## 5 Experimental Verification
### Experimental Results and Analysis
The meanings of Peaks (6) and (7) are the same as Peak (3) and (4). As can be seen from (c), the data frame length is significantly lower than the standard protocol data frame length. The length of a single application extension frame is long, but the transmission period is long and has little effect on traffic. Application extension frame SYNC is 0 xa53. As can be seen in conjunction with Figures 10 and 11, data traffic has been significantly reduced after the implementation of the extended protocol. In order to show more the effectiveness of this method in reducing data traffic, assuming one distribution network PDC communicates with 20 uMPMUs and one master station and sets 12 phasors (which compose of three-phase voltage, three-phase current, voltage, and current symmetrical components of phase a), 20 analog quantities (including active power P, reactive power Q, voltage, and current of 3, 5, 7 harmonics of each phase), and 4 digital quantities (such as external signal light, relay) to form one data unit. The setting of the data unit is same as the configuration of the uMPMU in the actual project. Two cases are explored here: Case 1 shows the calculation results according to the standard protocol; Case 2 corresponds to the calculation result using the method from this work. \(R_{\text{data}}\) selects the maximum value of 100 frames/s, and both \(R_{\text{YC}}+V_{\text{YC}}\) and \(R_{\text{YX}}+V_{\text{YX}}\) select 0.2 frames/s, and the unit length is set to 1 min. Considering the diverse application scenarios of uMPMU and PDC, the number of data units is between 1 and 4. The \(M_{\text{data}}\) of the two examples is calculated by using Equations (6) and (13). The result is shown in Figure 12. The abscissa is the data unit quantity, and the ordinate is the 1 min network communication data amount, and the unit is megabyte (MB). It can be seen from the calculation results shown in Figure 12 that the numerical value of Case 2 is smaller than the numerical value of Case 1 for a single uMPMU or PDC. As the amount of data units increases, the ratio between the value of Case 2 to the value of Case 1 decreases. The percentage in Figure 12a decreased from 77.57 to 64.1%, and the percentage in Figure 12b dropped from 57.6 to 55.86%, which further indicates the effectiveness of the proposed method in reducing the amount of network communication traffic. Figure 11: Extended protocol running result. (**a**) Communication data traffic when application extension frames delivery period is 2 s; (**b**) communication data traffic when application extension frames delivery period is 5 s; (**c**) application extension frames and data frames in extended protocol. With the time scale selected as 0.001 s, which is 1 ms, more details can be observed. In order to avoid interference of the rest of the data with the result, the filter is set to display only data from the PDC's data pipeline and command pipeline. Whether it is an application extension frame containing analog or digital quantities, its single frame length is limited, so when the data that is to be transmitted is too large, it is divided into multiple frames. Figure 13 shows this situation. At the same time, due to the data priority processing, two application extended frames containing the same type of information are not sent together, but the second frame is sent after multiple data frames are sent. The uniform transmission of the data frames is not affected. The test result for the remote control function is shown in Figure 14. The filter condition is the port number of the PDC command pipeline. Here, 1 is a remote control selection message sent by the main station, 2 is a remote control confirmation message of the PDC reply, 3 is a remote control execution message sent by the main station, and 4 is a remote control execution confirmation message of the PDC reply. The remote control process of the PDC and the PMU is the same as the above process, in which the PDC plays the role of forwarding information and mapping remote control points.