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The residential sector in Brunei is the highest electricity consumer due to the cheap electricity tariff. The high consumption, primarily generated from natural gas, causes environmental harm. The government implemented a net-metering program to encourage the residents to adopt PV systems, but cheap tariffs hinder the adoption. Hence, this study aims to learn the role of electricity tariffs in adopting PV systems and consequently study the effects on the carbon footprint. This study calculated the sizes of the most cost beneficial PV systems under four electricity tariff structures: (1) current tariff, increasing block tariff (IBT), (2) previous tariff, decreasing block tariff (DBT), (3) proposed IBT tariff (mild), (4) proposed IBT tariff (aggressive). Then, economic feasibility and environmental studies were conducted. Lastly, this study investigated what the results would mean nationwide. The study found that under the current IBT and DBT, it is highly infeasible for the residents to install PV systems in terms of both economic and environmental. Under the mild IBT, the PV systems were calculated to have a payback period (PB) of 25 years and a return on investment (ROI) between -9.8% and 0.1%. On a positive note, the pollutant gas emissions can be reduced by 173,541kg/year nationwide, (14%) of the current emissions. Under the aggressive IBT scheme, the PB is between 18.02 and 22.93 years, and the ROI is between -1.8% and 1.7%. The total gas pollution in the country can be reduced by 254,212kg/year nationwide, 21% of the current emissions. Nationwide, implementing the mild IBT or the aggressive IBT can motivate the residents to install PV systems which could generate between 240 MW and 376 MW. Based on the results, although it is highly infeasible for the residents to install PV systems under all the tariff structures, there is a positive outcome in reducing carbon emissions and reaching the national renewable energy goal.

In this paper, the robust stabilization for the networked microgrid system is presented. A microgrid implements master-slave control architecture where the communication channel is utilized to exchange the reference current signals. With this structure, a time delay exists in the reference control signal which may lead to instability. The analysis of the control strategy is carried out in dq reference frame. The microgrid is constituted by PV and wind energy sources supplying a load through voltage source inverters. The stochastic nature of renewable energy sources introduces uncertainties which can be represented as fluctuations in the voltage and the current. The main contribution of the paper is formulating the controller design of the microgrid with communication delay and uncertainties in the model as H∞ control problem and Lyapunov–Krasovskii functional is utilized to develop stability criterion in bilinear matrix inequality form. Grey wolf optimizer is used to minimize the performance index and derive the stabilizing controller. The microgrid performance is tested through simulation using the time-varying nonlinear model of the microgrid. The results prove that satisfactory current and power-sharing are attained even with the existence of time delays and uncertainties.

In classical power systems, frequency measurements are transferred via a specialised communication channel, resulting in time delay. The time delay plays a major role in a power system, which can reduce the dynamic performance of the load-frequency control (LFC) system and can destabilise the system. The research to date has tended to focus on developing a new algorithm to determine the delay margin (DM) rather than looking into a hybrid algorithm which includes a nature-inspired metaheuristic optimisation technique. This paper introduces a novel method for computing the DM based on grey wolf optimisation (GWO), specifically for the constant time delay. In the proposed method, GWO is employed to optimise the minimum error of the spectral radius and to determine the best design variable of the crossing frequency. With the help of the proposed method, the sweeping range is no longer required, which improves the accuracy of the result. To evaluate the proposed method, a two-area network power system is considered as a case study. Furthermore, the effect of the PI controller gains on the DM is taken into account. The proposed method efficacy is demonstrated by comparing it with the most recently published methods. The results demonstrate that the proposed method is remarkably better than the existing methods found in the literature, where the smallest percentage inaccuracy using the simulation-based DM based on GWO is found to be 0.000%.

Weak grid conditions challenge the grid integration of offshore wind farms. Especially grids with low inertia and large grid impedance questions frequency and voltage compliance capabilities. Grid-forming wind turbines are a promising technology for weak grids due to the nature of their control strategy. This paper explains the difference in how weak grid conditions are described in the literature and shows how the voltage stability margin changes with the short-circuit ratio and X/R ratio. With that knowledge, the frequency and voltage compliance capabilities of three grid-forming controls in an offshore wind farm are investigated and benchmarked. These three controls are a droop control, a virtual synchronous machine, and a synchronverter. This was done by quantifying their performance during a frequency disturbance with sensitivity to the short-circuit ratio, X/R ratio, and the inertia constant, H. It is concluded that the virtual synchronous machine is the most compliant grid-forming control and that DC-link modeling is of great importance when testing compliance during frequency disturbances.