Measuring and mitigating channel delay in remote data acquisition

Disclosed herein are systems and methods of calculating and mitigating time delays for electric power system samples received by remote data acquisition unit (RDAU), digitized, and transmitted to a receiving intelligent electronic device (IED). The IED may calculate time delays for various RDAUs, and establish wait windows for certain protection operations based on the samples needed for the protection operation and the calculated time delays for the various RDAUs. The IED may detect and report system or time signal anomalies based on changes to the calculated time delays from particular RDAUs.

TECHNICAL FIELD

This disclosure relates to measuring and mitigating for channel delay in remote data acquisition. More particularly, this disclosure relates to measuring a channel delay between multiple remote data acquisition units (RDAUs) and an intelligent electronic device (IED), and mitigating for the measured channel delay at the IED.

DETAILED DESCRIPTION

Electric power delivery systems are used to distribute electric power from electric power generation sources to loads, which may be close or distant from the generation sources. Such systems may include generators or other sources, transformers step up or down voltages, transmission lines, buses, distribution lines, voltage regulators, capacitor banks, reactors, circuit breakers, switches, and other such equipment. Electric power distribution equipment may be monitored, automated and/or protected using intelligent electronic devices (IEDs).

In some systems, IEDs obtain signals from the electric power delivery system via direct connection to current transformers (CTs), potential transformers (PTs), and the like. Such IEDs may be configured with the particular physical and electrical parameters of the connected CTs and/or PTs, and may further include sampling hardware and software for converting the analog signals to digitized analog signals useful for determining a state of the electric power delivery systems. In other systems, RDAUs may be in electrical communication with the CTs and PTs, and configured to sample and digitize the signals from the CTs and PTs, and provide digitized electrical signals corresponding with the sampled analogs to connected IEDs. Failure of the RDAU and/or the communication system between the RDAU and the IED may result in a failure of the IED to obtain signals necessary for monitoring the electric power delivery system. What is needed is a system for providing appropriate digitized analog signals to subscribing IEDs even upon failure of the RDAU and/or communication system.

In some cases, well-known features, structures or operations are not shown or described in detail. Furthermore, the described features, structures, or operations may be combined in any suitable manner in one or more embodiments. It will also be readily understood that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations.

Embodiments may be provided as a computer program product including a non-transitory computer and/or machine-readable medium having stored thereon instructions that may be used to program a computer (or other electronic device) to perform processes described herein. For example, a non-transitory computer-readable medium may store instructions that, when executed by a processor of a computer system, cause the processor to perform certain methods disclosed herein. The non-transitory computer-readable medium may include, but is not limited to, hard drives, floppy diskettes, optical disks, CD-ROMs, DVD-ROMs, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, solid-state memory devices, or other types of machine-readable media suitable for storing electronic and/or processor executable instructions.

Systems and methods described below are related to mitigating channel delay in power delivery systems. In a first embodiment, a system for providing electric power system signals to receiving intelligent electronic devices (IEDs) includes a first remote data acquisition unit (RDAU) in electrical communication with an electric power delivery system. The first RDAU may obtain electrical signals from the electric power delivery system, create digitized electrical signals from the obtained electrical signals, time stamp the digitized electrical signals according to a common time reference, and transmit the time stamped digitized electrical signals over a first communication path. A second RDAU in electrical communication with the electric power delivery system may obtain electrical signals from the electric power delivery system, create digitized electrical signals from the obtained electrical signals, time stamp the digitized electrical signals according to a common time reference, and transmit the time stamped digitized electrical signals over a second communication path. The system includes an IED that receives the common time reference. The IED may receive the time stamped digitized electrical signals from the first RDAU via the first communication path and the time stamped digitized electrical signals from the second RDAU via the second communication path. The IED may calculate a first time delay for the first communication path as a time delay from the sampling of the signal by the first RDAU to the receipt of the time-stamped digitized electrical signal at the IED. The IED calculates a second time delay for the second communication path as a time delay from the sampling of the signal by the second RDAU to the receipt of the time-stamped digitized electrical signal at the IED. The IED may establish a sample delay window for a predetermined protection operation based on the first time delay and the second time delay. The IED may continue receiving samples during the sample delay window. The IED may, upon lapse of the sample delay window, time align the samples received during the sample delay window. The IED may perform a protection operation using the time aligned samples received during the sample delay window.

FIG. 1Aillustrates a simplified one-line diagram of an alternating current electric power transmission and distribution system100consistent with embodiments of the present disclosure. Electric power delivery system100may be configured to generate, transmit, and distribute electric energy to loads. Electric power delivery systems may include equipment, such as electric generators (e.g., generators110,112,114, and116), power transformers (e.g., transformers117,120,122,130,142,144and150), power transmission and delivery lines (e.g., lines124,134,136, and158), circuit breakers (e.g., breakers152,160,176), busses (e.g., busses118,126,132, and148), loads (e.g., loads140, and138) and the like. A variety of other types of equipment may also be included in electric power delivery system100, such as voltage regulators, capacitor banks, and a variety of other types of equipment.

Substation190may include two generating sources110,112feeding bus118via transformers120,122. Transformer120may be monitored and protected using IED104.

Substation119may include a generator114, which may be a distributed generator, and which may be connected to bus126through step-up transformer117. Bus126may be connected to a distribution bus132via a step-down transformer130. Various distribution lines136and134may be connected to distribution bus132. Distribution line136may lead to substation141where the line is monitored and/or controlled using IED106, which may selectively open and close breaker152. Load140may be fed from distribution line136. Further step-down transformer144in communication with distribution bus132via distribution line136may be used to step down a voltage for consumption by load140.

Distribution line134may lead to substation151, and deliver electric power to bus148. Bus148may also receive electric power from distributed generator116via transformer150. Distribution line158may deliver electric power from bus148to load138, and may include further step-down transformer142. Circuit breaker160may be used to selectively connect bus148to distribution line134. IED108may be used to monitor and/or control circuit breaker160as well as distribution line158.

Electric power delivery system100may be monitored, controlled, automated, and/or protected using intelligent electronic devices (IEDs), such as IEDs104,106,108,115, and170, and a central monitoring system172. In general, IEDs in an electric power generation and transmission system may be used for protection, control, automation, and/or monitoring of equipment in the system. For example, IEDs may be used to monitor equipment of many types, including electric transmission lines, electric distribution lines, current transformers, busses, switches, circuit breakers, reclosers, transformers, autotransformers, tap changers, voltage regulators, capacitor banks, generators, motors, pumps, compressors, valves, and a variety of other types of monitored equipment.

As used herein, an IED (such as IEDs104,106,108,115, and170) may refer to any microprocessor-based device that monitors, controls, automates, and/or protects monitored equipment within system100. Such devices may include, for example, remote terminal units, differential relays, distance relays, directional relays, feeder relays, overcurrent relays, voltage regulator controls, voltage relays, breaker failure relays, generator relays, motor relays, automation controllers, bay controllers, meters, recloser controls, communications processors, computing platforms, programmable logic controllers (PLCs), programmable automation controllers, input and output modules, digital sample publishing units, merging units, and the like. The term IED may be used to describe an individual IED or a system comprising multiple IEDs.

A common time signal may be distributed throughout system100. Utilizing a common or universal time source may ensure that IEDs have a synchronized time signal that can be used to generate time synchronized data, such as synchrophasors and sampled values. In various embodiments, IEDs104,106,108,115, and170may receive a common time signal168. The time signal may be distributed in system100using a communications network162or using a common time source, such as a Global Navigation Satellite System (“GNSS”), or the like.

According to various embodiments, central monitoring system172may comprise one or more of a variety of types of systems. For example, central monitoring system172may include a supervisory control and data acquisition (SCADA) system and/or a wide area control and situational awareness (WACSA) system. Central monitoring system172may be configured to provide protective operations for the system100. A central IED170may be in communication with IEDs104,106,108, and115. IEDs104,106,108and115may be remote from the central IED170, and may communicate over various media such as a direct communication from IED106or over a wide-area communications network162. According to various embodiments, certain IEDs may be in direct communication with other IEDs (e.g., IED104is in direct communication with central IED170) or may be in communication via a communication network162(e.g., IED108is in communication with central IED170via communication network162).

In various embodiments, IEDs104,106,108,115, and170may be configured to monitor the frequency of alternating current waveforms in system100. The measurements may be used in connection with the systems and methods disclosed herein for control of system100. The IEDs may utilize common time source168to time-align measurements for comparison across system100.

Network162may be used to transmit information among various components in system100, including IEDs108,115,170, and central monitoring system172. In order to increase reliability, network162may include redundant communication paths between communicating devices. Such redundant paths may be selectively enabled when a first communication path is unavailable or disabled. Network162may include a variety of devices (e.g., multiplexers, routers, hubs, gateways, firewalls, switches, etc.) and technologies (e.g., connectionless communication network, SDN networks, etc.)

Measurements made by IEDs104,106,108, and115may be communicated to central IED170and/or central monitoring system172. In some embodiments, one or more of IEDs108and115may be configured to send a confirmatory signal through network162to central IED170. In the illustrated embodiment, central IED170is in contact with IEDs108and115via analog communication channels180and182, respectively.

In several embodiments, IEDs may obtain electric power delivery system signals via RDAUs. RDAUs may be in electrical communication with primary equipment (via, for example, current transformers (CTs) and/or potential transformers (PTs) or the like) and configured to receive electric power system signals therefrom and create digitized electric power system signals for IEDs. Such digitized electric power system signals may be digitized analog signals. The digitized analog signals may be packetized and transmitted to the subscribing IED. The RDAUs may communicate the digital samples to the subscribing IEDs as “Sampled Values” (“SVs”). RDAUs may further be configured to provide control signals to primary equipment on the electric power delivery system. For example, an RDAU may be in communication with a circuit breaker, and designed to open and/or close the circuit breaker upon receipt of a command from an IED.

RDAUs may include an input for receiving electrical signals from CTs, PTs, or the like, and digitizing such electrical signals for use by IEDs. To that end, RDAUs may comprise an analog-to-digital converter configured to sample and digitize the incoming analog signals and provide the digitized signals. The RDAU may further comprise a processing module configured to organize the digitized signals into communication packets, and communicate the packetized digitized signals directly to a subscribing IED or to a communication system configured to transmit the packetized digitized signals to a subscribing IED.

FIG. 1Billustrates an alternative portion of the electric power transmission and distribution system ofFIG. 1A, with an accompanying monitoring system. In particular,FIG. 1Billustrates substation191, which may be used in the place of substation190ofFIG. 1A. Substation191may include RDAUs103and105in electrical communication with transformer120, RDAUs103and105configured to obtain analog electrical signals via CTs. The RDAUs103and105may sample and digitize the obtained analog electrical signals and transmit the digitized analog signals to IED104. The signals may be sent via network107to IED104. A common time signal168may be distributed to RDAUs103and105via network107. In various embodiment, the common time signal168may be distributed to IED104via the network, whereas in other embodiments IED104may separately receive common time signal168.

Generator112may provide electrical energy to bus118via transformer122. RDAUs109and111may obtain electrical signals from both sides of transformer122via, for example, CTs. RDAUs109and111may sample the analog signals and send digitized analog signals to IED113. As illustrated, RDAUs109and111may be in direct communication with IED113. In various embodiments, RDAUs109,111may communicate with IED113via a network. Although not separately illustrated, RDAUs109and111, and IED113may receive a common time signal, such as, for example, time signal168.

The RDAUs, network(s), and IEDs of substation191may communicate according to various protocols. In one embodiment, the various devices may communicate according to a direct process bus protocol, PROFIBUS, fieldbus, or the like. For example, communication lines113and115may be point-to-point process bus communication channels.

FIG. 2illustrates a simplified one-line diagram of a portion of an electric power delivery system, and the IEDs that may be used to monitor and protect the portion of the electric power delivery system. The electric power delivery system may include a power line202and a feeder204connected thereto. The feeder204may include a transformer206configured to step down the electrical potential on the feeder204. The feeder204may further include a circuit breaker212that may be configured to open and/or close on command, to disconnect or connect the remaining portion of the feeder204from downstream portions of the electric power delivery system.

Feeder204may be monitored and protected by a IED242, which may be located local to the feeder204or remotely from the feeder204. The IED242may be configured to monitor and protect a first portion of the electric power system on a first side of the circuit breaker212. To monitor and protect the first portion of the electric power delivery system, the IED242may obtain electrical information from the electric power delivery system from an RDAU222. The RDAU222may obtain electric signals from the first portion of the electric power delivery system using, for example, CT214. The RDAU222may be configured to obtain electric power signals using CT214, sample and digitize the electric power system signals, packetize the digitized signals, and transmit the packets to the IED242via a communication network232.

The RDAU222may be in communication with a common time signal252. The common time signal252may be a signal such as the common time signal168ofFIG. 1. The RDAU222may include a time stamp provided by the common time signal252with samples provided to the IED242.

The IED242may be configured to receive measurements from the RDAU222via a communications network232. The communications network232may comprise simply a switch, or be as complex as a network of communications switching devices. IED242may be in communication with the common time source252to receive a common time signal therefrom. IED242may be further configured to determine electric power system conditions using measurements provided by the RDAU222, and send signals to the RDAU222to operate the circuit breaker212upon determination of predetermined electric power system conditions.

In various embodiments, the222may be configured to receive sampling instructions from IED242. That is, IED242may indicate when samples are to be taken by RDAU222and transmitted to IED242. However, samples may be expected at a certain time by IED242, but delayed due to the communications system232and sampling overhead in RDAU222.

Although an RDAU222is illustrated inFIG. 2, any device capable of receiving commands, sampling, and transmitting a digitized analog signal representing the sample is considered. Such devices may be in the form of RDAUs, sampled values publishers, merging units, IEDs, or the like. The RDAU can have a point-to-point or point-to-multipoint connection with the IEDs, although illustrated inFIG. 2, RDAU222is in communication with a single IED242for simplicity. The RDAU measures the analog signals and converts the samples into digital samples. The conversion process results in a time delay. These digital samples are published periodically and travel through point-to-point or point-to-multipoint networks to the IEDs and this also results in a time delay. The sum of these two delays may be termed a total network delay herein.

In one embodiment, IED242may calculate the total network delay. For this calculation, the IED242may first detect that the RDAU222and the IED242are both time-synchronized to the same high accuracy time source252. If a common time source is detected (also referenced as “coupled clock mode”), the IED242will start measuring the total network delay. RDAU222will send messages that include analog data measurements, the time that the measurement is taken and may also include time synchronization status of the RDAU222. These timestamps can be in the form of actual timestamps or in the form of an integer that represent the time slots in a second. For example, if a second is divided into 1000 slots, each time slot represents 1 ms. Slot index 0 represents the top of a second. Slot index499represents 500 ms in a second. If the incoming timestamps are in the form of a human readable timestamp, the IED242compares its local time to the timestamp and calculates the time delay, which is the total network or total channel delay. If the incoming timestamps are the form of an integer, the IED242derives a number that represents its current time slots and it compares its own value to the incoming integer. The difference can then be converted back into the total network delay.

One particular embodiment complies with the IEC 61850 9-2 Sampled Values Relay standard. In this embodiment, the IED242may be a sampled values relay that periodically receives samples from the RDAU222in the form of a remote sampled values publisher. The publisher222sends each sample with a smpCnt attribute. These samples go through a network232. This smpCnt attribute is an integer that represents the interval in which the publisher222took the sample. To measure the total network delay, IED242also calculates its local smpCnt. In one embodiment, the sampling frequency may be 4000 Hz. If IED242locally derived smpCnt is 5 and the incoming smpCnt in the Sampled values messages is 2, the channel delay can be calculated as (5−2)*1 second/sampling frequency (4000)=0.75 ms. Another method of calculating the total network delay is to convert the received smpCnt into the absolute time and then compare with the local IED time. The time difference calculated is the total network delay.

This information can be reported via request-response sequences such as ASCII commands. In several embodiments, system-wide channel delays can be reported and graphically visualized. An IED can use communication protocols such as IEC 61850 MMS, DNP3, and other SCADA protocols to send its measured channel delays to an HMI or SCADA. With some HMI designs, an operator can monitor the channel delays in the entire communication system.

FIG. 3illustrates a simplified one-line diagram of calculation and mitigation of channel delays for system that includes multiple RDAUs reporting to a single IED. The electric power system ofFIG. 3includes a power line and a bus302in connection with three feeders304,306, and308. A first RDAU322is in electrical communication with feeder304via a CT to obtain current measurements therefrom. A second RDAU324is in electrical communication with feeder306via a CT to obtain current measurements therefrom. A third RDAU326is in electrical communication with the bus302via a PT to obtain voltage measurements therefrom. A fourth RDAU328is in electrical communication with the first feeder304via a PT to obtain voltage measurements therefrom. The first RDAU322is in communication with IED342via communications line362. The second RDAU324is in communication with IED342via communications line366. The third RDAU326is in communication with IED342via communications network and communications line368. The fourth RDAU328is in communication with IED342via communications line364.

Each RDAU322-328and IED342receive a common time signal such as common time signal352.

As illustrated, each RDAU322-328has different communications pathways to IED342. Accordingly, it is likely that each RDAU322-328has different communications and network delays to IED342, and samples received by IED342at a particular time from RDAUs322-328are likely not to be time coordinated according to sampling instant. According to several embodiments herein, IED342may calculate a network delay for each RDAU322-328, and mitigate for the varying sampling instant. IED342may calculate the total network delay for each RDAU322-328according to the embodiments described above.

In one embodiment, the first RDAU322digital samples travel on path362and this results in a time delay of AT1. These samples include the current measurements. Samples from fourth RDAU328travel on path364and this results in a time delay of AT2. These samples may include A phase voltage. Samples from the third RDAU326travel on path368which may include a network and this results in a time delay of AT3. These samples include3phase voltage measurements. IED342may perform protection operations such as, for example, distance Mho element protection using digitals samples from RDAU322and RDAU326. To ensure the Mho element impedance calculation, voltage and current must come from the same time instance, the channel delay asymmetry between communication path362and communication path368is accommodated and samples are aligned.

IED342measures the delays for path362and path368using the embodiments disclosed herein. To mitigate for differences in the total network delay for the various RDAUs, IED342may determine a wait time and wait for the determined wait time for samples from different RDAUs to arrive, and then align the samples from the same time instance for use by various protection elements. This determined wait window may be calculated as greater than AT1and AT3(the total network delays for the communication paths for the specific operation).

According to several embodiments, different wait windows may be established for different protection operations, depending on which samples are needed for the various protection operations. For example, a differential operation may require current measurements from two RDAUs. The wait window for the specific differential operation may be determined based on the total network delays for only those two RDAUs. Where, in the same IED, a protection operation may include bus protection requiring current samples from each feeder attached to the bus and voltage samples from the bus. The IED may be configured to establish a wait window for the bus protection operation based on the total network delays of the RDAUs providing the various current measurements from each feeder and the voltage from the bus. The IED may be configured to provide both protection operations, each with different wait windows for samples from different IEDs. The IED may be configured to provide any number of monitoring, automation, and protection operations, and establish different wait windows for each of the various monitoring, automation, and protection operations.

Setting a wait window may be performed by the IED342according to the following. The wait window can be dynamically set or fixed. If it is fixed, it is set to be greater than the maximum of (ΔT1, ΔT2, . . . ΔTn). This value can be estimated or calculated by users. ΔTn represents the channel delays of the nth stream of digital samples. When setting dynamically, the IED first sets its delay to be a much larger number such as 10 ms. The IED then measures the delay for different digital sample streams. In this specific example, the IED342will measure the delay for communications channels362,364,366, and368. The IED then sets its wait window to be slightly greater than max (ΔT1, ΔT2, . . . ΔTn). Thus, it will be able to align the digital samples from the same time instance before using these samples for protection. It should be noted, if using a fixed network delay, a protection element's operating time will be delayed by this fixed network delay. If the network path changes due to Parallel Redundancy Protocol (PRP), High Availability Seamless Redundancy (HSR) networks, or any other reasons, such that the measured channel delay is greater than the maximum threshold, the IEDs alarm the system operator regarding the significant changes in network path delay. The IEDs can be configured to continue the protection operations or disable protection upon these scenarios.

In another embodiment, the channel delay measurements may be used to identify misbehaving time synchronization sources/clocks and fine tune network paths. The IED342ofFIG. 3may receive digital samples streams from multiple RDAUs322,324,326,328. Each RDAU322-328is time synchronized by a time source352. Each digital sample includes the analog measurements, the time that the measurement is taken and the time synchronization status of the RDAU. A time synchronization status may include whether the local time of the RDAU322,324,326, and328is synchronized to the time source352, whether accuracy of the local clock is within an expected limit, the type of clock source352being used, accuracy of the local clock, or the like.

The IED342monitors the time synchronization status of each incoming digital stream for changes in channel delay. The IED342reports a much longer or a sudden change channel delay for the digital data stream. For example, if the channel delay from RDAU326undergoes a large and/or sudden channel delay change, but RDAU326has the same time synchronizations status as other RDAUs, then IED342may determine an error in time synchronization status, and report the error. The reported channel delays help engineers to identify misbehaving time synchronization/clocks or misbehaving network communications giving that the RDAUs are the same. If it is an issue of the network paths, with the reported channel delay measurements, the communication network may be reconfigured based on the reported channel delays. This helps minimize delays in protection decisions contributed by the total channel delay.

A specific example is the IEC 61850 samples values network. If an IED receiving 5 IEC 61850 9-2 SV streams from multiple RDAUs and these RDAUs are the same, the IED reports a sudden change of the channel delay of an SV stream, network engineers can first check the clock. If it is not an issue of the clock, engineers can start investigating the network path. The network path can include one or more switches. Engineers will need to identify the exact issues and fine tune the network path. Smaller channel delays help minimize delays in protection decisions contributed by the total channel delay.

FIG. 4illustrates an embodiment of an IED400. The IED400includes a bus420connecting a processor430or processing unit(s) to a memory440, a network interface450, and a computer-readable storage medium470. The network interface450may include communications circuitry (e.g., transceiver) to communicate with RDAUs, a central monitoring station, or other IEDs. The computer-readable storage medium470may include or interface with software, hardware, or firmware modules for implementing various portions of the systems and methods described herein. The separation of the modules is merely an example, and any combination of the modules or further division may be possible.

The computer readable storage medium470may include an event detection module480configured to detect an occurrence of a predetermined electrical event within a portion of an electrical power delivery system and communicate the occurrence with other IEDs within the electrical power delivery system. The medium470may also include a transmission module482configured to generate and transmit communications to other monitoring IEDs within the electrical power delivery system, wherein each of the plurality of monitoring IEDs is configured to monitor a distinct portion of the electrical power delivery system, a SCADA system, or the like. The medium470may further include a receiving module484configured to receive communications from each of the plurality of the signal processing devices reporting to the IED400. The communications may include time stamps from the signal processing devices. Additionally, the medium470may include a report generation module486configured to generate a system-wide event report based on the received communications and detected events.

The computer-readable storage medium470may include a delay calculation module488configured to calculate a channel delay for each of the signal processing devices reporting to the IED400using the various embodiments described herein. The computer readable storage medium470may further include a sample coordination module490in communication with the delay calculation module488and the event detection module. The sample coordination module490may be configured to operate according to the various embodiments described herein to use the calculated channel delays from the delay calculation module488coordinate samples from the various signal processing devices, and make such coordinated samples available for the event detection module480.

FIG. 5illustrates a block diagram of a RDAU500, according to various embodiments disclosed herein. Embodiments of the RDAU500may be utilized to implement the systems and methods disclosed herein. For example, the RDAU500may be configured to receive analog signals from a portion of a power system, sample the analog signals, and communicate digitized analog signals to subscribing IEDs; and take actions as directed by an IED.

The RDAU500may include a communications interface502configured to communicate with an IED. The communications may be via a communications network or direct communications as described in more detail herein. The communications interface502may include a separate communications interface to communicate with one or more IEDs, to transmit the digitized analog signals.

The RDAU500may also include a time input506, which may be used to receive a time signal. The time input may receive the common time signal. In certain embodiments, a common time reference may be received via the time input506or communications interface502. One such embodiment may employ the IEEE1588protocol.

A monitored equipment interface508may be configured to receive equipment status information from, and issue control instructions to a piece of monitored equipment, such as an electrical generator, breaker, voltage regulator controller, and/or the like. According to various embodiments, the monitored equipment interface508may be configured to interface with a variety of equipment of an electric power delivery system.

A computer-readable storage medium510may be the repository of one or more modules and/or executable instructions configured to implement any of the processes described herein. In some embodiments, the computer-readable storage medium510and the modules therein may all be implemented as hardware components, such as via discrete electrical components, via an FPGA, and/or via one or more ASICs.

In the illustrated embodiments, a data bus512may link a monitored equipment interface508, the communications interface502, the time input506, and/or the computer-readable storage medium510to a processor514.

The processor514may be configured to process communications received via the communications interface502, the time input506, and/or the monitored equipment interface508. The processor514may operate using any number of processing rates and architectures. The processor514may be configured to perform various algorithms and calculations described herein using computer executable instructions stored on computer-readable storage medium510. Processor514may be embodied as a general purpose integrated circuit, an application specific integrated circuit, a field-programmable gate array, and/or other programmable logic devices.

In certain embodiments, the RDAU500may include a sensor component516. In the illustrated embodiment, the sensor component516is configured to gather data from a location of the electric power delivery system (not shown) using a current transformer518and/or a voltage transformer520. The voltage transformer520may be configured to step-down the power system's voltage (V) to a secondary voltage waveform522having a magnitude that can be readily monitored and measured by the RDAU500. Similarly, the current transformer518may be configured to proportionally step-down the power system's line current (I) to a secondary current waveform524having a magnitude that can be readily monitored and measured by the RDAU500. Although not separately illustrated, the voltage and current signals V and I may be secondary signals obtained from equipment instruments designed to obtain signals from power system equipment. For example, a secondary voltage signal V may be obtained from a potential transformer (PT) in electrical communication with a conductor. A secondary current signal I may be obtained from a current transformer (CT) in electrical communication with a conductor. Various other instruments may be used to obtain signals from electric power delivery systems including, for example, Rogowski coils, optical transformers, and the like.

An analog-to-digital converter526may multiplex, sample and/or digitize the measured voltage and/or current signals to form corresponding digitized current and voltage signals. Similar values may also be received from other distributed controllers, station controllers, regional controllers, or centralized controllers. The values may be in a digital format or other format. In certain embodiments, the sensor component516may be utilized to monitor current signals associated with portion of an electric power delivery system. Further, the sensor component516may be configured to monitor a wide range of characteristics associated with monitored equipment, including equipment status, temperature, frequency, pressure, density, infrared absorption, radio-frequency information, partial pressures, viscosity, speed, rotational velocity, mass, switch status, valve status, circuit breaker status, tap status, meter readings, conductor sag and the like.

The A/D converter526may be connected to the processor514by way of the bus512, through which digitized representations of current and voltage signals may be transmitted to the processor514. As described above, the processor514may be used to apply equipment status, measurements, and derived values to an IED module (e.g., the modules in the computer-readable storage medium510). The processor514may be used to monitor and protect portions of an electric delivery system, and issue control instructions in response to the same (e.g., instructions implementing protective actions).

A monitored equipment interface508may be configured to receive status information from, and issue control instructions to a piece of monitored equipment. The monitored equipment interface508may be configured to issue control instructions to one or more pieces of monitored equipment.

The computer-readable storage medium510may be the repository of one or more modules and/or executable instructions configured to implement certain functions and/or methods described herein. For example, the computer-readable storage medium510may include a communication module536to control communications with the subscribing IED. The communications module536may include instructions for formatting and translating communications between the RDAU500and the subscribing IED. The communications module536may include instructions for assigning a time stamp to communications to the subscribing IED.

The storage medium510may also include a protective action implementation module536that includes instructions for taking a control action or sending a control instruction via the monitored equipment interface508to the primary equipment. In some embodiments, the processor430may send, via the communication circuitry, a control signal to control operation of one or more relays, reclosers, or sensors, based at least in part on the time-aligned samples to allow more accurate control of power on power distribution systems to improve reliability of the power distribution system.

The control module540may be configured for interacting with monitored equipment connected to distributed controller via the monitored equipment interface508and/or via the communications interface502.

Systems and methods described herein may improve IED technology in power systems by enabling functionality of protection and control operations on power systems based on time aligned samples from different RDAUs, each of which may have different internal clocks. Further, the operation of the IED may be improved by time aligning the samples by more accurately monitoring its remote data acquisitions. Moreover, in some embodiments, IED technology may be improved by adjusting network paths (e.g., path between switches, relays, or other electronic devices on the power system) based on the time delays to improve network efficiency. In this manner, IEDs may assess events on power systems in a more accurate and reliable manner by having time aligned samples, thereby improving stability of the power system. Further, the IED may more accurately control circuit breakers on the power distribution due to the improved functionality of the IED, thereby improving operation of the power distribution system.

This disclosure has been made with reference to various embodiments, including the best mode. However, those skilled in the art will recognize that changes and modifications may be made to the embodiments without departing from the scope of the present disclosure. While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, elements, materials, and components may be adapted for a specific environment and/or operating requirements without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure.

This disclosure is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope thereof. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element. The scope of the present invention should, therefore, be determined by the following claims: