Amplitude and maximum force damping system4 answersAmplitude-selective damping systems play a crucial role in controlling vibrations by adjusting damping forces based on the displacement amplitudes. These systems are designed to provide varying levels of damping depending on the input displacement, offering less damping for small displacements and increased damping during maneuvers or larger vibrations. The maximum amplitudes of vibration responses are essential in engineering to ensure safety and reliability. Studies have shown that damping in systems can be highly nonlinear and dependent on the maximum vibration amplitude reached in a cycle, with significant increases in damping observed with larger amplitudes. Implementing advanced control laws like resonant-force-feedback (RFF) can enhance control authority and stability, especially in scenarios with low stiffness ratios. These findings highlight the importance of considering amplitude and maximum force in damping systems for effective vibration control.
Stochastic modeling approach on power system resilience?5 answersA stochastic modeling approach is proposed for assessing power system resilience. This approach considers the effects of component multistate failures, interdependencies between power and communication networks, and the degradation of network performance. The approach incorporates a discrete time Markov process to model the transitions between failure states. It also introduces a new robustness measure that integrates topology information, component damage, and performance degradation. Another study focuses on optimizing control schemes to maximize system resilience by anticipating and responding to potential failure contingencies. Additionally, a framework is proposed that evaluates power system resilience by considering various factors such as loss of load probability, system fragility, and recovery difficulties. These approaches are tested on different power system models to demonstrate their effectiveness.
What are the parameters with uncertainty in power systems?5 answersUncertain parameters in power systems include load demand, wind energy, photovoltaic energy, plug-in electric vehicles, electricity price, and load growth. Additionally, the forecasting of renewable energy generation, load demand, and utility prices in virtual power plants (VPPs) is also subject to uncertainty. Grid parameters in power system state estimation can be uncertain due to various reasons, such as lack of documentation or parameter variation due to weather conditions. The stability of power systems is affected by uncertain parameters of equipment. In power system studies, there are diverse uncertain parameters such as loads, electricity price, wind power generation, and photovoltaic power generation.
How can the damping coefficient of a synchronous machine be calculated?5 answersThe damping coefficient of a synchronous machine can be calculated using various methods. One approach involves acquiring the voltages and currents of the machine before and after a frequency change, and then using a pre-established expression to calculate the damping coefficient. Another method involves analyzing the damping torque and the dynamics of the transient/subtransient reactances to understand the damping mechanism of synchronous generators. Based on this analysis, a dynamical virtual impedance can be used to emulate the damping mechanism and eliminate the need for a large damping coefficient in virtual synchronous machines. Additionally, a damping configuration method involves building a model of the virtual synchronous machine and calculating a response function of output active power variation to load-side frequency variation. The extreme values of this response function can then be solved to obtain a maximum value expression of the output active power, which can be used to configure the damping of the virtual synchronous machine.
What are the inertia estimation methods in power system?5 answersInertia estimation methods in power systems include the use of virtual inertia control strategies, wide-area monitoring systems (WAMS) information, and the kinetic energy theorem of the generator. Virtual inertia control strategies reshape the output characteristics of power-electronics-interfaced renewable energy sources and battery storage systems, and the estimation of inertia has become a concern for grid operators. The proposed methodology using WAMS information accurately estimates the rate of change of frequency (RoCoF) and the amplitude of active power deviations, allowing for the estimation of inertia constants of all generation units. The kinetic energy theorem is used to analyze the power variation of a single generator after disturbance and derive the expression of inertia for a single generator, which can be used to estimate the equivalent inertia of the system. These methods provide accurate estimation of power system inertia, which is crucial for grid planning and ensuring system stability.
How can the transient parameters of a power system stabilizer be optimized to improve the stability of the system?3 answersThe transient parameters of a power system stabilizer can be optimized to improve the stability of the system through various methods. One approach is to use a multi-objective optimization algorithm, such as the Genetic Algorithm, to optimize the parameters of the power system stabilizer. Another method is to use a fuzzy logic controller in conjunction with the power system stabilizer to improve transient stability. Additionally, the parameters of the power system stabilizer can be tuned using different techniques, such as the Heffron-Phillips PSS multimachine model and the Zieglar-Nicholas PSS controller tuning. Particle Swarm Optimization (PSO) can also be employed to optimize the parameters of the power system stabilizer and enhance stability. Furthermore, integrating the power system stabilizer with the excitation system can improve transient stability.