Substation device clock synchronization improving method

Abstract

The invention discloses a substation device clock synchronization improving method. The method comprises following steps of step 1, calculating the frequency offset of a local clock; solving the maximum likelihood estimation value of the frequency offset eta of the local clock; step 2, calculating the phase offset of the local clock; calculating the average value of N times of clock synchronization phase offsets phik as a phase offset value phi; step 3, compensating the crystal oscillator natural frequency of the local clock; and step 4, compensating the local clock. For that when the network load of an intelligent substation is relatively high, network transmission round-trip delays are asymmetric, correction of the local clock through one-time clock synchronization according to a conventional precision time protocol PTP is relatively high in error, the invention provides the substation device clock synchronization improving method; and according to the method, through adoption of a statistics method, after many times of time synchronization, the optimum solutions of the frequency offset and phase offset errors of the local clock are calculated, and further compensation is carried out.

Description

technical field [0001] The invention relates to an improved method for clock synchronization of substation equipment, belonging to the technical field of substation network time synchronization. Background technique [0002] The modern substation takes the digitalization of the whole station information, the networking of the communication platform, and the standardization of information sharing as the basic requirements, and automatically completes basic functions such as information collection, measurement, control, protection, monitoring, and measurement. However, regardless of the calculation and processing of measurement and control devices, protection devices, or metering devices, the sampling data should be collected at the same time point to avoid phase and amplitude errors. For protection such as overcurrent protection, because the short-term stability of the local crystal oscillator clock of the microcomputer protection is very high, it will not affect the operatio...

AI Technical Summary

Problems solved by technology

Although IEEE1588 eliminates the impact of upper-layer processing delay and physical layer processing delay through the PTP protocol, it has the same limitations as all network timing algorithms. The transmission delay of time information is based on the same transmission direction, but in actual use, it is impossible to absolutely satisfy this premise

Although the IEEE1588 protocol introduces transparent clocks and boundary clocks, the switch needs to support the IEEE1588 clock mechanism. At the same time, the randomness and low frequency of network transmission delay measurement, but when the network load changes suddenly, the packet will be in the transmission direction. The difference in delay becomes larger, so the assumption that formula (1.1) and formula (1.2) are established - the round-trip delay of information packet exchange is equal is not true, figure 1 Middle T m1 , T s1 , T s3 , T m3 The line connecting the four points will be a non-isosceles trapezoid. If the local clock phase offset is simply calculated by formula (1.2), it will bring a large error to the correction of the local clock

[0011] This method only compensates the phase offset of the local clock, but does not compensate the frequency offset of the local clock

The root cause of the phase offset is that the local crystal oscillator clock frequency is not very accurate, and there is an error compared with the main clock frequency. After a long period of error accumulation, the phase deviation is caused.

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