## 4 Power Data Virtual Planet Layer
### Specific Implementation  
As a bridge for communicating underlying devices with advanced applications, the virtual plane layer receives power data from different sources at the bottom layer and quickly adjusts the power data format to provide advanced applications in the form of unified data. The virtual plane divides the data flow and the control flow, and consists of two key parts: the data warehouse and the application scheduling with control functions, as shown in Figure 5. We open up a continuous memory space in the virtual plane as a data warehouse. The data warehouse can buffer power data in a multi-layer processing structure and respond to the data requirements from the application layer according to the type of data. In other words, it provides the data services needed for distribution advanced applications. Considering that distribution applications are usually concerned with new power data, for simple applications, it is suggested to use a first in first out (FIFO)  
Figure 4: Distribution Network Information Processing Structure. structure as a data warehouse for simplicity. For complex applications, multiple long-term power data is typically involved. In this case, the virtual plane not only needs to open up a large storage space as a data warehouse, but also needs to use a hash search method to quickly find the required data in the data warehouse. Application scheduling is a core part of the entire virtual plane. It is responsible for the data interface of the underlying devices with upper applications and the power data management of this layer, mainly to achieve the following functions [24]. 1. Exchange information with the underlying hardware devices. The information may come from data directly collected in a \"hard-wired\" control mode or from a communication network in the form of a message. The virtual plane layer is responsible for receiving the processed power data with different formats, such as current value, voltage value and switch state. 2. According to a certain format, the messages sent from the bottom layer are quickly adjusted to power data in a uniform format and placed into the data warehouse in turn according to the data type. 3. Provide power data with a unified format to the distribution network advanced application in the upper layer. When the monitoring, protection, control, power distribution management, and other advanced applications in the upper layer require specific data, the application layer sends a request to the virtual plane layer to obtain the required power data. The application scheduler will respond to the request in real time, extract the qualified data from the data warehouse through the data filter, and send it to the corresponding distribution network advanced application in time. It can be seen from the specific implementation of the virtual plane layer that the layer essentially acts as a data preprocessing function. In the traditional method, every distribution network advanced application generally deals directly with the tedious work of communication and protocol conversion. Due to the heterogeneous multi-source and multi-protocol characteristics of the distribution network, as the number of advanced applications in the distribution network increases, the software programing implemented by traditional methods will become more complex and scaled. Figure 5: Detailed Implementation of Virtual Plane. The virtual plane layer avoids the direct conversion of various communication methods and protocols. It adopts data driven mode and provide two-way interactions. The virtual plane layer can receive data from both the advanced application calls in the upper layer and field IEDs in the lower layer. Once data come into the data warehouse of the virtual plane layer, the application scheduling starts to identify the data attribute. If the data has real-time requirements, such as the operation command of the switch, the scheduling link will process it immediately. If it is not real-time data, batch processing is used to improve the efficiency of data processing.