1. Logical node Logical node LN is a key component of IEC 61850 object-oriented modeling. LN embodies a modeling approach to the modular decomposition of substation automation functions. Each logical node is a module that represents a specific function. Multiple logical nodes work together to complete control, protection, measurement, and other functions.
2. Data
The XCBR logical node contains various types of information such as Pos (position), BlkOpn (trip lock), and is defined as data Pos and BlkOpn. Pos and BlkOpn can be seen as smaller modules that continue to decompose the XCBR.
3. Data attributes
In fact, the information contained in Pos and BlkOpn still needs further decomposition. Pos data contains at least two kinds of information: status and control.
The status information status contains the circuit breaker's actual position value value (the off, on, intermediate, and bad-state), the quality of the position data, and the time-scale at which the circuit breaker is dislocated. (timestamp) Three aspects of information.
The control class information control includes a control value ctlVal (on or off), an originator of the last control command, and a control command number (ControlNum).
In IEC 61850, the value, quality, and timestamp information contained in the Pos data is defined as a data attribute (DA).
4. Common data type CDC
XDIS is a logical node that represents an isolation switch type device. Its Position contains information similar to the Position in the XCBR, so a common data type DPC can be extracted from both. DPC can be applied not only to data models of circuit breaker equipment, but also to data model definitions of isolating switch equipment.
The common data class embodies a modular design concept. Each common data class is a module that can be reused multiple times. You can reduce the duplicate description of the same data definition, improve the efficiency of use, and also ensure the consistency of data attribute definitions.
The common data class DPC is used in turn to define the data Pos in the XCBR logical node. Pos can be regarded as a DPC-derived class. It inherits all DPC data attributes (such as ctlVal, origin, ctlNum, and stVal, etc.), so it is not necessary to list all data attributes when defining data Pos. Just refer to DPC.
Logical nodes - data - data attributes are a tree structure. Data attributes are the lowest level component of the tree model.
Logical node names, data names, and data attribute names are collectively referred to as Object Names in IEC 61850. Concatenating object names of different levels into a string forms an Object Reference. An object reference, also known as an object index, can visually indicate the location of an object in a tree model. Logical nodes, data, and data attributes all have their own references.
5. Dataset
There are various data in the substation IED, some need to be transmitted in real time (such as current and voltage values), and some can be transmitted slowly (for example, power value, power). Since there are hundreds of IEDs in high-voltage substations, and the network communication bandwidth is limited, if these data are sent together without being grouped, it may affect the real-time nature of data transmission and even cause traffic jams.
After the concept of data set is introduced, data sets can be used to conveniently group and package data. For example, data that needs to be transmitted in real time can be grouped into one data set, and data with less stringent transmission time requirements can be divided into another data set. Transmission.
6. Logical devices divide logical nodes with common or common characteristics into one logical device.
7. The server describes the behavior of a device "externally visible". The so-called "external visibility" refers to the ability of other devices (clients or other IEDs) to access its internal resources or data over a communications network. All external visual information in the IED is contained in the server.
8. The access point IED communicates with the station-level network through different access points and communicates with the process-level network. The access point describes the connection between the IED and the actual communication network. It can be seen as an abstraction of the device's physical communication port.
9. Communication mode
IEC 61850 contains a total of "client-server" and "publisher-subscriber" two communication modes.
(1) The MMS service adopts the "client-server" mode on the transmission mechanism. In the substation automation system, the station-level equipment is generally modeled as an IEC 61850 client, such as a substation monitoring host and a telecontrol workstation. The bay layer IED is generally modeled as an IEC 61850 server, such as a microcomputer protection device, a measurement and control device, and the like.
(2) "Publisher-subscriber" is also called peer-to-peer communication mode. It allows point-to-multipoint direct communication between a data sender and multiple receivers. It is suitable for large data traffic and real-time High demanding occasions. Both SV and GOOSE services require high real-time performance. Both of them use this communication mode.
10. Hierarchical Model Server-> | Logical Device0| Logical Device1->| Logical Nodes0
| Logical Nodes1->
| Data0| Data1->| DA0| DA1
11. Communication services
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