Control device, control method and program

Abstract

A control device (100) configured to control a plurality of decentralized power suppliers (10) connected to an energy system (2), the control device (100) comprising: a first computing unit (110) configured to calculate in advance a reactive power to be output by each of the decentralized power suppliers (10) in the event of a fault in the power system (2); a command output unit (120) configured to output a command signal to each of the decentralized power suppliers (10) to cause each of the decentralized power suppliers (10) to output the reactive power calculated in advance by the first calculation unit (110) when it is detected that a fault has occurred in the power system (2); and a second computing unit (130) configured to input system data including a performance parameter at a plurality of nodes (13) of the energy system (2) to the first computing unit (110), wherein the first computing unit (110) is configured to update the reactive power to be output by the decentralized power suppliers (10) in a cycle that is longer than one data cycle of the system data, based on the system data; and the first computing unit (110) is configured, when a performance parameter cannot be detected at any node (13) among a plurality of nodes (13) of the energy system (2), to supplement missing data at the node (13) at which the performance parameter cannot be detected.

Description

TECHNICAL BACKGROUND1. TECHNICAL FIELD

[0001] The present invention relates to a control device, a control method and a program. 2. STATE OF THE ART

[0002] In the prior art, a technology is known that performs a power flow calculation when a fault occurs in an electrical grid (for example, Patent Document 1). Patent Documents 2 to 10 disclose related technologies.

[0003] Patent Document 9 discloses a method for exchanging electrical power with an electrical supply grid having a grid frequency by means of a converter-controlled generating unit, in particular a wind turbine or a wind farm, at a grid connection point.

[0004] Patent Document 10 discloses a power system stabilization device including an indicator calculation unit for calculating an acceleration index representing the acceleration of a generator for supplying electric power to the power system using the generator power, which is the output of the generator, and the generator phase difference, which indicates the temporal change in the phase angle of the generator power. The device further includes a threshold determination unit for determining whether or not the acceleration index exceeds a preset threshold, and a control command unit for generating a control command for control details representing a correction of the stabilization control set in advance for the threshold when the acceleration index exceeds the threshold. Patent Document 1: Japanese Patent Application Laid-Open No. JP 2011 - 61 970 A Patent Document 2: Japanese Patent Application Laid-Open No. JP 2016 - 208 654 A Patent Document 3: Japanese Patent Application Laid-Open No. JP 2017 - 60 355 A Patent Document 4: Japanese Patent Application Laid-Open No. JP 2017 - 112 709 A Patent Document 5: Japanese Patent Application Laid-Open No. JP 2018 - 57 117 A Patent Document 6: Japanese Patent Application Laid-Open No. JP 2018 - 57 119 A Patent Document 7: Japanese Patent Application Laid-Open No. JP 2013 - 74 668 A Patent Document 8: Japanese Patent Application Laid-Open No. JP 2007 - 288 877 A Patent Document 9: German Laid-Open Application No. DE 10 2018 102 220 A1 Patent Document 10: US Patent Application US 2017 / 0 353 033 A1 BRIEF DESCRIPTION OF THE INVENTION TECHNICAL TASK

[0005] In a control device configured to control a plurality of distributed power suppliers connected to an electric power system, it is preferable that a command signal based on an appropriate calculation is output to the distributed power suppliers even when a fault occurs in the power system. SOLUTION TO THE TASK

[0006] To achieve the above object, according to one aspect of the present invention, a control device according to claim 1 is provided. The control device is configured to control a plurality of distributed power suppliers connected to an electric power system. The control device may include a first computing unit and a command output unit. The first computing unit may be configured to precalculate a reactive power to be output by each of the distributed power suppliers in the event of a fault in the power system. The command output unit may be configured to output a command signal to each of the distributed power suppliers to cause each of the distributed power suppliers to output the reactive power precalculated by the first computing unit when it is detected that a fault has occurred in the power system.

[0007] The first calculation unit may also be configured to precalculate the reactive power for each of two or more types of faults in the power system. The command output unit may also be configured to output the command signal corresponding to a type of fault that has occurred in the power system.

[0008] The first computing unit may also be configured to further calculate an output suppression amount in each of the decentralized power suppliers in the event of a power system failure. The command output unit may be configured to output the command signal further containing information corresponding to the output suppression amount.

[0009] The first computing unit may also be configured to precalculate the output suppression amount for each of two or more types of faults in the power system. The command output unit may also be configured to output the command signal corresponding to a type of fault that has occurred in the power system.

[0010] The control device further comprises a second computing unit configured to input system data, including a power parameter at a plurality of nodes of the energy system, to the first computing unit. The first computing unit is also configured to update the reactive power to be output by the decentralized power suppliers based on the system data in a cycle that is longer than one data cycle of the system data.

[0011] The first computing unit is configured, when a performance parameter cannot be acquired at any node among a plurality of nodes, to supplement missing data at the node at which the performance parameter cannot be acquired.

[0012] A second aspect of the present invention relates to a control method for controlling a plurality of decentralized power suppliers according to claim 5.

[0013] A third aspect of the present invention relates to a program according to claim 6. Further aspects of the invention are the subject of the subclaims, the drawings and the description of embodiments.

[0014] The summary does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a subcombination of the features described above. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an example of a structure of a control device 100 according to an embodiment of the present invention. Fig. 2 shows an example of a reaction when a fault occurs in an energy system 2. Fig. 3 is a flowchart showing an example of a control method according to an embodiment of the present invention. Fig. 4 is a flowchart showing another example of the control method according to the embodiment of the present invention. Fig. 5 is a flowchart showing another example of the control method according to the embodiment of the present invention. Fig. 6 is a flowchart showing another example of the control method according to the embodiment of the present invention. Fig. Figure 7 shows an example of a computer 2200 in which many of the aspects of the present invention may be embodied in whole or in part. DESCRIPTION OF THE EMBODIMENTS

[0015] The present invention is described below using exemplary embodiments of the invention. However, these following exemplary embodiments are not to be understood as limiting the invention formulated in the claims. Furthermore, all combinations of features described in the exemplary embodiments are not necessarily essential for achieving the object of the invention.

[0016] Fig. 1 shows an example of the configuration of a control device 100 according to an embodiment of the present invention. The control device 100 of the present embodiment is configured to calculate in advance the active power and reactive power to be output by each of the distributed power suppliers 10-1 and 10-2 in a predetermined cycle, assuming that a fault occurs in a power system 2. When a fault actually occurs, the control device 100 outputs a command signal to the distributed power suppliers 10-1 and 10-2 to cause the distributed power suppliers 10-1 and 10-2 to output the precalculated active power and reactive power.

[0017] When a fault occurs, the distributed power suppliers 10-1 and 10-2 suppress the output of active power. The control device 100 may also be configured to calculate in advance an output suppression amount in each of the distributed power suppliers 10-1 and 10-2 as information about the active power to be output. When a fault actually occurs, the control device 100 may output a command signal containing information corresponding to the pre-calculated output suppression amount. The output suppression amount may be information related to a suppression amount of active power in each of the distributed power suppliers 10-1 and 10-2. The output suppression amount may be a target value of active power, a reduction amount, or an attenuation rate of the current electric power.

[0018] The control device 100 can be implemented by one or more computers. The computer can be a workstation or a personal computer.

[0019] The energy system 2 is electrically connected to the plurality of decentralized power suppliers 10-1 and 10-2. The energy system 2 may also be connected to at least one conventional power supplier 20. The number of decentralized power suppliers 10-1 and 10-2 and the number of conventional power suppliers 20 is not limited to the Fig. 1 case.

[0020] The distributed power suppliers 10-1 and 10-2 (which may also be collectively referred to as the distributed power supplier 10) are small-scale power generators arranged in a decentralized manner. The distributed power supplier 10 may also be referred to as a distribution power supply. The distributed power supplier 10 may also be a power supplier for a solar panel-based power generator, a wind power generator, a fuel cell power generator, and the like.

[0021] The distributed power supplier 10-1 includes a distributed power supplier main body 11-1 and a power converter 12-1. The distributed power supplier main body 11-1 is configured to generate electrical power. The power converter 12-1 is configured to convert the electrical power generated by the distributed power supplier main body 11-1 into electrical power corresponding to the power system 2. The power converter 12-1 may be a device referred to as a PCS (“Power Conditioning System”) or an inverter. Similarly, the distributed power supplier 10-2 may also include a distributed power supplier main body 11-2 and a power converter 12-2.

[0022] The conventional power supplier 20 is also referred to as a system power supply or a non-decentralized power supplier. The conventional power supplier 20 may also be a facility configured to supply power provided by a power supplier that manages the energy system 2. The conventional power supplier 20 may be, for example, a power plant, a substation, or a transformer. The energy system 2 may be an energy supply system controlled by the conventional power supplier 20. The decentralized power suppliers 10-1 and 10-2 and the conventional power supplier 20 form a node, which is connected to the energy system 2 at a node 13-1, a node 13-2, and a node 23, respectively.

[0023] The power system 2 may include fault detection units 14-1 and 14-2. The fault detection units 14-1 and 14-2 (which may be collectively referred to as fault detection unit 14) may be arranged at a plurality of predetermined locations in the power system 2. The fault detection unit 14-1 may include a sensor unit 15-1 and a switch 16-1. Similarly, the fault detection unit 14-2 may include a sensor unit 15-2 and a switch 16-2. The fault detection unit 14 is also referred to as an overload relay. The sensor unit 15 is configured to measure electrical line or current flowing through a power line in the power system 2.The fault detection unit 14 may also be configured to calculate an integrated value obtained by integrating a time during which a value measured by the sensor unit 15 exceeds an upper limit (wiring capacitance) and a deviation amount exceeding the upper limit. The fault detection unit 14 may determine that a fault has occurred when the integrated value exceeds a predetermined value. The switches 16-1 and 16-2 interrupt the power supply when it is determined that a fault has occurred.

[0024] Fig. Figure 2 shows an example of a response at the time of a fault in the power system 2. The vertical axis indicates a power flow in the power line, ie, electrical power. The horizontal axis shows time. In the Fig. In the example shown in Figure 2, a waveform of the output power oscillates after a fault occurs due to the control of a power generator and the like. Fig. 2, the switch 16 switches off the energy system 2 within 1 to 2 seconds after an error occurs.

[0025] When a fault occurs in the power system 2, the control device 100 is required to shut down the distributed power supplier 10 in parallel with the power system 2 or suppress an output of the distributed power supplier 10 to properly manage the power line. Generally, the power system 2 is configured to maintain a voltage at an appropriate value by sourcing reactive power from the distributed power supplier 10. Therefore, if all the distributed power suppliers 10 are shut down in parallel, reactive power is not supplied, making it difficult to maintain a voltage at an appropriate value.

[0026] When the number of distributed power suppliers 10 connected to the power system 2 is large, the electrical power of the distributed power suppliers 10 occupies most of the power flow flowing in the power line. Therefore, when a fault occurs in the power system 2, it is important to control the power flow in the power line and suppress the output of the distributed power supplier 10. If the output of the distributed power supplier 10 is suppressed more than necessary, it may have a consequential impact on the power generation system.

[0027] If a fault in a power line causes a voltage drop due to a decrease in reactive power and excessive power suppression, this may in some cases lead to subsequent tripping of the power generation system. Therefore, the control device 100 is preferably configured to calculate an appropriate output suppression amount in each of the distributed power suppliers 10 and an appropriate reactive power required to maintain a voltage in the power system 2.

[0028] In order for the control device 100 to calculate an appropriate output suppression amount in each of the distributed power suppliers 10 and an appropriate reactive power, the control device 100 is preferably configured to perform an optimal power flow calculation. On the other hand, taking into account an overcurrent tolerance time of the power line, the corresponding output suppression amount and the reactive power in the event of a fault are preferably acquired within a period of 2 seconds or less, more preferably 1 second or less, after a fault occurs. However, it may take 2 seconds or more from the start to completion of a calculation including the optimal power flow calculation.

[0029] The control device 100 is configured to perform a calculation in advance, including calculating the optimal power flow according to a type of virtual fault, in a fixed cycle. When a fault actually occurs, the control device 100 selects a solution suitable for a type of fault from pre-calculated solutions of optimization problems. Then, the control device 100 outputs the selected solution as a command value. The solution to the optimization problem may include an output suppression amount ΔP and a reactive power Q. By the above method, it is possible to command the solution to the optimization problem as a command value, which would otherwise require a long time.

[0030] As in Fig. As shown in Figure 1, the control device 100 includes a first computing unit 110 and a command output unit 120. The control device 100 may further include a second computing unit 130. The first computing unit 110 is configured to calculate in advance a reactive power to be output by each of the distributed power suppliers 10 in the event of a fault in the power system 2. The first computing unit 110 is configured to calculate in advance an output suppression amount of the active power to be suppressed by each of the distributed power suppliers 10 in the event of a fault in the power system 2.

[0031] The command output unit 120 is configured to output a command signal to each of the distributed power suppliers 10 to cause each of the distributed power suppliers 10 to output the reactive power calculated in advance by the first calculation unit 110 when it is detected that a fault has occurred in the power system 2. In the present example, the command signal may further include information according to the active power output suppression amount.

[0032] The second computing unit 130 is configured to input system data, including a performance parameter at a plurality of nodes of the energy system 2, to the first computing unit 110. For example, the second computing unit 130 comprises a data acquisition unit 132 and a data processing unit 134. The data acquisition unit 132 is configured to acquire system data relating to the energy system 2 to be regularly evaluated. The system data contains a performance parameter relating to a plurality of nodes, in particular to the decentralized power supplier 10 and the conventional power supplier 20 of the energy system 2. The performance parameter comprises at least one of the variables voltage, current, active power, and reactive power. For example, the performance parameter comprises a voltage, active power, and reactive power.

[0033] The data acquisition unit 132 may also be configured to obtain the performance parameter from the power converter 12 from each of the distributed power suppliers 10 or to obtain the performance parameter from other sensors. The system data may include fault information. The fault information may be information about characteristic values ​​of a current and the like measured by the sensor unit 15-1 and the sensor unit 15-2. The data acquisition unit 132 may generate a fault detection trigger when the fault information is detected. The fault detection trigger may include information indicating that a fault has occurred and information about a type of fault.

[0034] The second computing unit 130 is configured to acquire the system data for each predetermined cycle, referred to as a sampling cycle. The sampling cycle is, for example, 2 seconds or shorter, particularly preferably 1 second or shorter. The sampling cycle of the performance parameter of the system data and the sampling cycle of the error information may be different.

[0035] The data processing unit 134 is configured to process data acquired by the data acquisition unit 132. For example, the data processing unit 134 performs operations such as changing the data format, denoising, supplementing, and the like. The data processed by the data processing unit 134 is transmitted to the first computing unit 110 as the system data. The system data may include characteristic values ​​such as an active power P, a reactive power Q, a voltage V, a current I, and the like.

[0036] The first computing unit 110 includes, for example, a data supplementing unit 111, an optimal power flow computing unit 112, a storage unit 113, and a command value storing unit 114. When the performance parameter cannot be acquired at any one of the plurality of nodes, the data supplementing unit 111 supplements missing data in the system data based on the system data of another node or another time point. Specifically, when the performance parameter cannot be acquired at any one of the plurality of nodes, data is caused to be missing in the system data of the corresponding node. In this case, cross-domain data processing may be performed. The cross-domain data processing may be processing of calculating missing data at a specific time at the nodes based on other system data that are adjacent in space or time.For example, a state of missing data at a node can be estimated from the system data at one or a plurality of spatially adjacent nodes.

[0037] The optimal power flow calculation unit 112 is configured to perform an optimal power flow (OPF) calculation. The operation of the power system 2 has a plurality of operating constraints such that a voltage value at each node, a power flow value in each electrical power line, and an output of each power supplier must be maintained within appropriate ranges. Ideally, the power system 2 should be operated in such a way that the purposes are optimized while simultaneously satisfying all of the plurality of constraints. Calculating the optimal power flow (OPF) determines an operating state (power flow section) that optimizes a predetermined purpose while simultaneously satisfying various constraint conditions.

[0038] In this example, the optimal power flow calculation unit 112 is configured to calculate in advance the active power, the reactive power, and a voltage to be output by each of the distributed power supplies 10 for each of two or more types of fault A and fault B in the power system 2. For example, in each operation state (power flow section), considering the two or more types of fault A and fault B in the power system 2, the optimal power flow calculation unit 112 may calculate an output suppression amount, which is an amount of active power to be suppressed by each of the distributed power supplies 10, and an output of reactive power.

[0039] The optimal power flow calculation unit 112 may also be configured to calculate a command value including information about the reactive power to be output by each of the distributed power suppliers 10 and information corresponding to the output suppression amount to be suppressed for each assumed fault. The types of fault may include a difference in the location of the interrupted power line, a difference in the number of interrupted power lines, and the like. The first calculation unit 110 may also be configured to calculate the active power output suppression amount and the active power of each distributed power supplier 10 during normal times when no fault occurs.

[0040] The storage unit 113 is configured to store in advance information required for the optimal power flow calculation unit 112 to calculate the optimal power flow. The storage unit 113 may be configured to store in advance, as needed, information about the connection type of the plurality of nodes of the power system 2 in the power system, ie, the decentralized power supplier 10 and the conventional power supplier 20.

[0041] The command value storage unit 114 may be a database in which command value specifications 115-1 and 115-2 of the output suppression amount of active power, reactive power, and the like in each of the distributed power suppliers 10 are stored for each of the different types of fault A and fault B. The command value storage unit 114 may also be configured to store a command value specification 116 such as the output suppression amount of active power, the output of active power, and the like in each of the distributed power suppliers 10 at normal times when no fault occurs.

[0042] The first arithmetic unit 110 is configured to update command values, such as the reactive power to be output by the distributed power supplier, the output suppression amount, and the like, based on the system data in a cycle longer than a data cycle of the system data. The data cycle of the system data may be a sampling cycle of data, specifically a sampling cycle for which the second arithmetic unit 130 acquires the system data. Therefore, the update cycle of the command value for the first arithmetic unit 110 is longer than the sampling cycle of the data for the second arithmetic unit 130. Therefore, the first arithmetic unit 110 functions as a long-cycle arithmetic unit, and the second arithmetic unit 130 functions as a short-cycle arithmetic unit.

[0043] The sampling cycle for the short-cycle calculation by the second computing unit 130 can be 1 second to 2 seconds. The update cycle for the long calculation cycle by the first computing unit 110 is 2 seconds or longer. The long calculation cycle can be, for example, 10 seconds, 1 minute, 10 minutes, or 30 minutes. The long calculation cycle can be calculated according to a degree of load fluctuation or output fluctuation of the power system 2, which is a target.

[0044] The command issuing unit 120 includes a selection unit 122 and a transmission unit 124. The command issuing unit 120 may also be an interrupt processing unit configured to perform interrupt processing. The command issuing unit 120 is configured to receive a fault detection trigger as interrupt information. The selection unit 122 is configured to select a command value stored in the command value storage unit 114 according to the type of fault that has occurred. When fault A has occurred, the selection unit 122 selects the command value 115-1 for each of the distributed power suppliers 10 according to fault A. Similarly, when fault B has occurred, the selection unit 122 selects the command value 115-2 for each of the distributed power suppliers 10 according to fault B.

[0045] The transmission unit 124 is configured to output a command signal based on a command value included in the command value set 115 selected by the selection unit 122 according to the type of fault. The transmission unit 124 may also be configured to output a command signal including a reactive power value to be output by each of the distributed power suppliers 10 and an output suppression amount to be suppressed. Furthermore, the transmission unit 124 may also be configured to output a command signal including the active power and the output suppression amount in each of the distributed power suppliers 10 during normal times when no fault occurs.

[0046] Fig. 3 is a flowchart showing an example of a control method according to an embodiment of the present invention. First, a second calculation step by the second calculation unit 130 will be described. The second calculation step is referred to as a short-cycle calculation process. The second calculation unit 130 acquires system data to be regularly evaluated regarding the power system 2 (step S101). The second calculation unit 130 detects a fault in the power system 2 based on the presence of fault information in the system data (step S102). If a fault has occurred in the power system 2 (YES in step S102), the second calculation unit 130 generates a fault detection trigger (step S103). The fault detection trigger may include information indicating that a fault has occurred and information about a type of fault.

[0047] If no fault has occurred in the power system 2 (NO in step S102), the second computing unit 130 processes data acquired by the data acquisition unit 132 (step S104). The second computing unit 130 inputs system data, including a performance parameter at a plurality of nodes of the power system 2, to the first computing unit 110 (step S104). The nodes may include the plurality of distributed power suppliers 10 and at least one conventional power supplier 20. The second computing unit 130 periodically repeats the processes from step S101 to step S104. The cycle is 2 seconds or shorter, and more preferably 1 second or shorter.

[0048] The following describes the long-cycle calculation processing, which is a first calculation step of the first calculation unit 110. The first calculation unit 110 acquires the system data from the second calculation unit 130. If there is a shortage in the system data due to an inability to acquire the performance parameter at any one node among the plurality of nodes (YES in step S201), the first calculation unit 110 can supplement the missing data in the system data by using system data that are adjacent in time or space (step S202).

[0049] If the supplementation cannot be completed normally (NO in step S203), processing returns to step S201. The first computing unit 110 again acquires the system data from the second computing unit 130. Note that the processes from step S201 to step S203 may be omitted. If there is a temporary shortage in the system data, processing may return to step S201 without performing the supplementation process (step S202). In this case, the first computing unit 110 may be configured to wait for the acquisition of new system data without shortage in the time series before starting processing.

[0050] The optimal power flow calculation unit 112 of the first computing unit 110 performs the optimal power flow calculation (step S204). In the present example, the optimal power flow calculation unit 112 sets, as the evaluation function, a sum of the electric power transmission losses at normal times, an output suppression amount at normal times, an output suppression amount at the time of a fault, an electric power deviation amount at normal times, and an electric power deviation amount at the time of a fault. The optimal power flow calculation unit 112 calculates a solution that can minimize the evaluation function while satisfying the constraint conditions.

[0051] In this example, the evaluation function is formulated as shown in the following equation (1). In this example, the same function is used as the evaluation function during normal times and at the time of a fault. Different constraints are used for normal times and at the time of a fault. A dashed variable denotes a variable at the time of a fault. formula 1 minP,Q,FP,FQ,FP',FQ',θ,V,θ',V',ΔP,ΔP',δ ∑i∈N(∑k∈GiPk+∑k∈DiP¯k−dip+∑k∈DiΔPk+∑k∈DiΔP'k+ρe2+ρe'2) here N: set of nodes g: Set of nodes for conventional electricity suppliers G i ⊆ g: Set of nodes for conventional electricity supplier at node i EN D: Set of nodes for decentralized electricity supplier D i ⊆ D Set of nodes for decentralized electricity supplier at node i ∈ N P i active electrical power at node i ∈ N at normal times P l : active electrical power at decentralized electricity supplier node i∈D i in normal times ∑k∈giPk: Total active electrical power at decentralized electricity supplier nodes during normal times ∑k∈DiP¯k: Sum of predicted electrical power values ​​at a decentralized electricity supplier node at normal times diP: active electrical power load at node i ∈ N at normal times ∑k∈giPk+∑k∈DiPk¯−dip: electrical power transmission loss at normal times ΔP i : Output suppression amount at decentralized electricity supplier node i∈D i in normal times ΔPi': Output suppression amount at decentralized electricity supplier node i∈D i at the time of the error ∑k∈DiΔPk: Sum of output suppression amounts at decentralized electricity supplier nodes during normal times ∑k∈DiΔPk': Sum of output suppression amounts at decentralized power supplier node at the time of the error e: Amount of deviation of the voltage at normal times e': voltage deviation at the time of the fault ρ: penalty for the amount of deviation of the voltage ρe 2 : Deviation amount of electrical power at normal times ρe' 2 : Amount of deviation of electrical power at the time of the fault

[0052] In this example, a ratio expression for considering a demand and supply balance and a power flow equation are considered as the equation constraints during normal times. The ratio expression for considering a demand and supply balance is expressed by equation (2-1) and equation (2-2) as follows. Formula 2 Boundary conditions at normal times

[0053] Demand-supply equilibrium boundary condition ∑k∈GiPk+∑k∈DiP¯k−∑k∈DiΔPk−∑(jc):ijc∈εFijcP−∑(jc):jic∈εFijcP−diP−(Vi)2gis=0,∀i∈N ∑k∈GiQk+∑k∈DiQk−∑(jc):ijc∈NFijcQ−∑(jc):jic∈εFijcQ−diQ+(Vi)2bis=0,∀i∈N here, c ∈ C: i Set of nodes ε ⊆ N × N × C: set of branches FijcP: Active power on branch ijc ∈ ε at normal times ∑(jc):ijc∈εFijcP: Active power transferred from i to j at node jc ∑(jc):jic∈εFijcP: Active power transferred from j to i at node jc V i : voltage amplitude at node i ∈ N at normal times gis: : shunt conductance at node i ∈ N Q i : Reactive power at node i ∈ N at normal times ∑k∈giQk: Sum of reactive power at the conventional electricity supplier node i ∈ g at normal times ∑k∈DiQk: Sum of reactive power at the decentralized electricity supplier node i ∈ g at normal times FijcQ: Blinking power on branch ijc ∈ ε at normal times ∑(jc):ijc∈εFijcQ: Reactive power transferred from i to j at node jc ∑(jc):jic∈εFijcQ: Reactive power transferred from j to i at node jc diQ: Reactive power load at node i ∈ N at normal times : until: Susceptance at node i ∈ N

[0054] Note that in Equation (2-1) and Equation (2-2), a branch set ε represents a set (c, i, j) of two branches (i, j) directly connected to a node c. Vi and Vj represent the voltages of node i and node j of the branches directly connected to node c. Shunt conductance and susceptance represent adjustable RL elements (resistance, inductance component) connected to a node. For example, the RL element may represent a phase adjustment device provided for an electrical substation, etc.

[0055] The power flow equation is expressed by an equation (3-1), an equation (3-2), an equation (3-3) and an equation (3-4) as follows. Formula 3 Power flow equation FijcP=1τijc2gijcεVi2−1τijcViVj(gijcεcos(θi−θj)+bijcεsin(θi−θj)), ∀ijc∈ε FjicP=gijcεVj2−1τijcViVj(gijcεcos(θj−θi)+bijcεsin(θi−θj)), ∀ijc∈ε FijcQ=−1τijc2(bijcε+bijcc2)Vi2−1τijcViVj(gijcεcos(θi−θj)−bijcεsin(θi−θj)), ∀ijc∈ε FjicQ=−(bijcε+bijcc2)Vj2−1τijcViVj(gijcεcos(θi−θj)−bijcεsin(θi−θj)), ∀ijc∈ε here, τ ijc : Zweig transformer value ijc ∈ ε end: Zweig conductivity ijc ∈ ε θ i , θ j : Voltage phase at Zweig i, j ∈ N to normal times chief: Aperture value of Zweig ijc ∈ ε bijcC: Blind conductivity of the Zweig charge at Zweig ijc ∈ ε

[0056] Note that at each node i, a case where electric power comes out from its own node i to another node j is represented by equation (3-1) and equation (3-3), and a case where electric power comes in from another node j to its own node i is represented by equation (3-2) and equation (3-4). Note that conductance and susceptance at branch ijc are RL elements present in the power line and numerically indicate, for example, a resistance and an inductance component of the power line. The susceptance of the branch charge at branch ijc indicates a capacitor element (C) present in the power line.

[0057] As inequality constraints during normal times, upper and lower limits of each variable, upper and lower limits of the output of a power generator, and operation constraint conditions can be set. In this example, a capacity constraint of the power line, a voltage constraint, an active power constraint of the distributed power supply 10, an active power constraint of the output suppression amount, a reactive power constraint of the distributed power supplier 10, and an apparent power constraint of the distributed power supplier 10 are considered. The capacity constraint of the power line is expressed by the following equation (4). The voltage constraint is expressed by the following equation (5). The active power constraint of the distributed power supplier 10 is expressed by the following equation (6).The active power constraint of the output suppression amount is expressed by the following equation (7). The reactive power constraint of the distributed power supplier 10 is expressed by the following equation (8). The apparent power constraint of the distributed power supplier 10 is expressed by the following equation (9). Formula 4 Boundary conditions at normal timesInequality condition

[0058] Electrical power transmission capacity limitation of the power line −F¯ijcP≤FijcP≤F¯ijcP,∀ijc∈ε here, F¯ijcP: upper limit of the active power in branch ijc ∈ ε

[0059] Voltage limitation: VLi−e≤Vi≤VUi+e,∀i∈N here, V Li , V Ui : Lower and upper limits of the voltage amplitude at node i ∈ N Active power limitation of the decentralized power supplier PLi≤P¯i−ΔPi≤PUi,∀i∈D here, PLi , P Ui : Lower and upper bound of active power at the power supplier i ∈ D ∪ g Active power restriction of the output suppression amount (which does not exceed the original output) 0≤ΔPi≤P¯i,∀i∈D

[0060] Reactive power limitation of the decentralized electricity supplier QLi≤Qi≤QUi,∀i∈D here, Q Li , Q Ui : Lower and upper limits of the reactive power at the electricity supplier i ∈ D ∪ g Apparent power limitation of the decentralized electricity supplier (P¯i−ΔPi)2+Qi2≤Si2,∀i∈D here, S i : Upper limit of apparent power

[0061] On the other hand, the relational expression for considering a demand and supply balance and the power flow equation are considered as the equation constraint at the time of each fault. The relational expression for considering a demand and supply balance for considering the demand and supply balance is expressed by equation (10-1) and equation (10-2) as follows. Formula 5 Boundary conditions at the time of each fault

[0062] Demand-supply equilibrium boundary condition ∑k∈GiPk+∑k∈DiP¯k−∑k∈DiΔPk−∑k∈DiΔPk'−∑(jc):ijc∈εFijcP'−∑(jc):ijc∈εFijcP'−diP'−(Vi')2giS=0,∀i∈N ∑k∈GiQk'+∑k∈DiQk'−∑(jc):ijc∈NFijcQ'−∑(jc):jic∈εFijcQ'−diQ'+(Vi')2biS=0,∀i∈N here, ∑k∈DiΔPk: Spending restrictions during normal times ∑k∈DiΔPk': Output limitation at the time of an error FijcP': Active power in branch ijc E ε at the time of a fault ∑(jc):ijc∈εFijcP': Active power transferred from i to j in node jc at the time of a fault ∑(jc):jic∈εFijcP': Active power transferred from j to i in node jc at the time of a fault diP': Active power load in node i E N. at the time of a fault Vi': Voltage amplitude in node i ∈ N at normal times Qk': Reactive power load in node i E N. at the time of a fault ∑k∈giQk': Sum of reactive power at the conventional electricity supplier node i ∈ g i at the time of an error ∑k∈DiQk': Sum of reactive power at the decentralized electricity supplier node i E g i at the time of an error FijcQ': Reactive power in branch ijc E ∈ at normal times ∑(jc):ijc∈εFijcQ': Reactive power transferred from i to j in the node at the time of a fault It ∑(jc):jic∈εFijcQ': Reactive power transferred from j to i in node je at the time of a fault It diQ': Reactive power load in node i ∈ N at the time of a fault

[0063] The power flow equation at the time of a fault is expressed by an equation (11-1), an equation (11-2), an equation (11-3) and an equation (11-4) as follows. Formula 6 Boundary conditions at the time of each fault Power flow equation FijcP'=1τijc2gijcε'V'i2−1τijcV'iV'j(gijcε'cos(θi'−θj')+bijcε'sin(θi'−θj')),∀ijc∈ε FjicP'=gijcε'V'j2−1τijcV'iV'j(gijcε'cos(θj'−θi')+bijcε'sin(θj'−θi')),∀ijc∈ε FijcQ'=1τijc2(bijcε'+bijcC'2)V'i2−1τijcV'iV'j(gijcε'cos(θi'−θj')−bijcε'sin(θi'−θj')),∀ijc∈ε FjicQ'=−(bijc'+bijcC'2)V'i2−1τijcV'iV'j(gijcε'cos(θj'−θi')−bijcε'sin(θj'−θi')),∀ijc∈ε here, τ ijc : Transformer step value on branch ijc ∈ ε gijcε': Conductivity at branch ijc ∈ ε at the time of a fault θi', θj': Voltage phase at nodes i, j ∈ N at the time of a fault bijcε': Susceptance on branch ijc ∈ ε at the time of a fault bijcc': Reactive conductance of the branch charge on branch ijc ∈ ε at the time of a fault

[0064] As the inequality constraints at the time of a fault, upper and lower limits of each variable, upper and lower limits of the output of a power generator, and operation constraint conditions can be set. In this example, Equation (12) indicating the capacity constraint of the power transmission line, Equation (13) indicating the voltage constraint, Equation (14) indicating the output suppression amount constraint of the distributed power supplier 10, Equation (15) indicating the reactive power constraint of the distributed power supplier 10, and Equation (16) indicating the apparent power constraint of the distributed power supplier 10 can be considered. Note that the upper and lower limits of each inequality become zero when a node i is shut down in parallel.Therefore, the active power and reactive power output by the parallel-connected decentralized power supplier 10 also become zero. Formula 7 Boundary conditions at the time of each fault Power flow equation Capacity limitation of the power line −F¯ijcP≤FijcP'≤F¯ijcP, ∀ijc∈ε here, F¯ijcP: Upper limit of the active power in branch ijc ∈ ε

[0065] Voltage limitation at the time of a fault VLi−e'≤Vi'≤VUi+e', ∀i∈N here, V Li , V Ui : Lower limit and upper limit of the voltage amplitude at node i ∈ N Boundary condition of the output suppression amount of the decentralized power supplier (0: parallel off. 1: not parallel off) PLiδi≤P¯i≤ΔPuiδi, ∀i∈Dδi∈{0, 1}, ∀i∈D

[0066] Boundary condition of the reactive power of the decentralized power supplier (0: parallel off, 1: not parallel off) QLiδi≤Qi≤Quiδi, ∀i∈Dδi∈{0, 1}, ∀i∈D here, Q Li , Q Ui : Lower and upper limits of the reactive power at the electricity supplier i ∈ D ∪ g Boundary condition of the apparent power of the decentralized electricity supplier (P¯i−ΔPi−ΔPi')2+Qi'2≤Si2, ∀i∈D here, S i : Upper limit of apparent power

[0067] The optimal power flow calculation by Equation (1) and Equations (10-1) to (16) is performed in advance for each assumed fault. If a power line interruption (L pattern) and a power supply failure (M pattern) are assumed as the assumed fault, the optimal power flow calculation can be performed in advance for each fault of N (= L + M) patterns.

[0068] In Fig. 3, the first arithmetic unit 110 performs the optimal power flow calculation. The first arithmetic unit 110 generates the reactive power and the output suppression amount as the command values ​​for each assumed fault in advance through the optimal power flow calculation and updates them regularly (step S205). Furthermore, in the present example, the first arithmetic unit 110 performs the optimal power flow calculation at normal times using Equation (1) to Equation (9). The first arithmetic unit 110 generates the reactive power and the output suppression amount as the command values ​​at normal times. The first arithmetic unit 110 generates a normal time trigger to indicate that the command values ​​have been generated at normal times (step S206).

[0069] It should be noted that the first calculation unit 110 preferably regularly calculates in advance the output suppression amount and the reactive power for each assumed fault using the optimal power flow (OPF) calculation, and that the evaluation functions, the equality conditions, and the inequality conditions are not limited to the equations expressed by Equation (1) to Equation (16).

[0070] Next, a command output step by the command output unit 120 will be described. The command output unit 120 receives a fault detection trigger, thereby detecting that a fault has occurred in the power system 2. When the command output unit 120 receives the fault detection trigger (YES in step S301), the selection unit 122 selects the reactive power, the output suppression amount, and the like corresponding to the detected fault content from the reactive powers and the output suppression amounts calculated in advance for each fault by the first calculation unit 110 (step S302).

[0071] The transmission unit 124 transmits a command signal to each of the distributed power suppliers 10. The command signal transmitted from the command output unit 120 may include information for causing each of the distributed power suppliers 10 to output the pre-calculated reactive power, along with information corresponding to the pre-calculated output suppression amount.

[0072] In the present example, the command output unit 120 determines whether the normal time trigger is received (YES in step S304). If the command output unit 120 receives the normal time trigger (YES in step S304), the command output unit 120 generates a command signal including the reactive power information and the output suppression amount, which are the command values ​​at normal times (step S305). Then, the transmission unit 124 transmits the command signal including the command values ​​at normal times to each distributed power supplier 10 (step S306).

[0073] Fig. Fig. 4 is a flowchart showing another example of the control method according to the embodiment of the present invention. Steps S401 to S404 are similar to those shown in Fig. 3. In the present example, in the second calculation step, if the performance parameter cannot be acquired at any one of the plurality of nodes, the second computing unit 130 generates missing information indicating that data is missing (step S406). For example, the data processing unit 134 generates the missing information indicating that data is missing. The second computing unit 130 notifies the first computing unit of the missing information (step S406).

[0074] The first computing unit 110 determines in the first computing step whether the missing information has been received (step S501). If the missing information is received (YES in step S501), the first computing unit 110 supplements the missing data in the system data (step S502). Thereafter, the processes from step S503 to step S506 and step S601 to step S606 are similar to the processes from step S203 to S206 and step S301 to step S306 in Fig. 3. Therefore, an overlapping description is omitted.

[0075] In Fig. 3 and Fig. 4, the cases where the control device 100 outputs the command signal including the information for causing the distributed power suppliers 10-1 and 10-2 to output the pre-calculated reactive power and the information corresponding to the pre-calculated output suppression amount were described. The present invention is not limited to this.

[0076] Fig. Fig. 5 is a flowchart showing another example of the control method according to the embodiment of the present invention. The processes from step S701 to step S704 and step S801 to step S803 are similar to the processes from step S101 to S104 and step S201 to step S203 in Fig. 3. Therefore, an overlapping description is omitted.

[0077] The first computing unit 110 performs the optimal power flow calculation in step S804. However, in the present embodiment, the first computing unit 110 calculates in advance the output suppression amount in each of the distributed power suppliers 10 in the event of a fault in the power system 2 (step S805). The output suppression amount is calculated for each assumed fault. The output suppression amount is calculated and updated regularly.

[0078] When the command output unit 120 receives the fault detection trigger (YES in step S901), the selection unit 122 selects an output suppression amount value corresponding to the detected fault content from the output suppression amount values ​​calculated in advance for each fault by the first calculation unit 110 (step S902). The transmission unit 124 of the command output unit 120 outputs a command signal containing the information corresponding to the output suppression amount in each of the distributed power suppliers 10 to each of the distributed power suppliers 10 (step S903).

[0079] Fig. 6 is a flowchart showing another example of the control method according to the embodiment of the present invention. Fig. The processes shown in Figure 6 are similar to those in Fig. 5, except that the operations of steps S804 and S805 in Fig. 5 are replaced by the processes of steps S1104 and S1105, and the process of step S902 is replaced by the process of step S1202. In particular, the processes from step S1001 to step S1004 in Fig. 6, the operations from step S1101 to step S1103 and the operations from step S1201 and step S1203 are similar to the operations from step S701 to step S704 in Fig. 5, the operations from step S801 to step S803, and the operations from step S901 to step S903. Therefore, a detailed description is omitted.

[0080] The first computing unit 110 performs the optimal power flow calculation in step S1104. However, in the present embodiment, the first computing unit 110 calculates in advance the reactive power to be output by each of the decentralized power suppliers 10 in the event of a fault in the power system 2 (step S1105). The reactive power value is calculated for each assumed fault. The reactive power value is calculated and updated regularly.

[0081] When the command output unit 120 receives the fault detection trigger (YES in step S1201), the selection unit 122 selects a reactive power value corresponding to the detected fault content from the reactive power values ​​calculated in advance for each fault by the first calculation unit 110 (step S1202). The transmission unit 124 of the command output unit 120 outputs a command signal to each of the distributed power supplies 10 to cause each of the distributed power supplies 10 to output the precalculated reactive power (step S1203).

[0082] As in Fig. 5 or Fig. 6, the reactive power and the output suppression amount in each of the distributed power suppliers 10 may be periodically updated in advance using the optimal power flow calculation, and when a fault occurs, the command signal containing information about the reactive power and the output suppression amount that are periodically updated may be output to each of the distributed power suppliers 10.

[0083] As described above, according to the control device 100 of the present embodiment, it is possible to calculate the appropriate reactive power value in each of the distributed power suppliers 10 in advance by performing the optimal power flow calculation according to the assumed error. Therefore, it is possible to prevent a voltage drop due to an increase in reactive power in advance.

[0084] Furthermore, according to the control device 100 of the present embodiment, it is possible to calculate the appropriate active power or the output suppression amount of the active power in each of the distributed power suppliers 10 in advance by performing the optimal power flow calculation according to the assumed error. This can prevent a consequential effect on the power generation system due to unnecessary suppression of the output of the distributed power supplier 10.

[0085] According to the control device 100 of the present embodiment, the time-consuming calculation of the optimal power flow is not started only after a fault occurs, but the calculation of the optimal power flow is regularly performed in advance. Therefore, it is possible to acquire the corresponding output suppression amount and reactive power at the time of a fault within 2 seconds or less after the fault occurs. For this reason, according to the control device 100 of the embodiment, it is possible to transmit the corresponding command signal to each of the distributed power suppliers 10 early upon the occurrence of a fault. Thus, it is possible to start the corresponding control without exceeding the overcurrent tolerance time of the power line.

[0086] According to the control device 100 of the present embodiment, it is possible to detect a fault early without prolonging the sampling cycle, while it is possible to prolong the update cycle by calculating the reactive power and the output suppression amount in advance by the optimal power flow calculation.

[0087] Fig.7 shows an example of a computer 2200 in which a variety of aspects of the present invention may be embodied in whole or in part. A program installed on the computer 2200 may cause the computer 2200 to perform operations associated with the apparatus of the embodiment of the present invention or one or more portions thereof and / or cause the computer 2200 to perform the method of the embodiment of the present invention or steps thereof. Such a program may be executed by a CPU 2212 to cause the computer 220 to perform certain operations related to some or all of the flowchart and block diagram blocks described herein.

[0088] The computer 2200 according to the present embodiment includes a CPU 2212, a RAM 2214, a graphics card 2216, and a display device 2218, which are interconnected by a host controller 2210. The computer 2200 also includes input / output units, such as a communications interface 2222, a hard disk 2224, a DVD-ROM drive 2226, and an IC card drive, which are connected to the host controller 2210 via an input / output controller 2220. The computer also includes legacy input / output units, such as a ROM 2230 and a keyboard 2242, which are connected to the input / output controller 2220 via an input / output chip 2240.

[0089] The CPU 2212 is configured to operate according to programs stored in the ROM 2230 and the RAM 2214, thus controlling each unit. The graphics card 2216 is configured to capture the image data generated by the CPU 2212 into an image buffer or the like located in the RAM 2214 or within the graphics card itself, and to display the image data on the display device 2218.

[0090] The communication interface 2222 is configured to communicate with other electronic devices over a network. The hard disk 2224 is configured to store programs and data used by the CPU 2212 in the computer 2200. The DVD drive 2226 is configured to read the programs or data from the DVD-ROM 2201 and provide the programs or data to the hard disk 2224 via the RAM 2214. The IC card drive is configured to read programs and data from an IC card and / or write programs and data to the IC card.

[0091] The ROM 2230 is configured to store a boot program or the like that is executed by the computer 2200 upon startup, and / or a program that depends on the hardware of the computer 220. The input / output chip 2240 can also be configured to connect various types of input / output devices to the input / output controller 2220 via a parallel port, a serial port, a keyboard port, a mouse port, or the like.

[0092] A program is provided through a computer-readable medium, such as the DVD-ROM 2201 or the IC card. The program is read from the computer-readable medium, installed on the hard disk 2224, the RAM 2214, or the ROM 2230, which are also examples of the computer-readable medium, and executed by the CPU 2212. The information processing described in these programs is read into the computer 2200, thereby creating cooperation between a program and the various hardware components described above. An apparatus or method can be formed by implementing the operation or information processing according to the use of the computer 2200.

[0093] For example, when communication occurs between the computer 2200 and an external device, the CPU 2212 may execute a communication program loaded into the RAM 2214 to instruct the communication processing to the communication interface 2222 based on the processing described in the communication program. The communication interface 2222, under the control of the CPU 2212, reads transmission data stored in a transmission buffer processing area arranged on a storage medium such as the RAM 2214, the hard disk 2224, the DVD-ROM 2201, or the IC card, and transmits the read transmission data to a network or writes reception data received from a network into a reception buffer processing area or the like arranged on the storage medium.

[0094] Furthermore, the CPU 2212 may be configured to cause all or a necessary part of a file or database stored on an external storage medium such as the hard disk 2224, the DVD-ROM drive 2226 (DVD-ROM 2201), the IC card, or the like, to be read into the RAM 2214, thereby performing various types of processing on the data in the RAM 2214. The CPU 2212 is configured to write the processed data back to the external storage medium.

[0095] Various types of information, such as various types of programs, data, tables, and databases, may be stored in the storage medium to undergo information processing. The CPU 2212 may also be configured to perform various types of processing on the data read from the RAM 2214, including various types of operations, information processing, condition judgment, conditional branching, unconditional branching, information search / replacement, etc., as described in this disclosure and denoted by a program instruction sequence, and write the result back to the RAM 2214. The CPU 2212 may also be configured to search for information in a file, a database, etc., in the storage medium.For example, if a plurality of entries, each having an attribute value of a first attribute linked to an attribute value of a second attribute, are stored in the storage medium, the CPU 2212 may search for an entry from the plurality of entries that satisfies the condition whose attribute value of the first attribute is designated, and read the attribute value of the second attribute stored in the entry, thereby obtaining the attribute value of the second attribute linked to the first attribute that satisfies the predetermined condition.

[0096] The program or software modules described above may be stored in the computer-readable medium or near the computer 2200. Furthermore, a storage medium such as a hard disk or RAM provided to a server system connected to a dedicated communications network or the Internet may be used as the computer-readable medium, thereby making the programs available to the computer 2200 over the network.

[0097] While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above-described embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above-described embodiments.

Claims

[1] A control device (100) configured to control a plurality of decentralized power suppliers (10) connected to an energy system (2), the control device (100) comprising: a first computing unit (110) configured to calculate in advance a reactive power to be output by each of the decentralized power suppliers (10) in the event of a fault in the power system (2); a command output unit (120) configured to output a command signal to each of the decentralized power suppliers (10) to cause each of the decentralized power suppliers (10) to output the reactive power calculated in advance by the first calculation unit (110) when it is detected that a fault has occurred in the power system (2); and a second computing unit (130) configured to input system data including a performance parameter at a plurality of nodes (13) of the energy system (2) to the first computing unit (110), wherein the first computing unit (110) is configured to update the reactive power to be output by the decentralized power suppliers (10) in a cycle that is longer than one data cycle of the system data, based on the system data; and the first computing unit (110) is configured, when a performance parameter cannot be detected at any node (13) among a plurality of nodes (13) of the energy system (2), to supplement missing data at the node (13) at which the performance parameter cannot be detected. [2] Control device (100) according to claim 1, wherein the first computing unit (110) is configured to calculate the reactive power for each of two or more types of faults in the power system (2) in advance, and the command output unit (120) is configured to output the command signal corresponding to a type of fault occurred in the power system (2). [3] Control device (100) according to claim 1 or 2, wherein the first computing unit (110) is configured to further calculate an output suppression amount in each of the decentralized power suppliers (10) in the event of a fault in the power system (2), and the command output unit (120) is configured to output the command signal further including information corresponding to the output suppression amount. [4] Control device (100) according to claim 3, wherein the first calculation unit (110) is configured to calculate the output suppression amount for each of two or more types of faults in the power system (2) in advance, and the command output unit (120) is configured to output the command signal corresponding to a type of fault occurred in the power system (2). [5] Control method for controlling a plurality of decentralized power suppliers (10) connected to an energy system (2), the control method comprising: Performing a first calculation to calculate in advance a reactive power to be output by each of the decentralized power suppliers (10) in the event of a fault in the power system (2); Outputting a command signal to each of the decentralized power suppliers (10) to cause each of the decentralized power suppliers (10) to output the reactive power calculated in advance in the first calculation when it is detected that a fault has occurred in the power system (2); Inputting system data including a performance parameter at a plurality of nodes (13) of the energy system (2); Updating, based on the system data, the reactive power to be output by the decentralized power suppliers (10) in a cycle that is longer than one data cycle of the system data; and if a performance parameter cannot be detected at any node (13) among a plurality of nodes (13) of the energy system (2), supplementing missing data at the node (13) at which the performance parameter cannot be detected. [6] A program that causes a computer to execute a control method according to claim 5 for controlling a plurality of decentralized power suppliers (10) connected to an energy system (2).

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