In order to improve the dynamic stability monitoring and analysis abilities, Phasor Measurement Units (PMUs) are installed in the corresponding substations and power plants. Furthermore, the use of a wide area measurement system (WAMS) serves to view the system’s state from the dispatching center.
The PCS-996 Phasor Measurement Unit (PMU) is mainly applied for the measuring synchronized phasor, and the recording dynamic process of the power system. The PCS- 996 consists of Phasor Measurement Units (PMU) and phasor data concentrators (PDC). The core phasor measurement unit characteristics include the synchronized phasor measurement, based on standard clock signals and timekeeping capacity without the standard clock signal. In addition, the system is designed to achieve high-speed communication capacities between the localized PMUs and the central WAMS. The standard communication protocol is IEEE C37.118. A PDC is used to collect data from several PMUs, and then the PDC sends the data to the WAMS control center. In addition, the auxiliary function of the local storage of the phasor data can be equipped with PDCs. WAMS consists of PCS-996 series PMUs and PDCs, a clock synchronization system, high-speed communication network equipment and the analysis systems of the master substation. Furthermore, WAMS can realize dynamic process monitoring and analysis of the regional electric network and the cross-regional electric network.
Phasor calculation function
Calculate amplitudes and phase angles of phasor, such as Ua, Ub, Uc, U1, Ia, Ib, Ic, I1, Eq, etc.
Calculate measurement values, such as P, Q, f, df/dt etc.
Supervise binary signals, such as disconnector status, protection operation signal, PSS operation signal, etc.
Real-time communication function: send phasor data to PDC or WAMS control center through IEEE C37.118 protocol.
Triggered recording function: electric quantities or binary inputs can trigger the recording function with COMTRADE standard.
Fault Recording Function
Event records including 1024 IO events, 1024 alarm events and 1024 device logs.
Disturbance recording (also called triggered recording) function: 1024 fault reports, and 1024 disturbance waveforms, and file format of waveform is compatible with COMTRADE file.
Data concentration function
The PCS-996 PDC receives real-time phasor data from several PMUs. Then the PDC sends this accumulated data to the WAMS.
Dynamic recording function: store and backup phasor data locally.
Two RJ-45 Ethernet port and two fiber Ethernet ports, which support IEC60870-5-103, or IEC61850 protocol. These two RJ-45 Ethernet ports can also be used for FTP service.
One RS-485 serial port is used for clock synchronization.
One front RS-232 serial port is used to test and configure the device.
The phasor measurement unit is used to measure the synchronized phasor in the substation. It collects and records the phasor and binary inputs of the bus, line, main transformer and so on.
The phasor measurement unit is utilized in the measuring of the synchronized phasor of the power plant. It collects and records the phasor and binary inputs of the generator, including internal voltage potential, power angle, the terminal voltage, current and so on. In addition, it collects and records 4-20mA signals, which can be excitation voltage, current, rotating speed, frequency modulation and so on. PCS-996B can measure two generators and two AC bays.
The phasor data concentrator receives and stores the synchronized phasor data from PCS-996A and PCS-996B through direct connections via optical fibers. Meanwhile, it can communicate with the WAMS station or the monitoring system and send synchronized phasor data to them in real-time. The PCS-996G provides at least four independent network ports and can communicate with more than eight WAMS stations. Through the extension of communication plug-ins, it can accomplish further communication with more WAMS stations.