Multi-mapping IEC 61400-25 gateway project
This technical document describes an IEC 61400-25 gateway that connects a simulated wind power plant to any client using the mappings specified in the standard IEC 61400-25-4.
The available communication interfaces include:
The gateway exposes a set of relevant variables as, the active and reactive power of each wind turbine and the production total of the wind power plant. It also provides a common interface to start, stop and modify the power factor of each wind turbine.
This gateway was configured following the requirements requested by the USE61400 25 user group association, in the REFERENCE SERVER EDITION 2 project.
USE61400 25 users group focuses on the use of the IEC 61400-25 standard for monitoring and controlling of wind power plants.
If you want to get access to the gateway please request information to the association using the contact email: firstname.lastname@example.org
IEC 61400-25 communication interface to monitor and control a wind power plant is not allocated to a specific automation level. It can be located either at each wind turbine or also at a gateway or controller located at the wind power plant (station) level.
The first option implies that the wind turbine manufacturer exposes an IEC 61400-25 standard interface in their turbine. This option is graphically represented in the following picture.
This second option isolates the wind turbines from the external interface provided by the gateway. The communication between the gateway and the wind turbines can also use standard communication or it can use a proprietary or private protocol.
This second approach was implemented in the gateway described in this project. The internal communication between the gateway and the wind turbine controllers was implemented using the mapping to MMS as described in IEC 61400-25-4.
The REFERENCE SERVER is built by a set of pieces of software to simulate as a much as possible the active and reactive power control of an IEC 61400-25 standard wind power plant.
The building blocks of the REFERENCE SERVER are:
The complete architecture is depicted in the following picture.
The Virtual Wind Turbine simulation is a Windows based application that uses the Modbus TCP server port (502) to provide a set of holding registers with the wind speed, wind direction and temperature at 24 different locations. It also shows the number of clients connected accessing to its Modbus registers.
Each Wind Turbine simulator uses the data of the simulations, the status of the wind turbine (running or stopped) and also the power factor requested to indicate the active and reactive power generator.
The following picture shows the logics block diagram that perform these calculations in each Wind Turbine simulator.
The Wind Power Plant server is a Windows application that connect to the wind turbine controllers using an MMS connection and exposes their information in its own server using the IEC 61400-25-2 and IEC 61850-7-4 logical nodes. It also performs some calculation to count the total active and reactive power and the total number of wind turbines running.
The WPPS can be connected with any client using the IEC 61400-25-4 standard. For those users have no application ready, USE61400-25 provides a set of Windows based applications to validate communication with the available mappings.
Four different desktop application are provided all of them with the same interface but a different communication protocol behind.
Using any of these applications, the user can start and stop the simulated wind turbines and also it can change the power factor setting from 0.8 to 1 in order to modify the wind power plant reactive power generation.
From the Wide Area Network, the gateway is available on a public IP address using the standard ports for the communication protocols described in IEC 61400-25-4.
Apart from the IEC 61400-25 standard ports, a web access is provided through a web server that can be accessed with any standard web browser. In this example we use Chrome, but any other browser can be used.
The REFERENCE SERVER requires two configuration files to perform its task of gateway:
The IEC 60870-5-104 information is linked to the CID file using the approach described in IEC 61400-25-4 and the Technical Specification IEC 61850-80-1. The DNP3 information is linked to the CID file using also the same approach.
The logics are configured using PLC Open XML language and the information is included also in the CID file using a Private section.
The gateway uses its IEC 61850 client driver to connect with the Wind Turbine controllers. Once the connection is established, it configures and enables the allocated report control blocks and receive the status of the values and measurements only when they change.
It the connection with a Wind Turbine controller is lost, the information exposed in the Wind Power Plant Server for this controller changes its quality to invalid plus old-data indicating the lack connectivity to the IED. The Wind Power Plant Server tries periodically to recover the communication with any server disconnected.
When a command is received by any of the client interfaces (DNP3, IEC 60870-5-104, MMS or WS), if the server controllable data object is linked to a specific wind turbine controller, the WPPS uses the MMS client interface to send the appropriate command to the controller. This sequence is used to start and stop the wind turbine controllers and to modify their power factor.
USE61400-25 is working on the development of guidance in the use of OPC-UA to the exchange of IEC 61400-25 information. In the past, IEC 61400-25-4 described the use of OPC-XML-DA, unfortunately this interface was not so extended as OPC-DA or its update to OPC-UA. Once the use of OPC UA is clarified the gateway could be extended to support the OPC interface.
Although the initial focus of the project is the interoperability of different implementations of the communication mappings described in IEC 61400-25, the interoperability without secure communication have no sense in the existing automation world.
Applying IEC 62351 requirements and features, will make the gateway an open, interoperable and also secure demonstration of the IEC 61400-25 standard.
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Categories: wind power plant monitoring and control, IEC 61400-25, gateway, mapping, communication protocols