Reverse flow power control device and reverse flow power control method

Abstract

To provide an inverse load flow power control device and a control method for inverse load flow power to prevent deviation from conditions regarding the inverse load flow power.SOLUTION: According to the embodiment, an inverse load flow power control device 100 prevents inverse load flow from a plant including a renewable energy power generation device, a power conditioner 20, and a load device 30 to a power system. The inverse load flow power control device 100 includes: an input unit 110 that receives the output power of the power conditioner 20, load power to the load device 30, an actual value of received power and the minimum received power value; a storage unit 130; and an arithmetic unit 120 having an output control unit 121p that calculates an output command calculation value, a load control unit 121h that calculates a load command calculation value, and a command value recalculation unit 122 that calculates an output command value to the power conditioner 20 so that the received power value from the power system does not fall below the minimum received power value by using each actual value, the output command calculation value, the load command calculation value, and the minimum received power value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a reverse flow power control device and a reverse flow power control method. [Background technology]

[0002] Renewable energy power plants, such as large-scale solar power plants and wind power plants, earn income by selling all of their output power to the commercial power grid (hereafter referred to as the power grid). Therefore, the load within a renewable energy power plant is only the power for auxiliary equipment such as air conditioning, and they do not receive power from the power grid except during times when there is almost no output power.

[0003] In recent years, hydrogen production using renewable energy without emitting CO2 has been attracting attention, and plants are being built that combine large-scale hydrogen production equipment with renewable energy power generation equipment. Since such plants aim to use renewable energy for self-consumption, they may not have a contract for reverse power flow (selling power) to the power grid. In such cases, reverse power flow to the power grid is prevented by always receiving a constant amount of power.

[0004] On the other hand, there is a method to vary the plant load according to renewable energy. In this case, control delays may occur due to the influence of the control cycle and communication method, and momentary reverse power flow may occur. If unintended reverse power flow occurs, it may affect the power grid and, in the worst case, cause a power outage.

[0005] Even in a similar plant, if the required amount of hydrogen is small, it is possible to generate revenue by selling excess renewable energy back to the power grid. However, when backflowing power to the power grid, it is necessary to comply with output control commands requested by general electricity transmission and distribution companies. When this request is made, the backflow power must be kept below the output control command. However, if the plant load is changed to match the renewable energy, a control delay will cause a momentary backflow power that exceeds the output control command, resulting in financial penalties, and repeated violations may result in the power grid restricting the backflow.

[0006] Hereinafter, the power purchased from the power grid will be referred to as received power, and the power sold from renewable energy to the power grid will be referred to as reverse flow power. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-171129 Summary of the Invention [Problem to be solved by the invention]

[0008] If reverse power flow is likely to occur, it is possible to respond by using protection functions to stop the generation of renewable energy. However, once power generation is stopped, it may take time to restart power generation due to check work to restore it, and during that time the output power of the renewable energy will not be available.

[0009] For this reason, it is necessary to use control functions, not protection functions, to operate in a way that prevents reverse power flow while achieving a predetermined purpose.Even if reverse power flow is possible, if a general electricity transmission and distribution company requests an output control command, it is necessary to operate in a way that keeps the reverse power flow below the output control command.

[0010] The problem to be solved by the present invention is to prevent deviation from the conditions regarding reverse flow power. [Means for solving the problem]

[0011] According to an embodiment, a reverse flow power control device is a reverse flow power control device that prevents generation of reverse flow power from a plant having a renewable energy power generation device, a power conditioner capable of adjusting output power of the renewable energy power generation device, and a load device and connected to an external power system from the plant to the power system, and includes an input unit that receives information including actual values ​​of the output power, load power supplied to the load device, and received power received by the plant from the power system, as well as a minimum received power value that is the minimum value of the received power, and a storage unit that stores the information received by the input unit. and a calculation unit that calculates command values ​​for the output power and the load power based on the information stored in the storage unit and the respective actual values, and an output unit that outputs command values ​​to the load device and the power conditioner, wherein the calculation unit includes an output control unit that calculates an output command calculation value, a load control unit that calculates a load command calculation value, and a command value recalculation unit that calculates an output command value to the power conditioner using the respective actual values, the output command calculation value, the load command calculation value, and the minimum received power value so that the received power value, which is the value of the received power, does not fall below the minimum received power value. a calculation interval adjustment unit that sets a calculation interval that generates a plurality of calculation steps for the dead time in the renewable energy power generation device, the power conditioner, and the load device; Equipped with the command value recalculation unit calculates a change in the received power value in a section up to after the plurality of calculation steps in which the command value is reflected due to the dead time, and calculates the output command value such that the received power value does not fall below the minimum received power value. It is characterized by: [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the relationship between a reverse flow power control device according to a first embodiment and a plant that is the subject of the control device; [Figure 2] 1 is a block diagram showing a configuration of a reverse flow power control device according to a first embodiment. [Figure 3] 1 is a control block diagram showing the content of processing by a backward flow power control device 100 according to a first embodiment. [Figure 4]4 is a conceptual graph for explaining details of the recalculation of an output command value in the backward flow power control method according to the first embodiment. [Figure 5] FIG. 3 is a flowchart showing the procedure of a reverse flow power control method according to the first embodiment. [Figure 6] FIG. 10 is a block diagram showing the configuration of a reverse flow power control device according to a second embodiment. [Figure 7] 10 is a conceptual graph for explaining details of the recalculation of an output command value in a backward flow power control method according to a second embodiment. [Figure 8] FIG. 10 is a block diagram showing the configuration of a reverse flow power control device according to a third embodiment. [Figure 9] FIG. 10 is a control block diagram showing the configuration and operation of a reverse flow power control device according to a third embodiment. [Figure 10] FIG. 10 is a flowchart showing the procedure of a reverse flow power control method according to a third embodiment. [Figure 11] FIG. 10 is a block diagram showing the relationship between a reverse flow power control device according to a fourth embodiment and a plant that is the subject of the control. [Figure 12] FIG. 10 is a block diagram showing the configuration of a reverse flow power control device according to a fourth embodiment. [Figure 13] 10 is a conceptual graph for explaining details of the recalculation of an output command value in a backward flow power control method according to a fourth embodiment. [Figure 14] FIG. 10 is a block diagram showing the relationship between a reverse flow power control device according to a fifth embodiment and a plant that is the subject of the control. [Figure 15] FIG. 10 is a block diagram showing the configuration of a reverse flow power control device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a reverse flow power control device and a reverse flow power control method according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be denoted by common reference numerals and redundant description will be omitted.

[0014] [First embodiment] FIG. 1 is a block diagram showing the relationship between a reverse flow power control device 100 according to the first embodiment and a plant 1 that is the target of the control device.

[0015] The plant 1 targeted by the reverse flow power control device 100 includes a renewable energy power generation plant (“PV”) 10, a power conditioner (“PCS”) 20, and a load device 30.

[0016] The PV 10 is a device that converts natural energy into electricity, such as, but not limited to, a photovoltaic power generation device.

[0017] The PCS 20 receives DC power generated by the PV 10 as input and outputs AC power, and adjusts the level of the AC power to a predetermined value equal to or lower than the input power level.

[0018] The load device 30 is a device that consumes power, such as, but not limited to, a hydrogen production facility. The load device 30 has a local controller 31. The local controller 31 controls the state of each load of the load device 30 in response to an external load power command so that the power consumed by the load device 30, i.e., the load power, matches the load power command value.

[0019] The plant 1 is provided with an intra-plant bus 3, and the PCS 20 and the load devices 30 are each connected to the intra-plant bus 3 via a connection line 4. The intra-plant bus 3 is also connected to an external power system 2 via a connection line 4. A wattmeter 50 is provided on each connection line 4. That is, an output wattmeter 51 is provided on the connection line 4 between the intra-plant bus 3 and the PCS 20, a load wattmeter 52 is provided on the connection line 4 between the intra-plant bus 3 and the load devices 30, and a power meter for trade 53 is provided on the connection line 4 between the intra-plant bus 3 and the power system 2, making it possible to measure and monitor the flow of power.

[0020] The reverse flow power control device 100 accepts the outputs of the power meter 50 of the plant 1, i.e., the outputs from the output power meter 51, the load power meter 52 and the power meter for trade 53, as an actual output power value 51a, an actual load power value 52a and an actual power meter for trade 53a, and outputs a PCS output command value PCSset and a load command value Lset to the PCS 20 and the load device 30 of the plant 1, respectively.

[0021] FIG. 2 is a block diagram showing the configuration of the reverse flow power control device 100 according to the first embodiment.

[0022] The reverse flow power control device 100 has an input unit 110, a calculation unit 120, a storage unit 130, and an output unit 140. The reverse flow power control device 100 may be a collection of individual devices, for example, a computer system.

[0023] The input unit 110 receives the output power actual value 51a from the output power meter 51, the load power actual value 52a from the load power meter 52, and the power trade actual value 53a from the power trade meter 53, as well as other external inputs required for control. The other external inputs required for control include the control parameters of the control circuit, which will be described later regarding the reverse flow power control device 100, and planned values ​​for the minimum received power, output power, and load power.

[0024] The calculation unit 120 includes a control calculation unit 121 , a command value recalculation unit 122 , and a change rate limiter 123 .

[0025] The control calculation unit 121 performs control calculations using the planned values ​​of output power and load power, and the actual output power value 51a and actual load power value 52a received by the input unit 110 as inputs, to calculate a provisional PCS output command value and a provisional load command value. The control calculation unit 121 has a first subtraction unit 121a and a first control circuit 121b related to the load command value, and a second subtraction unit 121c and a second control circuit 121d related to the output command value. Note that, although the present embodiment shows an example in which the control calculation unit 121 performs PID control, other control methods may be used.

[0026] The command value recalculation unit 122 performs recalculation based on the control calculation result by the control calculation unit 121 to calculate the PCS output command value PCSset. Details of the calculation unit 120 will be described later with reference to FIG.

[0027] The change rate limiter 123 increases the output of the command value recalculation unit 122 to the PCS 20 at a constant rate rather than increasing it suddenly, thereby stabilizing the control.

[0028] The storage unit 130 includes a planned value storage unit 131 , a control parameter storage unit 132 , a minimum received power storage unit 133 , a performance value storage unit 134 , a command value calculation result storage unit 135 , and a recalculation result storage unit 136 .

[0029] The planned value storage unit 131 stores the planned values ​​of the load power and the output power read by the input unit 110. Here, the planned values ​​read by the input unit 110 are time-series values ​​for the period during which the reverse flow power control device 100 performs control. However, the input unit 110 may sequentially read the planned values ​​for a predetermined time span, and the planned value storage unit 131 may sequentially store and store them in response.

[0030] The control parameter storage unit 132 stores the load control parameter P L and the output control parameter P P Here, the control parameters are, for example, the gain, integral time, and differential time in the case of PID control.

[0031] The minimum receiving power storage unit 133 stores the minimum receiving power read by the input unit 110 .

[0032] The actual value storage unit 134 stores and memorizes the outputs (actual values) of the power meter 50 read by the input unit 110, i.e., the output power actual value 51a, the load power actual value 52a, and the trading power actual value 53a. These actual values ​​to be stored may be only the values ​​read by the input unit 110 immediately before calculation, or may store a certain number of sampling values ​​in chronological order.

[0033] The command value calculation result storage unit 135 stores the calculation results of the control calculation unit 121. The calculation results to be stored may be only the most recent calculation result by the control calculation unit 121, or may store the results of multiple calculations up to the most recent time in chronological order.

[0034] The recalculation result storage unit 136 stores the calculation results of the command value recalculation unit 122. The calculation results to be stored may be only the most recent calculation result by the command value recalculation unit 122, or may store the results of multiple calculations up to the most recent time in chronological order.

[0035] The output unit 140 outputs the load command calculation value Lcal(t), which is the calculation result of the control calculation unit 121, as the load command value Lset(t) to the load device 30, and outputs the PCS output command value PCSset(t), which is the calculation result of the command value recalculation unit 122, to the PCS 20.

[0036] FIG. 3 is a control block diagram showing the details of the processing performed by the backward flow power control device 100 according to the first embodiment.

[0037] Roughly speaking, there are a part related to commands to the load device 30 and a part related to commands to the PCS 20.

[0038] The part relating to the command to the load device 30 is as follows.

[0039] The input unit 110 receives a load plan value Plan-L, which is a planned value of the load power, and L(t), which is the actual load power value 52a from the load power meter 52. Here, the value of the load plan value Plan-L is stored in the planned value storage unit 131 and is used as the target value Lref(t) of the load power at each time point. The load control unit 121h of the control calculation unit 121 calculates a load command calculation value Lcal(t) for issuing a load command to the load device 30 based on these signals.

[0040] Here, the load control unit 121h includes a first subtraction unit 121a and a first control circuit 121b. The first subtraction unit 121a subtracts the load power actual value L(t) from the load power target value Lref(t) to generate a deviation signal e L The first control circuit 121b outputs the deviation signal (t). e L (t), a control calculation is performed, and the load command calculation value Lcal(t) is calculated using the following equation (1). Lcal(t) =F L (Lref(t),L(t),P L ) (1) where F L is that Lcal(t) is a function of Lref(t), L(t) and P L This means that it is a function of .

[0041] For example, when the control by the load control unit 121h is PID control, Lcal(t) is obtained by the following equation (2). Lcal(t) =K PL e L (t)+K IL ∫e L (t)dt+K DL ·de L (t) / dt ···(2) where K PL , K. IL , and K. DL is the load control parameter PL is.

[0042] The calculated load command calculation value Lcal(t) is output from the output unit 140 to the local controller 31 of the load device 30 as a load command signal Lset(t).

[0043] The part related to the command to PCS20 is as follows:

[0044] The input unit 110 receives a planned value Plan-P of output power and PCS(t), which is the actual output power value 51a from the output power meter 51. Here, the value of the planned value Plan-P is stored in the planned value storage unit 131 and is used as the target value PCSref(t) of the output power at each time point. The output control unit 121p of the control calculation unit 121 calculates an output command calculation value PCScal to be sent to the PCS 20 based on these signals.

[0045] Here, the output control unit 121p has a second subtraction unit 121c and a second control circuit 121d. The second subtraction unit 121c subtracts the output power actual value PCS(t) from the output power target value PCSref(t) to generate a deviation signal e P The second control circuit 121c outputs the deviation signal e P Control calculation is performed based on (t), and the output command calculation value PCScal(t) is calculated using the following equation (3). PCScal(t) =F PCS (PCSref(t),PCS(t),P P ) (3) where: F PCS is the sum of PCScal(t), PCSref(t), PCS(t) and P P This means that it is a function of .

[0046] For example, when the control by the output control unit 121p is PID control, cal (t) is obtained by the following equation (4). PCScal(t) =K PP eP (t)+K IP ∫e P (t)dt+K DP ·de P (t) / dt ···(4) where K PP , K. IP , and K. DP is the output control parameter P P is.

[0047] Command value recalculation unit 122 calculates an output command value PCSset(t) based on the output command calculation value PCScal(t) calculated by output control unit 121p, the load command calculation value Lcal(t) calculated by load control unit 121h, and the minimum received power value Rmin stored in minimum received power storage unit 133 of storage unit 130, so that the received power value R(t) from the grid does not fall below the minimum received power value Rmin. Here, the received power value R(t) is the value obtained by subtracting the output power value PCS(t) from the load power value L(t). The calculation contents in command value recalculation unit 122 will be described in detail later with reference to FIG. 4.

[0048] The output command value PCSset(t) calculated by the command value recalculation unit 122 is limited by the change rate limiter 123 so that the rate of change, i.e., the speed of change of the value, is below a predetermined value, and then output from the output unit 140 to the PCS20 as the output command value PCSset(t).

[0049] FIG. 4 is a conceptual graph for explaining the details of the recalculation of the output command value in the reverse flow power control method according to the first embodiment. The horizontal axis represents time, and the vertical axis represents each power (kW). Δt is the time width of the control step, i.e., the control period. 4 This shows the case where the calculation cycle, i.e., the calculation step time width, matches the control cycle Δt. That is, the actual value of each power is obtained at time t, and after calculation, a command value is output at the next control step time (t+Δt). Details are explained below.

[0050] First, the load control unit 121h calculates the load command value Lset(t) for the load power. As described above, the local controller 31 of the load device 30 receives the load command value Lset(t) and controls the load power value L(t+Δt) used by the load device 30 so that it matches the load command value Lset(t). Therefore, at the next control step time (t+Δt), the value of the load power value L(t+Δt) can be approximated to the value of the load command value Lset(t). Here, the increase in the load power after Δt (L(t+Δt)-L(t)) is denoted as ΔL.

[0051] Similarly, for output power, the output control unit 121p calculates an output command calculation value PCScal(t). As described above, when the PCS 20 receives an output command of this value, it controls the output power value PCS(t+Δt) so that it coincides with this value PCScal(t). Therefore, in this case, at the next control step time (t+Δt), the output power value PCS(t+Δt) can be approximated to this value PCScal(t). Here, the increase in output power after Δt in this case (PCS(t+Δt)-PCS(t)) is denoted as ΔPCS.

[0052] Here, the command value recalculation unit 122 calculates the PCS output command value PCSset(t), which is an output command value that will not cause the predicted value R(t) of the received power to fall below the minimum received power value Rmin, based on command values ​​that can be approximated as the respective predicted values ​​at the next control step time (t+Δt), i.e., the load command value Lset(t) and the output command calculation value PCScal(t), as well as the actual received power value R(t).

[0053] Specifically, the PCS output command value PCSset(t) is calculated by the following equation (5). PCSset(t) =H(PCScal(t),PCS(t),Lcal(t),L(t),R(t),Rmin) ···(5)

[0054] Here, equation (5) can be expressed as the following equation (6). PCSset(t) =PCS(t)+min(-ΔL+ΔPCS,R(t)-Rmin)+ΔL =PCS(t) +min(-{Lcal(t)-L(t)} +{PCSset(t)-PCS(t)},R(t)-Rmin) +{Lcal(t)-L(t)} (6)

[0055] 5 is a flowchart showing the procedure of the reverse flow power control method according to the first embodiment. The procedure of the reverse flow power control method will be described below with reference to FIG.

[0056] First, parameters are read (step S10). Specifically, the input unit 110 reads the load control parameters P L The input unit 110 reads the output control parameter P P is read and stored in the control parameter storage unit 132 (step S12). Furthermore, the input unit 110 reads the minimum received power value Rmin and the minimum received power storage unit 133 stores it (step S13).

[0057] Next, other external data is read (step S20). Specifically, the input unit 110 reads the load plan value Plan-L and the output plan value Plan-P, and the plan value storage unit 131 stores them (step S21). In addition, the input unit 110 stores the load power actual value Plan-L as the power actual value. L The load power actual value (t) and the output power actual value PCS(t) are received and stored in the actual value storage unit 134 (step S22). L The received power actual value R(t) obtained by subtracting the output power actual value PCS(t) from (t) is also stored in the actual value storage unit 134.

[0058] Next, the control calculation unit 121 of the calculation unit 120 calculates a command value (step S30). Specifically, the load control unit 121h of the control calculation unit 121 calculates a load command calculation value Lcal(t) (step S31). The obtained load command calculation value Lcal(t) is output as a load command value Lset(t) to the local controller 31 of the load device 30, as will be described later (step S60).

[0059] Furthermore, the output control unit 121p of the control calculation unit 121 calculates the output command value calculation value PCScal(t) (step S32). The calculated load power command value Lset(t), the output command value calculation value PCScal(t), and the received power value R(t) obtained by subtracting the output command value calculation value PCScal(t) from the load command calculation value Lcal(t) are stored in the command value calculation result storage unit 135.

[0060] Next, the command value recalculation unit 122 performs recalculation using each power actual value stored in the actual value storage unit 134 and the calculation result stored in the command value calculation result storage unit 135 to calculate the PCS output command value PCSset(t) (step S50). This result is output as the output command value PCSset(t) from the output unit 140 to the PCS 20 via the change rate limiter 123. In addition, the load command calculation value Lcal(t) obtained in step S30 is output as the load command value Lset(t) to the local controller 31 of the load device 30 (step S60). 。

[0061] In the calculation unit 120 described above, calculations are performed on the absolute values ​​of the load power and the output power, i.e., on the values ​​themselves, but this is not limited to this. For example, instead of the load power command value Lset(t), the output command value calculated value PCScal(t), and the output command value PCSset(t), the amount of change from the actual value (ΔL, ΔPCS, etc.) may be calculated, and the absolute values ​​of the load power command value and the output power command value may be calculated in the output unit 140. In this way, calculations can be simplified by calculating the amount of change rather than the absolute values ​​of the command calculated value and the command value.

[0062] In the above embodiment, the case where the output command value PCSset(t) is calculated using a min function based on one minimum received power value Rmin has been described as an example, but the present invention is not limited to this. For example, the input unit 110 may read multiple thresholds instead of the minimum received power and then store them in the minimum received power storage unit 133, and the amount of change up to each threshold may be calculated, and the command value recalculation unit 122 may calculate the average, median, and maximum value thereof.

[0063] As described above, according to the reverse flow power control device 100 of this embodiment, in each control step, the control calculation result is not output as is to the PCS 20, but recalculation is performed so that the received power value R(t) does not fall below the minimum received power value Rmin. As a result, reverse power flow from the plant 1 to the power system 2 can be prevented.

[0064] [Second embodiment] FIG. 6 is a block diagram showing the configuration of a backward flow power control device 100a according to the second embodiment.

[0065] This embodiment is a variation of the first embodiment, and relates to a case where there is dead time in the response of some or all of the renewable energy power generation plant (PV) 10, the power conditioner (PCS) 20, and the load device 30.

[0066] In this embodiment, the calculation unit 120a further includes a calculation interval adjustment unit 124, and the storage unit 130a further includes a dead time storage unit 137.

[0067] The input unit 110 accepts dead time DLi information as an external input, and the dead time storage unit 137 stores this. Furthermore, the actual value storage unit 134 stores at least (M+1) times, described later, of each piece of power actual value data. Here, if dead time DLi information (i=1 to 3) exists for each of the PV 10, PCS 20, and load device 30, the maximum value thereof is set as the dead time DL.

[0068] The calculation interval adjustment unit 124 calculates the calculation interval Δt based on the dead time DL and the normal calculation time interval Δtn using the following equations (7) and (8). M = ROUND(DL / Δtn,0) (7) Δt=DL / M (8) Here, ROUND(DL / Δtn, 0) rounds up the decimal point of the numerical value of (DL / Δtn) to make it an integer.

[0069] FIG. 7 is a conceptual graph for explaining details of the recalculation of the output command value in the backward flow power control method according to the second embodiment.

[0070] FIG. 7 shows an example in which five steps of calculation are performed for the dead time DL, that is, the above-mentioned case where (M+1) is 5.

[0071] The difference from the first embodiment is that, after the load control unit 121h calculates the load command calculation value Lcal, the output control unit 121p calculates the output command calculation value PCScal, and the received power value R for the first four steps as shown in the following equations (9) to (12), the command value recalculation unit 122 calculates the output command after the dead time has elapsed, i.e., for the fifth step, as shown in the following equation (13).

[0072] Rm(t+Δt) =R(t)+Lcal(t-4Δt)-PCScal(t-4Δt) ···(9)

[0073] Rm(t+2Δt) =Rm(t+Δt)+Lcal(t-3Δt)-PCScal(t-3Δt) ···(10)

[0074] Rm(t+3Δt) =Rm(t+2Δt)+Lcal(t-2Δt)-PCScal(t-2Δt) ···(11)

[0075] Rm(t+4Δt) =Rm(t+3Δt)+Lcal(t-Δt)-PCScal(t-Δt) ···(12)

[0076] PCS set =PCScal(t-Δt) +min(-{Lcal(t)-Lcal(t-Δt)} +{PCScal(t)-PCScal(t-Δt)}, Rm(t+4Δt)-Rmin) +{Lcal(t)-Lcal(t-Δt)} ···(13)

[0077] To generalize this, when the dead time is τ steps, the future received power is calculated using the following equation (14), and the PCS output command value PCSset(t) is calculated using equation (15). Rm(t+(τ-1)Δt) =Rm(t+(τ-2)Δt) +Lcal(t-Δt)-PCScal(t-Δt) (14)

[0078] PCSset(t) =PCScal(t-Δt) +min(-{Lcal(t)-Lcal(t-Δt)} +{PCScal(t)-PCScal(t-Δt)}, Rm(t+(τ-1)Δt)-Rmin) +{Lcal(t)-Lcal(t-Δt)} ···(15)

[0079] In the above embodiment, the dead times of the load device 30 and the PCS 20 are the same, but the same concept can be applied to cases where the dead times are different.

[0080] However, if the dead time differs between the two, it is desirable that the dead time of the PCS 20 be shorter than the dead time of the load device 30 .

[0081] As described above, in this embodiment, even if the dead time is large, it is possible to prevent the received power value Rm(t) from falling below the minimum received power value Rmin.

[0082] [Third embodiment] FIG. 8 is a block diagram showing the configuration of a backward flow power control device 100b according to the third embodiment.

[0083] This embodiment is a modification of the first embodiment, and takes into consideration the response characteristics of a renewable energy power generation plant (PV) 10, a power conditioner (PCS) 20, and a load device 30.

[0084] In this embodiment, the input unit 110 receives characteristic models that model these response characteristics as external inputs. The storage unit 130b further includes a characteristic model storage unit 138 that stores these characteristic models. The calculation unit 120b further includes a predicted value calculation unit 125 that calculates a predicted value of the response using these characteristic models. The predicted value calculation unit 125 includes an output predicted value calculation unit 125a and a load predicted value calculation unit 125b.

[0085] Each characteristic model may be a single characteristic table or a combination of characteristic tables. Alternatively, the calculation of the predicted output value PCSpd(t+Δt) by the predicted output value calculation unit 125a and the calculation of the predicted load value Lpd(t+Δt) by the predicted load value calculation unit 125b may be performed using functions such as the following equations (16) and (17), respectively. PCSpd(t+Δt)=F P (PCScal(t),qP ) ···(16) Lpd(t+Δt)=F L (Lcal(t),q L ) ···(17) where q P and q L is a set of constants (characteristic constants) related to each characteristic. For example, in the case of a first-order lag or second-order lag, it is the time constant and gain.

[0086] The calculation of the output predicted value PCSpd(t+Δt) by the output predicted value calculation unit 125a and the calculation of the load predicted value Lpd(t+Δt) by the load predicted value calculation unit 125b are not limited to the above, and any method, whether linear or nonlinear, may be used as long as it can predict future power based on the command value to each device. For example, a deep learning prediction method such as a neural network or a random forest using a tree structure may be used.

[0087] FIG. 9 is a control block diagram showing the configuration and operation of a backward flow power control device 100b according to the third embodiment.

[0088] With regard to the part relating to commands to the load device 30, the load control unit 121h of the control calculation unit 121 calculates the load command calculation value Lcal(t), and the output unit 140 outputs this value as the load command value Lset(t), which is the same as the first embodiment.

[0089] Meanwhile, with regard to the part relating to commands to the PCS 20, the parts that are different from the first embodiment will be described below.

[0090] First, the load predicted value calculation unit 125b calculates the load predicted value Lpd(t+Δt) using the load command calculation value Lcal(t) calculated by the load control unit 121h.

[0091] Second, the output predicted value calculation unit 125a calculates the output predicted value PCSpd(t+Δt) using the output command calculation value PCScal(t) calculated by the output control unit 121p.

[0092] Third, the command value recalculation unit 122 calculates the PCS output command value PCSset(t), which is an output command value such that the predicted value R(t+Δt) of the received power does not fall below the minimum received power value Rmin, based on the respective predicted values ​​at the next control step time (t+Δt), i.e., the load predicted value Lpd(t+Δt) and the output predicted value PCSpd(t+Δt), and the actual received power value R(t).

[0093] Specifically, instead of equation (5) in the first embodiment, the PCS output command value PCSset(t) is calculated based on each predicted value using the following equation (18). PCSset(t) =H(PCSpd(t),PCS(t),Lpd(t),L(t),R(t),Rmin) ···(18)

[0094] Here, if one were to strictly apply the same idea as in the first embodiment, it would be necessary to use the inverse function of PCSpd(t) and PCS(t) to find an output command value PCSset(t) that does not fall below the minimum received power value Rmin, but this would be complicated, and in reality, it is considered that the control responses and response characteristics of the PV 10, PCS 20, and load device 30 can be ignored from the perspective of the reverse flow power control device 100. In such a case, the PCS output command value PCSset(t) can be obtained by correcting ΔR (see FIG. 4) from the output prediction value PCSpd(t), as in the following equation (19): PCSset(t)=PCSpd(t+Δt)-ΔR ···(19)

[0095] 10 is a flowchart showing the procedure of a reverse flow power control method according to the third embodiment. The steps up to step S30 are the same as those in the first embodiment. Only the differences from the first embodiment will be described below.

[0096] In this embodiment, a predicted value calculation step (step S40) is further included. In detail, the load predicted value calculation unit 125b calculates a load power predicted value to calculate a load predicted value Lpd(t+Δt) (step S41), and the output predicted value calculation unit 125a calculates an output power predicted value to calculate an output predicted value PCSpd(t+Δt) (step S42).

[0097] In this embodiment, in the output command value recalculation step S50a, the PCS output command value PCSset(t) is calculated based on each predicted value using equation (19) instead of equation (5) in the first embodiment.

[0098] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained. Furthermore, by predicting future power using a model of each device, it is possible to take into account the influence of the characteristics of each device, and it is possible to more reliably reduce the possibility that the received power will fall below the minimum received power.

[0099] [Fourth embodiment] FIG. 11 is a block diagram showing the relationship between a reverse flow power control device 100c according to the fourth embodiment and a plant 1c that is the target of the control device 100c.

[0100] This embodiment is a modification of the first embodiment, and the plant 1c further includes a storage battery 40 and a charge / discharge wattmeter .

[0101] FIG. 12 is a block diagram showing the configuration of a reverse flow power control device 100c according to the fourth embodiment. The reverse flow power control device 100c further includes a storage battery control unit 121q. Furthermore, a command value recalculation unit 122c is provided instead of the command value recalculation unit 122 in the first embodiment, and what is recalculated is not the output command value to the PCS 20 in the first embodiment, but a charge / discharge command value to the storage battery 40. Other than this, the fourth embodiment is the same as the first embodiment. The following description will focus on the parts that are different from the first embodiment, and a description of the parts that are the same as the first embodiment will be omitted.

[0102] FIG. 13 is a conceptual graph for explaining details of the recalculation of the output command value in the backward flow power control method according to the fourth embodiment.

[0103] The output command calculation value PCScal(t) calculated by the output control unit 121p is output from the output unit 140 to the PCS 20 as the output command value PCSset(t).

[0104] The battery control unit 121q calculates, by control calculation, a charge / discharge command calculation value BATcal(t) for the storage battery 40. Here, ΔBAT is the amount of change in the charge / discharge command calculation value BATcal(t) relative to the charge / discharge actual value BAT(t) of the storage battery 40. Here, if the change is charging, ΔBAT is positive, and if the change is discharging, ΔBAT is negative.

[0105] The command value recalculation unit 122c calculates a charge / discharge command value BATset(t), which is a charge / discharge command value that will not cause the predicted value R(t) of the received power to fall below the minimum received power value Rmin, based on command values ​​that can be approximated as the respective predicted values ​​at the next control step time (t+Δt), i.e., the load command calculation value Lcal(t), the output command calculation value PCScal(t), and the charge / discharge command calculation value BATcal(t), as well as each actual value.

[0106] Specifically, the charge / discharge command value BATset(t) is calculated by the following equation (20). Charge / discharge command value BATset(t) =G(PCScal(t),PCS(t),Lcal(t),L(t), BATset(t)BAT(t), R(t),Rmin) ···(20)

[0107] Here, equation (20) can be expressed as the following equation (21). BATset(t) =BAT(t) -{Lcal(t)-L(t)}+{PCSset(t)-PCS(t)} -min(-{Lcal(t)-L(t)}+{PCSset(t)-PCS(t)} -{BATcal(t)-BAT(t)},R(t)-Rmin) ···(twenty one)

[0108] As described above, in the plant 1c targeted by the reverse flow power control device 100c in this embodiment, a storage battery 40 is provided, and thus the PCS 20 can charge the storage battery 40 without suppressing the power generated by the PV 10, thereby making maximum use of renewable energy.

[0109] According to this embodiment, the reverse flow power control device 100c for such a plant 1c recalculates the command value to the storage battery 40 using the minimum received power value Rmin as a condition, and then outputs the charge / discharge command value BATset(t). As a result, it is possible to avoid a situation in which the received power value R(t) falls below the minimum received power value Rmin due to a control delay, or a reverse flow occurs.

[0110] [Fifth embodiment] FIG. 14 is a block diagram showing the relationship between a reverse flow power control device 100d according to the fifth embodiment and a plant 1 that is the target of the control device.

[0111] This embodiment is a modification of the first embodiment, and is an embodiment in which, under certain conditions, reverse flow power is permitted from the plant 1 to the power system 2. Therefore, when reverse flow power is permitted, a reverse flow permission signal 2a is sent from the power system 2 to the reverse flow power control device 100d.

[0112] FIG. 15 is a block diagram showing the configuration of a backward flow power control device 100d according to the fifth embodiment.

[0113] The input unit 110 receives a reverse flow permission signal 2a sent from the power grid 2. Here, the reverse flow permission signal 2a includes an allowable time period ΔTp during which reverse flow is permitted, and a maximum reverse flow power value Smax that is the upper limit of the reverse flow at that time.

[0114] The storage unit 130d further includes a maximum backward flow power storage unit 139 that stores and stores the permissible time period ΔTp and the maximum backward flow power value Smax received by the input unit 110.

[0115] The calculation unit 120d further includes a control condition determination unit 126. The control condition determination unit 126 designates one of two control states (a first control state and a second control state) based on the permissible time period ΔTp and the maximum backward flow power value Smax stored in the memory unit 130d.

[0116] The command value recalculation unit 122d performs processing according to each control state.

[0117] First, the first control state is a case where reverse power flow is not permitted, as in the first embodiment. d calculates an output command value PCSset(t) based on the output command calculation value PCScal(t) calculated by the output control unit 121p, the load command calculation value Lcal(t) calculated by the load control unit 121h, and the minimum received power value Rmin stored in the minimum received power memory unit 133 of the memory unit 130, so that the received power value R(t) from the grid does not fall below the minimum received power value Rmin.

[0118] The second control state is a state in which reverse power flow is permitted during the permitted time period ΔTp by the reverse power flow permission signal 2a sent from the power system 2. d calculates an output command value PCSset(t) using the following equation (22) based on the output command calculation value PCScal(t) calculated by the output control unit 121p, the load command calculation value Lcal(t) calculated by the load control unit 121h, and the maximum reverse flow power value Smax stored in the maximum reverse flow power memory unit 139 of the memory unit 130, so that the reverse flow power S(t) to the grid does not exceed the maximum reverse flow power value Smax.

[0119] Here, equation (22) can be expressed as the following equation (23). PCSset(t) =PCS(t)+min(-ΔL+ΔPCS,S(t)-Smax)+ΔL =PCS(t) +min(-{Lcal(t)-L(t)} +{PCSset(t)-PCS(t)},S(t)-Smax) +{Lcal(t)-L(t)} (23)

[0120] In the above, the reverse flow permission signal 2a is described as including the permissible time period ΔTp during which reverse flow is permitted and the maximum reverse flow power value Smax, which is the upper limit of the reverse flow at that time, but this is not limiting. For example, the reverse flow permission signal 2a from the power grid 2 may include only the maximum reverse flow power value Smax. In this case, the control condition determination unit 126 can specify the first control state while the reverse flow permission signal 2a is not being sent from the power grid 2, and the second control state while the signal is being sent.

[0121] As described above, according to this embodiment, even when reverse flow is permitted, the output command value PCSset(t) to the PCS 20 is recalculated using the maximum reverse flow power value Smax of the reverse flow permission signal 2a acquired from the power system 2, thereby preventing the reverse flow power from exceeding the maximum reverse flow power value Smax due to control delay.

[0122] According to the embodiment described above, it is possible to prevent deviation from the conditions regarding the backward flow power.

[0123] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Features of each embodiment may be combined. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0124] 1...plant, 2...power system, 2a...maximum reverse flow power, 3...intra-plant busbar, 4...connecting line, 10...renewable energy power generation equipment (PV), 20...power conditioner (PCS), 30...load equipment, 31...local controller, 40...storage battery, 50...power meter, 51...output power meter, 51a...actual output power value, 52...load power meter, 52a...actual load power value, 53...power trading meter, 53a...actual power trading value, 54...charge / discharge power meter, 54a...actual charge / discharge power value, 100...reverse flow power control device, 110...input unit, 120...calculation unit, 121...control calculation unit, 121a...first subtraction unit, 121b...first control circuit, 121c ...second subtraction unit, 121d...second control circuit, 121h...load control unit, 121p...output control unit, 121q...battery control unit, 122...command value recalculation unit, 123...change rate limiter, 124...calculation interval adjustment unit, 125...prediction value calculation unit, 125a...output predicted value calculation unit, 125b...load predicted value calculation unit, 126...control condition determination unit, 130...storage unit, 131...planned value storage unit, 132...control parameter storage unit, 133...minimum receiving power storage unit, 134...actual value storage unit, 135...command value calculation result storage unit, 136...recalculation result storage unit, 137...dead time storage unit, 138...characteristic model storage unit, 139...maximum reverse flow power storage unit, 140...output unit

Claims

1. A reverse flow power control device for a plant having a renewable energy power generation device, a power conditioner capable of adjusting the output power of the renewable energy power generation device, and a load device, and connected to an external power system, the reverse flow power control device preventing the generation of reverse flow power from the plant to the power system, an input unit that receives information including actual values ​​of the output power, the load power supplied to the load device, and the received power that the plant receives from the power grid, as well as a minimum received power value that is the minimum value of the received power; a storage unit that stores the information received by the input unit; a calculation unit that calculates command values ​​for the output power and the load power based on the information stored in the storage unit and the respective actual values; an output unit that outputs a command value to the load device and the power conditioner; Equipped with The calculation unit an output control unit that calculates an output command calculation value; a load control unit that calculates a load command calculation value; a command value recalculation unit that calculates an output command value to the power conditioner using the respective actual values, the output command calculation value, the load command calculation value, and the minimum received power value so that a received power value, which is a value of the received power, does not fall below the minimum received power value; and a calculation interval adjustment unit that sets a calculation interval that generates a plurality of calculation steps for the dead time in the renewable energy power generation device, the power conditioner, and the load device; Equipped with the command value recalculation unit calculates a change in the received power value in a section up to after the plurality of calculation steps in which the command value is reflected due to the dead time, and calculates the output command value such that the received power value does not fall below the minimum received power value. A reverse flow power control device characterized by:

2. The storage unit further includes a characteristic model storage unit that stores a characteristic model that models response characteristics of the renewable energy power generation device, the power conditioner, and the load device received by the input unit; the calculation unit further includes an output prediction value calculation unit and a load prediction value calculation unit that calculate an output prediction value and a load prediction value, respectively, based on the output command calculation value, the load command calculation value, and the characteristic model; the command value recalculation unit calculates the output command value to the power conditioner using the respective actual values, the output predicted value, the load predicted value, and the minimum received power value so that the received power value does not fall below the minimum received power value.

2. The reverse flow power control device according to claim 1 .

3. the storage unit stores not only the minimum receiving power value but also a plurality of threshold values; the command value recalculation unit calculates a command value to the power conditioner so as to prevent the reverse flow power by calculation using a plurality of the threshold values.

2. The reverse flow power control device according to claim 1 .

4. The reverse flow power control device described in Claim 3, characterized in that the command value recalculation unit calculates the command value using the maximum, minimum, average, or median value in calculations using multiple threshold values.

5. 2. The reverse flow power control device according to claim 1, wherein the command value recalculation unit performs calculations based on amounts of change from the respective actual values.

6. The plant further comprises a storage battery; the command value recalculation unit calculates a charge / discharge command value for the storage battery using the respective actual values, the output command calculation value, the load command calculation value, and the minimum received power value so that the received power value does not fall below the minimum received power value.

2. The reverse flow power control device according to claim 1 .

7. The plant is allowed to reverse power flow to the power grid under the condition that the reverse power flow does not exceed a maximum reverse power flow power value; In the above-mentioned permitted cases, the command value recalculation unit calculates the output command value to the power conditioner using the respective actual values, the output command calculation value, the load command calculation value, and the minimum received power value so that the power value of the reverse flow does not exceed the maximum reverse flow power value.

7. The reverse flow power control device according to claim 1, wherein the reverse flow power control device is a power supply.

8. A method for controlling reverse power flow, for a plant having a renewable energy power generation device, a power conditioner capable of adjusting the output power of the renewable energy power generation device, and a load device, and connected to an external power system, for preventing the generation of reverse power flow from the plant to the power system, comprising: an external information receiving step in which an input unit receives information including actual values ​​of the output power, the load power supplied to the load device, and the received power received by the plant from the power grid, as well as a minimum received power value that is a minimum value of the received power, and the information is stored in a storage unit; a command value calculation step in which an output control unit calculates an output command calculation value and a load control unit calculates a load command calculation value based on the information stored in the storage unit and the respective actual values; an output command value recalculation step in which a command value recalculation unit calculates an output command value to the power conditioner using the respective actual values, the output command calculation value, the load command calculation value, and the minimum received power value so that a received power value, which is a value of the received power, does not fall below the minimum received power value; an output step in which an output unit outputs a command value to the load device and the power conditioner; and The output command value recalculation step includes: a calculation interval adjusting unit setting a calculation interval that generates a plurality of calculation steps for the dead time in the renewable energy power generation device, the power conditioner, and the load device; a step of calculating a change in the received power value in a section up to after the plurality of calculation steps in which a command value is reflected due to the dead time, and calculating the output command value such that the received power value does not fall below the minimum received power value; A reverse flow power control method comprising:

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