Determining the reliability status of electrical networks

Abstract

A method for determining the reliability state of an electrical network (1), the electrical network comprising a plurality of interconnected electrical devices (T1, Util, JDB1, D1), the method comprising the steps of: a) identifying an undesirable event at a given location in the electrical network; b) traversing at least one subset starting from the given location; c) identifying the electrical devices of the electrical network; d) determining a list of events of concern associated with the identified electrical devices and which may lead to the undesirable event; e) determining a total unavailability value associated with the identified electrical devices; f) repeating steps b) through e); and g) calculating the reliability state of the electrical network based on the total unavailability value associated with each of the traversed electrical devices.

Description

Technical Field

[0001] This invention relates to a method for determining the reliability status of an electrical network. Background Technology

[0002] The reliability and quality of electrical network operation are crucial to ensuring the transmission and distribution of electricity from power generation centers to electricity consumers.

[0003] Therefore, many risk assessment tools and methods are known to be available for analyzing the reliability, availability, security, and maintainability of electrical networks. These methods enable the systematic modeling of the interactions between the different components that make up an electrical network, in order to investigate potential faults in the electrical network and derive various failures of the network.

[0004] For example, the paper “Fault Tree-Based Reliability Assessment of a 132-kV Transmission Line Protection Scheme” (Samuel et al., Journal of Engineering Research, 2013, Vol. 2, No. 10, pp. 100-106) describes a case study in which a fault tree is generated to analyze general faults in a 132kV transmission line.

[0005] This fault tree is constructed as follows: it begins with an unexpected event, then imagines possible intermediate events that could explain that unexpected event, and then treats each intermediate event as a new unexpected event. Thus, the fault tree is generated by progressively traversing the tree down to the basic event and by imagining possible causes for each event at the level under consideration.

[0006] However, this known method may prove time-consuming because a complete representation of the electrical network needs to be considered from the outset of the implementation.

[0007] Furthermore, this method is particularly suitable for general faults, such as those described in the aforementioned literature concerning transmission lines, but it is less suitable when it comes to finding the cause of a fault at another given location in an electrical network.

[0008] Therefore, the object of this invention is to provide a method for determining the reliability status of an electrical network, which is particularly simple to implement. Summary of the Invention

[0009] This invention improves upon this situation.

[0010] A method for determining the reliability state of an electrical network comprising multiple interconnected electrical devices, modeled by a single-line representation, is proposed. The method includes the following steps:

[0011] a) Identify undesirable events at a given location in an electrical network, which correspond to electrical network hazard conditions that result in partial or complete, temporary or permanent, unavailability of power at that location;

[0012] b) Starting from a given position, traverse at least one subset, which includes electrical devices among multiple electrical devices in an electrical network;

[0013] c) Identify electrical devices in a subset of the electrical network traversed in step b);

[0014] d) Identify a list of events of concern that are associated with the identified electrical equipment and may lead to undesirable events, with each event of concern corresponding to a cause that may, individually or in combination, lead to an undesirable event;

[0015] e) Considering the list of events of concern, and the unavailability and repair time associated with each event of concern in the list of events of concern, determine the total unavailability value associated with the identified electrical equipment;

[0016] f) Repeat steps b) through e), and the method is interrupted once a predetermined number of electrical protection devices (two or more) have been traversed in the subset; and

[0017] g) Calculate the reliability status of the electrical network based on the total unavailability value associated with each of the traversed electrical devices.

[0018] Therefore, a simple and easy-to-implement method has been obtained to determine the cause of failure at any location in an electrical network and the expected reliability.

[0019] According to one embodiment, at least one electrical device in the electrical network is selected from transformers, switches, circuit breakers, contactors, disconnectors, busbars, batteries, protective relays, monitoring equipment, control equipment, and telecommunications equipment.

[0020] According to another embodiment, the electrical network includes at least one real electrical device and at least one virtual electrical device, the virtual electrical device being configured to model the relationships between the components of the electrical network, and more specifically, to model the relationships between the components of the electrical network that play a key role in the operation of the electrical network.

[0021] According to another embodiment, the method is interrupted once the virtual electrical device is identified in step c) of the method.

[0022] Therefore, this method only considers the critical parts of the network, which makes it possible to quickly analyze the reliability of electrical networks.

[0023] According to another embodiment, a given location in the electrical network corresponds to the location of the busbar.

[0024] According to another embodiment, the subset is traversed upstream from a given location (i.e., toward at least one power source of the electrical network) and / or downstream (i.e., toward at least one electrical load of the electrical network).

[0025] According to another aspect, a computer program comprising instructions that, when executed by a processor, cause the method according to the invention to be implemented.

[0026] According to another aspect, a processing apparatus is proposed, on which a computer program comprising instructions for implementing the method according to the invention is recorded. Attached Figure Description

[0027] Other features, details, and advantages will become apparent after reading the description provided below and examining the accompanying drawings, in which:

[0028] Figure 1 It is a simplified single-line diagram of an electrical network.

[0029] Figure 2 This is a schematic representation of an embodiment of the method according to the present invention.

[0030] Figure 3 Through the Figure 1 The single-line diagram is a representation of the fault tree obtained by implementing the method according to the present invention.

[0031] Figure 4 It is a block diagram representation of a processing apparatus configured to implement the method according to the invention. Detailed Implementation

[0032] The accompanying figures and descriptions contain most of the essentially defined elements. Therefore, they can be used not only to better illustrate the contents of this disclosure, but also, where appropriate, to aid in its definition.

[0033] Electrical Networks

[0034] Figure 1 An example of a single-line diagram of electrical network 1 (especially medium-voltage and / or high-voltage electrical network 1) is shown.

[0035] In the following text, the terms “medium voltage” and “high voltage” are generally accepted, with “medium voltage” referring to voltages higher than 1000 volts of alternating current (AC) and 1500 volts of direct current (DC), but not higher than 52000 volts of alternating current and 75000 volts of direct current, and the term “high voltage” referring to voltages strictly higher than 52000 volts of alternating current and 75000 volts of direct current.

[0036] Electrical networks allow the transmission and distribution of electricity, particularly by connecting at least one power source G to one or more loads CP1. The power source G can be of any type, particularly fossil fuel-based or renewable power sources.

[0037] Between the power source G and the load CP1, the electrical network includes multiple electrical devices that may be distributed in a substation (not shown).

[0038] Electrical equipment provides the functions of connecting or disconnecting power, controlling, measuring and / or protecting parts or all of an electrical network.

[0039] In a non-exhaustive and purely illustrative manner, electrical equipment may be selected from transformers, switches, circuit breakers, contactors, disconnectors, busbars, batteries, protective relays, monitoring equipment, control equipment, and telecommunications equipment.

[0040] However, according to the present invention, any electrical device known in itself and that can be used in an electrical network can be envisioned.

[0041] To simplify and aid understanding, in Figure 1 The single line shown in the middle Figure 1 Examples include a limited number of electrical devices. Specifically... Figure 1 Only transformer T1, two busbars Util and JDB1, and circuit breaker D1 are shown. However, the invention can be extended to more complex electrical networks including a greater number of electrical components. According to some examples, the electrical network may include more than one hundred or even more than one thousand electrical devices. Similarly, the electrical network may include a larger number of connected loads and power sources.

[0042] based on Figure 1 The electrical network shown is a single line Figure 1 The purpose of this invention is to determine the reliability status at a given location in an electrical network.

[0043] method

[0044] Will be combined in the following text Figure 2 The method according to the present invention is described.

[0045] Before implementing this method, the representation of the electrical network to be studied (especially the single-line representation) must be modeled.

[0046] During modeling, each location or node in the network is assigned one or more parameters, allowing its operational state to be simulated. Therefore, network nodes can include one or more electrical devices, electrical loads, or power sources.

[0047] The electrical equipment considered during modeling can be real or virtual.

[0048] A "virtual electrical device" is understood to be a device that does not physically exist in an electrical network, but when modeled, it simplifies the assessment of reliability status during the implementation of the method. For example, a virtual electrical device can allow various nodes in an electrical network to be electrically and virtually connected.

[0049] In the first step 100 of the method, an unwanted event corresponding to a fault or failure at a given location in the electrical network is first identified.

[0050] "Given location" is understood to refer to any point in an electrical network that corresponds in particular to a location of an electrical load or device. A given location can be located in a location different from one or more power sources.

[0051] A given location, in particular the location of a substation busbar, allows for the connection of various electrical loads and the branching of electrical networks.

[0052] "Fault or failure" is understood to refer to a hazardous condition of an electrical network that results in partial or complete, temporary or permanent, unavailability of power at a given location.

[0053] Once an unwanted event is identified, the method includes traversing the single-line graph starting from a given position (step 101).

[0054] In particular, the single-line graph is traversed upstream and / or downstream from a given position.

[0055] "Upstream and / or downstream" should be understood as referring to traversing the single-line diagram from a given position towards the power source and / or electrical load, respectively.

[0056] Whenever there is an electrical device on a traversal path in a single-line graph (step 102), the method includes several steps that allow determining an unavailability value associated with the electrical device in question.

[0057] Therefore, one or more events of concern are associated with each electrical device (step 103). Each event of concern corresponds to a cause that leads to a failure or malfunction of the device in question and may, individually or in combination, result in an undesirable event.

[0058] For example, events of concern for circuit breakers may be related to mechanical failures, such as insulation failures, circuit breaker failures, or premature tripping.

[0059] The event of concern may also be related to the failure or unavailability of another electrical device located upstream or downstream of the electrical device in question. Therefore, a short circuit downstream of the electrical device is likely to propagate through the electrical network and cause upstream unavailability. According to another example, if no other power source is available to provide the required power, an upstream power failure may cause downstream unavailability. Therefore, whether to traverse the single-line diagram upstream or downstream may depend on the undesirable event in question.

[0060] Therefore, it is determined whether each event of concern associated with the device in question could individually or in combination lead to an undesirable event (step 104).

[0061] If an event of concern could lead to an undesirable event, this is taken into account when calculating the unavailability value of the electrical equipment in question. In particular, the method is repeated to account for all events of concern (step 105).

[0062] The unavailability value of event j can be calculated based on various parameters, particularly the mean time between failures of electrical equipment. Specifically, the unavailability value of event j can be approximated as the unavailability rate t of event j. ind and repair time T repair The product of and makes:

[0063]

Mathematical Formula 1

[0064] Ind j =t ind,j ×T repair,j

[0065] Failure rate t ind This corresponds to the probability of the event of interest occurring.

[0066] Repair time T repair This corresponds to the time required to repair a fault or malfunction in electrical equipment. Repair time T repair This can depend on local parameters, such as the type of electrical equipment in question, the location of the equipment in the electrical network, the repair strategy provided, the availability of spare parts for repair, and the options for reconfiguring the electrical network.

[0067] Therefore, depending on the electrical equipment in question, the repair time T repair There could be significant changes, especially regarding whether the equipment needs to be completely replaced or simply overhauled to be operational again.

[0068] Obtain the total unavailability value ind associated with electrical equipment I for all events of interest j.i total (Step 106).

[0069] Total unavailability value ind i total In particular, it can be equal to the sum of the unavailability values ​​of each event j of concern associated with electrical device i, such that:

[0070]

Mathematical Formula 2

[0071]

[0072] Once the total unavailability value for electrical device i has been calculated, the single-line diagram is traversed to the next electrical device i+1 (step 107), that is, the next electrical device i+1 electrically connected to electrical device i. In the case of a new electrical device, steps 102 to 107 are then repeated.

[0073] When the same electrical device is traversed multiple times, it is not necessary to recalculate the total unavailability value, but it can be considered that the total unavailability value is equal to the unavailability value calculated for the same electrical device that has been traversed before.

[0074] The method according to the invention can be interrupted based on one or more interruption criteria, which allows only a portion of the electrical network to be considered, and thus limits computation time and computational requirements.

[0075] According to one embodiment, the method can be interrupted once virtual electrical devices, rather than real electrical devices, have been traversed. This is because, although virtual components are modeled in the electrical diagram under consideration, virtual devices cannot propagate faults or malfunctions in the electrical network.

[0076] According to another embodiment, the method can be interrupted once a predetermined number (e.g., two or more) of electrical protection devices have been traversed without reaching the power source. This allows for limiting the computation time required to implement the method, while eliminating any remaining traversal that would have an inconsequential impact on the final reliability calculation. The protection devices can be circuit breakers or switches, or more generally, any device that can interrupt current and thus isolate a portion of the electrical network.

[0077] The number of electrical protection devices that need to be traversed before the method is interrupted may be even greater, especially for applications that require higher reliability and accuracy.

[0078] This yields the total unavailability value for each electrical device. The overall reliability of the electrical network can then be calculated (step 108). Therefore, the overall reliability or reliability state of the electrical network can be a measurement of the network's ability to provide the required power. More specifically, overall reliability can be the probability that a subset of electrical devices will not experience a failure or malfunction within a defined time period, based on their unavailability values. Based on this overall reliability, corrective or maintenance actions can be implemented.

[0079] Therefore, the method according to the invention is performed step by step by traversing a single-line diagram starting from a given position and analyzing the electrical devices that are connected to each other one by one.

[0080] This method can traverse only a subset of the single-line diagram specific to the unwanted events in question. Therefore, it is not necessary to traverse the entire single-line diagram. Thus, a "subset" is understood to refer to a portion of an electrical network that includes electrical devices that are electrically connected to each other.

[0081] Figure 3 Is with Figure 1 The graphical representation of a single-line graph in [the context of a graph]. More accurately, Figure 3 It is a fault tree (FT), which is an engineering technique used to evaluate the safety and reliability of a static system.

[0082] Fault trees graphically represent possible combinations of events that allow for the generation of predefined, undesirable events. Therefore, this graphical representation demonstrates causal relationships.

[0083] In a manner known per se, a fault tree comprises logical connectors (or logic gates) that form connections between various branches and / or events. The connectors operate as follows:

[0084] OR: If at least one input / lower-level event occurs / exists, then the output / higher-level event occurs;

[0085] AND: An output / higher-level event will only occur if all input / lower-level events have occurred / existed (fault combinations are also called "pairs"); and

[0086] K / N: The output / higher-level event occurs by majority vote if at least K (where K is an integer used to parameterize the behavior of the gate) of the N input / lower-level events occur / appear.

[0087] according to Figure 3 In the embodiment shown, event E1 is not expected to be an unavailability of power at bus Util.

[0088] The events of concern associated with bus Util are fault A in bus Util and power supply failure E2 in bus JDB1. Since the two events of concern, A and E2, are independent (connected via the "OR" connector), the following results are obtained:

[0089]

Mathematical Expression 3

[0090] Ind Util =Ind A +Ind E2

[0091] The single-line graph is also traversed upstream until the bus JDB1.

[0092] The events of concern associated with bus JDB1 are fault G of circuit breaker D1, fault B of bus JDB1, fault C of transformer T1, propagation E3 of short circuit from downstream, and power unavailability F of electrical network.

[0093]

Mathematical Expression 4

[0094] Ind JDB1 =Ind E2 =Ind G +Ind B Ind C +Ind E3 +Ind F

[0095] Event E3, related to the propagation of the short circuit, originates from two lower-level events: circuit breaker D1 failing to open (D), and a short circuit (E) on electrical load CP1. Specifically, since the two events D and E are interdependent (connected via the "AND" connector), the following result is obtained:

[0096]

Mathematical Expression 5

[0097] Ind E3 =Ind D ×Ind E

[0098] The single-line diagram can then be traversed upstream to transformer T1, listing all events of concern associated with the transformer (transformer failure and bus power supply loss), and so on, all the way up to the power source or until the interruption criterion.

[0099] The single-line diagram can eventually be traversed downstream, all the way to electrical load CP1, listing all events of concern associated with each electrical device that could lead to undesirable events.

[0100] However, in Figure 3 These other events are not considered in the fault tree.

[0101] Once the events of interest for each electrical device are identified (for bus Util and JDB1 only, e.g.) Figure 3 As shown), values ​​characterizing the reliability state of an electrical network can be calculated:

[0102]

Mathematical Expression 6

[0103] Ind util =Ind E1 =Ind A +Ind G +Ind B +Ind C +Ind D ×Ind E +Ind F

[0104] The severity of an undesirable event can be determined, for example, by using failure mode, effects, and criticality analysis (FMECA). Based on the obtained severity values, corrective actions can be specified for the electrical network, prioritizing the resolution of the causes of the events of concern with the highest severity values.

[0105] Processing equipment

[0106] To implement the above method, the present invention also relates to Figure 4 The processing device 10 shown is, for example, a computer or any other device with computing capabilities, particularly via a processor. The processing device 10 may also include a graphical user interface or a text-based user interface that allows interaction with a user.

[0107] Prior to implementing this method, the user can generate a graphical representation of the electrical network in the form of a single-line diagram via the modeling unit. The single-line diagram can be stored in the processing device 10, for example, in the format of an XML file.

[0108] The single-line diagram consists of various components stored in a database on processing device 10 or a remote server. These components are selected from electrical equipment, electrical loads, and power supplies and are arranged at the nodes of the electrical network. Each electrical device is assigned a failure mode corresponding to the event of concern and the associated unavailability and repair time.

[0109] Based on the single-line diagram of the modeled network, the value characterizing the reliability state of the electrical network can be determined by a computational unit. The computational unit considers the unwanted events discussed and implements the steps of the above method.

[0110] A computing unit (including the method) that can be interrupted by an interruption standard allows the reliability status of the electrical network to be obtained as an output.

[0111] Of course, the present invention is not limited to the embodiments described above, which are provided merely as examples. It includes various modifications, alternatives, and other variations that can be conceived by those skilled in the art within the context of the present invention, especially any combination of the various operating modes described above, which can be used alone or in combination.

[0112] In particular, although the method has been described for electrical networks, it is also applicable to other types of networks that allow transportation and distribution, such as hydraulic or pneumatic networks, for which it is necessary to determine the network's reliability status.

Claims

1. A method for determining the reliability state of an electrical network (1), the electrical network comprising a plurality of interconnected electrical devices (T1, Util, JDB1, D1), the electrical network being modeled by a single-line representation, the method comprising the following steps: a) Identify an undesirable event at a given location in the electrical network, the undesirable event corresponding to an electrical network hazard state that causes partial or complete, temporary or permanent power unavailability at the given location; b) Starting from a given position, traverse at least one subset, which includes electrical devices among a plurality of electrical devices in an electrical network; c) Identify electrical devices in a subset of the electrical network traversed in step b); d) Determine a list of events of concern associated with the identified electrical equipment and capable of causing the undesirable event, wherein each event of concern corresponds to a cause that leads to a failure or malfunction of the identified electrical equipment and can cause the undesirable event alone or in combination; e) Taking into account the unavailability rate and repair time associated with each concern event in the list of concerns, determine the total unavailability value associated with the identified electrical equipment; f) Repeat steps b) to e), and the method is interrupted once a predetermined number of electrical protection devices, greater than or equal to two, have been traversed in the subset; as well as g) Calculate the reliability status of the electrical network based on the total unavailability value associated with each of the traversed electrical devices.

2. The method according to claim 1, wherein, At least one electrical device in the electrical network is selected from transformers, switches, circuit breakers, contactors, disconnectors, busbars, batteries, protective relays, monitoring equipment, control equipment, and telecommunications equipment.

3. The method according to any one of the preceding claims, wherein, The electrical network includes at least one real electrical device and at least one virtual electrical device, the virtual electrical device being configured to model the relationships between the elements of the electrical network.

4. The method according to claim 3, wherein, Once a virtual electrical device is identified in step c) of the method, the method is interrupted.

5. The method according to claim 1 or 2, wherein, The given position in the electrical network corresponds to the position of the busbar.

6. The method according to claim 1 or 2, wherein, Starting from the given position, the subset is traversed upstream, i.e., towards at least one power source of the electrical network, and / or the subset is traversed downstream, i.e., towards at least one electrical load of the electrical network.

7. A computer program comprising instructions that, when executed by a processor, causes the method according to any one of claims 1 to 6 to be performed.

8. A processing apparatus having a computer program recorded thereon comprising instructions for carrying out the method according to any one of claims 1 to 6.

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