What is the difference between IEC 61850-9-1 and IEC 61850-9-2?

IEC 61850-7-2 defines abstract models and services used for the information exchange between IED's in a substation automation system. A particular model is the model for the transmission of sampled values. All the other models are mapped to a concrete communication stack as defined in IEC 61850-8-1. On the other side, IEC 61850-9-1 and IEC 61850-9-2 are dedicated to specify the mapping of the model for the transmission of sampled values.

The basic concept of the model for transmission of sampled values is shown in Figure 1. The data content to be transmitted is defined by data and a dataset. The control block (MSVCB – multicast sampled value control block) refers to the dataset and includes additional configuration parameters like e.g. the identification of the message transmitted (MsvID) or the sample rate (SmpRate). The sampled value message to be transmitted over the network is build based on that configuration information.

Figure 1 - Model for the transmission of sampled values

The mapping as specified in IEC 61850-9-1 is restricted to the specification of the mapping of the sampled value message. The dataset used to specify the data content of the message is fix and predefined (according the specification in IEC 60044-8). The coding of the message uses a fixed octetstring and follows the specification in IEC 60044-8. The control block (MSVCB) is predefined as well and can not be accessed over the communication interface. With that restricted scope, IEC 61850-9-1 is a unidirectional interface and intended to be used as a point–to–point link.

The mapping as specified in IEC 61850-9-2 is a mapping of the complete model for the transmission of sampled values. In addition to the mapping of the sampled value message, the mapping of the services to access the control block (MSVCB) is defined as well. The abstract coding of the message uses ASN.1.

Keywords:

mappings, part 9, sampled values, IEC 60044-8

provided by Christoph Brunner
ABB Switzerland Ltd
Convenor of TC57 / WG12