A remote control method and system of a relay protection system

Abstract

The application discloses a remote control method and system of a relay protection system, and relates to the technical field of remote control.The method comprises the following steps: a control terminal and a controlled terminal determine an instruction code book in advance, and send the code book to a base station through a physical uplink shared channel; the base station generates a corresponding Msg4 response message and broadcasts the Msg4 response message to the controlled terminal; the controlled terminal receives the Msg4 response message, compares the Msg4 response message with the code book instruction through hash operation, and stores the matched instruction in a verified instruction queue; the controlled terminal feeds back performance data to the control terminal after executing the instruction; the control terminal optimizes channel parameters through a SPARROW algorithm, verifies and solidifies the parameters after updating the parameters through the base station configuration; the control terminal and the controlled terminal synchronously clear historical instruction records, the code book and a salt value register, and reset a communication link and a calculation unit to an initial state.The application embeds a hash truncated value in a CRI field and combines salt value interference, so that the base station only forwards but does not store an associated state, and effectively resists man-in-the-middle attacks and flow analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of remote control, in particular to a remote control method and system of a relay protection system. BACKGROUND

[0002] The remote control technology of the relay protection system is the core guarantee for the safe operation of the smart grid, and the existing technology mainly transmits control instructions through a special communication protocol or a public wireless network. Among them, the scheme based on the standard wireless communication protocol has become a research hotspot due to its advantages such as flexible deployment and low cost, and its typical implementation ways include: transmitting plaintext instructions through an encrypted tunnel, or using physical layer characteristics (such as channel state information) for instruction steganography. However, the implementation ways have significant defects: first, the security is insufficient, although the encrypted tunnel can protect the instruction content, the identity of the control end and the controlled end is exposed and is vulnerable to directional attacks; the physical layer steganography scheme is strong in concealment, but is affected by the time-varying characteristics of the channel and is prone to increase the bit error rate. Second, the dynamic adaptability is poor, the existing methods lack a closed-loop verification mechanism for the real-time state of the power grid, and cannot adjust the action delay according to dynamic parameters such as fault current decay rate and voltage recovery rate, which is easy to cause misoperation or refusal to operate. SUMMARY

[0003] In view of the above existing problems, the present application is proposed.

[0004] Therefore, the present application provides a remote control method of a relay protection system to solve the problems of poor instruction concealment and insufficient dynamic adaptability in relay protection remote control.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a remote control method of a relay protection system, which comprises,

[0007] The control end and the controlled end determine an instruction codebook in advance, which is sent to a base station through a physical uplink shared channel, and a corresponding Msg4 response message is generated and broadcast to the controlled end;

[0008] The controlled end receives the Msg4 response message, extracts the CRI field and the salt value after radio frequency demodulation, digital signal processing and CRC check, and compares them with the codebook instructions one by one through hash operation, and stores them in the verified instruction queue after successful matching;

[0009] The controlled end feeds back performance data to the control end after executing the instructions, the control end optimizes the channel parameters through the SPARROW algorithm, updates the truncation length, the salt value period and the initialization vector, and updates the parameters after configuration by the base station, and verifies and fixes the parameters;

[0010] The control end and the controlled end synchronously clear the historical instruction record, the code book and the salt value register, and reset the communication link and the computing unit to the initial state.

[0011] As a preferred scheme of the remote control method of the relay protection system, the corresponding Msg4 response message is generated by the following steps,

[0012] The control end converts the relay protection instruction in the predetermined code book into a specific numerical form in the CRI field of the Msg3 message frame according to the encoding rule, and randomly generates a salt value as a disturbance factor.

[0013] The base station extracts the CRI field after integrity checking of the Msg3, and stores it in the memory buffer after conversion to the MAC layer format by the physical layer.

[0014] The base station sets the CRI field value corresponding to the Msg3 in the Msg4 response message, and broadcasts it through the physical downlink shared channel.

[0015] As a preferred scheme of the remote control method of the relay protection system, the radio frequency demodulation, digital signal processing and CRC checking to extract the CRI field and the salt value include the following steps,

[0016] The controlled end converts the amplified radio frequency signal into an intermediate frequency signal through a mixer, and generates a digital intermediate frequency signal through band pass filtering, automatic gain control and analog to digital conversion.

[0017] The CORDIC algorithm is used to generate a quadrature reference carrier, and the in-phase / quadrature components are separated through digital down conversion, and the time domain complex baseband signal is output after downsampling.

[0018] OFDM demodulation, fast Fourier transform and resource block mapping are performed on the complex baseband signal, and the frequency domain subcarrier sequence is extracted and assigned to the subcarrier data of the Msg4.

[0019] As a preferred scheme of the remote control method of the relay protection system, the step of comparing the N-bit content of the extracted CRI field with the S-bit content of the salt value through hash operation and code book instruction means that the N-bit content of the extracted CRI field is concatenated with the S-bit content of the salt value, and the SHA-256 hash function is input to perform message padding, block processing and compression iteration, and the first L bits of the hash digest are intercepted and compared with the corresponding values of each instruction in the code book, and if the comparison is successful, the instruction is stored in the verified instruction queue, otherwise the Msg4 response message data is discarded after M instructions are traversed.

[0020] As a preferred scheme of the remote control method of the relay protection system, the step of executing the instruction by the controlled end includes the following steps,

[0021] The digital twin model requests the SCADA to provide power grid topology state data and PMU synchronous phasor data according to the verified instruction, and combines the data into a time-space data matrix;

[0022] The fault detection logic unit verifies according to the instruction type difference;

[0023] The adaptive parameter generator dynamically calculates the optimal action delay according to the verification result.

[0024] As a preferred scheme of the remote control method of the relay protection system, the step of optimizing the channel parameter by the SPARROW algorithm comprises the following steps,

[0025] The instruction receiving success rate, the end-to-end delay and the number of false actions in the feedback data after the controlled end executes the instruction are compared with the preset performance threshold;

[0026] When the index is not up to standard, the optimal truncation length is calculated by inversely solving the channel capacity formula, the salt value update period and the initialization vector are adjusted, the new parameters are transmitted to the base station through the IPSec encrypted tunnel to update the SIB broadcast message, and the configuration parameters are solidified after being tested and verified.

[0027] As a preferred scheme of the remote control method of the relay protection system, the step of resetting the communication link and the calculation unit to the initial state comprises the following steps,

[0028] The control end deletes the verified instruction queue record and covers the storage medium, physically erases the codebook to the all-zero state, and resets the linear feedback shift register of the salt value generator;

[0029] The controlled end turns off the radio frequency link power supply, covers the temporary buffer data through the DMA controller, resets the OFDM demodulator channel estimation matrix and the state register of the hash operation unit.

[0030] In a second aspect, the present application provides a remote control system of a relay protection system, comprising,

[0031] The instruction negotiation module determines the instruction codebook in advance by the control end and the controlled end, sends the codebook to the base station through the physical uplink shared channel, and generates the corresponding Msg4 response message broadcast to the controlled end;

[0032] The instruction verification module receives the Msg4 response message by the controlled end, extracts the CRI field and the salt value after radio frequency demodulation, digital signal processing and CRC check, compares the salt value with the codebook instruction through hash operation, and stores the matched instruction into the verified instruction queue;

[0033] An execution optimization module, after the controlled end executes the instruction, feeds back performance data to the control end, the control end optimizes the channel parameters through the SPARROW algorithm, updates the truncation length, the salt value period and the initialization vector, verifies and solidifies the parameters after updating by the base station configuration, and

[0034] A cleaning reset module, the control end and the controlled end synchronize to clear the historical instruction record, the code book and the salt value register, and reset the communication link and the computing unit to the initial state.

[0035] In a third aspect, the present application provides a computer device comprising a memory and a processor, the memory storing a computer program, wherein the computer program, when executed by the processor, implements any step of the remote control method of the relay protection system according to the first aspect of the present application.

[0036] In a fourth aspect, the present application provides a computer readable storage medium storing a computer program, wherein the computer program, when executed by the processor, implements any step of the remote control method of the relay protection system according to the first aspect of the present application.

[0037] The present application has the following beneficial effects: the CRI field is used to embed the hash truncation value and combined with the salt value interference, so that the instruction is transmitted without identity identification in the standard communication protocol, the base station only forwards and does not store the associated state, effectively resisting the man-in-the-middle attack and traffic analysis; the SCADA topological data and the PMU measurement value are fused in real time through the digital twin model, the differential verification strategy is adopted, and the best action delay is dynamically calculated combined with the inverse time limit characteristic formula, so that the high-voltage line protection action accuracy is improved; the digital twin model fuses the SCADA topological data and the PMU measurement data, realizes the overcurrent, topological and directional triple verification of the trip instruction through the space-time matrix analysis, reduces the misoperation rate, and the adaptive parameter generator dynamically adjusts the action delay according to the fault current decay rate to ensure the protection selectivity; the hash truncation length and the salt value update period are adjusted in real time based on the SPARROW algorithm, and the optimal balance between channel capacity and security is realized to shorten the end-to-end delay. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0039] Fig. 1 The flowchart of the remote control method of the relay protection system.

[0040] Fig. 2 The schematic diagram for generating the Msg4 response message.

[0041] Fig. 3 Fig. 1 is a schematic diagram of instruction verification and execution.

[0042] Fig. 4 Fig. 2 is a schematic diagram of SPARROW algorithm optimization. DETAILED DESCRIPTION

[0043] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0044] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given herein. In other instances, well-known methods have not been described in detail in order to avoid unnecessarily obscuring the present application. Therefore, the specific embodiments discussed herein are illustrative, and not restrictive, of the present application.

[0045] Secondly, the term "one embodiment" or "an embodiment" as used herein means that a particular implementation can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Furthermore, the following terms, as used in the specification and appended claims, shall not be limited to the items listed below, but shall have the meanings set forth herein. Additionally, unless otherwise noted, terms such as "first" and "second" are used to differentiate between similar elements, however, these elements should not be limited by these terms. The term "operatively coupled" is used to describe some useful connection between elements, however, the connection can not necessarily be direct. The term "operatively connected" is used to describe some useful connection between elements, however, the connection can not necessarily be direct.

[0046] BRIEF DESCRIPTION OF DRAWINGS Figs. 1-4 Fig. 1 is a schematic diagram of instruction verification and execution.

[0047] S1. The control end and the controlled end determine a codebook in advance before communication, wherein the codebook contains M kinds of relay protection instructions, for example, m1 corresponds to a trip instruction, m2 corresponds to a reset instruction, and so on until mM corresponds to the Mth kind of relay protection instruction. Each instruction is converted by a coding rule to ensure that it can be correctly identified and executed in the subsequent communication process; the control end starts a communication process in a communication network environment, constructs a Msg3 message frame according to a standard specified random access process.

[0048] Further, in the construction process, the control end selects the relay protection instruction to be sent from the pre-determined codebook.

[0049] The specific operation steps of converting each instruction by a coding rule are as follows:

[0050] The control end selects a target relay protection instruction from the code book, extracts a unique identifier corresponding to the target relay protection instruction as original input data, and simultaneously generates a random salt value of a specified length by a random generator; the original instruction identifier and the random salt value are spliced to form a composite instruction data with security protection; a standardized byte padding operation is performed on the composite instruction data to ensure that the data length meets the input requirements of a hash function. The padded composite instruction data is sent to an encryption hash operation unit to generate a fixed-length digest value using a hash algorithm; the generated fixed-length hash digest value is processed by a bit interception module to retain the first N significant bits as a core code segment; the core code segment is converted into a physical layer symbol sequence suitable for wireless channel transmission by a baseband modulator; and the symbol sequence is embedded in a CRI field of a Msg3 message frame according to the format specified by the communication protocol, to complete the complete conversion process of the instruction to the communication message.

[0051] In the CRI (contention resolution identifier) field of the Msg3 message frame, the selected relay protection instruction is converted into a specific numerical form according to a predetermined encoding rule to form an encoded instruction.

[0052] It should be noted that the conversion process of converting the selected relay protection instruction into a specific numerical form ensures that the instruction information can be completely and accurately embedded in the CRI field while maintaining compatibility with the standard communication protocol.

[0053] Further, the specific numerical form is an encrypted and protocol-adapted instruction digital fingerprint that retains the semantics of the original instruction and meets the security transmission requirements of wireless communication, and typical implementation methods include a hash truncated value, an encrypted short token, or an instruction index after error correction encoding.

[0054] After encoding, the control end sends the Msg3 message frame containing the encoded instruction to the base station through the physical uplink shared channel and randomly generates a salt value as an interference factor; after the base station receives the Msg3 message frame, the CRI field is processed according to the communication protocol specification to generate a corresponding Msg4 response message.

[0055] Further, the specific operation steps of processing the CRI field are as follows:

[0056] The base station first performs integrity check on the received Msg3 message, including checking whether the message format conforms to the standard, whether the CRC check is correct, etc.; the base station extracts the CRI field from the Msg3 message that passes the verification, and strictly follows the field position and length specified in the protocol during the extraction process to ensure that no other field content is misextracted; the base station converts the extracted CRI field from the physical layer format at the time of reception to the internal format that can be processed by the MAC layer, and the conversion process includes bit order adjustment, byte alignment processing, and value range check; the converted CRI value is stored in the memory buffer of the base station; when generating the Msg4 response message, the base station sets the processed CRI field to the value corresponding to the received Msg3 message.

[0057] The base station broadcasts the Msg4 response message containing the processed CRI field through the physical downlink shared channel.

[0058] Further, the Msg4 response message of the processed CRI field satisfies the following conditions: the controlled end can passively receive by listening to the physical downlink shared channel; for any relay protection instruction, there is a unique Msg4 response message corresponding thereto; the Msg4 response message does not contain the identity information of the control end and the controlled end; the base station does not retain the association state of Msg3 and Msg4.

[0059] S2. The controlled end starts the radio frequency receiving circuit, continuously listens to the physical downlink shared channel, captures the Msg4 response message containing the processed CRI field and performs low-noise amplifier amplification, the amplified radio frequency signal is input into the mixer and mixed with the fixed frequency signal generated by the local oscillator, the frequency of the local oscillator is set to the base station downlink center frequency minus the intermediate frequency frequency, and the intermediate frequency signal is output; after the intermediate frequency signal is filtered by the band-pass filter, the amplitude is adjusted by the automatic gain control amplifier, and the digital intermediate frequency signal is sampled by the analog-to-digital converter; the digital intermediate frequency signal is input into the digital demodulator, and the phase-accurate reference carrier is generated by the CORDIC algorithm; the digital intermediate frequency signal is twice mixed with the quadrature reference carrier by the digital downconverter, and the in-phase component and the quadrature component are separated; after the twice mixing, the signals of the in-phase component and the quadrature component separated are subjected to multi-stage decimation filter chain for down-sampling; the down-sampled in-phase component and the quadrature component are combined into a complex baseband signal, and the sampling interval is aligned with the orthogonal frequency division multiplexing symbol period, and the output is a time domain complex baseband signal.

[0060] The time domain complex baseband signal input automatic gain control loop dynamically adjusts the variable gain amplifier coefficient by detecting the signal envelope root mean square value to obtain a gain-adjusted signal; the gain-adjusted signal is sent to an orthogonal frequency division multiplexing demodulator, the cyclic prefix is removed first, and then the time domain signal is converted into a frequency domain subcarrier sequence through fast Fourier transform; according to the resource block mapping table of the physical downlink shared channel, the subcarrier data of the subcarriers assigned to the Msg4 response message is extracted from the frequency domain subcarrier sequence to obtain a frequency domain orthogonal frequency division multiplexing symbol sequence.

[0061] The frequency domain orthogonal frequency division multiplexing symbol sequence is demodulated and mapped to convert the modulation symbol into soft bit information; the soft bit information is recovered into the transmission block data before encoding through the forward error correction decoder; the decoded transmission block data is subjected to cyclic redundancy check, invalid data blocks failing the check are discarded, and the valid transmission block data is subjected to search for a synchronization header sequence to determine the starting boundary of the Msg4 response message frame, and is output as a time-aligned Msg4 response message bit stream.

[0062] The time-aligned Msg4 response message bit stream is hierarchically parsed according to the transmission block structure: the MAC layer header is stripped to obtain the load type indication, the CRI broadcast message is identified, the starting bit position of the CRI field and the offset of the salt value are located from the load data according to the field layout; the N-bit content of the CRI field and the S-bit content of the salt value are intercepted using a fixed-length extractor and stored in the continuous storage unit of the controlled end temporary buffer.

[0063] The controlled end reads the pre-extracted N-bit content of the CRI field and the S-bit content of the salt value from the continuous storage unit of the temporary buffer, loads the S-bit content of the salt value to the salt value register of the hash operation unit; at the same time, the pre-determined codebook is loaded from the non-volatile memory, and the first relay protection instruction in the codebook is selected as the current candidate instruction in sequence.

[0064] The bit stream of the current candidate instruction is concatenated with the S-bit content in the salt value register to form an input data stream with a length of N+S bits, which is input to the same SHA-256 hash function operation unit as the base station; the hash function operation unit performs SHA-256 standard operation on the concatenated N+S-bit data, including message padding, block processing, and 64 rounds of compression iteration, to finally generate a 256-bit hash digest.

[0065] The 256-bit hash digest is transmitted to the bit interception unit, the interception length L is set, and the first L bits of the hash digest are extracted as the truncated hash value of the current candidate instruction according to the pre-configured interception length L; the intercepted L-bit hash value is sent to the comparator for bit-by-bit comparison with the first L bits of the CRI field stored in the temporary buffer, and the comparator outputs a matching flag signal.

[0066] If the match flag signal is true, it is determined that the current candidate instruction is a valid relay protection instruction, which is stored in the verified instruction queue, and the subsequent candidate instruction traversal is terminated; if the match flag signal is false, the next candidate instruction in the codebook is selected to repeat the cascade, hash operation, interception and comparison, until all M candidate instructions in the codebook M are traversed.

[0067] When all M candidate instructions are traversed and the match flag signal is not triggered, the CRI field and the salt value in the temporary buffer are cleared, the Msg4 response message bit stream received this time is discarded, and the radio frequency receiving circuit waits for a new Msg4 response message.

[0068] S3. The relay protection instruction in the verified instruction queue is input to the digital twin model of the relay protection system, and the digital twin model immediately sends a data request command to the SCADA; after receiving the request, the SCADA extracts the current power grid topology state data from the SCADA real-time database, including the opening and closing position signals of all circuit breakers, the mechanical position indication of the disconnector, and the pre-configured protection area division parameters.

[0069] The digital twin model simultaneously sends a synchronous measurement request to the PMU device, and the PMU device returns the synchronous phasor data of three-phase voltage and current, including amplitude, phase angle and frequency information.

[0070] After receiving the current power grid topology state data provided by the SCADA, the digital twin model first performs data validity check, checks the CRC check code and time stamp continuity; converts the current power grid topology state data that passes the check into a node-branch association matrix, each element in the node-branch association matrix representing the connection state of the corresponding electrical node; at the same time, the phasor measurement data provided by the PMU device is detected and corrected for bad data, and abnormal values caused by measurement noise or communication interference are removed.

[0071] The digital twin model combines the node-branch association matrix provided by the SCADA and the synchronous phasor data provided by the PMU into a space-time data matrix.

[0072] Further, the row dimension of the space-time data matrix represents the electrical node number, and the column dimension includes voltage amplitude, phase angle, branch current and device state parameters.

[0073] The space-time data matrix is input to the fault detection logic unit, which performs differentiated verification according to the relay protection instruction type, as follows:

[0074] When the relay protection instruction is a trip instruction, the fault detection logic unit extracts the target line PMU three-phase current sampling sequence from the space-time data matrix, calculates the positive sequence current effective value using the full-cycle Fourier algorithm; compares the positive sequence current effective value with the overcurrent setting value, when the positive sequence current effective value is greater than or equal to the preset overcurrent setting value, the overcurrent flag is triggered; otherwise, a current non-exceeding warning is generated and the instruction execution is suspended.

[0075] The fault detection logic unit reads the node-branch association matrix provided by SCADA, locates the status of the circuit breakers at both ends of the target line; checks whether the status bits of QF1 and QF2 in the association matrix are closed and whether there is no maintenance sign on the adjacent branch; if the topology state is abnormal, a topology conflict event log is generated and the process is terminated.

[0076] The fault current direction measured by PMU is compared with the protection area boundary in the SCADA topology, and whether the fault point is located in the instruction target area is verified by calculating the phase angle difference of the fault component.

[0077] When the relay protection instruction is a reset instruction, the fault detection logic unit checks the clearing timestamp of the corresponding fault ID in the SCADA event record, and compares it with the current GPS time, when the time difference reaches the preset fault clearing confirmation time limit threshold, it is determined that the fault has been cleared; otherwise, a fault non-clearing warning is generated.

[0078] Further, the fault clearing confirmation time limit threshold is set according to the specific requirements of fault clearing time, for example, for 220kV and above voltage grade lines, the value range of fault clearing confirmation time limit threshold is 150-200ms, for 110kV voltage grade lines, the value range of fault clearing confirmation time limit threshold is 200-300ms, for 35kV and below voltage grade lines, the value range of fault clearing confirmation time limit threshold is 300-500ms.

[0079] The fault clearing confirmation time limit threshold refers to the minimum waiting time from detecting fault removal (such as circuit breaker tripping) to allowing reset operation.

[0080] The fault detection logic unit obtains the bus voltage U measured by PMU from the space-time data matrix, calculates the voltage recovery rate; when the voltage recovery rate reaches the preset recovery judgment threshold and continuously meets the preset stable cycle number, it is determined that the voltage recovery is effective.

[0081] Further, the voltage recovery judgment threshold is formulated according to the voltage stability rules, for example, for high-voltage power grid (220kV and above), the preset recovery judgment threshold is 90% of the nominal voltage, for medium-voltage power grid (35-110kV), the preset recovery judgment threshold is 88% of the nominal voltage, for low-voltage power grid (10kV and below), the preset recovery judgment threshold is 85% of the nominal voltage.

[0082] The determination of the number of stable periods is based on the characteristics of the transient process of the power system and the response characteristics of the protection device, for example, the high-voltage line protection takes 3 cycles (60 ms) to accurately capture the fault characteristics, the medium-voltage bus protection needs 5 cycles (100 ms) to identify the faults inside and outside the area, and the low-voltage distribution protection uses 8 cycles (160 ms) to avoid misjudgment of load fluctuations.

[0083] The fault detection logic unit inputs the verification result to the adaptive parameter generator. The adaptive parameter generator first analyzes the overcurrent flag, the topology conflict event log, or the fault non-clearing warning in the verification result. When the verification result shows that the relay protection instruction is a trip instruction and the overcurrent flag is triggered, the adaptive parameter generator extracts the current decay curve of three cycles after the fault occurs from the three-phase current sampling sequence provided by the PMU device, fits an exponential decay function using the least squares method, and calculates the fault current decay rate. According to the inverse time limit characteristic formula, the fault current decay rate is substituted into the inverse time limit curve equation to dynamically calculate the optimal action delay. At the same time, the adaptive parameter generator reads the node-branch association matrix provided by SCADA, performs a breadth-first search centered on the target line, traverses the adjacent two levels of electrical nodes, and combines the fault current direction information measured by PMU to generate a list of minimum isolation domain boundary nodes after excluding reverse current branches.

[0084] When the verification result shows that the relay protection instruction is a reset instruction and the voltage recovery rate reaches the preset fault clearing confirmation time limit threshold, the adaptive parameter generator extracts the standard deviation of the voltage fluctuation of the recent few cycles from the bus voltage sequence measured by PMU, and refers to the voltage stability criterion. When the voltage fluctuation is lower than the preset voltage fluctuation limit, the optimal action delay is set to zero to achieve instantaneous reset. Otherwise, the reset delay is extended in inverse proportion to the voltage recovery rate. If the fault detection logic unit outputs the current non-exceeding warning or the topology conflict event log, the adaptive parameter generator immediately generates an instruction discard flag and embeds a timestamp and a SCADA event ID in the flag.

[0085] Further, the determination of the voltage fluctuation limit is mainly based on the tolerance of power equipment and the requirements of power quality, for example, the continuous operation of rotating machines (generators / motors) allows a voltage deviation of ±5% of the rated value, the voltage fluctuation within the tap adjustment range of the transformer should not exceed ±2.5% of the rated value, and the long-term operation of the capacitor bank allows a voltage fluctuation of up to 110% of the rated value.

[0086] S4. The feedback data after the relay is executed is fed back to the control end through the uplink, and the feedback data packet contains the circuit breaker position signal, the fault recording waveform data, and the GPS timestamp accurate to the microsecond level; after receiving the feedback data packet, the control end performs data integrity check, checks the CRC check code and the timestamp continuity, and ensures that the data has not been tampered with in the transmission process.

[0087] The feedback data that passes the verification is parsed, and the control end extracts three key performance indicators from the data packet: relay protection instruction reception success rate, end-to-end execution delay, and misoperation times; the relay protection instruction reception success rate is calculated by the ratio of the number of successfully executed instructions to the total number of sent instructions in the period; the end-to-end execution delay is determined by comparing the difference between the relay protection instruction sending timestamp and the relay action timestamp; the misoperation times record the relay error execution or refusal to execute instructions.

[0088] The parsed key performance indicators are input into the SPARROW parameter optimization algorithm, and the instruction reception success rate is compared with the preset performance threshold value; when the success rate is lower than the preset performance threshold value, the channel parameter adjustment is triggered; the configuration parameters of the current ELISHA framework, such as the hash truncation length, the salt value update period, and the codebook size, are read.

[0089] Further, the performance threshold value is selected according to the grid voltage level (high voltage / medium voltage / low voltage) and the channel environment (strong interference / weak interference), for example, if the instruction reception success rate is less than the performance threshold value, the salt value update period is shortened; if the end-to-end delay is greater than the performance threshold value, the hash truncation length is reduced; if the misoperation times are greater than the performance threshold value, the salt value is regenerated or the redundant encoding is increased.

[0090] Based on the read current configuration parameters, inverse operation is performed according to the channel capacity calculation formula to solve the optimal truncation length that can meet the target channel capacity.

[0091] The control end generates a corresponding salt value update strategy according to the optimal truncation length, shortens the salt value update period, increases the frequency of dynamic changes, and updates the initialization vector of the salt value generator.

[0092] The updated parameters are transmitted to the base station through the IPSec encrypted tunnel; after the base station receives the new parameters, the ELISHA configuration parameters in the SIB broadcast message are immediately updated, including the new truncation length, the salt value update period, and the salt value register initialization vector.

[0093] After the base station completes the configuration parameter update, an acknowledgement message is sent to the control end; after the control end receives the acknowledgement, a verification test process is started, a test instruction sequence is sent, and new feedback data is monitored; if the test result meets the expectation, the current parameter configuration is fixed; otherwise, the optimization process is re-executed until a stable working state is reached.

[0094] S5. After receiving the base station configuration update confirmation and the verification test passing, the control end reads the fixed ELISHA configuration parameters and starts trace cleaning, as follows:

[0095] The history instruction record in the verified instruction queue is deleted from the memory, including the instruction content, the timestamp and the associated SCADA event ID, and a cover write operation is performed on the storage medium to ensure that it is not recoverable; the pre-stored code book is reset to a full zero state through a physical erasing circuit, and the code book index pointer is returned to the initial address; the linear feedback shift register of the salt value generator is forced to reset, and the S bit content of the current salt value register is output to the input end of the pseudo-random number generator after being XOR confused to generate a random termination sequence to cover the original salt value.

[0096] The controlled end synchronously executes the radio frequency link cleaning, and the specific implementation is as follows:

[0097] The low noise amplifier power supply is turned off, and the state machine of the digital baseband processor is reset; the N bit content of the CRI field and the S bit content of the salt value stored in the temporary buffer are initiated by the DMA controller to burst transmission, and are filled into the blank data area of the circular write; the channel estimation matrix of the orthogonal frequency division multiplexing demodulator is reset to the default value, and the intermediate register group of the fast Fourier transform operation unit performs a clear operation; the compression function state register of the hash operation unit is forced to initialize through a hardware reset signal, and the match flag latch of the intercept comparator triggers the edge clear circuit.

[0098] The embodiment also provides a remote control system of a relay protection system, which comprises:

[0099] An instruction negotiation module, the control end and the controlled end determine the instruction code book in advance, and the instruction code book is sent to the base station through a physical uplink shared channel, and a corresponding Msg4 response message is broadcast to the controlled end;

[0100] An instruction verification module, the controlled end receives the Msg4 response message, extracts the CRI field and the salt value after radio frequency demodulation, digital signal processing and CRC check, and compares the CRI field and the salt value with the code book instruction through hash operation, and stores the code book instruction in the verified instruction queue after successful matching;

[0101] An execution optimization module, the controlled end feeds back performance data to the control end after executing the instruction, the control end optimizes the channel parameters through the SPARROW algorithm, updates the truncation length, the salt value period and the initialization vector, and verifies and solidifies the parameters after updating the parameters through the base station configuration;

[0102] A cleaning and resetting module, the control end and the controlled end synchronously clean the history instruction record, the code book and the salt value register, and reset the communication link and the calculation unit to the initial state.

[0103] The embodiment also provides a computer device suitable for the remote control method of the relay protection system, which comprises a memory and a processor; the memory is used for storing computer executable instructions, and the processor is used for executing the computer executable instructions to realize the remote control method of the relay protection system proposed in the above embodiment.

[0104] The computer device can be a terminal, which includes a processor, a memory, a communication interface, a display screen and an input device connected by a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is configured to perform wired or wireless communication with an external terminal. The wireless communication can be achieved by WIFI, an operator network, NFC (Near Field Communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, a trackball or a touchpad arranged on the shell of the computer device, or an external keyboard, a touchpad or a mouse, etc.

[0105] The embodiment also provides a storage medium having a computer program stored thereon, the program being executed by a processor to implement the remote control method of the relay protection system according to the above embodiment. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as a static random access memory (SRAM), an electrically erasable programmable read-only memory (EEPROM), an erasable programmable read-only memory (EPROM), a programmable read-only memory (PROM), a read-only memory (ROM), a magnetic memory, a flash memory, a magnetic disk or an optical disk.

[0106] In summary, the application transmits the instruction without identity identification in the standard communication protocol by embedding the hash truncation value in the CRI field and combining the salt value interference, the base station only forwards and does not store the associated state, effectively resisting the man-in-the-middle attack and flow analysis; the real-time fusion of SCADA topological data and PMU measured values is realized through the digital twin model, the differential verification strategy is adopted, and the best action delay is dynamically calculated combined with the anti-time limit characteristic formula, so that the high-voltage line protection action accuracy is improved; the digital twin model fuses the SCADA topological data and the PMU measured data, realizes the overcurrent, topological and direction triple verification of the trip instruction through the space-time matrix analysis, reduces the misoperation rate, at the same time, the adaptive parameter generator dynamically adjusts the action delay according to the fault current decay rate, and ensures the protection selectivity; based on the SPARROW algorithm, the hash truncation length and the salt value update period are adjusted in real time, and the optimal balance between channel capacity and security is realized, and the end-to-end time delay is shortened.

[0107] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method of remote control of a protective relay system, characterized in that: The application relates to a method for transmitting relay protection instructions between a control terminal and a controlled terminal. The control terminal and the controlled terminal have a pre-determined instruction code book, and the control terminal sends the code book to the base station through a physical uplink shared channel to generate a corresponding Msg4 response message which is broadcast to the controlled terminal. The control terminal converts the relay protection instructions in the pre-determined code book into specific numerical forms in the CRI field of the Msg3 message frame according to an encoding rule and randomly generates a salt value as an interference factor. The base station extracts the CRI field after integrity checking of the Msg3 and stores the CRI field in a memory buffer after conversion into a MAC layer format through a physical layer. The base station sets the CRI field value corresponding to the Msg3 in the Msg4 response message and broadcasts the Msg4 response message through a physical downlink shared channel. The controlled terminal extracts the CRI field and the salt value after radio frequency demodulation, digital signal processing and CRC checking of the Msg4 response message, compares the CRI field and the salt value with the code book instructions through a hash operation, and stores the matched instructions in a verified instruction queue. The controlled terminal converts the amplified radio frequency signal into an intermediate frequency signal through a mixer, performs band pass filtering, automatic gain control and analog-to-digital conversion to generate a digital intermediate frequency signal. The CORDIC algorithm is used to generate a quadrature reference carrier, the in-phase / quadrature components are separated through digital down conversion, and a time domain complex baseband signal is output after down sampling. The complex baseband signal is subjected to OFDM demodulation, fast Fourier transform and resource block mapping, and a frequency domain subcarrier sequence is extracted and allocated to the subcarrier data of the Msg4. The CRI field and the salt value are concatenated, input into a SHA-256 hash function, subjected to message padding, block processing and compression iteration, and the first L bits of the hash digest are compared with the corresponding values of each instruction in the code book. The controlled terminal feeds back performance data to the control terminal, the control terminal optimizes channel parameters through the SPARROW algorithm, updates the truncation length, the salt value period and the initialization vector, verifies and solidifies the parameters after configuration and update of the base station, and resets the communication link and the calculation unit to the initial state. The controlled terminal executes the instructions, and the control terminal and the controlled terminal synchronize to clear historical instruction records, code books and salt value registers and reset the communication link and the calculation unit to the initial state.

2. The remote control method of a relay protection system according to claim 1, characterized by: The digital twin model requests the SCADA to provide power grid topology state data and PMU synchronous phasor data according to the verified instructions, and combines the data into a space-time data matrix. The fault detection logic unit verifies according to the instruction type difference. The adaptive parameter generator dynamically calculates the best action delay according to the verification result. The application further relates to a method for optimizing channel parameters through the SPARROW algorithm.

3. The remote control method of a relay protection system according to claim 1, characterized by: The application further relates to a method for analyzing the instruction reception success rate, the end-to-end delay and the misoperation times in the feedback data after execution of the instructions by the controlled terminal and comparing the data with preset performance thresholds. ​ When the index is not up to standard, the inverse solution channel capacity formula calculates the optimal truncation length, adjusts the salt value update period and initializes the vector, and transmits the new parameters to the base station through the IPSec encryption tunnel to update the SIB broadcast message, and solidifies the configuration parameters after testing and verification.

4. The remote control method of a relay protection system according to claim 1, characterized by: The resetting communication link and the computing unit to the initial state include the following steps, The control end deletes the verified instruction queue record and covers the storage medium, physically erases the code book to the all-zero state, and resets the linear feedback shift register of the salt value generator; The controlled end closes the radio frequency link power supply, covers the temporary buffer data through the DMA controller, resets the OFDM demodulator channel estimation matrix and the state register of the hash operation unit.

5. A remote control system of a relay protection system based on the remote control method of the relay protection system according to any one of claims 1 to 4, characterized in that: It includes, The instruction negotiation module, the control end and the controlled end determine the instruction code book in advance, and send it to the base station through the physical uplink shared channel, and generate the corresponding Msg4 response message broadcast to the controlled end; The instruction verification module, the controlled end receives the Msg4 response message, extracts the CRI field and the salt value after radio frequency demodulation, digital signal processing and CRC check, and compares them with the code book instructions through hash operation, and stores them in the verified instruction queue after successful matching; The execution optimization module, the controlled end feeds back the performance data to the control end after executing the instruction, the control end optimizes the channel parameters through the SPARROW algorithm, updates the truncation length, the salt value period and the initialization vector, and verifies and solidifies the parameters after updating by the base station configuration; The cleaning and resetting module, the control end and the controlled end synchronize to clear the historical instruction record, the code book and the salt value register, and reset the communication link and the computing unit to the initial state. 6.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is characterized in that: The processor executes the computer program to realize the steps of the remote control method of the relay protection system of any one of claims 1-4.

7. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program is executed by the processor to realize the steps of the remote control method of the relay protection system of any one of claims 1-4.

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