Analysis Of Load Frequency Control Research Articles

Design and Analysis of Load Frequency Control for a Two-Area Power System Using Conventional PID and FPID Controllers

Power system stability is required to maintain a continuous balance between power generation and load demand. Frequency control is also a major function of automatic generation control and one of the most important control problems in power system design and operation. So, a robust control system must be implemented for controlling the actual power and frequency. This paper mainly focuses on the design of a two-area power system with a rated frequency of 50 Hz, which is used in Myanmar, using the fuzzy-PID method to control the load frequency. It also aims to imply from one area to another when demand suddenly increases or decreases. It involves applying mathematical formulas and models to analyze how an automatic generation control works. The plan is first implemented in a single area before being modified to a two-area power system with and without controllers. The output results are simulated with MATLAB/ SIMULINK.

Stability analysis of load frequency control for power systems with interval time-varying delays

This study investigates the stability problem of load frequency control (LFC) for power systems with interval time-varying delays. The two categories of time delays, the lower bound being zero and non-zero, are considered. The systems can be described as time delay systems of load disturbances. First, an augmented Lyapunov–Krasovskii functional (LKF) is constructed. Some delay-dependent nonintegral terms and single integral terms are additionally introduced to make full use of the information on the system state variables and the time-varying delays. Second, to overcome the problem of nonlinear inequalities caused by the augmented LKF, the nonlinear inequalities are converted into linear matrix inequalities (LMIs) by applying the new negative definite inequality equivalence transformation lemma, which can be solved easily by the MATLAB LMI toolbox. A new stability criterion is presented by applying the Lyapunov stability theory. The stability criterion is less conservative than some existing literature studies, which further improves the stability margin for the power systems based on LFC. Finally, some numerical examples are given to show the effectiveness of the proposed method and the superiority of the results.

Stability Analysis of Load Frequency Control for Shipboard Microgrids With Occasional Large Delays

This brief investigates stability analysis of delayed load frequency control (LFC) system for shipboard microgrids (MG). Different from the previous works, a time-varying delay with occasional large value in a few time intervals is studied. Firstly, by dividing the delay into two regions, the LFC of shipboard MG is modeled as a linear system with a switched delay. Then, a stability criterion is proposed to analyze the relationship between the exponential stability of system and the length/frequency of large delay. Finally, a case study shows that the system may still remain stable for the large delay satisfying specific conditions, which illustrates the effectiveness and advantages of the proposed method.

Cybersecurity Analysis of Load Frequency Control in Power Systems: A Survey

Today, power systems have transformed considerably and taken a new shape of geographically distributed systems from the locally centralized systems thereby leading to a new infrastructure in the framework of networked control cyber-physical system (CPS). Among the different important operations to be performed for smooth generation, transmission, and distribution of power, maintaining the scheduled frequency, against any perturbations, is an important one. The load frequency control (LFC) operation actually governs this frequency regulation activity after the primary control. Due to CPS nature, the LFC operation is vulnerable to attacks, both from physical and cyber standpoints. The cyber-attack strategies ranges from a variety of attacks such as jamming the network communication, time-delay attack, and false data injection. Motivated by these perspectives, this paper studies the cybersecurity issues of the power systems during the LFC operation, and a survey is conducted on the security analysis of LFC. Various cyber-attack strategies, their mathematical models, and vulnerability assessments are performed to understand the possible threats and sources causing failure of frequency regulation. The LFC operation of two-area power systems is considered as a tutorial example to quantify the vulnerabilities. Mitigation strategies through control theoretic approaches are then reviewed and highlighted for LFC operation under cyber-attack.

Performance Analysis for Load Frequency Control of Interconnected Power Systems with Different Techniques

In the interconnected power system, frequency is one of the most important criteria determining system stability. Since interconnected systems consist of more than one region, load frequency control (LFC) is very complicated. For this reason, load frequency control analysis has been performed for interconnected power systems consisting of two and four regions in this article. Vortex Search Algorithm (VSA), Salp Swarm Algorithm (SSA) and Sine Cosine Algorithm (SCA) are used to determine the filter coefficient proportional-integral-derivative controller (PID-N) parameters of these interconnected systems. The results obtained are analyzed for % overshoot (%OS), % undershoot (%US) and settling time (ST) values for each region. It is observed that different system performances are obtained using by these methods. In addition, all system performances are significantly improved with the selected methods.

Frequency and voltage stabilisation in combined load frequency control and automatic voltage regulation of multiarea system with hybrid generation utilities by AC/DC links

ABSTRACT This article investigates the combined analysis of load frequency control (LFC) and Automatic voltage regulation (AVR) for two-area hybrid system. Classical PID controller is habituated as secondary controller. A novel differential evolution artificial electric field algorithm (DE-AEFA) is proposed in this paper to tune controller parameters. Initially, DE-AEFA algorithm is applied to test system 1 comprising two-area non-reheat thermal turbines. Later on, the study is extended to combined model named test system 2 to investigate combined LFC and AVR problem. Further, the system is extended to the incorporation of HVDC link with the existing AC tie-line in parallel. System dynamic performance is predominantly enhanced by AC/DC rather than only AC tie-line. The proposed scheme robustness is demonstrated by conducting sensitivity analysis.

Maiden application of cascade tilt‐integral–tilt‐derivative controller for performance analysis of load frequency control of interconnected multi‐source power system

This study presents a maiden application of cascade tilt-integral–tilt-derivative (CC-TI-TD) controller for the performance analysis of load frequency control (LFC) of interconnected multi-source power system (MSPS). The studied controller is realised based on cascade control theory and fractional order calculus. TI controller is used as a master controller and TD controller served as slave controller in the proposed CC-TI-TD controller. To demonstrate the performance of proposed CC-TI-TD controller, first, it is applied to single-area MSPS followed by two-area MSPS in the presence of electric vehicles (EVs). The proposed controller gains' parameters are optimised by state-of-the-art water cycle algorithm (WCA) according to the minimisation of fitness function. First, the effectiveness of proposed WCA-tuned CC-TI-TD controller over the WCA-tuned cascade proportional-integral–proportional-derivative (CC-PI-PD) controller and modified grey wolf optimisation-based tuned proportional-integral derivative and CC-PI-PD controllers has been explored in single-area-studied power system. Second, the performance of WCA-tuned CC-TI-TD controller with and without presence of EVs in a two-area interconnected MSPS is assessed with respect to another class of the fractional order controller termed as integral tilt-derivative controller. Lastly, sensitivity analysis and the effect of time delay on LFC performance are carried out to show the robustness of proposed CC-TI-TD controller.

Load frequency control of an asynchronous restructured power system: a fuzzy logic approach

This paper presents the analysis of load frequency control (LFC) of a two-area restructured power system interconnected via parallel ac/dc transmission links. Simulation results show that the limitations of PI controller can be overcome by including Fuzzy logic concept and thereby the dynamic performance can be improved substantially following a load change in any area. The dynamic responses for small perturbation have been observed with PI controller and fuzzy logic based PI controller and result of both have been compared.Keywords: Asynchronous tie-lines; Restructured power system; HVDC transmission links; Load frequency control; Fuzzy Logic based PI controller

Analysis of Load Frequency Control in a restructured multi-area power system with the Kalman filter and the LQR controller

The performance of power systems in restructured environments has become increasingly more complex due to the technical limitations and traditional requirements. To this end, electrical power systems act independently in the generation, transmission and distribution of electricity, leading to restructuring and deregulation. On the one hand, technical requirements for transmission lines and renewable energies will contribute to HVDC transmission. On the other hand, one of the main goals of the Automatic Generation Control (AGC) is to manage Load Frequency Control (LFC) in a multi-area power system. In order to examine the internal and intrinsic stability, the Linear Quadratic Regulator (LQR) control method was used but since neither all the state variables were available nor their measurements were noise-free, the LQR controller was used with the Kalman filter (KF) for the real-time control for solving the LFC problem. Finally in the section on the simulation, a comparison was made using MATLAB, between two multi-area power systems consisting of thermal and hydroelectric generation units, one of which with the HVDC transmission lines and the other one without them, in terms of frequency stability. Moreover, the simulation results indicated that the introduced control method led to the improved LFC performance in a multi-area power system with HVDC transmission links.

Quasi‐oppositional harmony search algorithm based optimal dynamic load frequency control of a hybrid tidal–diesel power generation system

In recent years, high penetration of distributed generations based on wind energy, solar energy and so on in the existing power system network has been noticed. However, due to their stochastic behaviour, operations under autonomous mode as well as in grid-connected mode are not an easy task. This has forced the power utilities to re-define frequency regulation criteria to enhance the overall system stability and reliability. In line with the same, dynamic performance analysis of load frequency control (LFC) of an autonomous hybrid power system model (HPSM) consisting of tidal power plant (TPP) and diesel power plant is explored in this study. A concept of deloaded TPP is adopted in the studied HPSM to utilise the available reserve power for the frequency support. Apart from this, the studied model also incorporates frequency regulation through inertia and damping control and supplementary control strategies. These control strategies are realised through conventional controllers whose gain values are optimised using quasi-oppositional harmony search algorithm (QOHSA) for the optimal dynamic performance of LFC. The efficacy of the proposed QOHSA is corroborated by comparing the results with those yielded by few other existing state-of-the-art algorithms.

Integral Performance Criteria Based Analysis of Load Frequency Control in Bilateral Based Market

Performance index based analysis is made to examine and highlight the effective application of Particle Swarm Optimization (PSO) to optimize the Proportional Integral gains for Load Frequency Control (LFC) in a restructured power system that operates under Bilateral based policy scheme. Various Integral Performance Criteria measures are taken as fitness function in PSO and are compared using overshoot, settling time and frequency and tie-line power deviation following a step load perturbation (SLP). The motivation for using different fitness technique in PSO is to show the behavior of the controller for a wide range of system parameters and load changes. Error based analysis with parametric uncertainties and load changes are tested on a two-area restructured power system. The results of the proposed PSO based controller show the better performance compared to the classical Ziegler-Nichols (Z-N) tuned PI and Fuzzy Rule based PI controller.

ENGLISH

Automatic Generation Control (AGC) or Load Frequency Control is a very important issue in power system operation and control for supplying sufficient and reliable electric power with good quality. AGC is a feedback control system adjusting a generator output power to remain defined frequency. One of the objectives of AGC is to maintain the system frequency at nominal value In the steady state operation of power system .An extended power system can be divided into a number of load frequency control areas interconnected by means of tie lines. Without loss of generality one can consider a three- area case connected by tie line. Here we are considering system, which is integration of two thermal power systems with hydro power system. That is area-1 and area-2 consists of thermal reheat power plant whereas area-3 consists of hydro power plant. The performance analysis of load frequency control for multi area inter connected system will be done in MATLAB/SIMULINK environment. As integration of multi area effects performance of system study of different characteristics using controllers like conventional PI ,PID, artificial intelligence FUZZY LOGIC controlling techniques are necessary in order to determine the effective gains of controller in efficient manner. And this knowledge about dynamic response characteristics will give us idea of controlling techniques that we need to implement for obtaining required frequency response at tie line stations.

Load frequency control in deregulated power system with wind integrated system using fuzzy controller

This paper presents the analysis of load frequency control (LFC) of a deregulated two-area hydro-thermal power system using fuzzy logic controller, with doubly fed induction generators (DFIGs) integrated into both the control areas. The deregulation of power sector has led to the formation of new companies for generation, transmission and distribution of power. The conventional two-area power system is modified to study the effects of the bilateral contracts of companies on the system dynamics. Deregulation creates highly competitive and distributed control environment, and the LFC becomes even more challenging when wind generators are also integrated into the system. The overall inertia of the system reduces, as the wind unit does not provide inertia and isolates from the grid during disturbances. The DFIGs integrated provide inertial support to the system through modified inertial control scheme, and arrests the initial fall in frequency after disturbance. The inertial control responds to frequency deviations, which takes out the kinetic energy of the wind turbine for improving the frequency response of the system. To enhance the participation of the doubly fed induction generator (DFIG) in the frequency control, optimal values of the speed control parameters of the DFIG-based wind turbine have been obtained using integral square error (ISE) technique. The dynamics of the system have been obtained for a small load perturbation, and for contract violation using fuzzy controller.

Adaptive Neuro-Fuzzy inference system for automatic generation control of interconnected hydrothermal plant

This paper presents the analysis of Load Frequency Control (LFC) of a two-area hydrothermal system under deregulated environment by considering Adaptive Neuro-Fuzzy Inference System (ANFIS). Fixed gain controllers for LFC are designed at nominal oper

The Application of Generation Rate Constraint in the Modeling of a Thermal Power System

The correspondence deals with the application of the Generation Rate Constraint (GRC) in the modeling of one or more thermal control areas. One or multithermal control areas are widely used in the literature with the synthesis and analysis of Load Frequency Control and Automatic Generation Control. Typically, two GRC values are used: 10% p.u. MW/min with non-reheat thermal unit, and 3% p.u. MW/min for a reheat unit. Researchers use these values to restrict the turbine generation rate; however, this is a wrong interpretation of the Power Plant Response committee report of March 1967. As a consequence, results related to automatic generation control and load frequency control over a period of 30 years are in doubt.