# Wide-Area Protection System for Radial Smart Distribution Networks
## 1 Introduction
Advancements in communication and measurement techniques that enhance the progress of wide-area protection through wide-area measurement systems in smart distribution networks are discussed in [21]. Additionally, the background of smart power grids is explained, along with how new technologies such as non-conventional instrument transformers, clock synchronization, and data synchronization contribute to the development of wide-area protection. In [22], a fast and reliable differential backup protection strategy is presented for medium voltage smart grids that is based on a proposed device detection method. This strategy accelerates fault isolation by starting device failure-related backup protection in advance and locking failed primary protection, which is predicted by the detection method. An integrated differential-based wide-area protection based on a three-level hierarchically structure is proposed in [23] for active distribution networks. In [24], various Artificial Intelligence (AI)-based approaches for fault location in smart grids are reviewed, along with technical suggestions such as wide-area communication tools including Phasor Measurement Units (PMUs), Intelligent Electronic Devices (IEDs), and smart meters. In modern medium voltage smart grids including various types of DERs, fault location and relay coordination are key challenges for protection systems. In response to these challenges, this paper presents a new wide-area protection system for modern distribution networks, aiming to simplify fault location and relay coordination processes. Methods which operate independently of communication systems should consider all possible network configurations for relay coordination. Consequently, the processes of fault detection and fault location need to be continuously updated to reflect these various combinations. In contrast, the fault detection procedure of the proposed method is universal and applicable to any network structure, eliminating the need for such updates. Hierarchical communication-based methods that use CPUs require an extensive data transmission network to handle real-time, continuous electrical parameters from across the network which imposes a significant computational burden for accurate fault location. In contrast, the proposed method simplifies this process by only needing the fault detection and direction signals from the network relays. Additionally, horizontal communication-based methods require a specific coordination process between relays or agents, which must be individually designated for each relay or agent. The proposed method, however, establishes this coordination process once, making it a uniform approach. In comparison to existing wide-area schemes for distribution networks that use differential approaches, the proposed ANN-based method significantly reduces the number of relays needed by leveraging the conventional structure of network relay placement. Furthermore, wide-area differential-based methods also require an extensive data transmission network. The proposed wide-area protection system uses a conventional relay placement architecture but introduces novel fault detection and fault location procedures. It employs universal fault detection modules based on Artificial Neural Networks (ANNs) and utilizes a proposed Fault Zone Relay Condition (FZRC) matrix for fault location. These novel procedures eliminate the need for extensive data transmission infrastructure. The main justifications for utilization of the proposed wide-area approach are as follows:  
- Simplification of relay coordination settings;  
- Recent advances in data communication systems render a safe and quick data transmission appropriate for protection system applications;  
- Compared to transmission networks, fault management timelines in distribution networks are more flexible;  
- The relay placement architecture follows conventional methods, requiring fewer relays compared to differential-based approaches.