Real-time Stability Analysis Research Articles

An effective method for real-time estimation of slope stability with numerical back analysis based on particle swarm optimization

Abstract The purpose of this article is to provide an effective approach to evaluate slope stability in real-time in a reservoir area, which is significant for carrying out risk management for landslide disaster prevention in various engineering practices. A comprehensive idea for stability estimation of bank slope under the influence of rainfall or the reservoir water level is presented in this work. Slope stability analysis and back analysis of soil parameters are both included based on numerical simulation. The mechanical parameters of the bank slope were first back-analyzed using particle swarm optimization (PSO), and real-time stability analysis with high accuracy and efficiency was then established based on multiple continuously monitored displacements. Two case studies were carried out in this study. The results show that (1) based on the real-time monitored displacement and numerical simulation, the mechanical parameters of the slope can be reasonably retrieved through PSO; and (2) based on the inverse mechanical parameters, the safety factors of the slope can be numerically obtained, so that the real-time estimation of slope stability can be realized.

Real-time and Multi-physics Fiber Optic Monitoring of Landslides in Three Gorges Reservoir Area

Accurate and real-time measurement of the evolution of landslides has become a great concern in recent years. Fiber Bragg grating (FBG), as a popular quasi-distributed fiber optic sensing technology, has been successfully applied to geotechnical and geohazard monitoring. In this paper, an FBG-based real-time monitoring system has been developed to capture the multi-physics evolution of creeping landslides. The system was employed to monitor the performance of the Majiagou and Xinpu landslides in the Three Gorges Reservoir (TGR) area of China, respectively. The results show that the FBG monitoring system can accurately obtain the variations of ground temperature, soil moisture, and deep displacements, which provides valuable information for evaluating the landslide deformation and failure mechanisms during the operation of the reservoir. In this way, real-time stability analysis and early warning can be achieved.

Real Time Stability Analysis with Distributed Generation in Multi-fed RDN Using PMU and Feed Forward Technique

— This paper analyses the stability issues of a multi-fed radial distribution network (RDN) by evaluating its states using a state-of-the-art technique under different operating condition. In its working principle, the entire RDN is visualized as a network comprising of N number of 2-bus sections cascaded sequentially. The required bus states are evaluated using the feed forward technique on the basis of the measurements from customized PMU(s) and smart meters (SMs) placed at suitable locations within the RDN. The inherent single iterative feature of the feed forward technique reduces the computational time leading toward the possibility of real time monitoring. The stability indices are evaluated based on these measured parameters for different case studies viz. normal, contingent, and faulty as well as inclusions and/or exclusions of renewables at different bus nodes conditions. The stability indices are also analyzed for inclusions and/or exclusions of renewables at different bus nodes. The findings of the analysis are summarized to propose the prediction about the abnormal running of the segment(s) of this multi-fed RDN in real time. The MATLAB simulation shows the nature of variation in voltage and power angle profiles of different buses with change in positions of DERs.

Model-free angle stability assessment using wide area measurements

A power system experiences different disturbances frequently where stability assessment is important for reliable operation. Synchronized data, from various buses, provided by wide area measurement system are resourceful for real-time stability analysis. Following a disturbance, generator rotors swing differently. Such rotor swings can be fast or slow based on the disturbance and system conditions, and may die down gradually (stable) or go on increasing (unstable). Therefore, rotor angle stability assessment is important for proper system operation. In this work, slow and fast swings are classified based on the relative rotor angle trend of the most disturbed generator pair. A predictive approach using auto-regression technique is used for stability assessment of fast swing. For slow swing, an index is proposed using Prony analysis. The proposed method identifies if the system is stable or moving towards instability, well in advance of actual instability point, enabling the system operator to take actions for preventing system collapse. No power system model is used, making the method fast and free from modelling errors. The proposed method is tested for New England 39 bus system, IEEE 118 bus system and 233 bus North Eastern Indian grid and found to be accurate. Comparative results with available method indicate the strength of the proposed method.

Real-Time Stability Analysis and Control of Multiconverter Systems by Using MIMO-Identification Techniques

DC distribution systems typically consist of several feedback-controlled switched-mode converters forming a complex power distribution system. Consequently, a number of issues related to stability arise due to interactions among multiple converter subsystems. Recent studies have presented methods such as passivity-based stability criterion, where the stability and other dynamic characteristics of an interconnected system can be effectively analyzed using bus-impedance measurement. Studies have presented online measurement techniques, where the bus impedance is obtained by combining together the measurements of input and output impedances of single converters in the system. Since the converters are coupled, the presented measurement techniques require several measurement cycles in order to sequentially measure the individual impedances to be combined to obtain the overall bus impedance. This paper presents a measurement technique based on injection of orthogonal binary sequences. Applying this method, all the impedances in the system can be simultaneously measured during one measurement cycle. Therefore, the overall measurement time of the bus impedance is reduced compared to conventional measurement techniques. Furthermore, the method guarantees that the system dynamics do not change between measurements, and therefore, the computed bus impedance is not distorted. Experimental results are presented and used to demonstrate the effectiveness of the proposed method in the design of a stabilizing controller for a notional dc system using positive feed-forward control.

Stability-indicating RP-HPLC method for simultaneous quantitation of tramadol and aceclofenac in presence of their major degradation products: Method development and validation

ABSTRACTPrimary objective of this study was to develop a stability-indicating reverse-phase high-performance liquid chromatography (HPLC) method for simultaneous quantitation of tramadol and aceclofenac in presence of their degradation products. The drugs were subjected to various International Conference on Harmonization recommended stress conditions, such as acid hydrolysis, alkaline hydrolysis, peroxide oxidation, thermolysis, and photolysis. The major degradation products got well resoluted from the analytes in HPLC analysis with a mobile phase composed of a mixture of 0.01 M ammonium acetate buffer (pH 6.5) and acetonitrile (65:35, v/v) through a Phenomenex Gemini C18 (250 mm × 4.6 mm, 5 µm particle size) column. The method was linear over a range of 15–60 µg/mL for tramadol and 40–160 µg/mL for aceclofenac concentration. The analytes were detected at a wavelength of 270 nm. The method was validated and found to be specific, accurate, precise, stable, and robust for its intended use. The method can be recommended for its future use in routine quality control, accelerated and real-time stability analysis of the formulations containing tramadol and aceclofenac combination.

Dynamic State Estimation Assisted Out-of-Step Detection for Generators Using Angular Difference

Out-of-step detection methods for generators depend on impedance measurements that are mapped from the angular difference between the generator source and the Thevenin equivalent of the interconnected system. Though implemented successfully with decades of operating experience, the mapping is not the most accurate due to a simplified model. This paper proposes an improved out-of-step detection method for generators by means of the most direct indicator—angular difference. The generator's rotor angle is estimated with a particle filter-based dynamic state estimator and the angular separation is then calculated by combining the raw local phasor measurements with this estimate. The method is also enhanced with the real-time stability analysis that is able to predict marginally unstable swings. The approach is illustrated via dynamic simulations on the New England 10-generator, 39-bus system. While consistent with the traditional schemes for out-of-step detection, the proposed method is advantageous in that it does not make any simplifying assumptions in its formulation, and provides early detection for unstable swings resulting in reduced stresses on the breaker and generator. The proposed approach shows great potential to supervise the conventional relay with availability of synchrophasor measurements and computational power.