Single Area Power System Research Articles

Analyzing Small-Signal Stability in a Multi-Source Single-Area Power System with a Load-Frequency Controller Coordinated with a Photovoltaic System

The frequency deviation from the nominal working frequency in power systems is a consequence of the imbalance between total electrical loads and the aggregate power supplied by production units. The sensitivity of energy system frequency to both minor and major load variations underscore the need for effective frequency load control mechanisms. In this paper, frequency load control in single-area power system with multi-source energy is analysed and simulated. Also, the effect of the photovoltaic system on the frequency deviation changes in the energy system is shown. In the single area energy system, the dynamics of thermal turbine with reheat, thermal turbine without reheat and hydro turbine are considered. The simulation results using Simulink/Matlab and model analysis using eigenvalue analysis show the dynamic behaviour of the power system in response to changes in the load.

Stability and stabilization of systems with a cyclical time-varying delay via delay-product-type looped-functionals

In this paper, the stability analysis and synthesis of systems with a cyclical time-varying delay are investigated. At first, the entire delay interval is divided into intervals of monotonically increasing and monotonically decreasing alternating cycles. Then, a Lyapunov-Krasovskii functional (LKF) with two delay-product-type looped-functionals is constructed based on different delay monotone intervals. For the generated quadratic function with respect to delay in the derivative of LKF, a matrix-injection-based method is utilized to obtain the negative-definite conditions of LKF’s derivative. A delay-dependent stability criterion with less conservatism is derived and the corresponding state-feedback control strategy is given consequently. Finally, a numerical example is utilized to show the superiority and the effectiveness of the proposed method, and a single-area power system under load frequency control is applied to verify the feasibility of the proposed control strategy.

Fractional delay-dependent load frequency controller design for a single-area power system with communication delay

Fractional delay-dependent load frequency controller design for a single-area power system with communication delay

Performance comparison of dynamically controlled particle swarm optimization and grey wolf optimizer for dynamic power reserve scheduling in multi areas problems

The primary goal of Multi-Area Economic Dispatch (MAED) is to effectively meet the dynamic power demands of multiple interconnected regions while optimizing the economical generation dispatch strategy. This paper introduces a comprehensive investigation into the application of two advanced optimization techniques, namely Dynamically Controlled Particle Swarm Optimization (DCPSO) and thereafter Grey Wolf Optimizer (GWO), and their variant adaptations to address the complex challenges posed by MAED issue. The performance and efficacy of these strategies are rigorously assessed in three distinct scenarios: (a) Single-Area Power System with Three Generation Units: This scenario represents a fundamental single-area power network comprising three generation units. (b) Two-Area System with Four Generating Units: In this case, a two-area system with four generating units is analyzed. (c) Four-Area System with Forty Generation Units and Six Tie Lines. In the most intricate scenario, a four-area interconnected power system is scrutinized, featuring a total of forty generation units. GWO technique produces the cost saving of $ 0.1 for single area, 2 area cost saving is $ 0.11 likewise for 4 area the cost saving is $ 474.10 over the PSO. The execution time taken by GWO is 12.7 sec. less compared to DPSO.

A Reinforcement Learning Based Coordinated but Differentiated Load Frequency Control Method With Heterogeneous Frequency Regulation Resources

As the diversification of frequency regulation resources, it is increasingly important to find a load frequency control (LFC) scheme that can effectively coordinate different resources. This paper proposes a coordinated but differentiated LFC control method that utilizes heterogeneous frequency regulation resources with their characteristics fully considered. The optimal LFC models for the single area and multi-area power systems are formulated as partially observable Markov decision process model (POMDP) and partially observable Markov game (POMG) considering the accessibility of system information. A deep reinforcement learning method called recurrent proximal policy optimization is leveraged to solve the POMDP and POMG models. Simulations based on historical data demonstrate that the proposed control scheme can better coordinate different resources and achieve superior control performance.

Virtual Inertia Implemented by Quasi-Z-Source Power Converter for Distributed Power System

This paper proposes a novel virtual inertia control strategy for distributed power systems with high penetration of renewable energy sources. The strategy uses a quasi-Z-source power converter to emulate the inertia response of a synchronous generator by regulating the DC-link capacitor voltage in proportion to the grid frequency deviation. This paper analyzes the effect of inertia on the frequency regulation of a single-area power system and derives the parameter design method and limitations of the virtual inertia. The paper also introduces the working principle and modulation technique of the quasi-Z-source power converter and presents the virtual inertia control scheme based on a voltage-frequency controller. The paper verifies the feasibility and effectiveness of the proposed strategy through MATLAB/Simulink simulations and dSPACE semi-physical experiments. The results show that the proposed strategy can reduce the frequency deviation and rate of change of frequency (RoCoF) by 20% and 50%, respectively, under load disturbances. The paper demonstrates that the quasi-Z-source power converter can provide flexible and adjustable virtual inertia for distributed power systems without additional energy storage devices.

Cubature Kalman filter and linear quadratic regulator for load frequency control

Several controllers address Load Frequency Control (LFC) to minimize deviations in system frequency caused due to rapid disturbances in load demand and Renewable Energy Source (RES) penetration. However, large power systems' complexity and the significant frequency deviations observed often limit these controllers. In order to address these issues, a novel Cubature Kalman filter (CKF) and Linear Quadratic Regulator (LQR) based on combined state estimation and optimal control is proposed. LQR is an optimal controller that curbs the frequency deviations by calculating optimal feedback gain values. The CKF is a novel state estimator algorithm used to estimate the state variables by minimizing the error between actual and estimated states. The proposed control is tested on a small single-area power system and a large-scale power system based in Egypt. The results obtained are compared with the existing Extended Kalman filter (EKF) and LQR-based control, Virtual Synchronous Generator (VSG) based control, and conventional Proportional-Integral-Derivative (PID) control with over and under frequency protection circuit (OUPFC). The efficacy of CKF-LQR is emphasized through the analysis of various simulation cases of the power system. The findings suggested that the proposed controller's performance was robust under frequency measurement noise, low inertia, sudden change in RES, and load switching. The outcome shows that the proposed control is robust and can effectively regulate the system frequency compared to the other controllers.

Load Frequency Control by Quadratic Regulator Approach with Compensating Pole using SIMULINK

In this research, for the load frequency control (LFC) challenge, we provide a few possible approaches to building an optimum PID controller. This scheme employs the Quadratic Regulator Approach with Compensating Pole (QRAWCP) approach. In both multi-area and single-area power systems, this control law is used to solve load frequency concerns. And the other scenario that is considerable, the controller's robustness is evaluated on the same systems in terms of non-linearities, external disturbances, and parametric uncertainty such as the Governor Dead Band (GDB) as well as the Generation Rate Constraint (GRC). The performance of the control method is evaluated using Simulink simulations.

Frequency Fluctuation Mitigation in a Single-Area Power System Using LQR-Based Proportional Damping Compensator

To maintain the stability of the power system, frequency fluctuations must be reduced in the shortest possible timeframe. Load frequency control (LFC) plays a critical role in achieving this objective by regulating the system frequency and the desired demand or output power in an interconnected network, thereby enabling the system to adapt the load disturbances. In order to effectively mitigate the frequency fluctuation caused by load variation in a single-area power system, a new control strategy integrating a linear quadratic regulator (LQR), a proportional controller, and a damping compensator is proposed in this paper. The proposed controller is named as the LQR-based proportional damping compensator which mitigates the frequency fluctuation of a single-area power system. MATLAB/Simulink simulation is conducted on a single-area power system to demonstrate the efficacy of the proposed control technique. The simulation results demonstrate that the proposed method successfully reduces frequency variations, maintains system frequency within reasonable limits, and substantially reduces the settling time as compared to other existing control techniques. Apart from the simulation analysis, to experimentally validate the performance of the proposed controller, a hybrid multiprocessor-based processor-in-loop (PIL) technique is also introduced in the paper. Both the simulation and experimental results prove the promising performance of the proposed controller for mitigating the frequency fluctuation of a single-area power system.

Direct Search Algorithm for Load Frequency Control of a Time-Delayed Electric Vehicle Aggregator

This article addresses the topic of frequency regulation of a single-area power system connected to an electric vehicle (EV) aggregator over a non-ideal communication network. It is considered that the command control action is received by the EV aggregator with constant delay and the power system includes uncertain parameters. Due to the presence of uncertainties and the delay term, the frequency regulation problem is non-convex and hard to solve. The present approaches in the literature convert the non-convex control design problem into a convex problem with a set of Linear Matrix Inequalities (LMIs), which is conservative and in many cases results infeasibility. In this paper, an innovative iterative algorithm, called direct search, is employed for the time-delayed system to design the unknown parameters of a pre-assumed controller. The controller choice is not limited and various controllers’ structures can be assumed. Without loss of generality, a proportional-integral (PI) controller is designed. The novel direct search algorithm can determine a feasible solution whenever at least one solution lays in the design space. Hence, by selecting a wide design space, we can anticipate that the PI controller guarantees closed-loop stability. Numerical simulations are carried out to demonstrate the performance of the developed controller compared to the state-of-the-art approach.

Based on Q-Learning Optimal Tracking Control Schemes for Linear Itô Stochastic Systems With Markovian Jumps

In this brief, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -learning algorithm is designed to solve the optimal tracking control problem (OTCP) for stochastic system with Markovian jump. The problem is formulated by stochastic augmented system composed of the dynamic system and the reference trajectory system and then using ideas from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -learning to provide a solution. Namely, a critic neural network (NN) is used to estimate the optimal cost function while an actor NN is used to approximate the optimal controller. Moreover, both the requirements of transition probability and system matrix are avoided via the designed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -learning algorithm. Finally, we apply the designed algorithm in a single-area power system to track continuous sinusoidal waveforms, and the simulation result is provided to show the effectiveness and applicability of the algorithm.

Load Frequency Control of Single-Area Power System with PI–PD Controller Design for Performance Improvement

Load Frequency Control of Single-Area Power System with PI–PD Controller Design for Performance Improvement

Load frequency controller for an islanded hybrid power system using WCO

This research proposes a new metaheuristic algorithm based on World Cup Optimization (WCO) to determine the optimal values of the Proportional Integral Deviation (PID) controller for the load frequency control problem. An islanded hybrid power system consists of a Wind Turbine Generator (WTG), Diesel Generation (DEG), and an Energy Storage System (ESS), such as a Battery Energy Storage System (BESS), Super Magnetic Energy Storage (SMES), and an Ultra Capacitor (UC) unit. A single-area power system was designed as a model network for the MATLAB-Simulink simulation. Furthermore, a hybrid system was employed with Proportional-Integral (PI) controllers and PI derivative controllers with proportionate gains to the DEG, and an ESS. A comparative performance assessment of the WCP was conducted to tune the PI and PID controllers. The simulation results indicate that a renewable integrated isolated power system with an Energy Storage System (ESS) tuned with a PID controller provides better responses than the PI controller for different loading conditions. Based on time settling, transient, and overshoot analysis, it is proven that a WCO-tuned PID controller is better than a PI controller.

Power System Dynamic Performance Analysis Based on Frequency Control by Proton Exchange Membrane Electrolyzers

Intermittency of renewable energy sources can cause greater frequency variations and with no other intervention, the generation reserve capacity of a power system needs to be significantly increased to ensure frequency stability, resulting in increased costs. With appropriate control actions, proton exchange membrane electrolyzers (PEMELs) can be used to regulate power system frequency stability, but their adjustable demand-side response capabilities need to be investigated. This article first introduces the dynamic characteristics of the PEMEL stack to examine the impact of incorporating the control loop of the PEMEL stack into a single-area power system populated with solar photovoltaic units, taking into account the communication time lag during the control signal transfer process. The dynamic performance of the proposed power system and steady-state errors are then analyzed demonstrating contribution of the PEMEL stack to frequency regulation services effectively. Moreover, the frequency stability of the power system with and without the PEMEL stack is assessed to illustrate improvement in the stability and robustness of the power system during system uncertainties. Numerical studies are used to validate the efficiency of the presented models and approaches.

Novel negative-definiteness conditions on the quadratic polynomial function with application to stability analysis of continuous time-varying delay systems

When analyzing the stability of time-varying delay systems in view of the Lyapunov–Krasovskii functional, a quadratic polynomial function with regard to time-varying delay is always generated. And it is particularly crucial to determine the negativeness of the matrix of such a quadratic form function for obtaining an analysis result expressed in linear matrix inequalities. This paper proposes a method of tangent intersection in the delay interval segmentation, producing the generalized quadratic convex conditions by further utilizing the cross point between every two tangent lines. It reduces the conservatism of the existing conditions remarkably without requiring unexplainable adjustable parameters and additional decision variables. Benefiting from the newly proposed quadratic convex conditions, the novel stability conditions are derived, the superiority of which is demonstrated through several widely used numerical instances and single area power system PI control example.

Load Frequency Controller Design Based on the Direct Synthesis Approach Using a 2DoF-IMC Scheme for a Multi-Area Power System

To maintain reliable and sustainable power supply, the frequency should be kept constant under varying load conditions. The two degrees of freedom internal model control (2DoF-IMC) scheme is a robust control technique and is efficient for load-disturbance rejection problems in industrial process control. The asymmetry of IMC compared to other methods regarding controller design is that it does not guarantee the stability of the system by itself but is based on the stability of the controlled system. For the control of less-stable and unstable systems, it is therefore usually supplemented with an additional controller, establishing two degrees of freedom in the overall design. In this manuscript, the load-frequency-regulation problem was investigated using a 2DoF-IMC scheme for a single-area as well as a multi-area power system. In the 2DoF-IMC scheme, two controllers are used to control the set-point response and load-disturbance response separately. The set-point controller is designed through the internal model control (IMC) principle, whereas the load-disturbance rejection controller is designed via the direct-synthesis (DS) approach. In the DS approach, the closed-loop transfer function of the system model is matched with the desired closed-loop transfer function of the system and the disturbance-rejection controller is approximated at a very low-frequency point to obtain the proportional–derivative (PD) controller parameter. The simulation results of the proposed method provide satisfactory performance for load-frequency control (LFC) in the single-area power system and extended to two-area and four-area power systems. The effect of non-linearity, such as generation rate constraint (GRC), was investigated in the single-area power system to establish the efficacy of the proposed method. A random step loading pattern was also considered to confirm the robustness of the proposed method. The overall performance of the proposed control scheme is comparatively better than the recently reported work.

Performance Investigation of Wind Turbine Induction Generators connected with a Single-Area Power System

Wind turbine power is a vital source of renewable energy and accounts for major plants in generating electricity in various countries. The aim of this paper is to develop the physical model of three types of wind-turbine induction generators and to investigate their impacts on the frequency in a single-area power system. The generator types are as follows: (i) squirrel cage induction generator (SCIG); (ii) doublyfed induction generator (DFIG) and (iii) brushless doubly-fed induction generator (BDFIG). The analysis scenario is demonstrating the effect of variable wind speeds on the grid frequency under load variations. The simulation results show that BDFIG achieves better performance in comparison with DFIG and SCIG in terms of maintaining the grid frequency.

Adaptive event-triggered scheme for load frequency control of smart grid under DoS attacks

This paper studies the load frequency control (LFC) problem of smart grids under aperiodic denial-of-service (DoS) attacks. First, a switching observer model is constructed to deal with the unavailability of system status. Second, an adaptive event-triggered LFC scheme is proposed, which effectively reduces the update frequency of control signals and reduces the impact of aperiodic DoS attacks simultaneously. Third, by considering the impact of DoS attacks and event-triggered mechanisms at the same time, the system is modelled as a switching model. Then, by constructing a suitable piecewise Lyapunov functional, sufficient conditions are derived to ensure the exponential stability of the system with performance. In addition, the joint design method of observer and controller is also developed. Finally, a single-area power system is taken as an example to verify the effectiveness of the proposed method.

Load frequency control of A single area power system based EWOA Technique

Load frequency control of A single area power system based EWOA Technique

Optimal Voltage and Frequency Control in Solar Integrated Power Network

This study presents the modelling and simulation of a single area powersystem network containing three different generating sources, solar thermalpower plant (STPP), thermal, and diesel power plants. The simultaneousfrequency and voltage control problem has been investigated using LinearQuadratic Regulator (LQR) and State Feedback based Sliding Mode Control(SF-SMC) design. Also, the integration of Particle Swarm Optimization(PSO) has been considered for the selection of LQR cost function weightmatrices and SMC control parameters. Proper selection of LQR and SF-SMCparameters allows the controllers to handle the complexities involved in avery efficient manner and also augments necessary robustness in the con-troller design. The transient performance of the PSO based LQR and SF-SMCcontrolled system has been assessed in terms of time-domain performanceindices, and it has been compared with the conventional PID and 2-DOF PIDcontrollers. Additionally, the robustness of the proposed controllers has beentested and verified after contemplating variation in model parameters