Power Control System

Abstract

The power control system includes a generator installed in a run-of-river hydroelectric power plant, a storage battery, and a control device that controls the power factor of the power output from the generator to the transmission network to which the run-of-river hydroelectric power plant belongs, the charging and discharging of the storage battery, and the power factor of the power charged and discharged from the storage battery to the transmission network, and the control device is configured to be able to select the power factor of the power charged and discharged from the storage battery between a predetermined power factor and a power factor corresponding to the power factor of a type of reactive power that has a greater impact on the transmission network.

Description

[Technical Field]

[0001] The present invention relates to a power control system. [Background technology]

[0002] BACKGROUND ART An electric power system that combines a hydroelectric generator with a storage battery is known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7563684 Summary of the Invention [Problem to be solved by the invention]

[0004] In the power system described in Patent Document 1, when the hydroelectric power generation capacity is insufficient, the storage battery is discharged. However, simply discharging makes it difficult to supply power at a more appropriate power factor in accordance with the trend of reactive power generated in the power grid.

[0005] An object of the present invention is to provide a power control system that can supply power at a more appropriate power factor in accordance with the tendency of reactive power occurring in a power transmission network. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the power control system of the present invention is a power control system comprising a generator installed in a run-of-river hydroelectric power plant, a storage battery, and a control device that controls the power factor of the power output from the generator to the transmission network to which the run-of-river hydroelectric power plant belongs, the charging and discharging of the storage battery, and the power factor of the power charged and discharged from the storage battery to the transmission network, wherein the control device is configured to be able to select the power factor of the power charged and discharged from the storage battery between a predetermined power factor and a power factor corresponding to the power factor of a type of reactive power that has a greater impact on the transmission network.

[0007] In a preferred aspect of the present invention, when the type of reactive power that has a greater impact on the power transmission network is lagging reactive power, the control device controls the power factor of the power discharged from the generator in multiple stages in accordance with the power factor of the lagging reactive power.

[0008] In a preferred aspect of the present invention, when the type of reactive power having a greater impact on the power transmission network is lagging reactive power, the control device sets the power factor of the power discharged from the storage battery to the predetermined power factor while discharging the power from the storage battery to the power transmission network, and when the power factor of the type of reactive power having a greater impact on the power transmission network deteriorates, the control device sets the power factor of the power discharged from the storage battery to a power factor corresponding to the reactive power after the power factor has deteriorated.

[0009] In a preferred aspect of the present invention, the control device causes the storage battery to discharge when a down DR occurs in the power transmission network.

[0010] In a preferred aspect of the present invention, the control device causes the storage battery to be charged at the predetermined power factor.

[0011] In a preferred aspect of the present invention, the control device charges the storage battery when an up-DR occurs in the power transmission network and leading reactive power and lagging reactive power are balanced in the power transmission network. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a power control system that can supply power at a more appropriate power factor in accordance with the tendency of reactive power occurring in a power transmission network. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the main configuration of a run-of-river hydroelectric power plant to which the power control system is applied. [Figure 2] FIG. 2 is a graph showing the range of fluctuation in the amount of power generation according to the amount of water in the water tank 16. In FIG. [Figure 3] FIG. 3 is a schematic circuit diagram showing the main components provided in the power control system. [Figure 4] FIG. 4 is a schematic graph for explaining control that is performed depending on the presence or absence of reactive power in the power transmission network and the type of reactive power. [Figure 5] FIG. 5 is a schematic circuit diagram showing the main configuration of a power control system that is partially different from the power control system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram showing the main configuration of a run-of-river hydroelectric power plant to which a power control system 10 is applied. The run-of-river hydroelectric power plant shown in Fig. 1 is a power plant provided with the power control system 10, which includes a generator 30 (see Fig. 3) that generates electricity using water from a river R. The run-of-river hydroelectric power plant further includes an intake weir 11, an intake port 12, an intake channel 13, a grit basin 14, a headrace channel 15, a water tank 16, a penstock 17, a tailrace channel 18, a spillway 19, and the like.

[0015] The intake weir 11 draws in a portion of the water flowing in the river R into the intake port 12. The intake port 12 is an opening of the intake channel 13 on the intake weir 11 side, which is used to take in the water drawn in by the intake weir 11 into the intake channel 13.

[0016] The intake channel 13 guides the water taken in from the intake port 12 to the intake channel 13. The settling basin 14 settles impurities contained in the water guided by the intake port 12 and prevents anything other than water from flowing into the water channel 15. The impurities include, for example, sand.

[0017] The headrace 15 guides the water in the settling basin 14 to the water tank 16. The water tank 16 accumulates the water guided by the headrace 15. The water accumulated in the water tank 16 flows into the penstock 17 or the spillway 19.

[0018] The penstock 17 guides the water from the water tank 16 to the power control system 10. The water guided by the penstock 17 rotates the water turbine of the generator 30 (see FIG. 3 ) provided in the power control system 10, and flows into the outlet channel 18. The outlet channel 18 returns the water guided to the power control system 10 to the river R.

[0019] The spillway 19 directs excess water from the water tank 16 into the tailrace 18 or the river R. The amount of water flowing from the water tank 16 through the penstock 17 into the power control system 10 is regulated by a flow control mechanism of the water turbine.

[0020] 2 is a graph that schematically shows the range of fluctuation in the amount of power generated according to the amount of water in the water tank 16. The vertical axis of the graph in Fig. 2 represents the water level in the water tank 16. The horizontal axis of the graph represents the magnitude of the output of the generator 30 (see Fig. 3) of the power control system 10 according to the water level in the water tank 16.

[0021] As shown in the graph of Figure 2, the higher the water level in the water tank 16, the higher the output of the generator 30 (see Figure 3), i.e., the amount of power generated. However, even if the water level in the water tank 16 is at the lower limit, the output of the generator 30 will only be the minimum output. Here, the minimum output is not zero.

[0022] In a run-of-river hydroelectric power plant, water is taken in from intake 12 only when a minimum flow rate or more can be ensured, and only in an amount that corresponds to the flow rate of river R. In other words, in a run-of-river hydroelectric power plant, while water is being taken in from intake 12, there is always water in tank 16 above the lower water level limit, and the output of generator 30 continues to be above the minimum output.

[0023] Furthermore, the amount of water flowing through River R cannot be adjusted. Therefore, in a run-of-river hydroelectric power plant, there is a limit to how much power the generator 30 can generate. For example, in the case of a demand response (DR) used to adjust the supply and demand of electricity, even in an upward DR, i.e., when there is an excess supply of electricity to the power grid, the generator 30 continues to generate power at or above the minimum output. Also, in a downward DR, i.e., when there is a power shortage in the power grid, the generator 30 cannot generate power above the maximum output, and even generating maximum output can be difficult depending on the amount of water flowing through River R.

[0024] Therefore, the power control system 10 of the embodiment is provided with a configuration that enables additional adjustments to be made in terms of adjusting the amount of power supplied to the power grid 150 (see FIG. 3) in addition to adjusting the amount of power generated by the generator 30. The power control system 10 including such a configuration and the operation of the power control system 10 will be described below with reference to FIGS. 3 and 4.

[0025] 3 is a schematic circuit diagram showing the main components provided in the power control system 10. First, among the components provided in the power control system 10, the relationship relating to the connection between the generator 30 and the power grid 150 will be described. As described above, the generator 30 has a water turbine that rotates upon receiving water that flows into the power control system 10 from the water tank 16 via the penstock 17, and generates electricity in response to the rotation of the water turbine.

[0026] The electric power generated by the generator 30 is sent out via an output line 31. The voltage of the electric power sent out from the output line 31 is converted by a step-up transformer 32 into a voltage required by the power grid 150. The electric power whose voltage has been converted by the step-up transformer 32 is sent out to the power grid 150 via a transmission line 33.

[0027] A parallel circuit breaker 34 is provided between the output line 31 and the step-up transformer 32. A transmission circuit breaker 35 is provided between the step-up transformer 32 and the transmission line 33. The parallel circuit breaker 34 and the transmission circuit breaker 35 are circuit breakers that can open and close the current path, but in principle, they are maintained in a current-carrying state unless an abnormality occurs. In other words, the parallel circuit breaker 34 and the transmission circuit breaker 35 are not used for the purpose of interrupting the current to zero the power supply to the transmission line 33 when an up-driving current is occurring.

[0028] The power control system 10 also has a configuration for performing control according to the presence or absence of reactive power in the power transmission network 150 and the type of reactive power. The presence or absence of reactive power here refers to the presence or absence of a substantial influence of reactive power in terms of the presence or absence of a phase shift based on the phase of active power. The type of reactive power refers to whether it is leading reactive power or lagging reactive power, which will be described later. Specifically, the power control system 10 is provided with an excitation transformer 36. The excitation transformer 36 is connected to the output line 31 via a connection part 37, so as to be in a parallel relationship with the generator 30.

[0029] The power control system 10 is also provided with a control device 50. The control device 50 controls the voltage of the power output from the generator 30 by applying electrical control to the exciter 38 located on the opposite side of the connection part 37 across the excitation transformer 36. That is, voltage conversion according to the rated voltage required by the power transmission network 150 is performed by the above-mentioned step-up transformer 32, while voltage control according to the generation status of reactive power is performed by the control device 50 that controls the exciter 38.

[0030] Next, a configuration for performing additional adjustment that can be controlled independently of the amount of power generated by the generator 30 in terms of adjusting the amount of power supplied to the power grid 150 will be described. As such a configuration, the power control system 10 has a storage battery system 40. The storage battery system 40 is provided with a storage battery 41 and a PCS 42. The storage battery 41 is a battery that can store power by charging and discharge the stored power. The PCS 42 is a power conditioning system (PCS) that controls the charging and discharging of the storage battery 41. The PCS 42 also has a function of converting DC to AC and a function as a voltage regulator. Specifically, the PCS 42 has a function of converting DC power discharged from the storage battery 41 into AC power. The PCS 42 also has a function of converting AC power output from the generator 30 into rated DC power suitable for the storage battery 41 and charging the storage battery 41.

[0031] 3, the PCS 42 is connected to the output line 31 via a connection line 43 and a battery circuit breaker 44. The battery circuit breaker 44 is a circuit breaker that can open and close the current path between the PCS 42 and the connection line 43.

[0032] The PCS 42 operates under the control of the control device 50. The control device 50 controls the voltage and power factor output from the generator 30 to the power transmission network 150 to which the run-of-river hydroelectric power plant belongs, and the voltage and power factor charged and discharged from the storage battery 41 to the power transmission network 150. Control by the control device 50 performed depending on the presence or absence of reactive power in the power transmission network 150 and the type of reactive power will be described below with reference to FIG. 4.

[0033] FIG. 4 is a schematic graph illustrating the presence or absence of reactive power in the power transmission network 150 and the control performed depending on the type of reactive power. In the graph of FIG. 4, the horizontal axis represents the magnitude of active power. The greater the distance from the origin 350 along the horizontal axis, the greater the active power. Also, in the graph of FIG. 4, the vertical axis represents the magnitude of reactive power. Active power refers to power consumed by devices (loads) that consume power and are connected to the power transmission network 150. Reactive power refers to power that is not consumed by such loads. Furthermore, one side of the vertical axis relative to the origin 350 (the upper side of FIG. 4) represents leading reactive power. Also, the other side of the vertical axis relative to the origin 350 (the lower side of FIG. 4) represents lagging reactive power.

[0034] Leading reactive power is reactive power that is generated due to a current that is ahead in phase with respect to the electromotive force. The electromotive force referred to here corresponds to the power that is generated by the relationship between current and voltage as the rated power supplied from the generator 30 of the power plant to the power grid 150. Leading reactive power is mainly generated by capacitive loads included in equipment that consumes the power supplied to the power grid 150. Capacitive loads refer to a configuration that electrically functions as a capacitor.

[0035] Lagging reactive power is reactive power that is generated due to a current that lags in phase with respect to the electromotive force. Lagging reactive power is mainly generated by an inductive load included in equipment that consumes power supplied to the power grid 150. An inductive load refers to a configuration that functions electrically as a reactor, and corresponds to equipment (such as an electric motor) that includes a passive element with a winding structure that functions as an inductor.

[0036] First, we will describe an ideal situation where there is substantially no effect of reactive power in terms of phase shift. This ideal situation may occur, for example, when the effect of capacitive loads in grid 150 and the effect of inductive loads in grid 150 are ideally compensated for. In this ideal situation, the power supplied from generator 30 to grid 150 can be represented by arrow 210 extending from origin 350 along the horizontal axis representing active power.

[0037] Next, a state will be described in which the influence of leading reactive power is greater than the influence of lagging reactive power in the power transmission network 150, i.e., a state in which the influence of capacitive loads in the power transmission network 150 is relatively dominant compared to the influence of inductive loads in the power transmission network 150. In this state, the power supplied from the generator 30 to the power transmission network 150 can be represented, for example, by arrow 220. Arrow 220 is a straight arrow that starts at origin 350, is inclined to the vertical and horizontal axes, and extends toward one side of the vertical axis (the upper side in FIG. 4) with respect to the horizontal axis. Although not shown in FIG. 4, in a state in which the type of reactive power that has a greater influence on the power transmission network 150 is leading reactive power, the greater the degree of phase lead relative to the electromotive force, the greater the inclination angle of the arrow with respect to the horizontal axis.

[0038] Next, we will explain a state in which the influence of lagging reactive power in the power transmission network 150 is greater than the influence of leading reactive power, i.e., a state in which the influence of inductive loads in the power transmission network 150 is relatively dominant compared to the influence of capacitive loads in the power transmission network 150. In this state, the power supplied from the generator 30 to the power transmission network 150 can be represented, for example, by arrows 230, 240, and 250. The arrows 230, 240, and 250 are linear arrows that start at the origin 350, are inclined with respect to the vertical and horizontal axes, and extend toward the other side of the horizontal axis (the lower side in FIG. 4 ) of the vertical axis. Furthermore, when the type of reactive power that has a greater influence on the power transmission network 150 is lagging reactive power, the greater the degree of phase lag relative to the electromotive force, the greater the inclination angle of the arrow relative to the horizontal axis. Therefore, the power represented by arrow 250 has a greater degree of phase lag relative to the electromotive force than the power represented by arrows 230 and 240. Furthermore, the power represented by arrow 240 has a greater degree of phase lag relative to the electromotive force than the power represented by arrow 230. Hereinafter, the expression "leading reactive power is dominant" refers to the type of reactive power that has a greater impact on the power transmission network 150 being leading reactive power. Also, the expression "lagging reactive power is dominant" refers to the type of reactive power that has a greater impact on the power transmission network 150 being lagging reactive power.

[0039] In addition, when lagging reactive power is dominant, the greater the degree of phase lag relative to the electromotive force, the lower the power factor. Arrow 230 shown in FIG. 4 indicates power supplied in response to a power factor of 95%, for example, where lagging reactive power is dominant. Arrow 240 shown in FIG. 4 indicates power supplied in response to a power factor of 90%, for example, where lagging reactive power is dominant. Arrow 250 shown in FIG. 4 indicates power supplied in response to a power factor of 85%, for example, where lagging reactive power is dominant. These illustrated power factors are merely examples and are not intended to be limiting. Furthermore, the power factor control applied to power output in a state where lagging reactive power is dominant is not limited to three levels, where the power factor is 95%, 90%, or 85%, but may be two levels or four or more levels.

[0040] Generally, the active power supplied from the generator 30 to the power grid 150 depends on the energy input from the water turbine and is a stable value with little fluctuation. Therefore, in the explanation with reference to FIG. 4, for the purpose of simplifying the explanation, the magnitude of the active power component resulting from the power supplied from the generator 30 to the power grid 150 is unified at active power level 300. Furthermore, the power represented by arrow 210 is the power generated by the cooperation of the generator 30 and the step-up transformer 32. On the other hand, strictly speaking, the power represented by arrows 220, 230, 240, and 250 is generated by applying reactive power whose phase has been adjusted by weakening or strengthening the field of the generator 30 using the exciter 38, and then transforming it using the step-up transformer 32.

[0041] The active power level 300 reflects the fluctuation in the amount of power generated depending on the amount of water in the water tank 16, as described with reference to Fig. 2. Therefore, the position of the active power level 300 on the horizontal axis relative to the origin 350 can fluctuate within a range corresponding to the fluctuation range 310 shown in Fig. 2, depending on the amount of water in the water tank 16. However, in the description with reference to Fig. 4, a description of such fluctuation in the amount of power generated depending on the amount of water in the water tank 16 will be omitted.

[0042] In the power transmission network 150, the presence or absence of reactive power and the direction and degree of phase shift with respect to the electromotive force when either leading reactive power or lagging reactive power is dominant depend on the tendency of the devices that consume power connected to the power transmission network 150. In other words, from the perspective of the control device 50, the presence or absence of reactive power and the direction and degree of phase shift with respect to the electromotive force when either leading reactive power or lagging reactive power is dominant are external factors that cannot be controlled.

[0043] Hereinafter, the term "state of the power transmission network 150" refers to the presence or absence of reactive power in the power transmission network 150, and the direction and degree of phase shift relative to the electromotive force when either leading reactive power or lagging reactive power is dominant. The control device 50 applies control that includes response to the state of the power transmission network 150 when controlling the reactive power of the generator 30 via the excitation device 38 and when controlling the charge and discharge of the storage battery 41 via control of the PCS 42.

[0044] Specifically, the control device 50 externally acquires information indicating the state of the power transmission network 150. The information indicating the state of the power transmission network 150 is obtained from a sensor 151 provided in the power transmission network 150. The sensor 151 is a sensor device that measures active power, reactive power, voltage, and current in the power transmission network 150 and feeds back the measured values ​​to the control device 50. Such feedback is obtained periodically.

[0045] In a run-of-river hydroelectric power plant, as a rule, power is supplied without any additional impact on the state of the power grid 150. For example, when the reactive power has substantially no impact on the power grid 150 in terms of phase shift, the control device 50 controls the exciter 38 so that the power represented by the arrow 210 is supplied from the generator 30 to the power line 33. In this embodiment, the power ratings of the generator 30 and the step-up transformer 32 correspond to the arrow 210, i.e., the active power in the power grid 150, and when the power represented by the arrow 210 is supplied to the power line 33, the reactive power is not substantially changed by controlling the exciter 38.

[0046] Furthermore, when leading reactive power or lagging reactive power is dominant in the power transmission network 150, the control device 50 controls the exciter 38 so that power represented by arrow 220 is provided from the generator 30 to the power transmission line 33. That is, the control device 50 operates the exciter 38 to lower the voltage on the output line 31. Here, the degree of voltage drop due to the operation of the exciter 38 corresponds to the type of dominant reactive power. Furthermore, the control device 50 may further apply phase control on the output line 31 by controlling the exciter 38 depending on whether the reactive power is leading reactive power or lagging reactive power. When leading reactive power is dominant in the power transmission network 150, the control device 50 controls the exciter 38 so that, for example, power represented by arrow 220 is provided to the power transmission line 33. When lagging reactive power is dominant in the power transmission network 150, power represented by, for example, arrows 230, 240, or 250 is provided to the power transmission line 33 depending on the degree of phase lag.

[0047] Furthermore, the control device 50 applies control to the PCS 42 according to the presence or absence of DR and the type of DR that is occurring, thereby controlling the charging and discharging of the storage battery 41 according to the presence or absence of DR and the type of DR that is occurring.

[0048] Specifically, when a lowering DR occurs, i.e., when a power shortage occurs in the power grid, the control device 50 can increase the amount of power supplied to the power grid 150 by discharging the power stored in the storage battery 41. As a result, the active power of the power supplied to the power transmission line 33 increases from the active power level 300 shown in FIG. 4 toward the adjustment upper limit 401. Furthermore, when an uppering DR occurs, i.e., when a power surplus occurs in the power grid, the control device 50 can decrease the amount of power supplied to the power grid 150 by charging the storage battery 41. As a result, the active power of the power supplied to the power transmission line 33 decreases from the active power level 300 shown in FIG. 4 toward the adjustment lower limit 402.

[0049] In this way, in the embodiment, the storage battery system 40 is provided, and the control device 50 controls the PCS 42, thereby providing the run-of-river hydroelectric power plant with a "power supply adjustment function" that is independent of the amount of water flowing into the power control system 10 from the river R. The adjustment range of this "power supply adjustment function" is indicated by an adjustment range 400 between an upper adjustment limit 401 and a lower adjustment limit 402, with the active power level 300 as the reference.

[0050] More specifically, the control device 50 acquires information (DR information) indicating the presence or absence of DR and the type of DR that is occurring from an external source. The DR information is issued from facilities, equipment, or information processing devices managed by at least one of the government of the country in which the power transmission network 150 exists, the power company of that country, and an aggregator that supplies power using distributed power in that country. The control device 50 receives the DR information and applies control to the PCS 42 according to the presence or absence of DR and the type of DR that is occurring that is indicated by the DR information. In such control, the control device 50 further applies control that takes into account the state of the power transmission network 150 described above.

[0051] First, a case where the type of DR that has occurred is downward DR will be described. In the case of downward DR, when reactive power does not substantially affect the power transmission grid 150 in terms of phase shift, the control device 50 controls the PCS 42 to discharge the power charged in the storage battery 41 at the rated power (power factor 100%). The power discharged from the storage battery 41 in this way can be represented by arrow 411 in Fig. 4. Therefore, the power supplied from the power control system 10 to the power transmission grid 150 at this time is represented by a combination of arrow 210 and arrow 411 in Fig. 4. As a result, the active power supplied from the run-of-river hydropower plant to the power transmission grid 150 simply increases, making it possible to effectively deal with downward DR.

[0052] In the case of downsizing DR and when leading reactive power is dominant, the control device 50 controls the PCS 42 to discharge the power stored in the storage battery 41. Here, the control device 50 is configured to be able to select the tendency of voltage and power factor at which the power stored in the storage battery 41 is discharged. Specifically, when the PCS 42 is controlled to discharge the power stored in the storage battery 41 at the rated voltage (power factor 100%), the rated power discharged from the storage battery 41 can be represented by arrow 421 in FIG. 4. On the other hand, when the PCS 42 is controlled to discharge the power stored in the storage battery 41 at a voltage and power factor corresponding to the voltage and power factor of the generator 30 controlled by the exciter 38, the power discharged from the storage battery 41 can be represented by arrow 423 in FIG. 4.

[0053] In the case of downward DR, when leading reactive power is dominant, it is possible to arbitrarily select whether to discharge the power represented by arrow 421 or the power represented by arrow 423 from the storage battery 41, but it is more preferable that this be set in advance based on the trend of the power transmission network 150. Specifically, it is preferable that this be set in advance based on the size of the power network, the trend of power consuming devices connected to the power network, and simulation results that take these into consideration.

[0054] In the case of down-driving DR and lagging reactive power is dominant, the control device 50 controls the PCS 42 to discharge the power stored in the storage battery 41. Here, the control device 50 is configured to be able to select the voltage and power factor at which the power stored in the storage battery 41 is discharged. Specifically, when the PCS 42 is controlled to discharge the power stored in the storage battery 41 at the rated voltage (power factor 100%), the power discharged from the storage battery 41 can be represented by arrows 431, 441, and 451 in FIG. 4. On the other hand, when the PCS 42 is controlled to discharge the power stored in the storage battery 41 at a voltage and power factor corresponding to the voltage and power factor of the generator 30 controlled by the exciter 38, the power discharged from the storage battery 41 can be represented by arrows 433, 443, and 453 in FIG. 4. The power factors of the power represented by the arrows 411, 421, 431, 441, and 451 can be considered to be the rated voltage (power factor 100%). On the other hand, the power factors of the electric power represented by the arrows 423, 433, 443, and 453 are power factors less than the rated power factor, and can be considered to be power factors of reactive power of a type that has a greater impact on the power grid 150.

[0055] In the case of down DR, how the discharge from the storage battery 41 is represented when lagging reactive power is dominant corresponds to how the power provided to the transmission line 33 using the generator 30 as a power source is represented. Specifically, when the power provided to the transmission line 33 using the generator 30 as a power source is represented by arrow 230, the power discharged from the storage battery 41 is represented by arrow 431 or arrow 433. When the power provided to the transmission line 33 using the generator 30 as a power source is represented by arrow 240, the power discharged from the storage battery 41 is represented by arrow 441 or arrow 443. When the power provided to the transmission line 33 using the generator 30 as a power source is represented by arrow 250, the power discharged from the storage battery 41 is represented by arrow 451 or arrow 453.

[0056] Here, when viewed in terms of the efficiency of discharge from the storage battery 41, that is, the ratio of active power to the discharge amount (power factor), the power represented by the arrows 431, 441, and 451 has a higher power factor than the power represented by the arrows 433, 443, and 453. For this reason, in the embodiment, in the case of downward DR and when lagging reactive power is dominant, the control device 50 prioritizes discharge from the storage battery 41 at rated power (power factor 100%) as represented by the arrows 431, 441, and 451 over discharge represented by the arrows 433, 443, and 453.

[0057] On the other hand, when the discharge from the storage battery 41 at the rated power (100% power factor) is applied as indicated by the arrows 431, 441, and 451, the combined power of the power sourced from the generator 30 and the power sourced from the storage battery 41 no longer corresponds to the state of the power transmission grid 150. That is, when the power sourced from the storage battery 41 is at the rated power (100% power factor), the degree of transformation applied to the power sourced from the generator 30 by controlling the exciter 38 becomes small, and the degree of transformation no longer corresponds to the phase delay actually occurring in the power transmission grid 150. Such a mismatch in the degree of transformation may be unexpected behavior of power transmission from a run-of-river hydroelectric power plant. Such unexpected behavior may result in non-ideal convergence control of reactive power throughout the power transmission grid 150.

[0058] Therefore, in the embodiment, in the case of downward DR, when lagging reactive power is dominant, the control device 50 applies two-stage control as a control pattern for discharging from the storage battery 41 under the control of the PCS 42. The starting point for applying the two-stage control is the time when both the information indicating the state of the power transmission network 150 indicates that lagging reactive power is dominant and downward DR occurs.

[0059] Specifically, as the first stage of the two-stage control, the control device 50 first controls the PCS 42 so that the storage battery 41 discharges at the rated power (power factor 100%), as indicated by arrows 431, 441, and 451. Here, it is assumed that the latest information indicating the state of the power grid 150 obtained after the first stage is applied indicates a deterioration in the power factor of lagging reactive power. In this case, as the second stage of the two-stage control, the control device 50 controls the PCS 42 so that voltage control corresponding to the degree of transformation applied to the power sourced from the generator 30 by controlling the exciter 38 is also applied to the discharge from the storage battery 41. Therefore, in this case, the power discharged from the storage battery 41 via the PCS 42 after the second stage is applied is the power indicated by arrows 433, 443, and 453.

[0060] The deterioration of the power factor of lagging reactive power refers to the fact that lagging reactive power continues to be generated in the power grid 150 and the degree of phase lag becomes more pronounced with respect to the power output from the power control system 10. Therefore, if the degree of phase lag that occurred at the starting point at which the two-stage control is applied is used as a reference and the latest information indicating the state of the power grid 150 obtained after the starting point indicates a phase lag that is greater than the reference, this means that the power factor of lagging reactive power has deteriorated.

[0061] On the other hand, as a second stage of the two-stage control, the control device 50 continues discharging from the storage battery 41 at the rated voltage (100% power factor) as indicated by arrows 431, 441, and 451, unless the latest information indicating the state of the power transmission network 150 obtained after the first stage has been applied indicates a deterioration in the power factor of the lagging reactive power. However, even if this discharging continues, a change in control is applied when the latest information indicating the state of the power transmission network 150 thereafter indicates a deterioration in the power factor of the lagging reactive power. When this change in control is applied, the control device 50 controls the PCS 42 to apply voltage control corresponding to the degree of transformation applied to the power sourced from the generator 30 by controlling the exciter 38 to the discharging from the storage battery 41.

[0062] As an example, assume that, at the start point of application of the two-stage control, the voltage reflecting the degree of transformation imparted by controlling the exciter 38 to the power derived from the generator 30 as a power source is represented by arrow 230. Here, as described above, the power factor of the power represented by arrow 230 is 95%. In this case, the control device 50 controls the PCS 42 in the early stage of the two-stage control so that the power from the battery system 40 becomes the power represented by arrow 431. Here, as described above, the power factor of the power represented by arrow 431 can be considered to be the rated value (power factor of 100%). Next, assume that the power factor of the lagging reactive power deteriorates, and the degree of transformation imparted to the power derived from the generator 30 as a power source using the exciter 38 becomes the power represented by arrow 240. Here, as described above, the power factor of the power represented by arrow 240 is 90%. At this time, the control device 50 controls the PCS 42 in the early stage of the two-stage control so that the power from the battery system 40 becomes the power represented by arrow 443. Here, the power factor of the power represented by the arrow 443 can be considered to be a power factor (90%) corresponding to the power factor of the power represented by the arrow 240. In this way, when the reactive power that is dominant in the power grid 150 is lagging reactive power, the control device 50 of the embodiment sets the power factor of the power discharged from the storage battery 41 to the rated power factor (power factor 100%) while discharging the power from the storage battery 41 to the power grid 150, and when the power factor of the lagging reactive power in the power grid 150 deteriorates further, sets the power factor of the power discharged from the storage battery 41 to a power factor corresponding to the reactive power after the power factor has deteriorated further.

[0063] In the embodiment, the administrator of the power control system 10 can set the control device 50 to discharge the storage battery 41 at a power factor that is not limited to the above-described two-stage control but is pre-selected from a predetermined power factor and a power factor corresponding to the power factor of a type of reactive power that has a greater impact on the power grid 150. When such a setting is made, if a down DR occurs, the control device 50 controls the PCS 42 to discharge the storage battery 41 at the power factor selected in such a setting.

[0064] Next, a case where the type of DR that is occurring is upward DR will be described. In the case of upward DR, when the leading reactive power and lagging reactive power are balanced in the power transmission network 150, the control device 50 controls the PCS 42 to charge the storage battery 41 at the rated power (power factor 100%). As a result, the power supplied to the storage battery 41 from the output line 31 via the connection line 43 and the PCS 42 can be represented by arrow 412 in FIG. 4. At this time, the power supplied from the power control system 10 to the power transmission network 150 is represented by a combination of arrow 210 and arrow 412 in FIG. 4. As a result, the active power supplied from the run-of-river hydroelectric power plant to the power transmission network 150 is simply reduced, making it possible to effectively deal with upward DR.

[0065] On the other hand, in the case of an up-driving current, when either leading reactive power or lagging reactive power is dominant, regardless of whether the type of reactive power is leading reactive power or lagging reactive power, the control device 50 does not, in principle, charge the storage battery 41. This principle is based on the fact that if the storage battery 41 is charged when either leading reactive power or lagging reactive power is dominant, there is a non-zero possibility that the power factor of the reactive power will deteriorate due to a decrease in the active power supplied from the run-of-river hydroelectric power plant to the power grid 150.

[0066] If the storage battery 41 is charged when leading reactive power is dominant, the decrease in active power due to charging can be represented by arrow 422. If the storage battery 41 is charged when lagging reactive power is dominant, the decrease in active power due to charging can be represented by arrows 432, 442, and 452. The lines connecting the tips of the arrows 422, 432, 442, and 452 shown in FIG. 4 to the origin 350 have a larger inclination angle with respect to the horizontal axis than the lines connecting the bases of the arrows 422, 432, 442, and 452 shown in FIG. 4 to the origin 350. This larger inclination angle suggests the possibility of a deterioration in the power factor of reactive power. Therefore, in this embodiment, when either leading reactive power or lagging reactive power is dominant, the storage battery 41 is not charged in principle. In other words, the battery 41 is charged when the leading reactive power and lagging reactive power are balanced in the power transmission network 150, so that the effect of the phase shift due to the reactive power is not substantially present in the power transmission network 150.

[0067] However, the amount of power charged to the storage battery 41 may be reduced to a level that does not substantially worsen the power factor of reactive power, even when either leading reactive power or lagging reactive power is dominant, so that the storage battery 41 can be charged during an upward DR. The specific value that does not substantially worsen the power factor of reactive power is preferably determined in advance based on the size of the power grid, the trends of the power consumption devices connected to the power grid, and simulation results that take these factors into consideration. Furthermore, even when either leading reactive power or lagging reactive power is dominant in the power transmission grid 150, a special case may be applied if a condition exists that prioritizes charging the storage battery 41. When this special case is applied, the control device 50 charges the storage battery 41 after adjusting the power factor of the power from the generator 30 to a power factor corresponding to the active power, as indicated by arrow 210. The power factors of the power indicated by arrows 412, 422, 432, 442, and 452 can be considered to be rated (100% power factor).

[0068] As described above, according to the embodiment, the power control system 10 is a power control system including the generator 30 provided in a run-of-river hydroelectric power plant, the storage battery 41, and the control device 50 that controls the power factor of power output from the generator 30 to the power transmission network 150 to which the run-of-river hydroelectric power plant belongs, the charging and discharging of the storage battery 41, and the power factor of power discharged from the storage battery 41 to the power transmission network 150. The control device 50 is configured to be able to select the power factor of power discharged from the storage battery 41 between a predetermined power factor and a power factor corresponding to the power factor of a type of reactive power that has a greater impact on the power transmission network 150. Therefore, in the embodiment, power can be supplied with a more appropriate power factor depending on the trend of reactive power occurring in the power transmission network 150. Note that the direction of the phase shift due to reactive power with respect to active power refers to whether it is leading reactive power or lagging reactive power as described above. In the example shown in Fig. 4, arrows 411, 421, 431, 441, and 451 indicate power discharged from storage battery 41 and that can be considered to have a predetermined power factor. In the example shown in Fig. 4, arrow 423 indicates power discharged from storage battery 41 and that can be considered to have a power factor corresponding to the power factor when leading reactive power is dominant. In the example shown in Fig. 4, arrows 433, 443, and 453 indicate power discharged from storage battery 41 and that can be considered to have a power factor corresponding to the power factor when lagging reactive power is dominant.

[0069] Furthermore, when the lagging reactive power is dominant, the control device 50 controls the power factor of the power output from the generator 30 in multiple stages in accordance with the power factor of the lagging reactive power, thereby enabling power supply that corresponds to the power factor of the lagging reactive power with higher accuracy. Note that, in Fig. 4, arrows 230, 240, and 250 are shown as examples of arrows that indicate the power that is subject to multi-stage control.

[0070] Furthermore, when lagging reactive power is dominant, and the control device 50 controls the storage battery 41 to discharge power to the power grid 150 while setting the power factor of the power discharged from the storage battery 41 to a predetermined power factor, if the power factor of the lagging reactive power deteriorates further, the power factor of the power discharged from the storage battery 41 is set to a power factor corresponding to the reactive power after the power factor has deteriorated. This makes it possible to more flexibly change the behavior of the power supplied from the run-of-river hydroelectric power plant to the power grid 150 depending on whether the power factor of the lagging reactive power has deteriorated. Note that, in FIG. 4, arrows 431, 441, and 451 are shown as examples of arrows indicating power with a predetermined power factor. Also, in FIG. 4, arrows 433, 443, and 453 are shown as examples of arrows indicating power with a power factor corresponding to the reactive power after the power factor has deteriorated.

[0071] Furthermore, when a down DR occurs in the power transmission network 150, the control device 50 causes the storage battery 41 to discharge, thereby making it possible to more appropriately respond to the power supply and demand situation in the power transmission network 150.

[0072] Furthermore, the control device 50 causes the storage battery 41 to be charged at a predetermined power factor, thereby enabling the storage battery 41 to be charged more efficiently.

[0073] Furthermore, when an up DR occurs in the power transmission network 150 and the leading reactive power and lagging reactive power are balanced in the power transmission network 150, the control device 50 causes the storage battery 41 to be charged, thereby enabling the storage battery 41 to be charged more efficiently while suppressing the possibility of deterioration in the power factor of the reactive power.

[0074] (Variation) Next, a modified example having a partial configuration different from that of the embodiment will be described with reference to FIG.

[0075] FIG. 5 is a schematic circuit diagram showing the main components of a power control system 10A that is partially different from the power control system 10 shown in FIG. 3. In this modified example, the power control system 10 in the embodiment is replaced with the power control system 10A. As shown in FIG. 5, the power control system 10A is provided with a step-up transformer 61 and a connection line 62, which were not provided in the power control system 10. The step-up transformer 61 is a transformer dedicated to the battery system 40 and is connected to the PCS 42 via the battery circuit breaker 44. The step-up transformer 61 is provided to perform a transformation between an AC voltage corresponding to the rating of the power grid 150 and an AC voltage generated by the PCS 42 using the battery 41 as a power source. The connection line 62 connects the step-up transformer 61 to a relay unit 39 between the step-up transformer 32 and the power transmission circuit breaker 35. With the addition of the step-up transformer 61 and the connection line 62, the connection line 43 provided in the power control system 10 is omitted in the power control system 10A shown in Fig. 5. Except for the points particularly described above with reference to Fig. 5, the run-of-river type hydroelectric power plant according to the modified example is the same as the run-of-river type hydroelectric power plant according to the embodiment.

[0076] This modification is employed when it is difficult to merge the AC power generated by the PCS 42 using the storage battery 41 as a power source into the output line 31 via the connection line 43 as in the embodiment.

[0077] The above embodiment is merely an example, and can be modified as appropriate within the scope of the technical features of the present invention. [Explanation of symbols]

[0078] 10,10A power control system 30 Generator 32 Step-up transformer 36 Excitation transformer 38 Excitation device 40 Battery Storage System 41 Storage battery 42 PCS 50 Control device

Claims

1. a generator installed in the run-of-river hydroelectric power plant; A storage battery and a control device that controls the power factor of the power output from the generator to the power transmission network to which the run-of-river hydroelectric power plant belongs, the charging and discharging of the storage battery, and the power factor of the power charged and discharged from the storage battery to the power transmission network; A power control system comprising: The control device The power factor of the power charged and discharged from the storage battery is selectable between a predetermined power factor and a power factor corresponding to the power factor of a type of reactive power that has a greater impact on the power transmission network. Power control system.

2. When the reactive power of the type having a greater impact on the power transmission network is lagging reactive power, the control device controls the power factor of the power discharged from the generator in multiple stages in accordance with the power factor of the lagging reactive power. The power control system of claim 1 .

3. When the reactive power of the type having a greater impact on the power transmission network is lagging reactive power, the control device causes the storage battery to discharge the power to the power transmission network with the power factor of the power discharged from the storage battery set to the predetermined power factor, and when the power factor of the reactive power of the type having a greater impact on the power transmission network deteriorates, the control device sets the power factor of the power discharged from the storage battery to a power factor corresponding to the reactive power after the power factor has deteriorated. The power control system of claim 2 .

4. The control device causes the storage battery to discharge when a downdraft occurs in the power grid. The power control system according to any one of claims 1 to 3.

5. The control device causes the storage battery to be charged at the predetermined power factor. The power control system according to any one of claims 1 to 3.

6. The control device charges the storage battery when an up-DR occurs in the power transmission network and leading reactive power and lagging reactive power are balanced in the power transmission network. The power control system according to claim 5 .

Images