CN103036635A - Merging unit synchronization time hack method adaptive for relay protection application and based on Institute of Electrical and Electronic Engineers (IEEE) 1588 - Google Patents

Abstract

The invention belongs to the technical field of power transmission and transformation, and particularly relates to a method for synchronous time synchronization of a merging unit adapted to relay protection applications based on IEEE1588 time synchronization in an intelligent substation. The merging unit switches between three time synchronization states: out-of-synchronization state, Synchronous following state, synchronous punctual state. Based on the assumption that the frequency of the crystal oscillator of the merging unit cannot be mutated, the present invention compares its own clock with the timing clock, and discards the synchronizing message if the time difference exceeds the set range, which solves the occasional short-term blocking of the protection device during the practical application of IEEE1588 major problem. The invention has been fully tested and verified, can avoid short-term abnormalities of various clock systems on the basis of ensuring the reliability of the relay protection system, and can be directly applied to the merging unit of engineering application.

Description

Synchronous Time Synchronization Method for Merging Unit Adapted to Relay Protection Application Based on IEEE1588

technical field

The invention belongs to the technical field of power transmission and transformation, and in particular relates to a synchronous time synchronization method for merging units adapted to relay protection applications based on the IEEE1588 time synchronization mode in an intelligent substation.

Background technique

The power system is a whole composed of the production, transmission, distribution and consumption of electric energy, and occupies a very important position in the national economy. As the basis and premise of realizing low-carbon electricity, smart grid technology has developed rapidly in many countries in recent years. my country proposes to build a unified and strong smart grid with the UHV grid as the backbone grid, coordinated development of grids at all levels, and featuring informatization, automation, and interaction. As an important link in the power system, the substation is responsible for the tasks of voltage conversion and secondary distribution of electric energy. Smart substation is one of the core contents of a strong smart grid. It is an important component and an important support for the integration of wind energy, solar energy and other energy sources into the grid. requirements.

The synchronous sampling of electrical quantity information such as voltage and current in traditional substations is completed in the protection device. The sampling synchronous acquisition between different data channels of the protection device is realized by sending sample and hold pulses, and does not rely on external synchronization and time synchronization signals. Unified the clock source. Different from traditional substations, all intelligent electronic devices (Intelligent Electrical Devices, IEDs) in smart substations must be synchronized with each other and synchronized with external synchronization signal sources. Once the external synchronization signal is lost or the device timing is abnormal, it will cause the protection of the whole station to be blocked and stop running, which will seriously affect the safe and stable operation of the power system. The merging unit is an important part of the interface between the electronic transformer and the protection device. Its main function is to summarize the collected three-phase voltage and current data at the same time and output them in a certain format to the secondary protection and control equipment for information processing and operation. , so the clock synchronization of each IED is actually the clock synchronization of the merging unit.

At present, the commonly used clock synchronization methods in substations include pulse time synchronization, IRIG-B code time synchronization, simple network synchronous time synchronization (SNTP) and precise network synchronous clock (IEEE1588). According to the different applications of the substation, the IEC61850 standard puts forward different levels of synchronization accuracy requirements for IEDs in the substation, and the highest level of accuracy requires 1μs. IEEE1588 Precision Clock Protocol (PTP) is a clock protocol used in the field of industrial control and measurement. Through the combination of software and hardware, and the method of marking time on the physical layer hardware, the synchronization accuracy can reach sub-microsecond level. It can meet the synchronization accuracy requirements of all equipment in the substation.

Contents of the invention

At present, the application of IEEE1588 is still in the pilot stage in the construction of smart substations. Due to the problem that the switch suddenly and incorrectly set the dwell time when forwarding 1588 messages in the engineering site and laboratory, this high-precision network time synchronization Adoption of technology is hampered. When the above situation occurs, the merge unit (Merge Unit, MU) time jumps, and the serial numbers output are discontinuous, so the relay protection device is blocked and out of operation. From the technical requirements of the time synchronization system, of course neither the main clock nor the switch should have any time jump for any reason. If the timing equipment has the function of avoiding such anomalies, the reliability of synchronization will be improved. Based on this idea, the present invention proposes a systematic solution, so that the merging unit can intelligently identify such abnormalities, and the output characteristics can ensure the continuity and reliability of relay protection operation.

Based on the assumption that the crystal oscillator frequency of the merging unit cannot be mutated, the present invention compares its own clock with the timing clock, and discards the timing message if the time difference exceeds the set range. On the basis of this basic principle, fully considering the punctuality of the equipment and abnormal conditions such as master clock jumps, merging unit restarts, etc., a merging unit synchronous time synchronization method based on IEEE1588 adapted to relay protection applications is formed. This method has been fully tested and verified, and can avoid short-term abnormalities of various clock systems on the basis of ensuring the reliability of the relay protection system.

General principle of the present invention:

1. The merging unit cannot skip numbers in the synchronous state, and the protection is not blocked.

2. The full-second punctual edge of the main clock cannot jump, and the time deviation adjustment below a second can adopt a step size of 500ns for each time synchronization cycle.

The present invention is achieved through the following technical solutions:

Based on the IEEE1588-based synchronous time synchronization method of the merging unit adapted to relay protection applications, the merging unit switches between three time synchronization states: out-of-synchronization state, synchronous following state, and synchronous punctual state;

(1) The switching condition from "out of synchronization state" to "synchronous following state" is: consecutive N1(N1∈[2,60]) time synchronization cycles, and the time uniformity error of the timing source is less than T1(T1∈[2,4] ])us, at this time, the merging unit pulls the serial number; for N2 (N2∈[60,120]) consecutive time synchronization cycles, the time uniformity error of the timing source is less than T1(T1∈[2,4])us;

(2) The switching condition from "synchronous following state" to "synchronous punctual state" is: the absolute time error with the timing source is greater than T2(T2∈[5,125])us (one wrong timing), start the punctual timer;

(3) There are two switching conditions from "synchronous punctual state" to "out-of-synchronization state": the punctual timer timing is greater than or equal to T3(T3=5,60)min; continuous N3(N3∈[2,60]) The absolute time difference between the frame message and the merging unit is greater than T2(T2∈[5,125])us and the time uniformity is less than T1(T1∈[2,4])us;

(4) The switching condition from "synchronous punctuality state" to "synchronous following state" is: the absolute time difference between the time synchronization message of the continuous N4 (N4∈[3,20]) frame clock source and the merging unit is less than or equal to T4 (T4∈[5,125] ])us time uniformity is less than T1(T1∈[2,4])us, then the merging unit punctual timer is cleared and the timer is turned off;

(5) The merging unit is in the "synchronous following state": the absolute time error with the timing source is less than T5(T5∈[5,20])us, and it can be synchronized with the timing source through one or multiple time adjustments.

When the punctuality requirement of the merging unit is 4us/10min and the sampling frequency is 4000 points/second, set the switching index according to the following parameters:

(1) The switching condition from "out of synchronization state" to "synchronous following state" is: continuous N1=10 time synchronization cycles, the time uniformity error of the timing source is less than T1=3us, at this time the merging unit pulls the serial number; continuous N2=64 time synchronization cycle, the time uniformity error of the timing source is less than T1=3us;

(2) The switching condition from "synchronous following state" to "synchronous punctual state" is: the absolute time error with the timing source is greater than T2=10us (one wrong timing), start the punctual timer;

(3) There are two switching conditions from "synchronous punctual state" to "out-of-synchronization state": the punctual timer timing is greater than or equal to T3=10min; the absolute time difference between consecutive N3=10 frame messages and the merging unit is greater than T2=10us and Time uniformity is less than T1=3us;

(4) The switching condition from "synchronous punctuality state" to "synchronous following state" is: the absolute time difference between the time synchronization message of the continuous N4=10 frame clock source and the merging unit is less than or equal to T4=10us and the time uniformity is less than T1=3us, then The merging unit punctuality timer is cleared, and the timer is turned off;

(5) The merging unit is in the "synchronous following state": the absolute time error with the timing source is less than T5=10us, and it can be synchronized with the timing source through one or multiple time adjustments.

When the punctuality requirement of the merging unit is 48us/2h and the sampling frequency is 4000 points/second, set the switching index according to the following parameters:

(1) The switching condition from "out of synchronization state" to "synchronous following state" is: continuous N1=10 time synchronization cycles, the time uniformity error of the timing source is less than T1=3us, at this time the merging unit pulls the serial number; continuous N2=120 time synchronization cycle, the time uniformity error of the timing source is less than T1=3us;

(2) The switching condition from "synchronous following state" to "synchronous punctual state" is: the absolute time error with the timing source is greater than T2=10us (one wrong timing), start the punctual timer;

(3) There are two switching conditions from "synchronous punctual state" to "out-of-synchronization state": the punctual timer timing is greater than or equal to T3=60min; the absolute time difference between consecutive N3=60 frame messages and the merging unit is greater than T2=10us and Time uniformity is less than T1=3us;

(4) The switching condition from "synchronous punctuality state" to "synchronous following state" is: the absolute time difference between the time synchronization message of the continuous N4=10 frame clock source and the merging unit is less than or equal to T4=40us and the time uniformity is less than T1=3us, then The merging unit punctuality timer is cleared, and the timer is turned off;

(5) The merging unit is in the "synchronous following state": the absolute time error with the timing source is less than T5=40us, and it can be synchronized with the timing source through one or multiple time adjustments.

The advantages and effects of the present invention are: the present invention can avoid the abnormal output of the merging unit caused by the short-term abnormality of the switch and the master clock in the intelligent substation applying the IEEE1588 time synchronization technology, which causes the relay protection to be blocked. Problems that affect the reliable operation of substations. The synchronization reliability of the merging unit is greatly improved to meet the reliability requirements of relay protection. Popularization and application of the present invention will promote the application of IEEE1588 timing technology and relay protection network sampling technology in intelligent substation engineering.

Description of drawings

Figure 1 is a schematic diagram of the time synchronization state of the merging unit and the transition between states in the synchronous time synchronization method of the present invention.

Detailed ways

The present invention is applicable to all secondary equipment suppliers of smart substations that require reliable time synchronization. Especially when the intelligent substation adopts the relay protection equipment based on network sampling and the IEEE1588 network time synchronization method, the time synchronization method of the present invention can be used by the merging unit to improve the reliability of the relay protection system and avoid the blocking of the entire network relay protection due to abnormal network equipment , resulting in unprotected operation of the substation during the lockout period. The application of the invention in the merging unit of the intelligent substation can greatly improve the reliability level of the sampling technology of the relay protection network, and promote its application in the intelligent substation.

The merging unit is the process layer device of the smart substation, which completes the sampling task of the bay layer function including relay protection, and each bay merging unit needs to be synchronized through time synchronization. Adopt IEEE1588 to carry on the synchronous realization in the way of time and divide into two parts. Part of it is to implement the time synchronization principle based on IEEE1588, and this part is the underlying function of receiving the time synchronization message of the master clock. The other part is the realization of the function of correcting the clock frequency and phase of the device according to the received time synchronization message. In this part, the reliability of the time synchronization system needs to be fully considered, and the time synchronization method of the present invention is applied to the function realization of this part. As shown in Fig. 1, the state of the clock of the merging unit is divided into out-of-synchronization state and synchronous state according to the requirements of the present invention, and the synchronous state is divided into following and punctual subdivided states. The judgment of the equipment state and the transition condition between the states are realized according to the time synchronization method of the present invention.

The merging unit adopting the time synchronization method of the present invention greatly improves the application reliability of IEEE1588 time synchronization technology in intelligent substations, and greatly improves the reliability of relay protection network sampling. The invention systematically solves the serious problem of large-scale relay protection blocking caused by the time modulation of the merging unit caused by the abnormality of the switch correction domain encountered in the process layer application of the IEEE1588 timing technology and the electromechanical protection network sampling technology engineering application process of the intelligent substation.

The present invention has been realized in the merging unit, and has been applied in the Hejia 220kV intelligent substation in Chaoyang, and has been fully tested in the completed full-scale dynamic model test to verify its performance when setting different parameters.

1. When the time synchronization period is 1 second, the time synchronization method parameters of the merging unit are set to T1=2; T2=5; T3=5; T4=5; N1=2; N2=60; N3=2; N4=3.

The main clock is running normally, and the display enters the synchronization state 62 seconds after the merging unit is powered on. The main clock time jumps for 1 second and then recovers after 1 second, the merging unit is always in a synchronized state, and the output message is synchronized with the actual value. The main clock time jumps for 1 second and then recovers after 3 seconds, and the merging unit enters the out-of-synchronization state for 62 seconds and then re-enters the synchronization state. A random variable with an amplitude less than 1 second is added to the time output variable of the main clock, and the merging unit loses synchronization after 5 minutes. In the time output variable of the main clock, cancel the random variable whose amplitude is less than 1 second, and enter the synchronization state after 62 seconds. Add a random variable whose amplitude is less than 1 second to the time output variable of the master clock and cancel the random variable after the duration is 4 minutes, and the merging unit is always in a synchronous state. Add a random variable whose amplitude is less than 1 second to the time output variable of the main clock. The duration is 4 minutes. After canceling the random variable, add a jump of 1 second. After 2 seconds, the merging unit enters the out-of-synchronization state, and re-enters after 62 seconds. sync status.

2. When the time synchronization period is 1 second, the time synchronization method parameters of the merging unit are set to T1=4; T2=125; T3=60; T4=125; N1=60; N2=120; N3=60; N4=20.

The main clock is running normally, and the display enters the synchronization state 180 seconds after the merging unit is powered on. The main clock time jumps for 1 second and then recovers after 59 seconds, the merging unit is always in a synchronized state, and the output message is synchronized with the actual value. The main clock time jumps for 1 second and then recovers after 61 seconds, and the merging unit enters the out-of-synchronization state for 180 seconds and then re-enters the synchronization state. A random variable with an amplitude less than 1 second is added to the time output variable of the main clock, and the merging unit loses synchronization after 60 minutes. In the time output variable of the main clock, cancel the random variable whose amplitude is less than 1 second, and enter the synchronization state after 180 seconds. Add a random variable whose amplitude is less than 1 second to the time output variable of the main clock and cancel the random variable after the duration is 59 minutes, and the merging unit is always in a synchronous state. Add a random variable whose amplitude is less than 1 second to the time output variable of the main clock. The duration is 59 minutes. After canceling the random variable, add a jump of 1 second. After 125 seconds, the merging unit enters the out-of-synchronization state, and re-enters after 180 seconds. sync status.

3. When the time synchronization period is 1 second, the time synchronization method parameters of the merging unit are set as T1=3; T2=10; T3=10; T4=10; N1=10; N2=64; N3=10; N4=3.

The main clock is running normally, and the display enters the synchronization state 74 seconds after the merging unit is powered on. The main clock time jumps for 1 second and then resumes after 9 seconds, the merging unit is always in a synchronized state, and the output message is synchronized with the actual value. The main clock time jumps for 1 second and resumes after 11 seconds, and the merging unit enters the out-of-sync state for 74 seconds and then re-enters the synchronization state. A random variable whose magnitude is less than 1 second is added to the time output variable of the main clock, and the merging unit loses synchronization after 10 minutes. In the time output variable of the main clock, cancel the random variable whose amplitude is less than 1 second, and enter the synchronization state after 74 seconds. Add a random variable whose amplitude is less than 1 second to the time output variable of the main clock and cancel the random variable after the duration is 9 minutes, and the merging unit is always in a synchronous state. Add a random variable whose amplitude is less than 1 second to the time output variable of the main clock. The duration is 9 minutes. After canceling the random variable, add a jump of 1 second. After 10 seconds, the merging unit enters the out-of-synchronization state and re-enters after 74 seconds. sync status.

The test proves that the verification test within the parameter setting range of the method can improve the time synchronization reliability of the merging unit network. Combined with multiple tests and the technical requirements of merging units and relay protection equipment, it is recommended to use the third group of parameters.

Claims (3)

1. the synchronous setting means of merge cells of using based on the adaptation relaying protection of IEEE1588, it is characterized in that merge cells three kinds to the time switch between state: desynchronizing state, synchronously following state, synchronously punctual state;

(1) switching condition of " desynchronizing state " to " synchronously following state " is: N continuous 1 (N1 ∈ [2,60]) individual to the time cycle, time service source time homogeneity error is less than T1 (T1 ∈ [2,4]) us, this moment, merge cells drew sequence number; N continuous 2 (N2 ∈ [60,120]) individual to the time cycle, time service source time homogeneity error is less than T1 (T1 ∈ [2,4]) us;

(2) " synchronously following state " to the switching condition of " synchronously punctual state " is: with time service source absolute time error greater than T2 (T2 ∈ [5,125]) us(1 time wrong to the time), the startup timer of keeping time;

(3) " synchronously punctual state " has 2 to the switching condition of " desynchronizing state ": punctual timer timing is more than or equal to T3 (T3=5,60) min; N continuous 3 (N3 ∈ [2,60]) frame message and merge cells absolute time poor greater than T2 (T2 ∈ [5,125]) us and long-time uniformity less than T1 (T1 ∈ [2,4]) us;

(4) " synchronously punctual state " to the switching condition of " synchronously following state " is: N continuous 4 (N4 ∈ [3,20]) the frame clock source to the time message and merge cells absolute time poor less than or equal to T4 (T4 ∈ [5,125]) the us long-time uniformity is less than T1 (T1 ∈ [2,4]) us, timer is closed in the then punctual timer zero clearing of merge cells;

(5) merge cells is in " synchronously following state ": with time service source absolute time error less than T5 (T5 ∈ [5,20]) us, by once also repeatedly the time is adjusted with the time service source synchronous.

2. the synchronous setting means of merge cells used of described adaptation relaying protection based on IEEE1588 according to claim 1 is characterized in that requiring to be 4us/10min in that merge cells is punctual, by following parameter the switching index is set when sample frequency is 4000 points/second:

(1) switching condition of " desynchronizing state " to " synchronously following state " is: N continuous 1=10 to the time cycle, time service source time homogeneity error is less than T1=3us, this moment, merge cells drew sequence number; N continuous 2=64 to the time cycle, time service source time homogeneity error is less than T1=3us;

(2) " synchronously following state " to the switching condition of " synchronously punctual state " is: with time service source absolute time error greater than T2=10us(1 time wrong to the time), the startup timer of keeping time;

(3) " synchronously punctual state " has 2 to the switching condition of " desynchronizing state ": punctual timer timing is more than or equal to T3=10min; N continuous 3=10 frame message and merge cells absolute time poor greater than T2=10us and long-time uniformity less than T1=3us;

(4) " synchronously punctual state " to the switching condition of " synchronous following state " is: N continuous 4=10 frame clock source to the time message and merge cells absolute time poor less than or equal to T4=10us and long-time uniformity less than T1=3us, timer is closed in the then punctual timer zero clearing of merge cells;

(5) merge cells is in " synchronously following state ": with time service source absolute time error less than T5=10us, by once also repeatedly the time is adjusted with the time service source synchronous.

3. the synchronous setting means of merge cells used of described adaptation relaying protection based on IEEE1588 according to claim 1 is characterized in that requiring to be 48us/2h in that merge cells is punctual, by following parameter the switching index is set when sample frequency is 4000 points/second:

(1) switching condition of " desynchronizing state " to " synchronously following state " is: N continuous 1=10 to the time cycle, time service source time homogeneity error is less than T1=3us, this moment, merge cells drew sequence number; N continuous 2=120 to the time cycle, time service source time homogeneity error is less than T1=3us;

(2) " synchronously following state " to the switching condition of " synchronously punctual state " is: with time service source absolute time error greater than T2=10us(1 time wrong to the time), the startup timer of keeping time;

(3) " synchronously punctual state " has 2 to the switching condition of " desynchronizing state ": punctual timer timing is more than or equal to T3=60min; N continuous 3=60 frame message and merge cells absolute time poor greater than T2=10us and long-time uniformity less than T1=3us;

(4) " synchronously punctual state " to the switching condition of " synchronous following state " is: N continuous 4=10 frame clock source to the time message and merge cells absolute time poor less than or equal to T4=40us and long-time uniformity less than T1=3us, timer is closed in the then punctual timer zero clearing of merge cells;

(5) merge cells is in " synchronously following state ": with time service source absolute time error less than T5=40us, by once also repeatedly the time is adjusted with the time service source synchronous.

Images