Construction of Power Grid Stability Analysis System Based on Stochastic Process Theory

The author considers a nonlinear system at a quasistatically varying, stable equilibrium encountering a linear constraint on the system state and studies the consequent change in system stability. The author formulates the problem of a nonlinear vector field encountering a linear constraint and notes that the stability of the constrained system is usually determined by the stability of the constrained linearization of the system. Therefore he studies the stability of a linear system encountering a linear constraint and gives conditions on the constraint guaranteeing stability or a certain change in the degree of stability when the constraint is encountered. The objective is to study the stability of the constrained system directly from the stability of the system and the constraint without explicitly determining the constrained system. This allows analytic study of the process of encountering a constraint. An application to improving the voltage stability of an electric power system near voltage collapse by selectively locking tap-changing transformers is briefly discussed. >

Asymmetric Lévy noise changed stability in a gene transcriptional regulatory system

Introduction. The article is devoted to the analysis of the stability of the electric power system (EPS) in mountainous areas using the Hurwitz criterion. In mountainous regions, the EPS faces a number of specific problems, such as complex terrain, remoteness of consumers and an increased probability of power transmission line failures. An important task is to develop a mathematical model that takes these features into account and to conduct an analysis of the stability of the system using the Hurwitz criterion. The purpose of the research: stability analysis of the system “high-pressure hydroelectric power plant – electric power system” using the Hurwitz criterion; identification of critical parameters of the system that affect its stability, and application of various optimization methods to improve the reliability and safety of the EPS in mountainous regions. Objects and methods. The object of the study is the high-pressure hydroelectric power plant (HPP) of PJSC RusHydro – Zaramagskaya HPP. The following methods were used for stability analysis: numerical modeling (integration of differential equations); state variable method; Laplace method; frequency response method; analytical methods for finding an exact solution to differential equations. Results and discussions. The results of the study demonstrate that the Gurwitz criterion is an effective tool for analyzing the stability of complex electric power systems, especially in mountainous areas. In the work, this method was successfully applied to analyze the static stability of the system taking into account automatic excitation control. Conclusion. A mathematical model has been developed that takes into account the specific conditions of mountainous areas. An analysis of the static stability of the system has been conducted taking into account the automatic excitation control (AEC). Critical parameters that affect the stability of the system, such as the load angle and the AEC gain factors, have been identified. It has been shown that increasing the accuracy of voltage maintenance can lead to a violation of stability in high-load modes. A method has been proposed for determining the minimum permissible gain factor, which allows avoiding aperiodic instability. Prospects for further research. In the future, possible alternative methods of stability analysis should be considered, such as frequency methods or methods based on Lyapunov theory, which could complement the results obtained using the Hurwitz criterion. A more detailed dynamic stability analysis should also be presented, which could provide a more complete understanding of the system’s behavior in transient conditions.

With the construction of northern and western wind power base, large-scale regional wind power grid connection begins to affect power system and several power grid accidents in Fuxin grid resulted in partial off-grid in recent years, causing certain damages on the security and stability of power system.The author takes Fuxin power grid as example to analyze on two problems existing in large-scale wind power centralized grid connection: frequent fluctuations and reactive voltage control, study on the effect of large-scale wind power centralized grid connection on the security and stability of power system and proposes countermeasures and suggestions. Basic Situation of Fuxin Wind Power BaseFuxin wind farm are mainly based in the northwest area of Fuxin and eastern Zhangwu.By the end of 2014, there has been a wind power capacity of 1,693,300 kilowatts in operation, among which there are 6 220 kV substation, 5 66 kV substation that delivers power to load centers like Jinzhou and Shenyang by 220 kV tie line.According to Fuxin City Plan, there will be an installed capacity of 16,167,000 kilowatts by 2015, among which 8.117 million kW are thermal power (increasing 6.3 million kilowatts) and 8.05 million kilowatts are new energy (increasing 6.25 million kilowatts); power generation will be as much as 58.1 billion kwh.

This paper considers power networks governed by swing nonlinear dynamics and subject to disturbances. We develop a bilayered control strategy for a subset of buses that simultaneously guarantees transient frequency safety of each individual bus and asymptotic stability of the entire network. The bottom layer is a model predictive controller that, based on periodically sampled system information, optimizes control resources to have transient frequency evolve close to a safe desired interval. The top layer is a real-time controller assisting the bottom-layer controller to guarantee transient frequency safety is actually achieved. We show that control signals at both layers are Lipschitz in the state and do not jeopardize stability of the network. Furthermore, we carefully characterize the information requirements at each bus necessary to implement the controller and employ saddle-point dynamics to introduce a distributed implementation that only requires information exchange with up to 2-hop neighbors in the power network. Simulations on the IEEE 39-bus power network illustrate our results.

This article research on the DC access grid security and stability analysis. It combed the stability and security of electrified weak link, revealing the power grid dynamic characteristics of evolution mechanism. It study and formulation of reservoir in the power grid security and stability control strategy of DC power transmission system, the access of power grids in Tibet, AC / DC hybrid power grid by the end of security and stability control measures. The conclusion of the study, for reservoirs in AC DC hybrid power grid by the end of the safe and stable operation and control measures for reference to make the reasonable.

Stability analysis and reactive power compensation issue in a microgrid with a DFIG based WECS

Wide-area voltage control systems (WAVCS) are widely deployed in power grid to improve the voltage stability in transmission system using Flexible AC Transmission System (FACTS) devices. The WAVCS relies on wide-area measurement and control signals for closed-loop control of FACTS devices to improve the transient voltage stability in power grid in real-time. Since the WAVCS utilizes a cyber-layer communication during its normal operation, they are susceptible to cyber attacks from adversaries which can lead to a voltage collapse if the attacks go undetected and unmitigated. This paper proposes a supervised machine learning (ML)-based anomaly detection algorithm for detecting various stealthy cyber attacks in the context of WAVCS cybersecurity. In particular, a fuzzy logic-based wide-area controller, as proposed by the Bonneville Power Administration (BPA), is implemented on the Kundur’s four machine two-area system that is integrated with a static var compensator (SVC) to improve voltage profile on sensitive buses. Later, different types of data integrity attacks, including pulse and ramp attacks, are considered on the wide-area measurement and control signals to analyze the performance of the proposed anomaly detector. Our experimental evaluation shows a promising performance with a high true-positive rate (more than 99%) and low false-negative rate (less than 1%) while exhibiting a small prediction time.

The correctness of security control system strategy is very important to ensure the stability of power system. Aiming at the problem that the current security control strategy verification method is not enough to match the increasingly complex large power grid, this paper proposes a cyclic verification method of security control system strategy table based on constraints and whole process dynamic simulation. Firstly, the method is improved based on the traditional security control strategy model to make the strategy model meet certain generalization ability; And on the basis of this model, the cyclic dynamic verification of the strategy table is realized based on the constraint conditions and the whole process dynamic simulation, which not only ensures the high accuracy of strategy verification for the security control strategy of complex large power grid, but also ensures that the power system is stable and controllable. Finally, based on a certain regional power system, the optimal verification of strategy table verification experiment is realized. The experimental results show that the average processing time of the proposed method is 10.32s, and it can effectively guarantee the controllability and stability of power grid.

Control and Stability of the Multi-Robots System

The stochastic response and stability of a two-point mooring system are investigated for random sea state represented by a P-M sea spectrum. The two-point mooring system is modelled as an SDOF system having only stiffness nonlinearity; drag nonlinearity is represented by an equivalent linear damping. Since no parametric excitation exists and only the linear damping is assumed to be present in the system, only a local stability analysis is sufficient for the system. This is performed using a perturbation technique and by the application of Infante’s method. The analysis requires the mean square response of the system, which may be obtained in various ways. In the present study, the method using van-der-Pol transformation and F–P–K equation is used to obtain the probability density function of the response under random wave forces. From the moment of the probability density function, the mean square response is obtained. Stability of the system is represented by an inequality condition expressed as a function of some important parameters. A two-point mooring system is analysed as an illustrative example for a water depth of 141.5 m and a sea state represented by P-M spectrum with 16 m significant height. It is shown that for certain combinations of parameter values, stability of two-point mooring system may not be achieved.

In the modern society with a high dependence on power systems, the stable operation of the power grid is of utmost significance. Traditional approaches for analyzing power grid stability suffer from several limitations, including high computational complexity, notable sensitivity to data quality, and inadequate representation of dynamic characteristics. To address these issues, this paper proposes a power grid stability analysis method predicated on the Convolutional Neural Network (CNN). In this method, the discrimination of power grid stability is modeled as a binary classification problem. By performing preprocessing operations on the input data, such as outlier cleansing based on the 3 criterion and min-max normalization, the CNN's convolutional layers, pooling layers, and fully connected layers are utilized to extract features and classify the states. The case study is founded on the actual monitoring data of a regional power grid. The results demonstrate that the accuracy of the proposed method on both the training set and the test set is remarkably superior to that of the Fully Connected Neural Network (FNN). This method can offer effective technical support for the safe operation of the power grid.

Due to the increase of the proportion of nuclear power unit capacity in the power grid, the simulation analysis of the PWR nuclear power unit is increasingly important for power grid stability analysis, which is regarded as one of the important parts of China's nuclear power unit. The original mathematical model of the PWR nuclear power unit is very complex and not suitable for the stable calculation and actual measurement modeling of the power grid. Based on the actual modeling of conventional islands, a simplified simulation model of the nuclear island is proposed in this paper and is conducted the actual modeling test of nuclear islands and conventional islands at the NINGDE Nuclear Power Station and FUQING Nuclear Power Station in Fujian Province. In the load test, the models and parameters of the nuclear reactor control system, temperature control circuit, steam generator, speed control system, actuator, and steam turbine were measured. The nuclear island uses the mathematical model built by MATLAB in conjunction with PSD-BPA software for simulation verification. The simulation results can truly reflect the dynamic characteristics of the nuclear islands and conventional islands of PWR nuclear power units, providing mathematical models and parameters for grid stability calculations, which can be used for dispatching safety and stability calculations.

This paper presents the transient stability analysis of a robust nonlinear co-ordinated generator excitation by thyri-stor controlled series capacitor (TCSC) controller and a control strategy of a static synchronous compensator (STATCOM) is proposed to improve of power system. This study analyses the stability of aperiodically sampled-data control systems with and without communication delays by application using a new augmented Lyapunov functional method, which compared with most of existing methods that commonly require each term of a Lyapunov Krasovskii functional(LKF) to be non-negative, the proposed method waives this requirement by introducing an augmented term. A nonlinear feedback law for the generator is found, which linearises and decouples the power system model. Robust nonlinear control theory is then employed to design the nonlinear co-ordinated controller that consists of two controllers is the generator excitation and the TCSC controllers. The proposed control strategy of the STATCOM was then tested on a single machine infinite busbar system. Simulation results show that the proposed controller can ensure transient stability of the power system in a critical fault clearing time, which may occur at the generator busbar terminal. These criteria are extended to investigate the stability of the systems with polytopic uncertainties and the exponential stability of the system.

Perfect power system voltage stability is not possible in practice. Generally, the power grid is continually exposed to changes in its load and operating conditions. Therefore, dynamic stability analysis is one the most important and effective elements for greater security, stability and reliability of planning, design, operation and economic aspects of electric power networks. This study investigates and reports on the dynamic stability of the power system with a large‐scale photovoltaic system (L‐S PV). Two different scenarios with centralised PV power plants are considered in the medium voltage level without voltage regulation capabilities. Simulation results with these scenarios will show how the voltage instability decreases with the L‐S PV based on the bus status, disturbance location, and disturbance duration. In addition, the study discusses network terminal voltage, generator's rotor angle, generator's terminal current, generator's reactive power and electrical power output. This study is an extension of the earlier published conference paper.