the smaller the rectifier output current I, the more it contributes to energy conservation.

[0039] In the extreme, if all of the regenerative power could be stored and used to power the vehicle, the rectifier output current I would be unnecessary, and the power received from the power grid 4 and consumed could also be eliminated. Even if it cannot be eliminated, it can be minimized to compensate for the consumption of auxiliary equipment (not shown) and losses in each section, thereby contributing to energy conservation.

[0040] The storage device current D is a current that flows in either direction between the storage device 20 and the feeder line 2, charging in the negative direction and discharging in the positive direction. The waveform of the storage device current D during charging in the negative direction and the waveform of the regenerative current A have the same shape, but not all of the regenerative power is stored in the storage device 20, and certain conditions must be met.

[0041] 1 and 5, it is assumed that only vehicle 1 is present in the feeding section, so feeding current 50 is the same as vehicle current A of vehicle 1. When multiple vehicles 1 are present in the feeding section, feeding current 50 is the total value obtained by offsetting the sum of the auxiliary current A (not shown) and the powering current A of each of the multiple vehicles 1 at the same time with the sum of the regenerative current A.

[0042] 5 shows the time-series waveforms of the voltages and currents mentioned above, which will be explained below in the order of times t0 to t6. At time t0, vehicle 1 starts regeneration, and regenerative current A flows to feeder line 2, causing feeding voltage 40 to rise. When feeding voltage 40 reaches the upper limit charging voltage (second predetermined value) VC (FIG. 4) of power storage device 20, power storage device 20 starts charging with power running current A.

[0043] At time t1, when vehicle 1 stops supplying regenerative current, feeding voltage 40 stabilizes at no-load voltage V0, and power storage device 20 stops charging. At time t2, vehicle 1 starts powering, and when a power running current flows, rectifier 10 supplies the power running current to vehicle 1 via power line 2. At time t3, when feeding current 50 exceeds threshold current It, power storage device 20 starts discharging at voltage VD1 (see also FIG. 6), feeding voltage 40 becomes VD1, and rectifier 10 stops supplying current.

[0044] At time t4, when the storage device current D of the storage device 20 reaches the upper limit of output, the feeding voltage 40 drops to the no-load voltage V0, and the rectifier 10 supplies the current that is insufficient with only the current from the storage device 20. At time t5, when the reduced power running current can be entirely covered by the discharge current from the storage device 20, the rectifier 10 stops outputting, and the feeding voltage 40 becomes VD1, which is the discharge voltage of the storage device 20.

[0045] At time t6, when the powering current A falls below the threshold current It, the storage device 20 stops discharging, the feeding voltage 40 drops to the no-load voltage V0, and the rectifier 10 supplies the powering current A instead of the storage device 20. As described above, the substation 3A in Figures 1 to 5 employs a rectifier 10 with small voltage fluctuations during output.

[0046] According to the energy storage system in which the vehicle 1 runs on the power feeding section supplied with power from this substation 3A, it is possible to realize charging and discharging of the energy storage device 20 adapted to the regeneration and power running of the vehicle 1, thereby making effective use of the regenerative power and preventing regeneration failure. [Example]

[0047] Second Embodiment A power storage system according to a second embodiment of the present invention will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a functional block diagram and an explanatory graph of the operation of a control device 31 according to a second embodiment of the present invention. In a target voltage switch 301 shown in Fig. 6, a current controller 601 determines a discharge voltage command value 302, with a target value obtained by subtracting a practical upper limit of stable output current Is (hereinafter also referred to as "stable output current" or "third predetermined value") taking into consideration the lifespan of the rectifier 10, from the feeding current 50. Note that the stable output current Is is less than or equal to the threshold current It.

[0048] The operation explanatory graph in Fig. 6 is a graph for explaining the operation when target voltage switch 301 outputs discharge voltage command value 302, based on the magnitude relationship between VD1, V0, and VD0 shown in Fig. 4. When feeder current 50 - third predetermined value Is is less than 0, discharge voltage command value 302 shown in the graph outputs voltage VD0 lower than no-load voltage V0, and when it is 0 or greater, outputs voltage VD1 higher than no-load voltage V0.

[0049] Fig. 7 is a graph illustrating the operating waveforms of the control device 31 in Fig. 6, with the horizontal axis representing time t and the vertical axis representing the vehicle current (auxiliary / powering / regenerative current) A, the feeding voltage 40, the rectifier output current I, the storage device current D, and the feeding current 50. The behavior from time t0 to time t3 in Fig. 7 is the same as in Example 1 in Fig. 5.

[0050] The power storage system of the second embodiment shown in Fig. 6 and Fig. 7 differs from the power storage system of the first embodiment in the following respects: At time t3, when the power running current A exceeds the stable output current Is, the power storage device 20 starts discharging. The rectifier 10 maintains the stable output current Is, and the shortage of the vehicle current A is compensated for by the power storage device 20 discharging.

[0051] At time t6, when the power running current A falls below the stable output current Is of the rectifier 10, the power storage device 20 stops discharging. From time t3 to time t6, the feeding voltage 40 coincides with the no-load voltage V0. As described above, according to the power storage system of the second embodiment shown in Figs. 6 and 7, in addition to the same effects as those of the first embodiment shown in Fig. 5, frequent fluctuations in the feeding voltage 40 can be suppressed.

[0052] Fig. 8 is a functional block diagram illustrating a control device 32 according to a modified example of the control device 31 in Fig. 6. The voltage regulator 303 may be omitted from the control device 31 in Fig. 6, and the output of the discharge power command value 304 may be directly determined from the current controller 601, as shown in the control device 32 in Fig. 8. [Example]

[0053] The power storage system of Example 3 will be described with reference to the functional block diagram of Fig. 9. The power storage system of Example 3 differs from the power storage systems of Examples 1 and 2 in that it observes an output current 901 of a rectifier 10 and an output current 902 of a power storage device 20, and inputs the sum of the output current 901 and the output current 902 to a control device 30 as a feeding current 50. The power storage system of Example 3 can achieve the same effects as Examples 1 and 2 in a substation 3B where the feeding current 50 cannot be directly observed due to the configuration of the measurement device. [Example]

[0054] The power storage system of the fourth embodiment will be described with reference to the functional block diagram of Fig. 10. The power storage system of the fourth embodiment shown in Fig. 10 is different from the third embodiment in that an input voltage 1001 from a power grid 4 to a rectifier 10 is observed, and an output current 901 is calculated from the harmonic components or power factor contained in the input voltage 1001 by a load estimation device 1002.

[0055] The power storage system of Example 4 shown in Fig. 10 can achieve the same effect as Example 3 in a substation 3C where the output current 901 of the rectifier 10 cannot be directly observed due to the configuration of the measurement device. Note that, although the system configurations of Examples 1 to 4 show examples in which the electrical measurement points are installed on the positive electrode side, they may also be installed on the negative electrode side. Also, the measurement and command information relating to current in the system configurations of Examples 1 to 4 may be replaced with information relating to power.

[0056] In a thyristor rectifier, there is a correspondence between the magnitude of the load and the power factor, so the magnitude of the load can be determined by detecting the power factor. Therefore, in this substation 3C in which a thyristor rectifier is used for the rectifier 10, the energy storage system equipped with it, and the charge / discharge control method, the same effects can be achieved even if a power factor system is used instead of an ammeter or wattmeter.

[0057] The "magnitude of the load" refers to the magnitude of at least one of the current and power, and may be interpreted as either one. Also, if existing detection means such as a voltmeter, ammeter, wattmeter, power factor meter, or harmonic measuring means are functioning in the related facilities of this substation 3C as a means for detecting the magnitude of the load, it is acceptable to use these alone or in combination to easily measure the required quantity using the processed values.

[0058] This substation 3 can be summarized as follows: [1] As shown in FIG. 1, the substation 3 includes a rectifier 10 that converts AC power into DC power and a power storage device 20, and supplies power output from at least one of the rectifier 10 and the power storage device 20 to the vehicle 1.

[0059] The substation 3 further includes a first detector 51 and a second detector 41. The first detector 51 detects a feeding current (load magnitude) 50 supplied by the substation 3. The second detector 41 detects a feeding voltage 40 to the feeder line 2. The storage device 20 charges and discharges based on the following control conditions. The storage device 20 discharges when the feeding current 50 detected by the first detector 51 exceeds a first predetermined value (threshold current) It (FIG. 2). The storage device 20 charges when the feeding voltage 40 detected by the second detector 41 exceeds a second predetermined value (charging upper limit voltage) VC (FIG. 4) of the storage device 20.

[0060] In other words, the rectifier 10 of this substation 3 only feeds power in one direction from the output terminal and does not have the function of returning regenerative power to the power grid 4 to which this substation 3 is connected. If regenerative power attempts to enter in the direction opposite to the output direction, the rectifier 10 of this substation 3 cannot absorb it, and therefore the output voltage of the rectifier 10 shown in Figure 2 becomes significantly higher than the no-load voltage V0.

[0061] Therefore, the power storage device 20 provided in the substation 3 constituting the power storage system stores regenerative power from the vehicles 1 traveling in the feeding section. Most of the power required for powering the vehicles 1 is provided by the discharged power from the power storage device 20, and if the discharged power is insufficient, the shortage is made up for by the output power of the rectifier 10.

[0062] As a result, in the feeding section of the substation 3, which uses a rectifier 10 with little voltage fluctuation in its output characteristics, the storage device 20 charges and discharges in response to the generation of regenerative power and running power, thereby preventing regeneration failure and contributing to energy conservation.

[0063] [2] In the above [1], as shown in Figures 2, 4, and 5, the substation 3 preferably discharges the energy storage device 20 at a voltage VD1 higher than the no-load voltage V0 of the rectifier 10. One of the on-conditions for the rectifier 10 is that the anode on the input side has a higher potential than the cathode on the output side. Conversely, the rectifier 10 turns off when the cathode on the output side is made higher than the no-load voltage V0. In this way, if the rectifier 10 is in the output-off state and the energy storage device 20 is discharged at a voltage VD1 higher than the no-load voltage V0 to feed power, the power supply from the power grid 4 is stopped, which contributes to energy conservation.

[0064] [3] In the above item [1], as shown in Example 2 (times t3 to t6) in Figures 6 and 7, the substation 3 may discharge, from the power storage device 20, a load amount obtained by subtracting the amount exceeding the third predetermined value Is from the vehicle current A (auxiliary / powering current), which is the substation load. The third predetermined value Is is a practical upper limit value Is of the stable output current of the rectifier 10. As a result, the output current I of the rectifier 10 is maintained at the stable output current Is, as shown by I in Figure 7 (Example 2) compared to Figure 5 (Example 1), and the current that is insufficient with respect to the vehicle current A is compensated for by being discharged by the power storage device 20.

[0065] At time t6, when the powering current A falls below the stable output current Is of the rectifier 10, the energy storage device 20 stops discharging. From time t3 to time t6, the feeding voltage 40 coincides with the no-load voltage V0. Thus, according to the substation 3 of the second embodiment shown in Figs. 6 and 7, in addition to the same effects as those of the first embodiment, frequent fluctuations in the feeding voltage 40 can be suppressed. As a result, there is also the effect of extending the life of the equipment.

[0066] [4] In the above [1], as shown in FIG. 1, the first detector 51 may detect the feeding current 50 supplied from the substation 3 to the feeder line 2 as the magnitude of the load.

[0067] [5] In the above [1], the load estimation device 1002 shown in Fig. 10 may detect the magnitude of the load based on the power factor of the AC power and the discharge power of the power storage device 20. This makes it possible to reduce the amount of dedicated equipment required when adding a power storage function to an existing substation. The reason for this is as follows.

[0068] The thyristor rectifier 10 has an output characteristic in which the power factor decreases as the load increases. The transistor rectifier controls the voltage using PWM control. In contrast, the thyristor rectifier 10 uses a phase control system, which means that the output voltage is more stable than the transistor rectifier, but it is more likely to generate harmonics, which may have a negative impact on the power grid 4.

[0069] This substation 3C, which uses this thyristor rectifier 10, is often connected to the power grid 4 of the power utility. In such cases, monitoring is required, as there is an obligation to suppress power factor degradation caused by this substation 3C in order to maintain the transmission efficiency and stability of the power grid 4. Therefore, if this substation 3C has an existing power factor detection means, the detection results can be used to detect the magnitude of the load.

[0070] Furthermore, if existing detection means such as a voltmeter, ammeter, wattmeter, power factor meter or harmonic measuring means are functioning in the related facilities of this substation 3C as a means of detecting the magnitude of the load, it is acceptable to use these alone or in combination to easily measure the required quantity using the processed values.

[0071] [6] In the above [1], the first detector 51 shown in FIG. 1 may detect the magnitude of the load based on the harmonics of the AC power and the discharge power of the power storage device 20. When adding a regenerative power storage function to an existing substation, the amount of additional dedicated equipment required can be reduced. The reason for this is as follows. The thyristor rectifier 10 has an output characteristic in which the generation of harmonics increases as the load increases. Harmonics are noise that is harmful to signal control, etc., and need to be suppressed.

[0072] Furthermore, if a DC-DC voltage converter with a chopper circuit is installed to realize the power storage function, the generation of harmonics caused by this must be suppressed, and therefore monitoring must be strengthened. Therefore, if a harmonic measuring means is attached to the regenerative power storage function, the detection results can be used to detect the magnitude of the load.

[0073] [7] As shown in Figures 1, 9 and 10, the energy storage system of the present invention may be configured to be interconnected with any of the substations 3 described above in [1] to [6]. According to such an energy storage system, in the substation 3 that employs the rectifier 10 having output characteristics with little voltage fluctuation, the energy storage device charges and discharges in response to the generation of regenerative power and running power, thereby contributing to energy saving and preventing regeneration failure. [Explanation of symbols]

[0074] 1: vehicle, 2: feeder line (including overhead wire and trolley wire), 3, 3A, 3B, 3C: substation (main substation), 4: power system, 10: (thyristor) rectifier, 20: storage device, 30, 31, 32: control device, 40: feeding voltage, 41: second detection unit, 51: first detection unit, 50: feeding current, 60: charge / discharge command value, 301: target voltage switch, 302: discharge voltage command value, 303, 306: voltage regulator, 304: discharge power command value, 305: charge voltage command value, 307: charge power command value, 308: switch, 401: first output characteristic, 402: second output characteristic, 601: current controller, 901: output current, 902: output current, 1001: input voltage, 1002: Load estimation device, A: vehicle current (auxiliary / powering / regenerative current), B: storage device voltage, D: charge / discharge current, I: (thyristor) rectifier output current, IC: maximum charge current, ID: maximum discharge current, It: threshold current (first predetermined value), Is: (rectifier 10) stable output current (third predetermined value), Ir: (rectifier 10) rated current, t: time, V: (thyristor rectifier) ​​output voltage, V0: (rectifier 10) no-load voltage, VC: (storage device 20) upper limit charge voltage (second predetermined value), VD0: (storage device 20) voltage set lower than the no-load voltage V0 of the rectifier 10), VD1: (storage device 20) discharge voltage set higher than the no-load voltage V0 of the rectifier 10

Claims

1. A substation including a rectifier that converts AC power into DC power and a power storage device that supplies power from at least one of the rectifier and the power storage device to a vehicle, a first detection unit that detects the magnitude of the load supplied by the substation, and a second detection unit that detects a feeding voltage; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the voltage detected by the second detection unit exceeds a second predetermined value; Equipped with a power storage device, Discharging a load amount obtained by subtracting a third predetermined value from the regenerative storage substation load from the storage device; the third predetermined value is an upper limit of a stable output current at which the rectifier can output a stable current at a constant voltage; Substation.

2. The storage device discharges at a voltage higher than the no-load voltage of the rectifier. A substation comprising the electricity storage device according to claim 1.

3. The first detection unit detects a feeding current of the substation as a magnitude of a load. A substation comprising the electricity storage device according to claim 1.

4. A substation including a rectifier that converts AC power into DC power and a power storage device, the substation including a power storage device that supplies at least one of the power of the rectifier and the power storage device to a vehicle, a first detection unit that detects the magnitude of the load supplied by the substation, and a second detection unit that detects a feeding voltage; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the voltage detected by the second detection unit exceeds a second predetermined value; Equipped with a power storage device, the first detection unit detects the magnitude of the load based on a power factor of the AC power and the discharge power of the power storage device. Substation equipped with energy storage device.

5. A substation including a rectifier that converts AC power into DC power and a power storage device, the substation including a power storage device that supplies at least one of the power of the rectifier and the power storage device to a vehicle, a first detection unit that detects the magnitude of the load supplied by the substation, and a second detection unit that detects a feeding voltage; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the voltage detected by the second detection unit exceeds a second predetermined value; Equipped with a power storage device, the first detection unit detects the magnitude of the load based on the harmonics of the AC power and the discharge power of the power storage device. Substation equipped with energy storage device.

6. A power storage system interconnected with a substation, comprising the power storage device according to any one of claims 1 to 5.

7. A charge / discharge control method for a power storage system interconnected with a substation that supplies at least one of an output of a power storage device that receives and sends vehicle power and an output of a rectifier that converts AC power to DC power to the power storage system, comprising: a first detection unit that detects the magnitude of a load supplied from the substation; a second detection unit that detects a feeding voltage of the substation; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the feeding voltage detected by the second detection unit exceeds a second predetermined value; Discharging a load amount obtained by subtracting a third predetermined value from the substation load from the power storage device; the third predetermined value is an upper limit of a stable output current at which the rectifier can output a stable current at a constant voltage; A method for controlling charging and discharging of an electricity storage system.

8. The storage device discharges at a voltage higher than the no-load voltage of the rectifier. The charge / discharge control method for a power storage system according to claim 7.

9. The first detection unit detects a feeding current of a substation as a magnitude of a load. The charge / discharge control method for a power storage system according to claim 7.

10. A charge / discharge control method for a power storage system interconnected with a substation that supplies at least one of an output of a power storage device that receives and supplies vehicle power and an output of a rectifier that converts AC power to DC power to the power storage system, comprising: a first detection unit that detects a feeding voltage of the substation; a second detection unit that detects the magnitude of the load supplied from the substation; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the feeding voltage detected by the second detection unit exceeds a second predetermined value; the first detection unit detects the magnitude of the load based on a power factor of the AC power and the discharge power of the power storage device. A method for controlling charging and discharging of an electricity storage system.

11. A charge / discharge control method for a power storage system interconnected with a substation that supplies at least one of an output of a power storage device that receives and supplies vehicle power and an output of a rectifier that converts AC power to DC power to the power storage system, comprising: a first detection unit that detects a feeding voltage of the substation; a second detection unit that detects the magnitude of the load supplied from the substation; When the magnitude of the load detected by the first detection unit exceeds a first predetermined value, the power storage device discharges; charging the power storage device when the feeding voltage detected by the second detection unit exceeds a second predetermined value; the first detection unit detects the magnitude of the load based on the harmonics of the AC power and the discharge power of the power storage device. A method for controlling charging and discharging of an electricity storage system.

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