**3. WAMS process**

As mentioned at the beginning of this chapter, a WAMS process includes three different interconnected sub-processes (Yan, 2006): data acquisition, data transmitting and data

Wide Area Measurement System (WAMS) was firstly introduced by Bonneville Power Administration (BPA) in the late 1980s (Taylor, 2006). This was resulted from this fact that the Western System Coordinating Council (WSCC) faced a critical lack of dynamic information throughout the 1980s. As a result of this, in 1990, a general plan to address this problem was formed (Cai et al., 2005). Therefore, the Western Interconnection of the North

In 1995, the US Department of Energy (DOE) and the Electric Power Research Institute (EPRI) launched the Wide Area Measurement System (WAMS) Project. The aim of this project was to reinforce the Western System Dynamic Information Network called WesDINet. Dynamic information provided by WAMS of WesDINet has been very important and useful for understanding the breakups. This dynamic information can also be used for the purpose of avoiding future disturbances. Furthermore, during deregulation and restructuring process, information resources provided by this WAMS were utilized for

Since 1994, phasor measurement units (PMU) have been used in WAMS and they have provided synchrophasor measurements (Cai et al., 2005). It is noted that a complete survey of PMU will be presented in Section 4. Synchrophasor measurements may contribute previous functions or may introduce some new WAMS functions, which are never achieved previously by conventional measurements. When synchrophasor measurements are used as

There exists a precise and comprehensive definition of WAMS, which has been introduced

"The WAMS effort is a strategic effort to meet critical information needs of the changing

It can be mentioned that a WAMS needs an infrastructure to perform its tasks. This is also

The WAMS infrastructure consists of people, operating practices, negotiated sharing arrangements and all else that are necessary for WAMS facilities to deliver useful information. In recent years, PMU measurements are commercially available and are widely used in power systems. On the other hand, high speed and low cost communication systems; which are worked based on a layer model, are also well-established in power systems. As a result, the definition of WAMS is slightly different from past. Nowadays, a general definition of WAMS may be presented as follows: The WAMS combines the data provided by synchrophasor and conventional measurements with capability of new communication systems in order to monitor, operate, control and protect power systems in wide

As mentioned at the beginning of this chapter, a WAMS process includes three different interconnected sub-processes (Yan, 2006): data acquisition, data transmitting and data

America power system was the first test-bed for WAMS implementation.

data resources of a WAMS, such a WAMS will be called PMU based WAMS.

maintaining the system reliability (Hauer & Taylor, 1998).

by Hauer from BPA/Pacific NW National Labs (Taylor, 2006):

defined by Hauer (Taylor, 2006) as follows:

geographical area (Junce & Zexiang, 2005).

**2.1 History** 

**2.2 WAMS definition** 

power system".

**3. WAMS process** 

processing. Measurement systems and communication systems together with energy management systems perform these sub-processes, respectively.

In general, a WAMS acquires system data from conventional and new data resources, transmits it through communication system to the control center(s) and processes it. After extracting appropriate information from system data, decisions on operation of power system are made. Occasionally, WAMS may command some actions that are performed by system actuators in remote sites (Shahraeini et al., 2011). All of these facts indicate that WAMS denotes efficient usage of data and data flow to achieve a more secure and a better strategy for the flow of electrical energy. The WAMS process is illustrated in Fig. 1.

Fig. 1. WAMS Process in Power Systems.

An inspection of the above-mentioned facts together with Fig. 1 indicates that data itself is the fundamental requirement to perform WAMS functions. It can also be concluded that each sub-process has different responsibilities and different tasks that should be performed on system data. Consequently, WAMS main sub-processes should be studied from the data point of view.

In the rest of this chapter, data resources, applications and communication infrastructure of WAMS will be investigated.
