Advanced Control Strategies for UPFC in Power System to Enhance Control and Stability

Automatic Generation Control Optimization of an Isolated Power System Including Renewable Energy Penetration

This paper presents an enhanced version of controllers of frequency and voltage of an isolated power system. The optimal tuning includes the load‐frequency control system integrator loop, the governor, and the automatic voltage regulator that includes the PID parameters and amplifier gain. With such parameters, two objective functions shall be minimized, which are the frequency deviation and voltage deviation. Modern power systems embed renewable energy sources in generation and/or demand sides. Therefore, two real‐life signals of wind and photovoltaic power sources have been included as external disturbances affecting the main quality variables, the frequency and voltage, of the conventional thermal unit. With such assumptions, the problem of load‐frequency control (LFC) and automatic voltage regulator (AVR) becomes more challenging since the power system is assumed to be isolated and without interconnection to release the excess renewable energies to neighboring regions. In addition, it is rare in the literature to include the LFC and AVR in the same system model and that was based on little coupling sensitivity between AVR and LFC. With all these considerations, an optimization problem has been successfully solved via two metaheuristic optimizers, the political optimizer (PO) and Gray‐Wolf Optimizer (GWO). The improvements have been notable by dynamic simulations over sufficient time to allow abrupt system conditions. There are also some remarkable differences between PO and GWO that have been discovered and reported during research.

ROLE OF DISTRIBUTED GENERATION ON POWER SYSTEM STABILITY

Two-layer Emergency Frequency Control Scheme for Sending-end Power Grid With Multi-energy Storage Systems

With the increase of the proportion of the renewables, the system inertia and frequency regulation capability in the sending-end power grid have become seriously insufficient, making the frequency stability issue increasingly prominent. This paper proposes a two-layer emergency frequency control scheme for sending-end power grid with multi-energy storage systems (MESSs) to enhance the frequency stability. At the upper layer, the total power control commands of MESSs are optimized to minimize the control energy consumption, considering the constraints of frequency and control power. It achieves the optimal utilization of energy. At the lower layer, the power commands of each ESS are solved by the model predictive controller (MPC), with the objective of minimizing the loss cost and sate of charge (SOC) deviation of ESS, considering the operating characteristics of different ESS. It achieves the reasonable distribution of power. Finally, the effectiveness of the proposed control scheme are verified in IEEE-39 bus system. The results show that the proposed scheme can effectively enhance the system frequency stability for the sending-end system.

Dynamic Voltage Enhancement for Multi-Machine Power System Through PCH Based GCI

The recent trend of encouragement to renewable integration has resulted in an inverter-dominated hybrid grid. The time-scale of such integrated grid activities and its response time varies in a wide range. In such a scenario, the first challenge is to have a model that can capture both the dynamics of fast as well as slow components, and the second is stability analysis without compromising its time-varying impact. To address these issues, the paper includes the Port-Controlled Hamiltonian (PCH) Inverter formulation related to a interdisciplinary model for voltage stability analysis of inverter-dominated distribution grids. The interactions between slow network, load dynamics, intermediate converter-control dynamics, and fast electromagnetic states can be captured in the model. The PCH formulation provides an energy-based representation of the inverter dynamics, enabling systematic analysis of transient voltage response and post-disturbance recovery in inverter-integrated power systems. MATLAB is used to validate the proposed methodology in weak-grid and load-varying scenarios. A new PCH-based controller has been designed to tune the inverter PWM signal so that voltage stability can be supported to maintain the grid voltage profile.

Optimised PIDN–FACTS Control for Frequency Stability in Multi-Area Systems with Fuel Cell Integration

The growing induction of renewable and cleaner energy sources has made present-day interconnected power grids more complex, where frequency stability and tie-line power control are significant issues. This work presents a realistic two-area interconnected system modelled in MATLAB/Simulink comprising gas, reheat-thermal, and hydro units, with nonlinear consideration and a modified Proportional-Integral-Derivative-Filter (PIDN) controller design. The impact of the inclusion of a Fuel Cell (FC) unit with the grid on frequency stability is analysed, and a coordinated control strategy with Flexible AC Transmission System (FACTS) devices is developed. Several FACTS devices, namely Thyristor Controlled Series Capacitor (TCSC), Unified Power Flow Controller (UPFC), Interline Power Flow Controller (IPFC), and Static Synchronous Series Compensator (SSSC), are designed and integrated with the grid to improve frequency stability. Three population-based optimisation algorithms, viz, Grey Wolf Optimisation (GWO), Artificial Bee Colony (ABC), and Differential Evolution (DE), are used for minimising the cost function, Integral of Time multiplied by Absolute Error (ITAE), for optimal tuning of PIDN and FACTS controllers. A comprehensive study is performed across four scenarios, including single-area and multi-area Step Load Perturbations (SLP). The control performance of each strategy is evaluated based on the obtained ITAE, settling times, peak overshoots, peak undershoots, and rise times. Results demonstrate that GWO outperforms ABC and DE by achieving better control dynamics. Moreover, inclusion of FC achieves a substantial reduction in ITAE compared to conventional approaches, with values as low as 0.002044. FACTS devices further enhance performance, with IPFC consistently achieving the best damping, lowering ITAE to nearly half of the baseline PIDN–GWO values in multi-area disturbances. Overall, the study establishes that coordinated deployment of optimised controllers, FACTS technologies, and cleaner energy sources can significantly strengthen frequency regulation.

Enhanced voltage regulation and current sharing of radial DC microgrids

DC microgrids are gaining more attention as their control is simpler, their efficiency is higher and they are more reliable. DC microgrid control aims to regulate load voltage at the nominal value and share load among distributed generation units with a certain ratio. This paper presents a control strategy for radial DC microgrids that achieves these two goals accurately and simultaneously. It doesn’t require communication among distributed generators. Only global sensing is required and only one signal is transmitted among DGUs. Tianji Horse Racing Optimization algorithm was used to tune controller parameters. A stability analysis was conducted to evaluate the effect of load change on system stability. This control method has much faster dynamic response compared to previously reported methods. MATLAB Simulink was used to build a model for the microgrid to test the proposed control strategy. Its stability was tested by applying sudden load changes. Also, plug-in and plug-out capability was verified. Constant power load was also used to test the proposed control strategy performance. Communication delay effect was also tested.