Amrit Parajuli

This paper focuses on deriving power-system linear models directly from collected PMU data with the aim of feeding a wide-area damping controller (WADC) architecture. To this end, a data-assisted dominant modal realization in state space is derived from frequency-response data, impulse-response data, and the retained impulse dynamic subspace, enabling WADC synthesis without requiring a full phenomenological network model. Then, a discrete-time linear quadratic Gaussian (LQG) structure is synthesized on the identified dominant modal realization, combining damping action with reconstruction of reduced states from WAMS measurements. Finally, the symbiosis between the proposed realization and the controller is validated on the Kundur and New England–New York power networks by using modal displacement and nonlinear post-fault simulations, demonstrating coordinated damping through selected AVR supplementary inputs.

The integration of distributed generation is one of the most effective alternative methods for enhancing the voltage profile and reducing power loss in radial distribution systems. This study investigates the impact of integrating photovoltaic (PV) generation on distribution systems, considering radial distribution networks. The IEEE 33 bus radial distribution system and Panbari feeder of the Dharan substation are selected as candidate systems. Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) are proposed for determining the optimal location and sizing of single and multiple PV installations, considering minimum power loss as the objective function. The results are analyzed in terms of voltage profile improvement and power loss minimization with PV integration. Additionally, a comparative analysis is conducted for the system with PV integration and PV with capacitor bank for reactive power injection. An economic analysis is performed to determine the optimal number of Distributed Generator (DG) integrations. Through sensitivity analysis, the most sensitive buses are identified, and Power-Voltage (P-V) curves are plotted for these buses in the base case and cases after integration of PV only and PV with capacitor banks. The results are examined and compared in terms of load margin limit and critical voltage point. Among single and multiple PV integrations, the integration of two PV installations is found to be most suitable based on economic analysis. Simulation results demonstrate that the integration of PV sources in existing radial distribution systems has a positive impact on steady-state voltage stability. Furthermore, improvements in voltage profile and significant reductions in system power loss are observed.

Modern power systems are growing in complexity due to the installation of large generators, long transmission lines, the addition of inertialess renewable energy resources (RESs) with zero inertia, etc., which can all severely degrade the system frequency stability. This can lead to under-/over-frequency load shedding, damage to turbine blades, and affect frequency-sensitive loads. In this study, we propose a methodology to improve the two critical frequency stability indices, i.e., the frequency nadir and the rate of change of frequency (RoCoF), by formulating an optimization problem. The size and placement location of battery energy storage systems (BESSs) are considered to be the constraints for the proposed optimization problem. Thereafter, the optimization problem is solved using the three metaheuristic optimization algorithms: the particle swarm optimization, firefly, and bat algorithm. The best performing algorithm is then selected to find the optimal sizing and placement location of the BESSs. The analyses are all performed on the IEEE 9-bus and IEEE 39-bus test systems. Several scenarios which consider multiple generator outages, increased/decreased loading conditions, and the addition of RESs are also considered for both test systems in this study. The obtained results show that under all scenarios, the proposed method can enhance system frequency compared to the existing method and without BESSs. The proposed method can be easily upscaled for a larger electrical network for obtaining the optimized BESS size and location for the improvement of the system frequency stability.

After end of decades of loadshedding, the power system of Nepal is moving towards the scenario of self-sufficiency. The Government of Nepal has formulated a policy to add 20 GW of hydropower in the next ten years, making a ten-fold increase compared to the current capacity. Therefore, there is a high need for the assessment of the power system stability of the current Nepal grid to mitigate any potential issues that can occur due to the addition of this huge generation. This paper conducts a comprehensive assessment of the power system stability namely voltage (static), angle (transient and small signal), and frequency stability. The proposed assessment methodology consists of three stages: the first stage constitutes the selection and modeling of the components (generator, load, line, excitation system, governor, renewable energy resources) of the power system of Nepal. The second stage then uses the stability assessment tools: time domain simulations for frequency and transient stability, modal (eigenvalue) analysis for small signal stability and voltage stability, and sensitivity analysis for identification of critical areas prone to instability. The result shows that the current grid of Nepal has a low margin of the small signal stability. The critical clearing time of the system is approximately 0.51s. The result also show that there are five potential voltage instability areas in Nepal but is robust in terms of the frequency stability. Additionally, the integration of photovoltaic generation to the Nepal grid has also been studied in this paper. The study shows that the margin of the low frequency oscillatory stability decreases with the penetration of photovoltaic generation of the power grid of Nepal.

Intermittent distributed energy resources (DERs) add challenges to the modern power system network. On the other hand, information and communication technology (ICT) is changing traditional electricity grids into smart grids, which facilitates a decentralized system in which prosumers may participate in energy trading. Smart grids, DER integration, and network connectivity are adding complexity to the power system network day by day; Blockchain technology might be a great tool to manage the network’s operational complexity. The Blockchain provides for quicker, frictionless, secure, and transparent transactions. With the addition of smart contracts, it may be utilized to manage the expanding complexity of the contemporary power system. In this study, the authors focus on the scope, challenges, and potential future direction of Blockchain technology application in the power system. Blockchain has received interest and has been used for decentralized power system applications in recent years, but it is still young and has scalability, decentralization, and security concerns. This article discusses the interfaces and the possibilities that can assure trust, security, and transparency in decentralized power system applications and make a decentralized power system and power market possible.