The master station layer includes servers, workstations, and coordinated controllers.
Table 2 Communication protocol between the parts Layers Supplier local monitoring system Local controller Remote CMS layer Master station layer IEC-104 EPA IEC-104 PCS layer CAN Modbus –. 1) Master station layer.
Master station layer is mainly responsible for coordinated control and energy management, communication management, data acquisition, data processing and management.
Total active power demand of BESS, ( P_{all {text -} BESS}^ ), comes from the master station layer as shown in Fig. 5.
Total reactive power requirement of BESS, ( Q_{all {text -} BESS}^ ), comes from the master station layer as shown in Fig. 6.
As can be seen, a hierarchical distributed control scheme for BESS mainly includes three layers, namely, the master station layer, the local control and monitoring system (CMS) layer, and the device layer.
The equipments of coordination control layer mainly refers to microgrid operation controller, mainly in charge of sending corresponding control commands to the device layer and delivering execution information of the microgrid to the station layer.
Some key real-time running state data and control commands have been interactive between master station layer and local CMS layer through control network by using an Ethernet for plant automation (EPA) protocol based strong real-time Ethernet.
Detail running data of each transformer unit, including all single battery voltage, single battery temperature, and detailed operation information etc, have been transmitted from supplier local monitoring system to master station layer through IEC60875-5-104 (IEC-104) protocol based monitoring network.
Normally, the event responding time of the main station layer is mostly several seconds or minutes, the regulation of the coordination control layer is mostly required to be completed in a second, and the response of the device layer is required to be completed in several milliseconds.
