# Smart Grid Fault Mitigation and Cybersecurity with Wide-Area Measurement Systems: A Review
## 2 Background
### WAMS Components  
For full observability and monitoring capabilities, the WAMS architecture typically consists of the following components [3; 42]:  
1. PMUs;
2. Phasor data collectors;
3. Synchronizers like remote terminal units (RTUs) for PMU-based applications;
4. Communication infrastructure. This WAMS infrastructure was developed as an alternative to SCADA systems. In addition to the basic components of the WAMS infrastructure, more modern model variants like Wide-Area Monitoring and Control (WAMC) or Wide-Area Protection, Control, and Monitoring (WAPCAM) systems have incorporated several components that help enhance some of its operations [4]. The observability operation of the WAMS infrastructure provides sufficient data to control the EMS properly and, in some cases, conduct an under-frequency load shedding (UFLS) of the entire power network in addition to fault detection [22; 39; 43]. The PMUs collate the data from power system components, including being integrated with conventional energy infrastructures like current transformers and voltage transformers, to develop a more robust power system architecture [10; 42; 43]. This responsibility of the PMUs becomes necessary because most countries already have functional power systems in need of system maintenance and upgrade without a complete overhaul of the system for mostly national security reasons [10; 26; 44]. The US, where the technology was innovated and developed, has not fully replaced its conventional protection arsenals for WAMS due to cybersecurity concerns though modern cyber-physical systems are being integrated at a rapid pace [14]. In practice, however, the WAMS architecture is designed to integrate with existing infrastructures and make them as smart as possible in an age of increasing rhetoric of smart technology and green energy innovation [10; 22; 44]. If any of these modern innovation concepts are feasible, energy losses must be minimal for  
Figure 2: A typical infinite-bus power grid model. energy conservation to be properly executed efficiently. PMUs and PDCs work in synergy with nearby components to achieve this. In our opinion, the deployment of WAMS is entirely dependent on the quality of the delivery system as well as the communication infrastructure. Some researchers have synonymized PMUs for WAMS. Many researchers disagree with this assessment, but the distinction stems from the comparison of WAMS with conventional SCADA infrastructure [10; 22; 27; 44]. However, PMUs alone are also unable to properly analyze these data and relay them to the ECC for efficient actions and decisions to be taken [21; 28; 43]. WAMS, on the other hand, could consist of other energy infrastructures beyond PMUs, PDCs, and RTUs to fit and meet specific needs in a power system network [37; 43]. Going further, the main potential of WAMS is their application. A model cannot be accepted if its architecture is not fully analyzed. The delicate nature of WAMS means that there will be significant training on their handling and on the deployment of the technology [10]. Sub-Saharan African countries, where off-grid systems coupled with renewable energy sources are increasingly developed, require the synchronization of devices to ensure the optimized operation of the grid. The synchronization of the PMUs and other protection and control devices is achieved through the same-time sampling of voltage and current waveforms using timing signals from a GPS (as shown in Figure 3) [1; 2]. Synchronized phasor measurement elevates the standards of power system monitoring, control, and protection to a new level [21; 24; 45]. PMUs are the backbone of WAMS-based systems and have been proven instrumental in developing-world microgrid systems, especially with the integration of renewable energy sources [5; 13; 21]. This means that real-time system monitoring may be required to help reduce the impact of intermittency from renewable generation.