Method for synchronized detection of measurement data required for the control of differential protection means electrical energy lines

The invention relates to a method for synchronized detection of transmitted for control of differential protection devices electrical energy measurement data lines required, the combined to form packets over packet-switching networks between two network elements, their clocks are synchronized transmission and reception times of between network elements using measured - via the packet-switched network synchronization message transmitted.

Wherein differential protection devices for electric power lines to the power line at the ends of the measurement data acquired by evaluating the monitoring, it is necessary, only compare each other simultaneously acquired measurement data. This means, that the measuring points clocks need to be included, the synchronize are, in particular leading to difficulties, packet-switching networks is performed when the data transfer over, because the transmission time is determined in packet-switching networks of different such, for example of the number and type of network node, the respective packet traffic and the priority of the data packets to be transmitted-dependent parameters. To overcome such difficulties, it is known (wo 2013/107896 a1), provided in the transmitting network element with a time stamp to the measurement data packet from the receiving network element and to identify the reception timing of the packet transmission time and with the measurement data transmitted the transmission time, the transmission time by the receiving network element for the determination of measurement data to be taken into account so that respective comparative can. A synchronization of the two power supplies associated clocks provided therefor, by a predetermining what time clock network in a conventional manner via a precise time protocol (pTP) accomplished, provided by synchronizing messages are sent from the time clock with a time stamp determines, which the respective reception time of the clocks associated with the receiving network elements to be synchronized is however. The network elements to be synchronized with the clock sending a request to the network element with the time delay then determines clock, the back ends the reception time this delay requirement, so that from the transmission and the reception time of the synchronization message and the transmit - - and the receiving time of the delay requirement can be determined an existing difference between the times the time clock and the synchronizing clocks to determines times, but only provided a sufficiently symmetrical transmission network. The network node also involved to implement this synchronization procedure must be equipped accordingly.

The invention is based on the task thus, developing a method for synchronizing the clocks of two control a differential protection device for a packet-switched network having a plurality of network elements used electric power lines such nodes, for the differential protection can be ensured that a sufficient clock synchronization.

From a method of the type named above the invention solves the task in, that from the transmission - reception times the periods between successive synchronizing messages and one hand and on the other hand between the reception timings and transmission times from the transmitting and receiving periods are determined and used for synchronization of the clocks whose difference only those synchronizing message, where the absolute value of the difference between the transmission and reception time is below a predetermined threshold - tensioning.

If there is a difference between the clocks of the two network elements a simple gear tolerable synchronization of the two clocks can be made by the proposed measures, because by reason of the selection for a different duration play only such synchronizing message, the have a substantially equal duration, not matter the synchronization. Thus the delay difference and thus the smaller the difference between two successive synchronizing time differences is on the one hand and on the other hand transmission times between message whose reception times, the more accurate the clock synchronization can be carried out. The permissible upper limit these differences between the transmission interval and the reception interval is predetermined by a threshold value, the tolerance range to be observed for compliance with a particular measure for the synchronization of the clocks synchronizing determines the selection of the appropriate message.

Since the propagation time differences between successive synchronizing messages for detecting the receiving network element with the synchronizing clock to the synchronous message from the sending network element only the specific time and the receiving network element must be informed this time the reception time has associate, can also be carried out by means of the synchronization of the two clocks networks, do not satisfy the requirements for a PTP protocol.

In order to achieve an adaptive adaptation of the time synchronization to the respective network conditions, the difference can be stored several consecutive time intervals - the transmission and reception of the synchronizing messages and below the prescribed threshold selected lying with the smallest difference value between the transmission synchronizing messages each - and the reception interval for clock synchronization.

The process of the invention is explained in more detail with reference to the drawing. It show

Figure. 1 a schematic block diagram of a differential protection device and an electrical power line

Figure. 2 t is the time_seconds the time clock with the time of the T determines_s the clock to be synchronized during the transmission of synchronization messages in releasing relationship diagram

The differential protection device for an electric power line 1 comprises two network elements 2, 3, in which the control of the remaining energy from the power line for separating 1 4 network provided 5 circuit breaker, the evaluation of the necessary for monitoring the power line 1, the measurement data acquired by measuring devices 6, the transmitter and receiver for transmission of the measurement data and the clock to packets combined laying down the measuring -, transmitting and receiving times are combined. The data transmission takes place via a packet switched network the clocks of the two network elements 2 7th, 3 are synchronized, the duration of measurement data packets does not matter, because the transmitted measurement data by the marking of the measuring data packets with the transmission time can stamp by the clock of the sending network element 2 or 3 each time the measurement data are assigned on the side of the receiving network element 2 or 3, in order to actuate the circuit breaker of the power line at predetermined deviations 1 5 4 off from the energy network.

Synchronization of the two clocks of the network elements 2 substantially sufficient, for this purpose the clock of the two network elements 2 3rd Generation, 3 indicates the time, relative to the clock of the other network element is synchronized is therefore. In the case of the embodiment according to the Figure. 1 is accepted, that the clock of the network element 2 dictates the time, relative to the clock of the network element is the synchronize 3. Accordingly synchronizing messages containing the associated transmission times from the network element 2 are transmitted over the packet-switching network 7 to the network element 3, as the Figure. 2 closer can be taken, in which the time axis the synchronizing the clock of the sending network element 2 with T message_seconds the clock of the receiving network element 3 and the time axis T_s is described. For time T is_seconds i of the clock of the network element transmits the packet-switched network via a synchronizing message 2 this 7 to the network element 3, the this synchronizing message the reception time of Ti_s on the basis of the own, to synchronizing clock assigns. In the same way method with subsequent synchronization message. In the Figure. 2 a following synchronization message are the transmission time T_s2 and the receiving time T_e2 specified. The time difference between the reception times T from the respective duration dependent_s i and T_e2 compared to the time difference between two synchronizing messages whose transmission times T_seconds i and T_s2 as the time interval between the transmission times T let_s1 and T_s2 3 the network element from the transmitted time stamps to GB_SECONDS =E_s2 - T IS_seconds i and the respectively measured receiving timings to GB_s =E_e2 - T IS_s i in determining.

Since the synchronizing message is expected due to the transmission over a packet network 7 determines various maturities, only those synchronizing messages are according to the invention for synchronizing the clock of the network element 3 used, for transmission and reception intervals whose difference At of - GB_SECONDS and At_s applies: GB=|GB_SECONDS - GB_s | < sec applies, whose absolute value is smaller than a predetermined threshold s is. This means that delay differences can play only a minor role due to the substantially coincident travel times and the accuracy of the synchronization by a selection of synchronizing message adaptively with correspondingly small differences in the packet-switching network are adjusted to the respective atom transmission conditions. For this purpose it is appropriate, several successive synchronizing messages for transmission and reception intervals to determine the differences - only those synchronizing message for clock synchronization AT and use, each having the smallest difference t.

The running time for synchronizing messages from the network element 2 can flow not only differences for network element 3, but also in the opposite direction from network element 3 are determined for network element 2, the differences of the transmission and the reception intervals for synchronizing - by messages are detected in the opposite direction of transmission, allowing better alignment symmetrical networks.

Patent lawyers

John lovely diplDipl. type M.D.

Charles Mr Menrad light me. diplDipl. type M.D

4 spittelwiese, 4020 Linz as