Distributed Control for DER and Distribution Automation

by M. R. Bastos, M. N. Agostini, I. C. Decker, S. L. Zimath, A. S. e Silva, R. B. Leandro, M. A. Benetti, V. Zimmer, Brazil


The synchrophasors with the same time tag, reflect the instantaneous operating point of the power system. Since measurements are updated in a rate of sixty times per second, the dynamic characteristics of the power systems in real time can be monitored.

In this article the main results of the project “Development of a System for Analysis and Monitoring in Real Time of the Electric Network Dynamic Applying Synchronized Phasor Measurement for the Improvement of Supervision, Control and Protection Processes” (MedFasee CTEEP Project) are presented. The project started in January/2009, as a partnership with Federal University of Santa Catarina (UFSC) and the Reason Company.

The project includes the development of a hierarchical system for acquisition, process and storage of the phasor data and tools for monitoring and analysis (on-line and off-line) of the Brazilian Interconnected Power System (BIPS).

Main Equipment of the Prototype
A. Phasor Measurement Units – PMUs

PMUs used in the prototype are a functionality of the digital recorders type Reason RPV (RPV 304 and RPV 310). They have 16 analog channels, configurable for reading voltage or current signals. The connection schemes can be three-phase, with or without neuter, two-phase or single-phase. A WEB based configuration interface can be accessed through Ethernet using a browser. The PMU functionality is compatible with the IEEE C37.118-2011 Standard, with the frames sent by Ethernet. The transmission data rate is configurable in 10, 12, 15, 20, 30 or 60 frames per second. The internal acquisition rate is 256 points per cycle of the electric network (60 Hz).

The synchronization of the PMUs is made by Reason RT420 clocks that are synchronized by GPS. Each PMU is connected to a GPS clock that provides the time reference signals in format IRIG-B00 with CF extension (PPS signal, IEEE 1344:1995), used by the PMU to synchronize the acquisition process. Figure 4 exhibits the digital recorders and the clock used.

B. Phasor Data Concentrator System – PDCS
A Phasor Data Concentrator System (PDCS) receives the data from the PMUs assembling them in a concentrated structure. The PDCS stores historical data and provides the information for applications that assess the power system performance.

For the MedFasee CTEEP Project, a PDCS was developed with a decentralized architecture and a two-level hierarchical arrangement between PDCs (see Figure 1).
The function of each PDC in the structure depends on its hierarchical level. At the first level there are the Front End PDCs (FEPDCs) that communicate with the PMUs. Each FEPDC is responsible for the data concentration of a specified number of PMUs. It assembles and sends packets containing data of the PMUs, corresponding to the same instant of time. The FEPDC may also store the phasor data in its local database.

The Master PDC (MEPDC) is at the second hierarchical level. It communicates with all the FEPDCs, receiving and storing the data of the whole SPMS. The MEPDC provides the phasors for applications in real time and for off-line studies.

Expansibility is the main characteristic of this structure. New FEPDCs can be added together with new PMUs, so that the processing effort is shared.
Architecture of the SPMS Prototype
The SPMS prototype started with five PMUs, installed in three substations of CTEEP Company, and one PDCS installed in Bom Jardim.

Several alternatives were considered for the PMUs location and the most adequate for the project purposes were the substations Ilha Solteira (one PMU), Bauru (two PMUs) and Cabreúva (two PMUs). This choice allowed the monitoring of one of the 440 kV system corridors, providing measurements in locations near the generation plants, interconnections between several voltage levels and load centers.

The system operates since 2011 at the CTEEP Control Center, in Bom Jardim. It has contributed to expedite the analysis of events in substations and transmission lines.

Additional PMUs were later installed at the following substations: Jupiá, Bauru, Cabreúva, Ilha Solteira, Araraquara, Santo Ângelo, Interlagos e Embu-Guaçu, as shown in Figure 2.


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