A novel faulted section location technique for future active distribution networks

Distribution Network Operators (DNOs) face increasingly higher challenges to preserve quality and continuity of supply due to the widespread penetration of Distributed Energy Resources (DER) [1–8]. In parallel, more advanced technologies are being introduced into secondary substations for better observability and controllability. These features provided via instrumented substation assets and Information Communication Technologies (ICT) present opportunities for the development and implementation of new functions aiming to the effective operation and monitoring of active distribution networks [9–14]. This thesis focuses on one of these functionalities – that is, leveraging the ability of Low Voltage (LV) sensors to locate 11 kV unsymmetrical faults by monitoring and processing the network voltage profile during fault conditions. In particular, a novel technique has been developed which identifies the Faulted Section (FS) of the Medium Voltage (MV) feeder after a fault has occurred. The proposed algorithm, of which the successful operation depends solely on distributed LV voltage monitoring devices, represents the main contribution of the research work. A key characteristic is that, although the LV sensors connected at the secondary side of MV/LV step-down transformers require communication to transmit the data to a central point, they do not require time synchronisation. The technique facilitates the fault location procedure, which is of major importance as it accelerates restoration, reduces the system downtime, minimises repair cost, and hence, increases the overall availability and reliability of the distribution network. Moreover, the thesis deals with the challenges related to the complexity of modern distribution networks, taking into account ring topologies, MV lateral connections, pre-fault load unbalance and the presence of DERs. In this sense, the empirical characterisation of grid connection stability and fault response of small scale commercially available LV PV inverters was realised. The purpose was twofold: 1) highlight the diversity among the inverters’ responses as observed during the testing and indicate the risk of loss of PV generation during typical MV and HV level faults and 2) develop a dynamic model representing the behaviour of a real inverter under the applied physical testing conditions. The particular model was deployed in the power system studies conducted, aiding the evaluation of the FS location technique. Laboratory investigation was also carried out at the facilities of the Power Networks Demonstration Centre (PNDC) to further examine the performance of the developed faulted section location algorithm. The tests were performed in both MV radial and ring PNDC network configurations and measurements were acquired from various LV test-bays. It was demonstrated that the scheme can reliably identify the faulted section of the line while consistently maintaining high accuracy across a wide range of fault scenarios. Further sensitivity analysis demonstrates that the proposed scheme is robust against partial loss of communications and noise interference. The thesis concludes with an overview of future work that is required to further advance the concepts demonstrated.Distribution Network Operators (DNOs) face increasingly higher challenges to preserve quality and continuity of supply due to the widespread penetration of Distributed Energy Resources (DER) [1–8]. In parallel, more advanced technologies are being introduced into secondary substations for better observability and controllability. These features provided via instrumented substation assets and Information Communication Technologies (ICT) present opportunities for the development and implementation of new functions aiming to the effective operation and monitoring of active distribution networks [9–14]. This thesis focuses on one of these functionalities – that is, leveraging the ability of Low Voltage (LV) sensors to locate 11 kV unsymmetrical faults by monitoring and processing the network voltage profile during fault conditions. In particular, a novel technique has been developed which identifies the Faulted Section (FS) of the Medium Voltage (MV) feeder after a fault has occurred. The proposed algorithm, of which the successful operation depends solely on distributed LV voltage monitoring devices, represents the main contribution of the research work. A key characteristic is that, although the LV sensors connected at the secondary side of MV/LV step-down transformers require communication to transmit the data to a central point, they do not require time synchronisation. The technique facilitates the fault location procedure, which is of major importance as it accelerates restoration, reduces the system downtime, minimises repair cost, and hence, increases the overall availability and reliability of the distribution network. Moreover, the thesis deals with the challenges related to the complexity of modern distribution networks, taking into account ring topologies, MV lateral connections, pre-fault load unbalance and the presence of DERs. In this sense, the empirical characterisation of grid connection stability and fault response of small scale commercially available LV PV inverters was realised. The purpose was twofold: 1) highlight the diversity among the inverters’ responses as observed during the testing and indicate the risk of loss of PV generation during typical MV and HV level faults and 2) develop a dynamic model representing the behaviour of a real inverter under the applied physical testing conditions. The particular model was deployed in the power system studies conducted, aiding the evaluation of the FS location technique. Laboratory investigation was also carried out at the facilities of the Power Networks Demonstration Centre (PNDC) to further examine the performance of the developed faulted section location algorithm. The tests were performed in both MV radial and ring PNDC network configurations and measurements were acquired from various LV test-bays. It was demonstrated that the scheme can reliably identify the faulted section of the line while consistently maintaining high accuracy across a wide range of fault scenarios. Further sensitivity analysis demonstrates that the proposed scheme is robust against partial loss of communications and noise interference. The thesis concludes with an overview of future work that is required to further advance the concepts demonstrated

Enabling Disaster Resilient 4G Mobile Communication Networks

The 4G Long Term Evolution (LTE) is the cellular technology expected to outperform the previous generations and to some extent revolutionize the experience of the users by taking advantage of the most advanced radio access techniques (i.e. OFDMA, SC-FDMA, MIMO). However, the strong dependencies between user equipments (UEs), base stations (eNBs) and the Evolved Packet Core (EPC) limit the flexibility, manageability and resiliency in such networks. In case the communication links between UEs-eNB or eNB-EPC are disrupted, UEs are in fact unable to communicate. In this article, we reshape the 4G mobile network to move towards more virtual and distributed architectures for improving disaster resilience, drastically reducing the dependency between UEs, eNBs and EPC. The contribution of this work is twofold. We firstly present the Flexible Management Entity (FME), a distributed entity which leverages on virtualized EPC functionalities in 4G cellular systems. Second, we introduce a simple and novel device-todevice (D2D) communication scheme allowing the UEs in physical proximity to communicate directly without resorting to the coordination with an eNB.Comment: Submitted to IEEE Communications Magazin

Outlier Detection Techniques For Wireless Sensor Networks: A Survey

In the field of wireless sensor networks, measurements that significantly deviate from the normal pattern of sensed data are considered as outliers. The potential sources of outliers include noise and errors, events, and malicious attacks on the network. Traditional outlier detection techniques are not directly applicable to wireless sensor networks due to the multivariate nature of sensor data and specific requirements and limitations of the wireless sensor networks. This survey provides a comprehensive overview of existing outlier detection techniques specifically developed for the wireless sensor networks. Additionally, it presents a technique-based taxonomy and a decision tree to be used as a guideline to select a technique suitable for the application at hand based on characteristics such as data type, outlier type, outlier degree

Real-time co-ordinated resource management in a computational enviroment

Design co-ordination is an emerging engineering design management philosophy with its emphasis on timeliness and appropriateness. Furthermore, a key element of design coordination has been identified as resource management, the aim of which is to facilitate the optimised use of resources throughout a dynamic and changeable process. An approach to operational design co-ordination has been developed, which incorporates the appropriate techniques to ensure that the aim of co-ordinated resource management can be fulfilled. This approach has been realised within an agent-based software system, called the Design Coordination System (DCS), such that a computational design analysis can be managed in a coherent and co-ordinated manner. The DCS is applied to a computational analysis for turbine blade design provided by industry. The application of the DCS involves resources, i.e. workstations within a computer network, being utilised to perform the computational analysis involving the use of a suite of software tools to calculate stress and vibration characteristics of turbine blades. Furthermore, the application of the system shows that the utilisation of resources can be optimised throughout the computational design analysis despite the variable nature of the computer network