Under-frequency relays and power systems

Abstract

To provide a frequency drop relay and a power system conforming to IEC61850.SOLUTION: A frequency drop relay cancels interconnection of a low-order system with a high-order system by receiving a request signal conforming to a communication protocol of IEC61850 from a system control device. In addition, each of frequency drop relays 5a to 5f comprises an information modelling part 5k which stores modeling information obtained by modeling a function of a device of a non-control object among various devices constituting the low-order system and the high-order system and a function of a high performance electronic device of itself on the basis of a regulation of IEC61850. The modeling information includes a single driving function modeling part which dominates cancellation of the interconnection of the low-order system and a setting value as a cancellation threshold.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an under-frequency relay and a power system. [Background technology]

[0002] The importance of strengthening the resilience of power grids has been reaffirmed in the wake of recent large-scale power outages caused by natural disasters. Meanwhile, with the growing demand for decarbonization, renewable energy sources are expected to become the main source of power. As is well known, renewable energy sources impair the inertia of the power grid, and when renewable energy sources are connected to the power grid, the stability of the power grid frequency decreases.

[0003] Non-Patent Document 1 discloses a method for setting an under-frequency relay as a power frequency stabilization technology that takes into account various system conditions such as renewable energy power sources. This under-frequency relay is a circuit breaker that cuts off the load from the power system when the power frequency drops significantly due to a large-scale power source failure, etc., and restores the power frequency of the power system to the original frequency.

[0004] Meanwhile, IEC 61850 is an international standard that defines the communication protocols for intelligent devices in substations. IEC 61850 is a technical standard compiled by the Technical Committee of the International Electrotechnical Commission, and specifies communication protocols for different types of intelligent devices. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Turaj. Amraee, Mohammad. Ghaderi. Darebaghi, Alireza. Soroudi and Andrew. Keane, "Probabilistic Under Frequency Load Shedding Considering RoCoF Relays of Distributed Generators," in IEEE Transactions on Power Systems, vol. 33, no. 4, pp. 3587-3598 (2018). Summary of the Invention [Problem to be solved by the invention]

[0006] However, at present, no under-frequency relays compliant with IEC 61850 have been developed. Considering that renewable energy sources will increasingly become the main power source in the future, it is necessary to develop under-frequency relays compliant with IEC 61850 as soon as possible to increase the versatility of under-frequency relays. It is expected that increasing the versatility of under-frequency relays will further promote the use of renewable energy sources as the main power source.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an under-frequency relay and a power system that comply with IEC61850. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention employs, as a first solution relating to an under-frequency relay, a means for disconnecting a lower system from a higher system by receiving a request signal conforming to the IEC 61850 communication protocol from a system control device.

[0009] The present invention employs, as a second solution related to the frequency down-regulation relay, a solution in which the first solution described above is provided with an information model unit that stores modeling information obtained by modeling functions of non-controlled devices among various devices constituting the lower system and the upper system and functions of the device's own high-performance electronic device based on the provisions of IEC 61850.

[0010] The present invention employs a third solution relating to an under-frequency relay in the above-mentioned second solution, in which the modeling information includes an islanding function modeling section that governs the disconnection of the lower system and a setting value that is a disconnection threshold.

[0011] The present invention employs, as a fourth solution related to the under-frequency relay, any one of the first to third solutions, in which the lower system includes a renewable energy power source.

[0012] The present invention employs a fifth solution relating to a frequency down-regulation relay, in which any of the first to fourth solutions described above is configured with a relay main body and a high-performance electronic device that communicate with each other in accordance with the communication protocol.

[0013] In the present invention, as a solution for the power system, a solution is adopted in which an under-frequency relay according to any one of the above first to fifth solutions is provided between the lower system and the upper system. Effect of the Invention

[0014] According to the present invention, it is possible to provide an under-frequency relay and a power system that comply with IEC61850. [Brief description of the drawings]

[0015] [Figure 1] 1 is a system diagram showing a configuration of a power system in one embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a frequency down-relay according to an embodiment of the present invention. [Diagram 3] 1 is a block diagram showing a configuration of a system control device according to an embodiment of the present invention; [Figure 4] FIG. 2 is a schematic diagram showing a communication procedure between a power system control device and a frequency down relay in an embodiment of the present invention. [Diagram 5] FIG. 13 is a block diagram illustrating a variation of a frequency down-regulation relay according to an embodiment of the present invention. [Figure 6] FIG. 2 is a block diagram showing a configuration of an information model unit of a frequency down-relay according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the power system A in this embodiment will be described. This power system A is a power system for supplying power to the power receiving equipment of a consumer, and integrates power generation, transformation, transmission, and distribution. The power system A is operated and managed by a specific power utility, but generally, renewable energy sources operated and managed by a power utility different from the specific power utility are interconnected.

[0017] 1, such a power system A includes a main system 1, two transformers 2a, 2b, two first busbars 3a, 3b, six load feeders 4a-4f, six under-frequency relays 5a-5f, six lower systems 6a-6f, and a system controller 7. Among these components, the main system 1, the two transformers 2a, 2b, and the two first busbars 3a, 3b constitute the upper system of the present invention.

[0018] Here, among these components, components other than the six lower systems 6a to 6f are managed and operated by a specific power supplier that primarily manages and operates the power system A. In contrast, the six lower systems 6a to 6f are mainly managed and operated by a power supplier other than such a specific power supplier.

[0019] The main system 1 is made up of power plants and transmission and distribution networks that are exclusively operated and managed by the above-mentioned power utility companies, and is the main component of power system A. This main system 1 includes electrical facilities traditionally known as power plants, such as thermal power plants, hydroelectric power plants, and nuclear power plants. This main system 1 has traditionally been operated and managed by former general electric utilities (i.e., specific power utility companies) that have traditionally operated electric power businesses throughout the country.

[0020] The two transformers 2a and 2b are provided between the main system 1 and the first busbars 3a and 3b. That is, one input / output terminal of the transformer 2a is connected to the main system 1, and the other input / output terminal is connected to one of the first busbars 3a. The other transformer 2b has one input / output terminal connected to the main system 1, and the other input / output terminal connected to the other of the first busbars 3b. Such transformers 2a and 2b are power devices that convert the voltage of the power transmitted and received between the main system 1 and the first busbars 3a and 3b.

[0021] In general, the voltage (main system voltage) of the power (main system power) of the main system 1 is higher than the voltage (first system voltage) of the power (first system power) of the first busbars 3a, 3b. When the flow of the system power is from the main system 1 to the first busbars 3a, 3b, each transformer 2a, 2b steps down the main system voltage of the main system power and converts it to the first voltage. On the other hand, when the flow of the system power is from the first busbars 3a, 3b to the main system 1, each transformer 2a, 2b steps up the first system voltage of the first system power and converts it to the main system voltage.

[0022] The two first busbars 3a, 3b are electric wires provided corresponding to the two transformers 2a, 2b. That is, one first busbar 3a is connected to the other input / output terminal of one transformer 2a, and the other first busbar 3b is connected to the other input / output terminal of the other transformer 2b. Such first busbars 3a, 3b aggregate six load feeders 4a to 4f into two systems corresponding to the two transformers 2a, 2b.

[0023] The six load feeders 4a-4f are distribution lines (connection lines) for connecting the six sub-systems 6a-6f to the main system 1 via the transformers 2a, 2b and the first busbars 3a, 3b, and are provided corresponding to the six sub-systems 6a-6f. That is, the first load feeder 4a is provided corresponding to the first sub-system 6a, and has one end connected to one of the first busbars 3a and the other end connected to the first sub-system 6a.

[0024] The second load feeder 4b is provided corresponding to the second lower system 6b, with one end connected to one of the first bus bars 3a and the other end connected to the second lower system 6b. The third load feeder 4c is provided corresponding to the third lower system 6c, with one end connected to one of the first bus bars 3a and the other end connected to the third lower system 6c.

[0025] The fourth load feeder 4d is provided corresponding to the fourth lower system 6d, with one end connected to one second busbar 3b and the other end connected to the fourth lower system 6d. The fifth load feeder 4e is provided corresponding to the fifth lower system 6e, with one end connected to one second busbar 3b and the other end connected to the fifth lower system 6e. The sixth load feeder 4f is provided corresponding to the sixth lower system 6f, with one end connected to one second busbar 3b and the other end connected to the sixth lower system 6f.

[0026] The under-frequency relays 5a-5f are digital relays conforming to IEC 61850 and are provided in the middle of the load feeders 4a-4f corresponding to the lower systems 6a-6f, respectively. That is, the under-frequency relays 5a-5f are provided in the power system A between the lower systems 6a-6f and the upper system (the main system 1, the transformers 2a, 2b, and the first busbars 3a, 3b).

[0027] The first down frequency relay 5a is provided in the first load feeder 4a corresponding to the first lower system 6a. The second down frequency relay 5b is provided in the second load feeder 4b corresponding to the second lower system 6b. The third down frequency relay 5c is provided in the third load feeder 4c corresponding to the third lower system 6c.

[0028] The fourth down frequency relay 5d is provided in the fourth load feeder 4d corresponding to the fourth lower system 6d. The fifth down frequency relay 5e is provided in the fifth load feeder 4e corresponding to the fifth lower system 6e. The sixth down frequency relay 5f is provided in the sixth load feeder 4f corresponding to the sixth lower system 6f.

[0029] Each of these under-frequency relays 5a to 5f sets whether the downstream systems 6a to 6f are connected to or not connected to the first busbars 3a, 3b (i.e., connected to or not connected to the main system 1) based on the system frequency of the first system power. Although details will be described later, each of the under-frequency relays 5a to 5f has a function of detecting a rate of change (frequency change rate) of the system frequency of the first system power, and switches and sets a connection state between one end and the other end of each of the load feeders 4a to 4f to a conductive state (ON state) or a non-conductive state (OFF state) based on the frequency change rate and a previously stored setting value DO.

[0030] That is, when the frequency change rate of the first system power is within the range of the set value DO, each of the under-frequency relays 5a to 5f sets the load feeders 4a to 4f to a conductive state (ON state), thereby connecting the lower systems 6a to 6f to the upper system consisting of the main system 1, the transformers 2a, 2b, and the first busbars 3a, 3b.

[0031] On the other hand, when the rate of change of the frequency of the first system power deviates from the range of the set value DO, the under-frequency relays 5a-5f control the load feeders 4a-4f to a non-conductive state (OFF state) to disconnect the lower systems 6a-6f from the upper system. The set value DO of each of the under-frequency relays 5a-5f is a release threshold value that governs the release of the connection of the lower systems 6a-6f to the upper system.

[0032] Each of the under-frequency relays 5a to 5f is also a power interruption device having an external control function. That is, each of the under-frequency relays 5a to 5f performs switching control between the conductive state (ON state) and the non-conductive state (OFF state) based on the request signal S1 received from the system control device 7 in addition to autonomously switching between the conductive state (ON state) and the non-conductive state (OFF state) based on the above-mentioned frequency change rate and the set value DO.

[0033] Although details will be described later, each of the frequency down relays 5a to 5f has a communication function for performing bidirectional communication with the system control device 7 in accordance with a communication protocol compliant with IEC 61850 (IEC 61850 communication protocol), and receives a request signal S1 generated by the system control device 7 based on the IEC 61850 communication protocol.

[0034] The first under-frequency relay 5a controls whether the first downstream system 6a is connected to or not connected to the main system 1 based on the request signal S1 received via the above-mentioned IEC communication protocol. The second under-frequency relay 5b controls whether the second downstream system 6b is connected to or not connected to the main system 1 based on the request signal S1 received via the above-mentioned IEC61850 communication protocol. The third under-frequency relay 5c controls whether the third downstream system 6c is connected to or not connected to the main system 1 based on the request signal S1 received via the above-mentioned IEC communication protocol.

[0035] The fourth under frequency relay 5d controls whether the fourth subordinate system 6d is connected to or not connected to the main system 1 based on the request signal S1 received via the IEC 61850 communication protocol. The fifth under frequency relay 5e controls whether the fifth subordinate system 6e is connected to or not connected to the main system 1 based on the request signal S1 received via the IEC 61850 communication protocol. The sixth under frequency relay 5f controls whether the sixth subordinate system 6f is connected to or not connected to the main system 1 based on the request signal S1 received via the IEC 61850 communication protocol.

[0036] Each of the six under-frequency relays 5a to 5f includes the functional components shown in Fig. 2, namely, a circuit breaker 5g, a transformer 5h, an analog input / output unit 5i, a communication unit 5j, an information model unit 5k, an under-frequency relay calculation unit 5m, and a digital input / output unit 5n. Among these components, the analog input / output unit 5i, the communication unit 5j, the information model unit 5k, the under-frequency relay calculation unit 5m, and the digital input / output unit 5n configure an IED (Intelligent Electronic Device) as shown in the figure. This IED has specifications that comply with the IEC 61850 regulations.

[0037] The circuit breaker 5g is provided at an intermediate position of the load feeders 4a to 4f, and turns on / off the connection between one end and the other end of the load feeders 4a to 4f based on a switching signal input from the digital input / output unit 5n. That is, the circuit breaker 5g connects the lower systems 6a to 6f to the first busbars 3a, 3b (main system 1) in a conductive state, and switches the lower systems 6a to 6f to a non-connected state with respect to the first busbars 3a, 3b (main system 1) in a released state.

[0038] The transformer 5h has an input end connected to the first busbars 3a, 3b side of the load feeders 4a to 4f, that is, the upstream side of the circuit breaker 5g, and steps down the first system voltage of the load feeders 4a to 4f (that is, the first system) and outputs it to the analog input / output unit 5i. That is, the transformer 5h steps down the first system voltage to a voltage (measurement signal) that can be handled by an IED that complies with IEC61850.

[0039] The analog input / output unit 5i is an interface circuit that receives the measurement signal, converts the analog measurement signal into a digital signal that can be handled by the frequency down-regulation relay calculation unit 5m, and outputs the measurement data generated by the conversion to the frequency down-regulation relay calculation unit 5m.

[0040] The communication unit 5j is a functional component that performs communication with the system control device 7 in accordance with the IEC 61850 communication protocol, and receives, for example, a request signal S1 in accordance with the IEC 61850 communication protocol. The communication unit 5j outputs various requests received from the system control device 7 as the request signal S1 to the information model unit 5k or the digital input / output unit 5n.

[0041] The information model unit 5k is a storage unit that stores modeling information obtained by modeling the functions of non-controlled devices among various devices constituting the power system A and the functions of IEDs based on the provisions of IEC 61850. The information model unit 5k outputs the modeling information to the under-frequency relay calculation unit 5m in response to a request from the under-frequency relay calculation unit 5m.

[0042] The modeling information includes multiple Logical Nodes / Data Objects (LN / DOs) that are required to be implemented by IEC 61850, and "PFRCs" that are "Logical Nodes" defined in the IEC 61850 communication protocol for the frequency change rate relay. The PFRCs include the setting value DOs used in the under-frequency relay calculation unit 5m.

[0043] In the under-frequency relay calculation unit 5m, the frequency change rate calculated by a different calculation method for each PFRC and the setting value DO are compared simultaneously in parallel for the number of PFRCs. The necessity of outputting a switching control signal is finally determined by a logical calculation of the result of the comparison processing between the frequency change rate and the setting value DO, which are performed simultaneously in parallel.

[0044] The under-frequency relay calculation unit 5m calculates the rate of change (frequency change rate) in the system frequency of the main system power and the first system power based on the measurement data input from the analog input / output unit 5i, and determines whether or not to switch the circuit breaker 5g from a conductive state to an open state based on the frequency change rate and the setting value DO acquired from the information model unit 5k. When the under-frequency relay calculation unit 5m determines that the circuit breaker 5g should be switched from a conductive state to an open state, it generates a switch request signal indicating the switch and outputs it to the digital input / output unit 5n.

[0045] The digital input / output unit 5n is an interface circuit that converts the switching control signal, which is a digital signal, into a switching signal that can drive the circuit breaker 5g. The digital input / output unit 5n generates a switching signal based on the switching control signal input from the frequency down relay calculation unit 5m or the switching request input from the communication unit 5j, and outputs the switching signal to the circuit breaker 5g to directly operate the circuit breaker 5g.

[0046] The digital input / output unit 5n also acquires a signal (switching state signal) indicating the operating state of the circuit breaker 5g from the circuit breaker 5g. The digital input / output unit 5n outputs the switching state signal to the information model unit 5k. The information model unit 5k stores the operating state of the circuit breaker 5g based on the switching state signal.

[0047] The six sub-systems 6a to 6f are power generating facilities connected to the main system 1 via the load feeders 4a to 4f, the first busbars 3a and 3b, and the transformers 2a and 2b. That is, the first sub-system 6a is connected to the main system 1 via the first load feeder 4a, one of the first busbars 3a, and one of the transformers 2a. The second sub-system 6b is connected to the main system 1 via the second load feeder 4a, one of the first busbars 3a, and one of the transformers 2a. The third sub-system 6c is connected to the main system 1 via the third load feeder 4c, one of the first busbars 3a, and one of the transformers 2a.

[0048] Also, the fourth downstream system 6d is connected to the main system 1 via the fourth load feeder 4d, the other first busbar 3b, and the other transformer 2b. The fifth downstream system 6e is connected to the main system 1 via the fifth load feeder 4e, the other first busbar 3b, and the other transformer 2b. The sixth downstream system 6f is connected to the main system 1 via the sixth load feeder 4f, the other first busbar 3b, and the other transformer 2b.

[0049] As shown in the figure, each of these lower systems 6a to 6f includes a power generation device, a PCS (Power Conditioning Subsystem), a load, and a second bus. The power generation device is a renewable energy power source such as a wind power generator or a solar cell. The PCS converts the DC power generated by the power generation device into AC power.

[0050] The PCS is a power conditioner connected to the second busbar, which converts the power of the renewable energy source and the power generation device into the first system power of the first busbars 3a and 3b, and outputs it to the second busbar as the lower system power. The load is connected to the second busbar, and is a power consuming device that consumes the first system power or the lower system power.

[0051] These six lower systems 6a to 6f output status signals S2 indicating their own power generation states to the system controller 7. That is, the PCS of the first lower system 6a outputs a first status signal S2 indicating the operating state of its own power generation device to the system controller 7. The PCS of the second lower system 6b outputs a second status signal S2 indicating the operating state of its own power generation device to the system controller 7. The PCS of the third lower system 6c outputs a third status signal S2 indicating the operating state of its own power generation device to the system controller 7.

[0052] Moreover, the PCS of the fourth lower system 6d outputs a second status signal S2 indicating the operating states of its own renewable energy power source and power generation device to the system control device 7. The PCS of the fifth lower system 6e outputs a fifth status signal S2 indicating the operating states of its own renewable energy power source and power generation device to the system control device 7. The PCS of the sixth lower system 6f outputs a sixth status signal S2 indicating the operating states of its own renewable energy power source and power generation device to the system control device 7.

[0053] The power system control device 7 generates a request signal S1 based on such a status signal S2, and transmits the request signal S1 to each of the under-frequency relays 5a-5f to control each of the under-frequency relays 5a-5f. As will be described in detail later, the power system control device 7 generates a request signal S1 that complies with the IEC communication protocol based on the status signal S2, and transmits the request signal S1 to each of the under-frequency relays 5a-5f in a procedure that complies with the IEC communication protocol.

[0054] For example, when the system control device 7 detects, based on the status signal S2, that power generation in any of the lower systems 6a to 6f has stopped or is predicting such a stop, it generates a request signal S1 to disconnect a load corresponding to the power generation amount (dropping amount) of the stopped power generation (power dropout) from the main system 1. That is, the system control device 7 maintains the system frequencies of the main system power and the first system power within the normal range by disconnecting a load with a power consumption amount equivalent to the dropout amount from the first busbars 3a, 3b.

[0055] Such a system control device 7 includes a data acquisition unit 7a, a characteristic generation unit 7b, a control unit 7c, and a communication unit 7d as shown in Fig. 3. In addition, the control unit 7c includes a control target selection unit 7e and an adjustment unit 7f as shown in the figure.

[0056] The data acquisition unit 7a acquires the power generation output (renewable energy output) of the renewable energy power source in each of the lower systems 6a to 6f in real time based on the status signal S2. The data acquisition unit 7a calculates the total value of the power generation output of each of the lower systems 6a to 6f. The data acquisition unit 7a also acquires the power consumed by the load of each of the lower systems 6a to 6f in real time based on the status signal S2.

[0057] The characteristic generating unit 7b generates a renewable energy dropout characteristic indicating the amount of dropout of the renewable energy power source according to the frequency change rate of the system power of the power system A, based on the power generation output of each of the lower systems 6a to 6f acquired by the data acquiring unit 7a. This renewable energy dropout characteristic is a graph in which the horizontal axis indicates the frequency change rate of the system power and the vertical axis indicates the amount of dropout of the renewable energy power source, and has a characteristic that the amount of dropout increases as the frequency change rate increases, and the amount of dropout saturates when the frequency change rate reaches a certain value.

[0058] The control unit 7c generates a request signal S1 based on the renewable energy dropout characteristic generated by the characteristic generation unit 7b. That is, the control unit 7c generates the request signal S1 so as to disconnect a load power equivalent to the amount of dropout in accordance with the renewable energy dropout characteristic from the main grid 1. The control unit 7c includes a control target selection unit 7e and an adjustment unit 7f.

[0059] The control target selection unit 7e selects the under-frequency relays 5a-5f to be switched from a conductive state to a released state based on the load power of each of the lower systems 6a-6f acquired by the data acquisition unit 7a. For example, the control target selection unit 7e selects the under-frequency relays 5a-5f connected to the lower systems 6a-6f that have load power equivalent to the amount of dropout of the renewable energy power source as the control target.

[0060] The adjustment unit 7f generates a control command for adjusting the setting value DO of the control object selected by the control object selection unit 7e and outputs the control command to the communication unit 7d. That is, the adjustment unit 7f adjusts the setting value DO of the control object to control the control object so that the control object is switched from a conductive state to a released state.

[0061] The communication unit 7d is a functional component that performs communication with the communication unit 5j of each of the down-regulation relays 5a to 5f in accordance with the IEC 61850 communication protocol. The communication unit 7d generates a request signal S1 in accordance with the IEC 61850 communication protocol based on a control command input from the adjustment unit 7f, and transmits the request signal S1 to the communication unit 5j of each of the down-regulation relays 5a to 5f.

[0062] The communication unit 7d receives modeling information such as the setting value DO from the communication unit 5j of each of the under-frequency relays 5a to 5f and outputs it to the adjustment unit 7f. The adjustment unit 7f generates a control command by also referring to the modeling information acquired from each of the under-frequency relays 5a to 5f. That is, the power system control device 7 acquires and rewrites the setting value DO of each of the under-frequency relays 5a to 5f through two-way communication in accordance with the IEC61850 communication protocol.

[0063] Next, the operation of the power system A according to this embodiment, in particular the operation of disconnecting the lower systems 6a to 6f through cooperation between the system control device 7 and the under-frequency relays 5a to 5f, will be described in detail with reference to FIG.

[0064] Here, each of the under-frequency relays 5a to 5f autonomously switches the circuit breaker 5g from the conductive state to the open state by a determination process based on the rate of frequency change of the main system power (first system power) calculated by the under-frequency relay calculation unit 5m and the set value DO pre-stored in the information model unit 5k. That is, each of the under-frequency relays 5a to 5f disconnects each of the sub-systems 6a to 6f from the main system 1 so that the system frequency of the main system power (first system power) does not become abnormal.

[0065] In addition to such autonomous operation, each of the under-frequency relays 5a to 5f switches the circuit breaker 5g from the conductive state to the open state based on various requests received from the system control device 7. That is, each of the under-frequency relays 5a to 5f disconnects each of the subordinate systems 6a to 6f from the main system 1 under the control of the system control device 7 based on various requests compliant with the IEC61850 communication protocol.

[0066] For example, when acquiring a preset set value DO of each of the under-frequency relays 5a to 5f, the system control device 7 transmits a set value acquisition request to each of the under-frequency relays 5a to 5f as shown in Fig. 4(a). This set value acquisition request is a request signal that instructs each of the under-frequency relays 5a to 5f to transmit the set value DO included in the modeling information of each of the under-frequency relays 5a to 5f, and is transmitted from the communication unit 7d to the communication unit 5j of each of the under-frequency relays 5a to 5f using "GetDataValues" or "Report" defined in the IEC61850 communication protocol.

[0067] When the under-frequency relays 5a to 5f receive the setting value acquisition request at the communication unit 5j, the under-frequency relays 5a to 5f acquire the setting value DO from the information model unit 5k and transmit a setting value report to the power system control device 7. This setting value report is a signal including the setting value DO stored in the information model unit 5k as a part of the modeling information, and is transmitted from the communication unit 5j to the communication unit 7d of the power system control device 7 using "GetDataValues ​​response+" defined in the IEC61850 communication protocol.

[0068] Furthermore, when rewriting the set value DO of each of the under-frequency relays 5a to 5f, the system control device 7 transmits a set value rewrite request to each of the under-frequency relays 5a to 5f as shown in Fig. 4(b). This set value rewrite request is a request signal for rewriting the set value DO of each of the under-frequency relays 5a to 5f, and includes an updated value of the set value DO. The communication unit 7d of the system control device 7 transmits such a set value rewrite request to the communication unit 5j of each of the under-frequency relays 5a to 5f using "SetDataValues" defined in the IEC61850 communication protocol.

[0069] When the communication unit 5j of each of the under-frequency relays 5a to 5f receives the setting value rewrite request, the communication unit 5j transmits a reception report to the system control device 7. This reception report is for reporting to the system control device 7 that the setting value rewrite request has been normally received, and is transmitted from the communication unit 5j to the communication unit 7d of the system control device 7 using "SetDataValues ​​response+" defined in the IEC61850 communication protocol.

[0070] Then, when the transmission of the reception report is completed, each of the frequency down relays 5a to 5f rewrites the set value DO stored in the information model unit 5k to the updated value of the setting value rewrite request. Then, when the rewrite is completed, each of the frequency down relays 5a to 5f transmits a rewrite completion report to the power system control device 7. This rewrite completion report is a signal including the updated value, the rewrite time, etc., and is transmitted from the communication unit 5j to the communication unit 7d of the power system control device 7 by using "Report" defined in the IEC61850 communication protocol.

[0071] Here, when the system control device 7 identifies the controlled object based on the state signal S2, it transmits a setting value rewrite request only to the controlled object to rewrite the set value DO of the information model unit 5k to the updated value of the setting value rewrite request. Then, as a result of this rewrite, the frequency under-relay calculation unit 5m of the controlled object switches the circuit breaker 5g from the conductive state to the open state based on the frequency change rate of the main system power (first system power) and the updated value of the information model unit 5k.

[0072] Furthermore, when each of the under-frequency relays 5a to 5f is to be forcibly operated, the system control device 7 transmits a switching request to each of the under-frequency relays 5a to 5f as shown in Fig. 4(c). This switching request is a request signal for switching the circuit breaker 5g in each of the under-frequency relays 5a to 5f from a conductive state to a cut-off state, and is transmitted to the communication unit 5j of each of the under-frequency relays 5a to 5f using "Operate", "GOOSE" or "R-GOOSE" defined in the IEC 61850 communication protocol.

[0073] Each of the frequency down relays 5a to 5f transmits a reception report to the system control device 7 only when the communication unit 5j receives the above-mentioned switching request by "Operate." This reception report is for reporting to the system control device 7 that the switching request has been normally received, and is transmitted from the communication unit 5j to the communication unit 7d of the system control device 7 by using "Operate response+" defined in the IEC61850 communication protocol.

[0074] When the transmission of the reception report is completed, each of the down-frequency relays 5a-5f generates a switching signal based on the switching request at the digital input / output unit 5n, and outputs the switching signal to the circuit breaker 5g, thereby switching the circuit breaker 5g from a conductive state to a cut-off state.

[0075] Then, when the switching of the circuit breaker 5g is completed, each of the under-frequency relays 5a to 5f transmits a switching completion report to the system control device 7. This switching completion report is a signal including the switching time and the like, and is transmitted from the communication unit 5j to the communication unit 7d of the system control device 7 using "Report," "GOOSE," or "R-GOOSE" defined in the IEC 61850 communication protocol.

[0076] With such power system A and under-frequency relays 5a-5f, each of the under-frequency relays 5a-5f can be controlled through communication between the power system control device 7 and each of the under-frequency relays 5a-5f, which is compliant with the IEC 61850 communication protocol. Therefore, according to this embodiment, it is possible to provide the under-frequency relays 5a-5f and power system A that are compliant with IEC 61850.

[0077] The present invention is not limited to the above embodiment, and the following modifications are possible. For example, in the above embodiment, the IED (intelligent electronic device) in each of the down-frequency relays 5a to 5f is configured as a pair of devices, but the present invention is not limited to this. For example, as shown in FIG. 5, the IED (intelligent electronic device) may be configured by two devices, and the above embodiment may be implemented by mutual communication between the two devices. IED A similar function may be realized.

[0078] 5, the under-frequency relays 5a'-5f' (relay main bodies) are configured from circuit breakers 5g, transformers 5h, and MUs including analog input / output unit 5i, communication unit 5j, information model unit 5k, and digital input / output unit 5n, and an IED 8 (high performance electronic device) including a communication unit 8a, information model unit 8b, and calculation unit 8c is configured as a separate device from the under-frequency relays 5a'-5f'. The communication units 5j of the under-frequency relays 5a'-5f and the communication unit 8a of the IED 8 communicate with each other in accordance with the IEC 61850 communication protocol.

[0079] Finally, the above-mentioned information model units 5k, 8b will be further explained with reference to Fig. 6. Each of the information model units 5k, 8b includes an active islanding detection method modeling unit M1, a passive islanding detection method 1 modeling unit M2, and an active islanding detection method 2 modeling unit M3. One or more of these active islanding detection method modeling units M1, passive islanding detection method 1 modeling units M2, and active islanding detection method 2 modeling units M3 are provided in the information model units 5k, 8b.

[0080] The active islanding detection modeling unit M1 has four PFRC1 to PFRC4 as shown in the figure, and performs switching control based on the comparison results between the four frequency change rates and threshold values. On the other hand, the passive islanding detection modeling unit M2 has a single PFRC5, and the active islanding detection modeling unit M3 has a single PFRC6.

[0081] Such islanding detection passive method 1 modeling unit M2 and islanding detection active method 2 modeling unit M3 each perform switching control based on the comparison result between one frequency change rate and a threshold value. Note that each of the PFRCs 1 to 6 constituting such information model units 5k and 8b can individually set the frequency change rate calculation method and the setting value DO. [Explanation of symbols]

[0082] A Power system S1 request signal S2 Status signal 1 Main system 2a, 2b Transformer 3a,3b 1st bus bar 4a~4f Load feeder 5a~5f Under-frequency relay 5g circuit breaker 5h Transformer 5i Analog Input / Output Section 5j Communications Department 5k Information Model Division 5m Frequency drop relay calculation unit 5n Digital input / output section 6a~6f sub-system 7 Power System Control Device 7a Data Acquisition Section 7b Characteristic generation section 7c control section 7d Communication Department 7e Control target selection section 7f Adjustment part 8. IEDs 8a Communications Department 8b Information Model Section 8c Under-frequency relay calculation section

Claims

1. By receiving a request signal conforming to the IEC 61850 communication protocol from the system control device, the lower system is disconnected from the upper system; an information model unit that stores modeling information obtained by modeling functions of non-controllable devices among various devices constituting the lower system and the upper system and functions of its own high-performance electronic device based on the provisions of IEC 61850; The modeling information includes an islanding function modeling unit that governs the disconnection of the lower system and a setting value that is a disconnection threshold value, rewriting the setting value by receiving a setting value rewrite request conforming to the IEC 61850 communication protocol from the system control device; 2. An under-frequency relay comprising:

2. The under frequency relay of claim 1 , wherein the sub-system comprises a renewable energy source.

3. 3. The frequency downconversion relay according to claim 1, further comprising a relay body and a high-performance electronic device which communicate with each other in accordance with the communication protocol.

4. An electric power system characterized in that a frequency down relay described in any one of claims 1 to 3 is provided between the lower system and the upper system.

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