Power transmission systems enjoy various measurements at high-voltage (HV) substations, which make the estimation of electrical condition of the grid, i.e. voltages and power flows, viable. Distribution systems however have been conventionally operated with unidirectional power flows and on the other hand, had predictable behaviour. The paradigm shift from central large power plants to the high penetration of renewable energy sources within the distribution system has transformed the foregoing characteristics. Distribution systems are not passive predictable consumers of electricity anymore, rather active grids thanks to the distributed generation (DG) mainly based on intermittent wind or solar power.

Volatility introduced by renewables has raised concerns regarding the ability to monitor distribution systems in time, and taking concrete actions to counteract large disturbances and guarantee a high level of resilience. In this context, state estimation refers to the process of using the data received from existing meters/measurements to infer voltages and currents at different locations in the system. This process is not as easy as it may sound, particularly because of practical factors such as metering errors and communication latencies. Nonetheless, there is a consensus that distribution systems operators (DSOs) will soon be greatly in need of state estimation in order to take proper action against violating system conditions as swiftly as possible.

This PhD project is aimed at facilitating the state estimation process for distribution systems- with no need for new investment or necessarily resorting to new technologies. This will be achieved by relying on advanced solving techniques and taking advantage of fundamental characteristics of power systems. Four main objectives can be associated with the project as below:

1) Modeling the problem linearly without any approximations,
2) Carrying out the process in real-time even in the case of large-scale distribution grids,
3) Obviating the need for data synchronization while keeping the grid equations linear,
4) Incorporating pseudo-measurements to increase accuracy.

This project and its outputs will contribute to UK strengths and are aligned with the EPSRC delivery plan to build a resilient and connected nation. Real-time monitoring of distribution systems will enhance the electricity grids' resilience, thereby contributing to the "Energy security and efficiency" priority area that EPSRC defines as important to deliver its output of a "Resilient Nation". The project also relates to the ambitions set out by EPSRC for Energy Networks research areas. It ensures "affordable solutions for national needs" by exploiting existing measurement technologies and infrastructure in the UK electricity grids.