This study presents a technique to locate the source of faults in distribution systems, i.e. to pinpoint where the fault has occurred along the distribution system. More specifically, it localises the origin of short duration voltage variations (SDVVs) in a distribution system. Fault location (its origin) is estimated solely from the voltage waveforms during the fault. More specifically, the energies of the instantaneous symmetrical components corresponding to the voltage waveforms are used to estimate the fault location. The proposed localisation strategy considers that the signal records during a fault are captured at the feeder start node and at other nodes scattered along the distribution systems. Simulation results show the feasibility of the proposed technique to accurately localise the origin of faults in distribution systems.

Modern power system involves growing use of open channel communication in secondary frequency regulation which introduces time delay in the automatic generation control loop which may lead to system instability. This study proposes a novel power system frequency stabiliser (PSFS) which is a modified secondary controller in order to improve the system stability in the presence of large communication delays. An auxiliary signal is added to the secondary controller to provide additional damping. The gain of the controller is obtained by meta-heuristic methods. The proposed controller is first developed on a single area hydropower system and the same is then applied on the Western System Coordinating Council 3-machine, 9-bus power system. Furthermore, to show the effectiveness of the proposed PSFS in a large practical multi-area system; it is also applied to the IEEE 39-bus system. Results show that the proposed controller significantly improves the stability of a power system operating with large communication delay which is first considered as constant and then the stability improvement with the proposed PSFS in the presence of random communication delays is also shown. The PSFS performance is tested by the results obtained with MATLAB/Simulink simulations and further verified on a real-time simulator.

As a typical approach to demand response (DR), direct load control (DLC) enables a load service entity (LSE) to adjust the electricity usage of residential customers for peak shaving during a DLC event. Households are connected in low-voltage distribution networks, which are always three-phase unbalanced. However, existing work has not considered the detailed operational constraints of three-phase distribution networks, which may lead to decisions that deviate from reality or are even infeasible in practice. Moreover, centralised control may cause privacy and communication issues. This study proposes a distributed residential DLC method that considers the operational constraints of three-phase unbalanced distribution networks and privacy of residential customers. Numerical tests on IEEE benchmark systems demonstrate effectiveness of the method. The proposed distributed method can converge within 17 iterations in IEEE 123-bus distribution system, which demonstrates scalability of the proposed algorithm.

In some recent articles, the vulnerability of phasor measurement unit (PMU) to the time synchronisation attack by spoofing its global positioning system (GPS) has been highlighted as a threat to power grid protection, control and monitoring system. Having spoofed PMU GPS signals, one can manipulate the measurements and inject bad data to power grid protection and monitoring system. The existing anti-spoofing methods are all based on GPS signal analysis. The mentioned methods are just able to detect spoofing without any data refinement as the data of power grid has not been practically used in calculations. Furthermore, some of these methods lose their certainty in noisy and harsh environments due to low power of GPS signals. A novel anti-spoofing algorithm has been proposed based on power grid infrastructures which can join to any of the existing anti-spoofing algorithm to empower spoofing detection process. The proposed algorithm adopts phasor measurement analysis and state estimation methods to detect spoofing. The composite of this algorithm with any of the existing algorithms will not only cover the probable malfunctioning in spoofing detection but also be able to refine counterfeit measurements.

This study presents a two-stage planning framework of the battery energy storage system (BESS) and micro-turbine (MT) in a microgrid. In the first stage, the optimal allocation decisions are made before the actual realisation of the operational uncertainties. In the second stage, the optimal operation strategies are made for the microgrid by minimising the costs paid to the main grid, fuel cells, MTs, BESSs and controllable loads (CLs). The hot water system and interruptible load are considered as CLs. Their mathematical models are built to investigate their roles in smoothing renewable energy. In addition, efforts are made to keep the linearity of the formulated optimisation problem, and the backward scenario reduction method is adopted to further enhance the computational efficiency. The modified IEEE 33-bus radial system is used as a microgrid to verify the effectiveness of the proposed approach for both islanded and grid-connected microgrids. Sensitivity analysis has been conducted to compare the economics and robustness of the identified solutions.