**4.2.2 Phasor Data Concentrator (PDC)**

The main functions of a PDC are: to gather data from several PMUs, to reject bad data, to align the time stamps, and to create a coherent record of simultaneously recorded data. As a consequence, a snap-shot of phasors of the measured area can be obtained (Phadke & Thorp, 2008).

In some cases, a central PDC may concentrate the area data received from other PDCs and may provide phasors of the entire system.

A study of MTU tasks in a SCADA system indicates that the tasks and functions of PDC in SPMS systems are almost the same as those in SCADA systems.

Wide Area Measurement Systems 311

First DPRs sample rates were 4 to 20 samples per cycle, but nowadays, DPRs are available

The Circuit Breaker Monitor (CBM) is an electronic device that monitors circuit breakers. The CBM captures detailed information about each CB operation in real time; either the operation is initiated manually by the operator or it is initiated automatically by the protection and control equipments (Kezunovic, 2008b). The CBM data is also formed in

In general, the information about any system can be extracted from its raw data, which is measured by its data resources. In power systems, this can be achieved by a kind of computer aided tools known as "WAMS Applications" (Shahraeini et al., 2010). Typically, WAMS applications process the raw data measured by data resources and extract usable information for system operator, consumers and customers. Shahraeini et al. (2010) have classified WAMS applications into the three main groups: generation, transmission and distribution applications. Three next sub-sections are going to describe these three groups of

Generation applications (GEN): These applications are run in generation level in the way that they acquire and process data of generators in the control center(s). As its consequence, generator information can be obtained in the control center(s) all at once. Generator operation status monitoring and transient angle stability are some examples of such

In the above mentioned applications, generator status monitoring (GSM) is the most important GEN application since it provides all or part of real time information of generators in the control center. The first kind of GSM was implemented by using DFR as a data recorder (Lee et al., 2000). As DFRs can record the operational and non-operational data with very high sampling rates, they can be used as online recorders in generation sides. If the recorded data is transmitted to the control center in real time, the generator status can be monitored in the control center. After introducing PMUs to the power systems, the information provided by these units can also used for GSM application (Xiaorong et al., 2006). This has been resulted from the fact that PMUs provide phasor data in real time with

Transmission and sub-transmission applications (TRAN): In deregulated power industries, some applications are performed at transmission (or sometimes sub-transmission) level by independent system operator (ISO). Historically, these functions are performed by group of computer aided tools called energy management systems (EMS). State estimation (SE), load flow (LF), optimal power flow (OPF), load forecast (LF) and economical dispatch (ED) are

that sample at 64 to 128 samples per cycle (IEEE Inc., 2006).

**4.5 Circuit Breaker Monitor (CBM)** 

COMTRADE format.

applications.

**5. WAMS applications** 

**5.1 Generation aplications** 

applications (Xiaorong et al., 2006).

very high sampling rate (up to 60 samples per second).

**5.2 Transmission and Sub-Transmission applications** 
