Redundant transmission of data messages for information and control for HVDC transmission systems
A method for securely transmitting data messages in an HVDCT system. Each transmitting unit is connected to each receiving unit via at least two connection channels. Each data message includes a message counter that uniquely characterizes the data message, and each transmitting unit transmits the data message to each receiving unit via all of the connection channels. Each receiving unit calculates a comparison counter and compares it with the message counter in the received data message. If the message counter and the comparison counter do not match, a repetition request is transmitted to the transmitting unit for the purpose of transmitting a message counter that corresponds to the comparison counter. After the repetition request has been received, the transmitting unit accesses a transmission buffer, and the data message whose message counter corresponds to the comparison counter of the repetition request is transmitted via all of the connection channels.
1. A method for safe and secure transmission of data messages between at least one transmitting unit and at least one receiving unit in an HVDC transmission installation, wherein each transmitting unit is connected to each receiving unit via at least two connecting channels, the method which comprises:
providing each data message with a message counter uniquely identifying that data message, and each transmitting unit sending the data message via all the connecting channels to each receiving unit, thereby calculating the message counter using an incrementation rule that is clocked by a transmission of the data messages, and each receiving unit calculating a comparison counter using the same incrementation rule, clocked by a reception of the data messages;
storing, with each transmitting unit, data messages that have already been transmitted in a transmission buffer;
comparing, with the receiving unit, the message counter of each received data message with the comparison counter, and, if there is no match between the message counter and the comparison counter or if there is no match within a waiting period after reception of a data message, sending a repeat request to the transmitting unit to send a data message with a message counter corresponding to the comparison counter;
upon receiving the repeat request, accessing the transmission buffer with the transmitting unit and sending the data message via all the connecting channels whose message counter corresponds to the comparison counter received by way of the repeat request; and
providing at least two transmitting units and sending the same data messages to one another with the same message counters with the at least two transmitting units.
2. The method according to claim 1 , wherein the receiving unit rejects the reception of data messages whose message counter corresponds to that of data messages which have already been received.
3. The method according to claim 1 , which comprises utilizing at least two receiving units, each configured to send repeat requests.
4. The method according to claim 1 , which comprises storing the received data messages in a reception buffer with each receiving unit.
5. The method according to claim 1 , wherein a storage capacity of the transmission buffer is configurable.
6. The method according to claim 1 , which comprises sending the data message by way of a transmission protocol without a connection and without acknowledgement.