CN-122001509-A - Wireless-based three-phase data synchronization method in transformer substation

CN122001509ACN 122001509 ACN122001509 ACN 122001509ACN-122001509-A

Abstract

The invention relates to the technical field of three-phase data synchronization, in particular to a wireless-based three-phase data synchronization method in a transformer substation, which comprises the steps of setting up an independent synchronization arbitration terminal and a plurality of distributed data acquisition units, and broadcasting a synchronous beacon carrying a high-precision master time stamp by the synchronous arbitration terminal, establishing a frequency drift model of the local real-time clock relative to the master clock after receiving the synchronous beacon by each data acquisition unit, and calculating an accurate drift coefficient. Based on the drift coefficient, the data acquisition unit adopts a digital differential comprehensive algorithm to carry out periodic fine adjustment on the counter reload value of the local real-time clock. Meanwhile, the data acquisition unit binds sampling data with a sampling point position identifier at the receiving moment of the synchronous beacon, and the data fusion unit performs final sample alignment on the data stream from three phases according to the position identifier, so that dual high-precision synchronization of physical layer frequency synchronization and data layer phase alignment is realized.

Inventors

HE LONG
LIU YONG
LIU JUN
XI TAO
LIU HAIBO
WANG LIANG
LU CONG
ZHU YONGMING
MA JINCAI
LU GANG
ZHAO SHIYU
WEI XINHUI
DIAO HAIYANG
LI CUNMING
Bu Shouwen

Assignees

国网新疆电力有限公司昌吉供电公司
安徽正广电电力技术有限公司

Dates

Publication Date: 20260508
Application Date: 20251212

Claims (10)

1. A wireless-based three-phase data synchronization method in a substation, comprising: Generating a reference master clock signal by an oscillator in the synchronous arbitration terminal, generating a synchronous beacon data packet containing a 64-bit resolution master time stamp by the synchronous arbitration terminal based on the reference master clock signal, and broadcasting and transmitting the synchronous beacon data packet to all data acquisition units in a coverage range by a wireless transceiver module in a preset broadcasting period; the method comprises the steps that three data acquisition units continuously monitor synchronous beacon data packets through built-in wireless transceiver modules, when a microcontroller of any data acquisition unit detects that the reception of an effective synchronous beacon data packet is interrupted, a master time stamp is latched, the current count value of a local real-time clock counter is latched to serve as a local receiving time stamp, a time scale pair formed by the master time stamp and the local receiving time stamp is stored in a memory, a drift coefficient of the local real-time clock relative to the frequency deviation of the master clock is calculated, and an adjusted real-time clock interruption period target value is determined based on the drift coefficient; the central data fusion unit receives and analyzes the data from the data acquisition unit and outputs synchronous three-phase time sequence data.
2. The three-phase data synchronization method based on wireless in a transformer substation according to claim 1, wherein the calculation process of the drift coefficient and the real-time clock interrupt period target value is as follows: The data acquisition unit maintains a time mark pair queue in a memory of the data acquisition unit, and when the number of time mark pairs in the queue reaches a preset threshold, the microcontroller of the data acquisition unit adopts a least square method to perform linear regression fitting on a main time stamp sequence and a local receiving time stamp sequence of all the time mark pairs in the queue, and calculates a drift coefficient representing the frequency deviation of a local real-time clock relative to the main clock; The microcontroller of the data acquisition unit determines an adjusted real-time clock interrupt period target value according to the calculated drift coefficient, the target value is equal to the nominal sampling period divided by the drift coefficient, and executes a digital differential analyzer algorithm to dynamically adjust the interrupt reload value of the real-time clock counter in a time scale.
3. The wireless-based three-phase data synchronization method in a transformer substation according to claim 2, wherein the data acquisition units are each configured with a ring-shaped data buffer area for storing current or electric field intensity samples acquired by the analog-to-digital converter, and the storage address index of the next sample to be written in the ring-shaped data buffer area is recorded as a synchronization position identifier while the main timestamp and the local receiving timestamp are latched; And after the data acquisition unit completes the acquisition of one data block, the data block, a main time stamp contained in the last synchronous beacon triggering the data block acquisition period and a synchronous position identifier associated with the main time stamp are packaged together into a data frame, and the data frame is transmitted to the central data fusion unit through the wireless transceiver module of the data frame.
4. A method for synchronizing three-phase data based on wireless in a transformer substation according to claim 3, wherein the central data fusion unit receives and analyzes the data frame from the data acquisition unit, takes the received master time stamp as a global time reference, takes the synchronization position identifier as a phase reference point in the data block, performs cyclic shift or interpolation processing on each phase of data block, performs precise alignment on the three-phase data stream at the sample level, and finally outputs synchronized three-phase time sequence data.
5. The three-phase data synchronization method based on wireless in a transformer substation according to claim 1, wherein the wireless transceiver module of the synchronization arbitration terminal adopts a long-distance low-power spread spectrum modulation technology, the modulation mode is gaussian frequency shift keying combined with direct sequence spread spectrum, the spread spectrum factor is twelve, and the structure of the synchronization beacon data packet sequentially comprises a preamble field, a frame header field, a unique address field of the synchronization arbitration terminal, a 64-bit master time stamp field and a cyclic redundancy check code field.
6. The method of claim 2, wherein the queue of time-scale pairs is a circular buffer structure with a maximum capacity of ten time-scale pairs, and wherein the linear regression fit calculates the drift factor k= (Σ (Δt li *ΔT mi ))/(Σ(ΔT li 2 )) by least squares fitting the time difference sequences Δt mi and Δt li of adjacent time-scale pairs, wherein Δt mi ＝T m{i+1} -T mi ,ΔT li ＝T l{i+1} -T li , i are 1 to 9.
7. The method of claim 6, wherein the digital differential analyzer algorithm maintains a 32-bit error accumulator in the microcontroller, accumulates the frequency control word N to the error accumulator before each real-time clock interrupt service routine is completed, and if overflow occurs, sets the counter reload value of the current interrupt period to floor (T target /T base ) -1, otherwise, to floor (T target /T base ), wherein T target is the adjusted real-time clock interrupt period target value, T base is the local clock baseband period, and n=round ((T targe t/T base )*2 16 ).
8. A method for synchronizing three-phase data based on radio in a transformer substation according to claim 3, wherein the analog-to-digital converter is a 24-bit synchronous sampling analog-to-digital converter, the sampling operation is directly triggered by a real-time clock interrupt signal after frequency compensation, the depth of the ring-shaped data buffer area is 1024, the direct memory access controller manages data writing, the synchronous position identifier is a 16-bit unsigned integer, and the value range is 0 to 1023.
9. A method of three-phase data synchronization based on radio within a substation according to claim 3, wherein the data frames comprise a phase identification of the data acquisition unit, 256 24-bit sample samples, eight bytes of master time stamp, two bytes of synchronization position identifier and two bytes of frame check code, each phase data acquisition unit transmitting the data frames within an allocated time slot using a time division multiple access mechanism.
10. The wireless-based three-phase data synchronization method in a transformer substation according to claim 1, wherein the central data fusion unit selects a minimum value P min of a synchronization position identifier in a three-phase data block as an alignment reference, and circularly shifts left (P A -P min )、(P B -P min )、(P C -P min ) samples for a phase, B phase and C phase data blocks respectively, and if the shift amount is non-integer, linear interpolation or cubic spline interpolation is adopted to generate an intermediate sample; after finishing three-phase data stream alignment, the central data fusion unit calculates the synthesized zero sequence current amplitude under normal working conditions, and if the amplitude exceeds a preset noise threshold, a forced synchronization instruction is sent to the synchronization arbitration terminal through a wireless channel to trigger one-time instant synchronization beacon broadcasting.

Description

Wireless-based three-phase data synchronization method in transformer substation Technical Field The invention relates to a data synchronization method, in particular to a wireless-based three-phase data synchronization method in a transformer substation, and belongs to the technical field of three-phase data synchronization. Background With the deep advancement of smart power grid construction, the requirement of a substation automation system on high-precision synchronous sampling data is urgent, and especially in key application scenes such as single-phase grounding fault positioning, the synchronism of three-phase current and electric field signals directly determines the accuracy and positioning reliability of fault feature extraction. The traditional fault detection is mostly dependent on single-phase data or asynchronous three-phase data, so that key grounding characteristic quantities such as zero sequence current and the like are difficult to effectively capture, and the risk of misjudgment or missed judgment is obviously increased. Therefore, obtaining high-precision synchronous three-phase electric quantity has become a core premise for improving fault sensing capability of the power distribution network. The three-phase data synchronization method based on wireless communication is a preferable technical path of field terminal equipment due to flexible deployment, low cost and no need of depending on a wired time synchronization network. The method generally relies on the terminal to periodically broadcast time synchronization signals, and local sampling time sequences are adjusted after the time synchronization signals are received by each phase of acquisition units so as to realize the alignment of three-phase sampling points on a time domain. The core aim is to control the three-phase sampling synchronous error within the microsecond precision range by clock calibration and sampling point offset compensation under the constraint of the limited bandwidth and the uncertain transmission delay of the micropower wireless communication, thereby meeting the strict requirement of zero sequence synthesis on phase consistency. In the prior art, although the GPS/Beidou satellite pair time can realize nanosecond synchronization, the GPS/Beidou satellite pair time is dependent on external signals and is easy to lose efficacy in an indoor or shielding environment, the master station broadcasting pair time method is limited by a communication level and network delay, consistency among multiple terminals is difficult to ensure, and the sampling compensation method based on a communication channel can partially offset transmission jitter, but does not fully consider inherent drift and initial phase deviation of a local real-time clock (RTC), so that synchronization accuracy is gradually deteriorated under long-term operation. Especially under the working conditions of short duration and quick amplitude change of single-phase grounding fault current, if the synchronous error of the three-phase sampling points exceeds 60 microseconds (corresponding to about 1.1 degree of the power frequency phase angle error), the zero-sequence current waveform is obviously distorted, and the sensitivity and reliability of fault criteria are reduced. Therefore, a three-phase data synchronization method capable of dynamically calibrating the sampling initial position and effectively suppressing the phase offset by combining the minimum time unit of the RTC in a wireless communication environment is needed to realize high-precision and high-robustness fault feature acquisition. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a wireless-based three-phase data synchronization method in a transformer substation. The aim of the invention can be achieved by the following technical scheme: A three-phase data synchronization method based on wireless in a transformer substation is characterized in that an independent synchronization arbitration terminal and a plurality of distributed data acquisition units are established, the synchronization arbitration terminal broadcasts a synchronization beacon carrying a high-precision master time stamp, each data acquisition unit not only records instantaneous time deviation after receiving the synchronization beacon, but also carries out linear regression analysis on a plurality of groups of master-slave time stamp pairs which are continuously received, a frequency drift model of a local real-time clock relative to a master clock is established, and an accurate drift coefficient is calculated. Based on the drift coefficient, the data acquisition unit adopts a digital differential comprehensive algorithm to carry out periodic fine adjustment on the counter reload value of the local real-time clock, thereby realizing prospective compensation on the sampling period and locking the frequency of the local sampling clock and the frequency of the main clock. Meanwh