# Design and Application of a Distribution Network Phasor Data Concentrator
## 2 DPDC Application Requirements Analysis  
### \(\upmu\)MPMU-DPDC Networking Structures  
The PMUs in the transmission network WAMS are mainly installed in important substations and power plants. In actual engineering, the PDC is generally installed in the same screen cabinet as the PMU. Each device gets timing information from a unified synchronous clock source. PMUs can be directly connected to the PDC or connected to the PDC via a switch. If the PDC is not equipped, PMUs are directly connected to the switch in the plant. The WAMS main station connects to the power dispatch data network through the pre-communication subsystem and receives data from PDCs or PMUs. It can be seen that the working environment of the PDCs and the PMUs in the transmission network WAMS is not bad, the communication connection between the devices is relatively stable, and PMU's clock signal source is also reliable. Limited by the number of important components monitored in the plant, the number of PMUs connected to the PDC in the station will not be much.  
In contrast to the PDCs and PMUs in the above-mentioned transmission network WAMS, \(\upmu\)MPMUs are installed in the substation, as well as the feeder, ring network cabinet, DER and other points [3]. The \(\upmu\)MPMU outside the substation obtains the time signal through the external GPS antenna of the device. In addition to fiber optic Ethernet and Ethernet passive optical network (EPON), the communication method between the \(\upmu\)MPMUs and the DPDCs or the main station also uses communication methods with a higher delay such as power line communication (PLC) or a wireless private network. Considering the installation location and communication mode of the \(\upmu\)MPMUs and DPDCs, the networking modes of the \(\upmu\)MPMU-DPDC can be divided into three types, as shown in Figure 1.  
Figure 1a shows a centralized networking structure in which all the \(\upmu\)MPMUs and the DPDC are located in the station. This structure is consistent with the PMU-PDC networking structures in the transmission network. Figure 1b1,b2 indicates that the \(\upmu\)MPMUs are dispersedly installed on the ring main unit and each section of the feeder. The DPDCs are installed inside the station, and they communicate with \(\upmu\)MPMUs via wired communication such as EPON or PLC. Figure 1c indicates that the \(\upmu\)MPMUs are dispersedly installed at feeder line and DER connection points. The \(\upmu\)MPMU communicates with the upper device through a built-in wireless communication module or an external customer premise equipment (CPE). The DPDC or the main station is connected to the core network to receive data from the \(\upmu\)MPMU. In this case, the DPDC can be placed in a substation, core network or inside of a main station. If only a few scattered \(\upmu\)MPMUs use wireless communication, such \(\upmu\)MPMUs can communicate directly with the main station without going through the DPDC. This figure does not mean that the \(\upmu\)MPMU monitoring DER must use wireless communication. Under the conditions of proper installation cost, \(\upmu\)MPMU should choose low-latency fiber-optic communication.