巴西专利BR112014001356B1 method and device for determining a failed section of a power supply line

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专利摘要:
METHOD AND DEVICE FOR DETERMINING A FAILED SECTION OF AN ENERGY SUPPLY LINE. The present invention relates to a method for determining a failed section of a power supply line (10a) which is fed from one side and which is divided into a plurality of sections (14a-c) by switching (13a-d), where each switching device (13a-d) has an associated measuring device (15a-d). In order to make the method as sensitive and reliable as possible, the invention proposes that the following steps be carried out in the method: each measuring device (15a-d) detects a current signal at a measuring point (16a-d) that is arranged in the region of the respective switching device (13a-d), said current signal indicating a current flow at the respective measurement point (16a-d), samples the current signal to form current sample values, and determines a current measurement variable from the current sample values, each measurement device (15a-d) forms a delta current value as the difference between an instantaneous current measurement variable (...).
公开号:BR112014001356B1
申请号:R112014001356-0
申请日:2011-07-21
公开日:2020-10-20
发明作者:Norbert Schuster；Markus Spangler
申请人:Siemens Aktiengesellschaft；
IPC主号:

专利说明:

[001] The present invention relates to a method for determining a failed section of a power supply line that is fed from one side and that is divided into a plurality of sections by switching devices, where each switching device has an associated measuring device.
[002] Electricity supply networks at medium or low voltage levels are used for the transmission of electricity to individual end users. Since the deregulation of the energy supply, decentralized supplies to the energy supply network are also increasing, as is done in many countries. These decentralized feeds are by way of example known as producers of regenerative energy, that is, producers of energy that supply electricity from energy sources that can be rapidly renewed, such as wind or solar radiation. Energy producers of this type can be wind turbines or photovoltaic systems as an example.
[003] Power supply networks at medium and low voltage levels generally include power supply lines that are fed from one side and are divided into a plurality of sections for more effective monitoring. A network with this shape, unlike interconnected networks, is also called a radial system. Each section is delimited at its ends by means of switching devices which, depending on their switching capacity, can be constructed in the form of switches or circuit breakers. Individual end users in the form of electrical charges from energy producers in the form of power supplies can be connected to the individual sections. This construction is conventional in particular in markets developed by the USA, although power supply networks with power supply lines of this type that are fed from one side are also used in markets in Western Europe, for example in networks cable in the lower average voltage range (about 20 kV).
[004] For radial systems in the medium and low voltage ranges, reliable identification and fault localization must occur quickly in the event of a fault, in particular a short circuit, which occurs in one of the sections of a power supply line , that is, the section affected by the fault must be quickly and reliably identified and shut down.
[005] Electromechanical short-circuit indicators that are provided directly in the respective sections of the power supply line, are generally used for the identification and troubleshooting. These indicators react only in the case of high short-circuit currents that are significantly above the rated current of the power supply line. The devices are usually read manually, that is, the section affected by the short circuit is usually determined only after a relatively long period of time. Such a short-circuit indicator is known as an example from the German patent DE 10 2007 020 955 B4.
[006] A method is also known from the European patent EP 0 554 553 B1 in which the sections of a power supply line are delimited by switching devices (which are known as "disconnectors"). A corresponding protection unit is associated with the switching devices. The individual protection units are connected to each other and to a main protection unit via a communication line. A fault is identified by the main protection unit. This sends a query to the individual protection units that, with reference to a voltage signal, check if there is a fault in the section associated with them and send a corresponding response again. Those protection units that, with reference to the responses, identify that they isolate a fault-free section from a failed section, cause the switching contacts of the corresponding switching device to open.
[007] The invention is based on the objective of describing an optimally sensitive and reliable method of the type mentioned in the introduction and a measuring device that realizes such a method.
[008] To achieve this objective, a method according to the invention is proposed in which each measuring device detects a current signal at a measuring point that is arranged in the region of the respective switching device, the said signal being current indicates a current flowing at the respective measurement point, samples the current signal to form current sample values, and determines a current measurement variable from the current sample values; each measuring device forms a delta current value as the difference between an instantaneous current measuring variable and a previous current measuring variable that has been determined a fixed number of current signal periods before, the measuring device compares the value delta current with a current limit value and identifies a current jump when the delta current value is above the current limit value; each measuring device sends a first status message, which indicates a current jump, when a current jump is identified. A fault finding device identifies a fault as being present in that section of the power supply line that is bounded at one end by a switching device whose measuring device has identified a current jump, and is bounded at its other end by a switching device whose measuring device did not identify a current jump.
[009] An advantage of the inventive method is that a very sensitive fault identification can occur due to the formation of delta current values since the influences of electrical loads or inflow or efflux currents are ignored and only the part related to the fault is considered. Therefore, the method obtains a sensitivity that is below the rated current of the power supply line, so even high impedance faults can be detected.
[0010] The previous current values used to form the delta current value can be determined by way of example two or three periods of the current signal before the instantaneous current measurement variable. The fixed number does not have to be an integer, although selecting an integer is generally advantageous to avoid fluctuating effects. The current signal is sampled as an example at clock rates between 600 Hz and 1 kHz.
[0011] The first status message can include binary information as an example, so a large communication link bandwidth is not required for its transmission.
[0012] The inventive method is carried out separately for each phase in the case of a multiphase power supply line.
[0013] An advantageous modality of the inventive method establishes that the current measurement variable is determined as an effective value or as a basic oscillation component from the current sample values.
[0014] This modality has the advantage of performing the inventive method only when the current signals must be measured, so the use of expensive voltage transformers can be dispensed with in this regard. The delta current values are then calculated and the identification and fault location performed using only the measured currents.
[0015] However, if voltage transformers are present in any way, or if they can also be used for other purposes, it can also be determined that the current measurement variable is calculated from the current sample values and of the associated stress sample values. In this case, the current measurement variable can be, for example, an electrical energy (for example, an active energy or a reactive energy).
[0016] According to an additional modality of the inventive method, it can be determined that the current limit value is statically fixed.
[0017] Static fixation has the advantage that it manages relatively few device configurations and, therefore, comparatively simple device parameterization can occur. The static current limit value must in this case be fixed so that current fluctuations due to changes in the load or charging processes in the respective section are not classified as a current jump. The values suitable for adjusting the static current limit value are, for example, between about 5% and 15% of the valid nominal current for the respective section.
[0018] As an alternative for the static setting of the current limit value, according to an additional modality of the inventive method, it can also be determined that the current limit value is dynamically fixed.
[0019] The current limit value used respectively can therefore be adjusted to the instantaneous operation situation of the respective section.
[0020] Specifically, it can be determined in this context that the current limit value is dynamically formed as a function of a differential current value that is formed using a difference between the current measurement variable determined at the two ends of a section of the line power supply.
[0021] As a result, a measurement of the load and supply currents during normal operation occurs more or less at both ends of a section, so during operation, the responsiveness (for example, to moderately change the load conditions or power) can be adjusted in an adaptable way. In order not to make an adjustment unintentionally adaptable to a fault situation in the respective section, the current measurement variable to form the differential current value must be used where a current jump has not been identified.
[0022] According to an additional advantageous modality of the inventive method, it can also be determined that, instead of the previous current measurement variable, a fixed maximum value is used to form the delta current value if the current measurement variable exceeds a predefined limit comparison value.
[0023] An unwanted current jump identification by the measuring devices in the event of transformer saturation during a failure can be avoided as a result.
[0024] The comparison limit value can be formed as an example as a function of a differential current value that is formed using a difference between the current measurement variable determined at the two ends of a section of the power supply line .
[0025] Specifically, the limit value of comparison can be formed by way of example using the differential current and the nominal current according to the following equation: lv = IN.Í = I,
[0026] where IV indicates the limit value for comparison, IN, i is the nominal current valid at measurement point I and IDiff, i is the differential current value formed at measurement point i.
[0027] An additional advantageous embodiment of the inventive method determines that the error location device is a component of at least one of the measurement devices.
[0028] In this case, the identification and location of a fault are performed by one or more measuring devices.
[0029] Alternatively, it can also be determined that the fault finding device is a component of a central evaluation device different from the measuring devices.
[0030] This evaluation device can be, for example, a separate device integrated in a protection unit provided in the supply of the power supply line or a component of a network control installation, for example, a SCADA system (SCADA = Supervision and Data Acquisition System).
[0031] An additional advantageous modality of the inventive method determines that the measurement devices, if they do not identify a current jump, send a second status message at regular intervals, and this indicates that no current jump has been identified and that the devices measures repeat the first status message at intervals that are shorter than the intervals at which the second status message is sent.
[0032] In this case, the second status message is a cyclic message that at regular intervals announces a normal operating state for the respective section. The intervals used for this can be in seconds as an example (for example, between about 1-10 seconds). The first status message, on the other hand, is a spontaneous message that is transmitted as soon as a jump in the chain is identified and is repeated at very short intervals (for example, every few milliseconds). On the other hand, the functionality of the communication link between the individual measuring devices and the fault finding device can be verified in this way with reference to the second status messages correctly received and, on the other hand, it can be guaranteed that the first status message is generated as soon as a current jump is identified which could point to a failure. The frequent repetition of the first status message can ensure that information about the current jump reaches the receiver safely and is not lost as a result of individual telegram losses on the communication link.
[0033] It can be determined that, for example, status messages are sent as broadcast messages or multicast messages. This means that the information contained in the status messages is transmitted not only to one receiver but virtually simultaneously to all (broadcast) or to a plurality of receivers (multicast).
[0034] Status messages can be transmitted using any desired method. In the simplest case, binary signals can be applied to a copper conductor ("pilot conductor") for this purpose. A wide variety of transmission protocols, such as DNP 3 (Distributed Network Protocol) or control technology protocols, such as Modbus, can also be considered.
[0035] According to a particularly advantageous modality, it can be determined by way of example that status messages are formed as GOOSE messages for the IEC 61850 standard.
[0036] These GOOSE messages (Generic Object Oriented Substation Event) are described in the IEC 61850 standard, which regulates communication in particular electrical switches, and are particularly suitable for very fast transmission of short (in particular binary) content.
[0037] According to an additional modality of the inventive method, exact synchronization is not necessary for the transmission of the first status messages, for example, through GOOSE messages to IEC 68150. It is sufficient to take into account the maximum execution time through the communication network. In this respect, it can be determined that the fault finding device identifies a fault as being present in a given section of the power supply line if it is within a maximum period after a current jump in the meter is identified in a end of the section, a first status message from the measuring device does not materialize at the second end of the section.
[0038] The maximum period can take into account, for example, the transmission time between the respective measuring device and the fault location device and a time reserve for the non-synchronous sampling of the current signal at the respective measuring point .
[0039] To further increase security against wrong decisions, according to an additional advantageous modality of the inventive method, it can be determined that the fault location device only identifies a fault as being present in the given section if the delta current value of this measuring device, which identified the current jump, is above a confirmation limit value, which is formed as a function of a differential current value, which is formed using a difference between the current measurement variable determined in the two ends of a section of the power supply line.
[0040] An additional condition for the identification of a fault that actually exists can be imposed in particular in the case of current limit values that are selected as relatively low in relation to the identification of a current jump.
[0041] If the switching devices in the individual sections for disconnecting fault currents are suitable circuit breakers, then according to an additional advantageous modality of the inventive method, it can be determined that in the case of a fault identified in a given section of the line power supply, these switching devices that delimit that section of the power supply line are opened immediately.
[0042] Alternatively, it can also be determined that in the event of a fault identified in a given section of the power supply line, first a circuit breaker upstream of the switching devices on the supply side is opened and only after opening the circuit breaker that these switching devices delimit that section of the open power supply line.
[0043] With this alternative, compared to a circuit breaker, the switching devices in the sections can be less expensive circuit breakers, with a relatively low switching power since the fault current is switched off by the circuit breaker on the supply side, which is supposed to form , a primary switch for the power supply line.
[0044] In this sense, it can also be determined that the circuit breaker is closed again after the switching devices that delimit the failed section are opened.
[0045] The supply of energy to end users up to the failed section can be immediately restored in this way.
[0046] In order to allow the power supply to be restored as quickly as possible for the loads present downstream of the failed section, it can also be determined in this respect that after the switching devices that delimit the failed section are opened, a The connection is also closed to connect that part of the power supply line, which connects the end of the failed section away from the supply, to an additional supply.
[0047] Those loads and supplies that are arranged in the sections that are not affected by the fault can be quickly supplied with electricity again as a result.
[0048] The objective mentioned above is also achieved by a measuring device to determine a failed section that is fed from one side, in which the power supply line is divided by switching devices into a plurality of sections and wherein the measuring device may be associated with one of the switching devices.
[0049] According to the invention, it is determined that the measuring device is configured to carry out a method according to the invention.
[0050] A plurality of these measuring devices, together with a fault location device, form a system for determining a failed section of a power supply line that is fed from one side. The fault finding device can be a component of one of the measuring devices, it can be built as a separate device or it can be integrated into a higher-order protection unit or control device.
[0051] The invention should be explained in more detail below with reference to the exemplary modalities. In the drawings:
[0052] Figure 1 shows a schematic view of a first modality of an electricity supply network with two power supply lines that are fed from one side,
[0053] Figure 2 shows a schematic view of a second modality of an electricity supply network with a central fault location device.
[0054] Figure 1 shows in a schematic diagram part of an electricity supply network 10 which can be, by way of example, a medium voltage distribution network. The power supply network 10 includes a first power supply line 10a and a second power supply line 10b. The power supply lines 10a, 10b are supplied with electricity from one side by transformers 11a, 11b. Transformers can be powered on the primary side by one or more source (s). At its far end of the supply, the power supply lines 10a, 10b can in some cases be coupled to each other by means of a conventionally open connection switch 12. This will be discussed in more detail later.
[0055] In the exemplary embodiment according to Figure 1, the construction of the two power supply lines 10a and 10b is the same for simplicity purposes, so, except in explicitly mentioned points, the following statements regarding the supply line power lines 10a are representative for both power supply lines 10a and 10b.
[0056] The power supply line 10a is divided by means of switching devices 13a-d into a plurality of sections 14a-c. Each section 14a-c is bounded here by two switching devices 13a-d. The switching devices 13a-can be switches or circuit breakers depending on the switching capacity. On the supply side a circuit breaker 13e is provided to isolate the entire power supply line 10a from the supply by transformer 11a and therefore acts more or less as a main switch for the power supply line 10a.
[0057] The measuring devices 15a-d are associated with the individual switching devices 13a-d. These register current signals at measurement points 16a-d are arranged around the respective switching devices 13a-d. The signals indicate the current flowing in the power supply line at the respective measuring point 16a-d. A protection unit 15e is associated with circuit breaker 13e.
[0058] Electric consumers in the form of loads, or producers of electric energy in the form of sources can be connected to each section 14a-c of the power supply line 10a. Loads 17a and 17b and a source 17c are shown by way of example in Figure 1, and these are connected to sections 14a-c.
[0059] Individual measurement devices 15a-d are connected to each other via a communication link 19, so information can be exchanged between measurement devices 15a-d. Protection unit 15e is also connected to communication link 19. The communication link can be constructed as desired. In the simplest case, this can be a copper conductor ("pilot conductor") through which electrical signals can be transmitted. In addition, more complex communication links, in particular a communication bus, for example, based on Ethernet, can also be used.
[0060] The power supply network 10 is illustrated in Figure 1 in what is known as the "single line view" in which only one phase of the power supply network is shown. In fact, the power supply network 10 is conventionally a multi-phase network (for example, three phases). Therefore, the method described below is performed for each phase present.
[0061] If a fault, for example a short circuit, occurs in a section, the fault must first be identified as soon as possible and the fault current turned off. Then, the section of the power supply line affected by the fault must be identified and isolated so that sections in satisfactory condition can be supplied with electricity again as soon as possible.
[0062] A method for determining a failed section should be explained below using the example of a short circuit 18 present in section 14b.
[0063] Each measurement device detects a current signal for each phase by means of transformers arranged at measurement points 16a-d. The detected current signal is sampled by a sampler to form phase-related current sample values. Such sampling can take place as an example at a sampling rate of 600 Hz - 1 kHz. A current measurement variable is determined from the sample values using a computer (for example, a digital signal processor (DSP) or a central processing unit (CPU) of the measurement device. The current measurement variable can be be, for example, an effective value or a fundamental oscillation value (for example, for the 50 Hz component of the current signal). The fundamental oscillation value [is] obtained by digitally filtering the current sample values, in that a filter adjusted according to the fundamental oscillation determines a sinusoidal component of the sample values in an additional filter adjusted to the fundamental oscillation determines a cosine component of the sample values.The root of the sum of the squares of the components (sine and cosine) is determined to form the fundamental oscillation value. If the harmonics, which are produced, for example, when connecting transformers between measurement points 16a-d, are suppressed n in the case of the current measurement variable, the fundamental oscillation value is used. If harmonics are included in the evaluation in the case of the current measurement variable, then this can be obtained by forming the effective value. In general, a protective function can be temporarily suppressed in the measuring devices 15a-d and / or in the protection unit 15e when highly harmonic components occur. The advantage when using the effective value or the fundamental oscillation value is that, in addition to detecting the current signal, no additional measurements will have to be performed, so only current transformers are required. If, however, voltage transformers are already present or voltage transformers are also required for other purposes, the current measurement variable can also be formed from a mathematical link of current sample values and voltage sample values associated (for example, in the form of active energy or reactive energy). The way in which the current measurement variable is to be formed can be selected by the power supply network operator by means of appropriate parameterization of the measurement devices. In any measurement device determination, the current measurement variable gives the value lj (t), where j denotes the respective measurement device (for example, the current measurement variable I2 (t) is formed from the second measuring device 15b of the power supply line 10a). For simplicity purposes, only one phase will be considered here. Indeed, as mentioned, the current signal is measured and the current measurement variable is calculated for all phases of the power supply line 10a and is performed continuously for all measurement points.
[0064] The instantaneous value of the current measurement variable is subtracted from a previous current measurement variable, so a delta current variable Dlj (t) results as the difference. The previous current measurement variable has already been formed some periods (for example, 2-3) (N) of the previous current signal and stored in the respective measuring device, for example, in a ring memory. The previous current measurement variables do not necessarily have to be determined by an integer number of periods from the previous current signal, but the use of an integer is convenient to avoid oscillation effects. The delta current value is determined by way of example using a previous current measurement variable formed two periods (N) before according to the following equation: Dlj (t) = lj (t) -lj (t-2N).
[0065] During stable operation, the delta current variation Dlj (t) has a value close to zero since there is no change in current in the respective section 14a-c of the power supply line 10a.
[0066] The respective delta current value is compared with a current limit value SI in each measuring device 15a-d and a current jump is identified in the respective section when the delta current value is above the current limit value. A jump in the chain in this respect is considered to be a positive change in the chain of a certain minimum size. Immediately after identifying the current jump, the measuring devices 15a-d send the first status messages S1 j, which indicate a current jump identified at the measurement point j, via communication link 19. These first status messages S1j can be simple binary signals (low, high) as an example. In a preferred embodiment, binary signals of this type are transmitted as multicast messages in the form of the so-called GOOSE messages of the IEC 61850 standard.
[0067] In the example in Figure 1, an IF fault current, which is fed by transformer 11a, flows through the short-circuit point 18. The protection unit 15e identifies a current jump. Measuring devices 15a and 15b also identify a jump in the chain and send the first status messages S11 and S12. The remaining measuring devices 15c and 15d do not identify a current jump, however, (for example, since the current flow remains the same or still decreases), and do not send the first status messages. Instead, it can be determined that all measurement devices, which do not identify a current jump, emit a second status message S2j at regular intervals, that is, cyclically, where the intervals at which a second status message of this type is sent can be a few seconds as an example. The first status message S1j is also issued repeatedly in particular if the status messages are GOOSE messages, where the interval at which the first status messages are repeated is much shorter (for example, a few milliseconds) than the interval used for second status messages.
[0068] A static value as an example can be used as the current limit value S1 to evaluate the delta current value, and this can be adjusted, for example, at about 5% -15% of the valid nominal IN current for the respective section 14a-c (that is, with a current limit value of 5%, changes in the nominal current in the delta current value less than 5% of the nominal current do not generate the identification of a current jump). Constant values of the delta current, slight changes in the current, a load drop or disconnection of an external short-circuit current do not activate the identification of a current jump in this aspect.
[0069] The current limit value can also be dynamically determined, however, and adjusted to the level of a differential current value (for example, 25% of the differential current value) which is determined using the difference in the current sample values between adjacent measuring devices. Specifically, the differential current value can be formed as an example according to the following equation: I Diff, j = Icorr + K | (lj - lj + l) |.
[0070] Icorr is a correction value for the respective section and is intended to balance errors in determining current sample values (for example, due to charging currents, transformer failures, etc.). The safety factor k affects the sensitivity, that is, in the case of larger k values, the differential current value used as the current limit value for the delta current value is increased and the method for identifying a current jump is, therefore, less sensitive (the safety factor can adopt values of k = 1 ,,, 1,2 as an example). To determine the differential current value, the respective current measurement variable lj between measurement devices 15a-d must be replaced at each phase. This occurs, for example, in an interval of one second, and only while the delta current values are almost zero, through the message GOOSE through the communication network. The selection of a dynamic limit value has the advantage that the efflux and inflow currents in section 14a-c due to loads or sources are taken into account in the differential current value. The method has maximum sensitivity if no loads or sources are present.
[0071] The first status messages S1j are transmitted to a fault location device which, for example, can be a component of a measuring device (or all measuring devices) or can be integrated into the measuring unit protection 15e. The fault finding device can be connected to the protection unit, for example, with the trip condition there (for example, overcurrent protection or distance protection). The fault location device identifies the short circuit as being present in the section that is delimited by those measurement devices in which one of these identified a current jump and the other did not identify a current jump. In the case of Figure 1, the measuring device 15b identifies a jump in the chain while the measuring device 15c does not identify a jump in the chain. This can be identified by the fault finding device with reference to the presence or absence of the respective first status message. In this case, the fault finding device consequently identifies the short circuit in section 14b.
[0072] If switching devices 13a-d are circuit breakers that are capable of switching off short-circuit currents, then switching devices 13b and 13c, which delimit the faulty section 14b of the power supply line 10a, can subsequently open immediately. This can be caused by the measuring devices 15b and 15c themselves or triggered by the protection unit 15e by means of corresponding trigger commands.
[0073] If switching devices 13a-d are merely circuit breakers with a low switching capacity, then, following the fault location in section 14b, first circuit breaker 13e connected upstream of switching devices 13a-d on the supply side is opened. As a consequence, the identification of the current jump in the measuring devices 15a and 15b, and with them the formation of the first status message, decreases if the current in all the measuring points 16a-d in the power supply line 10a switched off by circuit breaker 13 and falls below the current limit value. Only after the circuit breaker 13a is opened, the switching devices 13b and 13c, which delimit the section 14b, are opened since the switching devices 13b and 13c are induced to open. This can occur through the measuring devices 15b and 15c themselves. Alternatively, switching devices 13b and 13c are opened by the circuit breaker controller or protection unit 15e. Circuit breaker 13e can be closed again with feedback from switching devices that the open state is prevalent. After switching devices 13b and 13c, which delimit the faulty section 14b, are opened, the connection switch 12, which connects that part of the power supply line 10a that joins the end of the faulty section 14b away from the supply, that is, section 14c, to the second power supply line 10b, can be closed, so the power supply can be restored to that section in satisfactory condition 14c.
[0074] To be able to form the delta current value even more reliably and to avoid effects due to transformer saturations that possibly occur during a short circuit, it can also be determined that a fixed maximum value is used to form the value current delta instead of the previous current measurement variable when the previous current measurement variable exceeds a predefined limit comparison value. The comparison limit value Icomp can also be adjusted as an example to the differential current value and also takes into account the nominal current applicable to the respective measurement point: Icompj = INJ + iDiffj ■
[0075] The maximum value can also adopt the size of the comparison limit value. For higher currents (in particular short-circuit currents), therefore, the delta current value is formed from the difference in the instantaneously calculated current measurement variable and the constant value of the Icomp comparison limit value. This prevents the delta current value that will be evaluated from becoming zero after a certain number of periods and, due to a subsequent saturation of a current transformer, a hyperfunction that occurs due to a delta current produced in this way. During a short circuit, the current flow is therefore limited to the portion related to the short circuit.
[0076] Fault tracing by means of the fault tracing device can be aided by way of example, with this time stamps are associated with the first status messages S1j of the respective measuring devices 15a-of the current in the measuring devices 15a-d are sampled synchronously. The method described above can also be performed particularly easily with measuring devices 15a-d that do not operate synchronously, as the fault finding device identifies a fault as being present in a given section of the power supply line if is within a maximum period after the identification of a current jump by the measuring device 15b at one end of section 14b, a first status message S13 of the measuring device 15c does not materialize at the second end of section 14b. In this respect, it is assumed that the measuring devices 15a-d send a first status message S1j immediately after a jump in the chain is identified. Therefore, the maximum duration includes the maximum transmission time from the respective measuring devices 15a-d to the fault location device, in addition to a reserve duration for the non-synchronous execution of a current jump identification on the fault devices. individual measure. The maximum transmission duration is twice the average transmission time between the respective measuring device 15a-d and the fault locating device or the transmission time that a message requires for direct and reverse transmission. This can be measured by direct time stamp of test messages.
[0077] In order to be able to distinguish the jumps in the current due to relatively large changes in the load (for example, switching to a high-power electrical load) from the jumps in the current due to short circuits even more reliably using the method, it can also be determined that the fault finding device only identifies a fault as being present in the specific section if the delta current value of that measuring device that identified the current jump is above a confirmation threshold value that is formed as a function of the differential current value. The differential current value itself adjusts adaptably to minor changes in the load, so a jump in the current can be better categorized as belonging to a load or a fault through this additional plausibility check. The level of the delta current value can be checked by the fault finding device or made by the respective measuring device itself. In the latter case, the sending of the first status message when this plausibility condition is not satisfied is suppressed by the respective measuring device.
[0078] Figure 2 finally shows an exemplary modality of a power supply network in which only the position of the fault finding device differs from the situation in Figure 1. Instead of one of the measuring devices or the measuring unit For protection, the fault finding device according to Figure 2 is integrated into a data processing device 20 of a network control center (for example, a SCADA system) that monitors the operation of the power supply network. Otherwise, the procedure already described in relation to Figure 1 is used in the case of fault identification and location, so this need not be discussed again separately.
[0079] To summarize, a method has been described above to allow the identification and location of failure in power supply lines that are fed from one side. The identification and fault location is robust in relation to supplies or loads in the sections of the power supply line and is carried out by a method of measuring the sensitive current that is carried out in the measuring devices that monitor the respective section of the line. In principle only currents measured by a current transformer are required, so no expensive voltage transformers need to be provided (the voltage signal can also be used, however, with existing voltage transformers). The method is characterized by the fact that only a few variables, usually binary, transmitted can be formed, for example, in the form of a GOOSE message to IEC 61850. The evaluation of these signals takes place on the measuring devices themselves or on a higher order device. which can be provided, for example, in food. The faulty line section can be isolated from the network by opening the switching devices that delimit it. With additional switching operations, those line sections of the network that are not affected by the short circuit can be supplied with power again. The power supply to sections of the line that are not affected can therefore be restored in seconds.

权利要求:
Claims (15)
[0001]
1. Method for determining a failed section of a power supply line (10a) that is fed from one side and that is divided into a plurality of sections (14a-c) by switching devices (13a-d) , with each switching device (13a-d) having an associated measuring device (15a-d), characterized by the fact that the following steps are carried out in the method: - each measuring device (15a-d) detects a signal current at a measurement point (16a-d) which is arranged in the region of the respective switching device (13a-d), the said current signal indicating a current flow at the respective measurement point (16a-d) ; - each measuring device (15a-d) shows the current signal to form current sample values, and determines a current measurement variable from the current sample values; - each measuring device (15a-d) forms a delta current value as the difference between an instantaneous current measurement variable and a previous current measurement variable that has been determined a fixed number of periods of the current signal before; - each measuring device (15a-d) compares the delta current value with a current limit value and identifies a current jump when the delta current value is above the current limit value, the current limit value being dynamically formed as a function of a differential current value that is formed using a difference between the current measurement variables determined at two ends of a section (14a-c) of the power supply line (10a), the value being current limit is dynamically fixed; - each measuring device (15a-d) sends a first status message, which indicates a current jump, when it identifies a current jump; - a fault finding device identifies a fault as being present in that section (14a-c) of the power supply line (10a) which is bounded at one end by a switching device (13a-d) whose measuring device ( 15a-d) has identified a jump in the chain, and is bounded at its other end by a switching device (13a-d) whose measuring device (15a-d) has not identified a jump in the chain.
[0002]
2. Method, according to claim 1, characterized by the fact that - the current measurement variable is determined as the effective value or as the basic oscillation component from the current sample values or from the current values current sample and associated voltage sample values.
[0003]
3. Method according to claim 1 or 2, characterized by the fact that - instead of the previous current measurement variable, a fixed maximum value is used to form the delta current value when the current measurement variable exceeds a predefined limit comparison value.
[0004]
4. Method according to claim 3, characterized by the fact that - the limit comparison value is formed as a function of a differential current value that is formed using a difference between the current measurement variables determined at the two ends section (14a-c) of the power supply line (10a).
[0005]
5. Method according to any one of the preceding claims, characterized by the fact that - the fault finding device is a component of at least one of the measuring devices (15a-d).
[0006]
6. Method according to any one of claims 1 to 4, characterized in that - the error location device is a component of a central evaluation device (for example, 20) different from the measuring devices (15a- d).
[0007]
7. Method, according to any of the preceding claims, characterized by the fact that - the measuring devices (15a-d), if they do not identify a current jump, send a second status message at regular intervals, and this indicates that no jump in the chain has been identified, and - the measurement devices (15a-d) repeat the first status message at intervals that are shorter than the intervals and the second status message is sent.
[0008]
8. Method according to any of the preceding claims, characterized by the fact that - status messages are formed as GOOSE messages according to the IEC 61850 standard.
[0009]
9. Method according to any one of the preceding claims, characterized by the fact that - the fault finding device identifies a fault as being present in a certain section (14a-c) of the power supply line (10a) if is within a maximum period after a measurement jump in the current by the measuring device (15a-d) at one end of the section (14a-c), a first status message from the measuring device (15-d) is not materializes at the second end of the section (14a-c).
[0010]
10. Method according to claim 9, characterized by the fact that - the fault finding device identifies only a fault as being present in the given section (14-c) when the delta current value of the measuring device (15a -d), which identified the current jump, is above a confirmation threshold value, which is formed as a function of a differential current value, which is formed using a difference between the current measurement variables determined at both ends section (14a-c) of the power supply line (10a).
[0011]
11. Method according to any one of the preceding claims, characterized by the fact that - in the event of a failure identified in a given section (14a-c) of the power supply line (10a), these switching devices (13a -d) that delimit this section of the power supply line (10a) are opened immediately.
[0012]
12. Method according to any one of claims 1 to 10, characterized by the fact that - in the event of a failure identified in a given section (14a-c) of the power supply line (10a), first, a circuit breaker (13e) upstream of the switching devices (13a-d) on the supply side it is opened and only after opening the circuit breaker (13e), those switching devices (13a-d) that delimit this section (14a-c) of the power supply line (10a) are open.
[0013]
13. Method according to claim 12, characterized by the fact that - after the switching devices (13a-d) that delimit the failed section (14a-c) are opened, the circuit breaker (13e) is closed again.
[0014]
14. Method according to claim 13, characterized by the fact that - after the switching devices (13a-d) that delimit the failed section (14a-c) are opened, a connection switch (12) is also closed to connect that part of the power supply line (10a), which joins the end of the failed section (14a-c) away from the supply, to an additional supply.
[0015]
15. Measuring device (15a-d) to determine a failed section of a power supply line (10a) that is fed from one side and is divided into a plurality of sections (14a-c) by devices switching device (13a-d), one of the switching devices (13a-d) may be associated with the measuring device (15a-d), characterized by the fact that - the measuring device (15a-d) is configured to carry out a method as defined in any one of claims 1 to 17.

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法律状态:
2018-12-26| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

2019-07-09| B06T| Formal requirements before examination [chapter 6.20 patent gazette]|

2020-04-14| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

2020-10-20| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 21/07/2011, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

申请号 | 申请日 | 专利标题

PCT/EP2011/062524|WO2013010591A1|2011-07-21|2011-07-21|Fault identification and location in a power supply line which is fed from one side|

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