# Design and Application of a Distribution Network Phasor Data Concentrator
## 1 Introduction  
With the distributed energy such as photovoltaics and wind power, flexible load and electric vehicles connected to the distribution network on a large scale, the stable operation of the distribution network faces new challenges in the aspects of the difficulties to quickly and accurately carry outthe state estimation, fault diagnosis and active control using monitoring and controlling methods of the traditional distribution network. To cope with these challenges, the synchronous phasor measurement technology is introduced to the distribution network [1; 2] with reference to the wide area measurement system (WAMS) widely used in transmission networks. The micro multifunctional phasor measurement unit (\(\upmu\)MPMU) is a miniaturized phasor measurement unit (PMU) that combines the functions of power distribution monitoring terminals [3], which can also be called a distribution network phasor measurement unit (DPMU) or micro phase measurement unit (\(\upmu\)PMU) [4]. \(\upmu\)MPMUs provide global positioning system (GPS)/BeiDou navigation satellite system (BDS)-based measurement data so that power signals at different locations can be put together for comparison and analysis, such as phase angle. \(\upmu\)MPMUs are mainly used to solve the problems of sensing and controlling in the distribution network, including fault information extraction and fault diagnosis, state estimation, voltage control, reactive power optimization and active control [4; 5]. In addition to PMUs, the transmission network WAMS also includes components such as phasor data concentrators (PDCs) and communication networks [6; 7]. According to the depiction of IEEE C37.244-2013 [8], the primary and most important role of the PDC is to aggregate and forward data of multiple PMUs according to timestamps. Based on this guidance, IEEE introduced the PDC standard IEEE Std C37.247-2019 [9] in 2019, which specifies the requirements for PDC. With the development of technology in this area, PDC further has the ability to process and store data and configure more functions according to different requirements. Although the current application of \(\upmu\)MPMUs in the distribution network is increasing, the corresponding distribution network phasor data concentrator (DPDC) has not received sufficient attention. In terms of PDC design, the PDC designed in [10] has a variety of data push logics and has a good performance in ensuring data integrity and latency but there is no targeted design for the PDC for the application scenario of the distribution network. Reference [11] proposed a software PDC that used a reliable communication protocol to establish a database system for efficient data storage and access. It is used as a low-cost alternative to large PDCs, while its application scenario is still in the transmission grid. Reference [12] discussed the design of PDC and the handling of anomalies. The anomalies handling is very meaningful, because DPDC may encounter these problems more frequently in the distribution network, but the article does not elaborate on the details of the anomalies handling scheme. Reference [13] proposed a software PDC for monitoring DER in a smart microgrid, which uses an adaptive compensation scheme to achieve an effective estimation of missing data elements, and proposed a monitoring unit to detect DER. Reference [14] considered the situation that more and more PDCs and PMUs were being installed in the distribution network, and proposed an active PDC with advanced functions to manage the delay according to the requirements of possible target applications. Reference [15] proposed a low-cost active PDC suitable for power distribution networks. The prototype of this PDC is based on the low-cost hardware platform SBC Raspberry Pi. Controlling costs is very important for the promotion of PDCs in the distribution network. At the same time, in order to meet the potential for increased equipment access, resources of a PDC should not be too limited.