Load Frequency Control Of Power System Research Articles

Load Frequency Optimal Active Disturbance Rejection Control of Hybrid Power System

The widespread adoption of the power grid has led to increased attention to load frequency control (LFC) in power systems. The LFC strategy of multi-source hybrid power systems, including hydroelectric generators, Wind Turbine Generators (WTGs), and Photovoltaic Generators (PVGs), with thermal generators is more challenging. Existing methods for LFC tasks pose challenges in achieving satisfactory outcomes in hybrid power systems. In this paper, a novel method for the multi-source hybrid power system LFC task by using an optimal active disturbance rejection control (ADRC) strategy is proposed, which is based on the combination of the improved linear quadratic regulator (LQR) and the ADRC controller. Firstly, an established model of a hybrid power system is presented, which incorporates multiple regions and multiple sources. Secondly, utilizing the state space representation, a novel control strategy is developed by integrating improved LQR and ARDC. Finally, a series of comparative simulation experiments has been conducted using the Simulink model. Compared with the LQR with ESO, the maximum relative error of the maximum peaks of frequency deviation and tie-line exchanged power of the hybrid power system is reduced by 96% and 83%, respectively, by using the proposed strategy. The experimental results demonstrate that the strategy proposed in this paper exhibits a substantial enhancement in control performance.

Delay-dependent stability analysis for load frequency control systems with time-varying delays

This paper introduces a delay-dependent criterion that addresses both computational accuracy and efficiency in dealing with delay-dependent stability challenges within multi-area load frequency control (LFC) systems. Firstly, the traditional power system LFC model is decomposed into delay-related and delay-independent parts using a model reconstruction technique. Subsequently, an augmented Lyapunov–Krasovskii functional (LKF) is formulated, focusing on the delay-related part of the model. The double integral component within the derivative of the LKF is constrained using the parameter-dependent slack matrices approach, resulting in a less conservative stability criterion. Finally, the proposed result is validated through case studies. Simulation results demonstrate that the proposed stability criterion significantly improves computational accuracy while maintaining better validity compared to existing approaches. Moreover, compared to the traditional LFC model, the reconstructed model offers substantial computational efficiency improvements, albeit with a slight decrease in computational precision.

Load frequency control of power system based on improved AFSA-PSO event-triggering scheme

Aiming at the impact of redundant information transmission on network resource utilization in current power systems, an improved event-triggered scheme based on particle swarm optimization and artificial fish swarm algorithm for power system load frequency control (LFC) with renewable energy is proposed. First of all, to keep the stability and security of power systems with renewable energy, the load frequency control scheme is investigated in this paper. Then, to relieve the communication burden and increase network utilization, an improved event-triggered scheme based on the particle swarm algorithm and artificial fish swarm algorithm is explored for the power system load frequency control. Then, by utilizing improved Lyapunov functional and the linear matrix inequality method, sufficient condition for the H∞ stability of the load frequency control system is established. Finally, a two-area load frequency control system and IEEE-39 node simulation models are constructed to verify the effectiveness and applicability of the proposed method.

Adaptive event‐triggering mechanism‐based N‐step predictive load frequency control for power systems with cyber attack

AbstractAlthough there have already been many works on the model predictive control (MPC) for load frequency control (LFC) of modern power systems, limited works can be found in the literature related to the output feedback MPC. This article studies an N‐step synthesis approach of output feedback MPC for LFC systems considering the problems of communication efficiency and network security. First, to improve the communication efficiency, an adaptive event‐triggering (AET) scheme involving two adaptive laws is designed to reduce the number of transmitted data packages which offers more flexible compared with existing event‐triggering schemes; Second, to handle the network security, a new model of LFC power system combining the AET scheme and random deception attack under an unified framework is established; Moreover, a synthesis approach of output feedback MPC with N‐step strategy is addressed for LFC of power system by parameterizing the infinite control moves into a series of output feedback laws. Compared with the existing predictive load frequency control methods, the present technique is shown as an useful way to improve the control performance since more degrees freedom is introduced by the N‐step strategy. Finally, the simulation experiment is carried out to verify our technique.

Two-Layer Robust Distributed Predictive Control for Load Frequency Control of a Power System under Wind Power Fluctuation

The frequency stability of interconnected power systems becomes quite challenging when incorporating renewable energy sources (mostly wind power). Distributed model predictive control (DMPC) is an effective method to maintain stable grid frequency and realize power system load frequency control (LFC). This paper proposes a two-layer robust DMPC for the LFC of an interconnected power system. In the scheme, the wind power penetrating the power grid is largely affected by the environment condition, and it is taken as an uncertain disturbance to the power system. The two-layer robust DMPC consists of a nominal DMPC controller and an ancillary DMPC controller. The nominal DMPCs coordinate with each other in achieving the systemwide LFC objective, where the systemwide objective is a strict convex combination of the local LFC objectives. The nominal optimization problems are solved supposing the wind power fluctuation is zero. The ancillary DMPC generates the actual control signal for each generation unit based on signals which are transmitted from the nominal DMPC controller. The simulation on a four-area interconnected power system demonstrates the effectiveness of the proposed algorithm in alleviating the frequency deviation caused by varying the load and uncertain wind power fluctuation.

Robust networked power system load frequency control against hybrid cyber attack

AbstractModern network and communication technologies are essential for the implementation and operation of load frequency control (LFC) systems. The measurements of crucial LFC system parameters will be compromised by attackers, rendering data received by the defence inaccurate and causing frequency fluctuations or even system collapse. To detect the potential attack on measured data and keep the LFC performance, an adaptive event‐triggered scheme with fractional order global sliding mode control scheme is proposed in this paper. Furthermore, Markov theory is employed for the modelling process with energy storage to present a multi‐area LFC power system considering renewable energy and hybrid cyber attacks. Stability and stabilisation criteria are built by employing improved Lyapunov stability theory and second‐order Bessel‐Legendre inequality. Finally, a two‐area LFC system under hybrid cyber attacks and a modified IEEE 39‐bus New England test power system with 3 wind farms are simulated to explore the efficacy of the proposed method.

Robust networked power system load frequency control against hybrid cyber attack

Robust networked power system load frequency control against hybrid cyber attack

Novel COVID-19 Based Optimization Algorithm (C-19BOA) for Performance Improvement of Power Systems

The ongoing pandemic due to novel coronavirus disease-2019 (COVID-19) has rapidly unsettled the health sector with a considerable fatality rate. The main factors that help minimize the spread of this deadly virus are the proper use of masks, social distancing and antibody growth rate in a person. Based on these factors, we propose a new nature-inspired meta-heuristic algorithm named COVID-19 Based Optimization Algorithm (C-19BOA). The proposed C-19BOA mimics the spread and control behavior of coronavirus disease centered on three containment factors: (1) social distancing, (2) use of masks, and (3) antibody rate. Initially, the mathematical models of containment factors are presented, and further, the proposed C-19BOA is developed. To ascertain the effectiveness of the developed C-19BOA, its performance is verified on standard IEEE mathematical benchmark functions for the minimization of these benchmark functions and convergence to the optimal values. These performances are compared with established bio-inspired optimization algorithms available in the literature. Finally, the developed C-19BOA is applied on an electrical power system load–frequency–control model to test its effectiveness in optimizing the power system parameters and to check its applicability in solving modern engineering problems. A performance comparison of the proposed C-19BOA and other optimization algorithms is validated based on optimizing the controller gains for reducing the steady-state errors by comparing the effective frequency and tie-line power regulation ability of an industrially applied Proportional–Integral–Derivative controller (PID) and Active Disturbance Rejection controller (ADRC). Moreover, the robustness of C-19BOA optimized PID and ADRC gains is tested by varying the system parameters from their nominal values.

Analytical tuning rules for second-order reduced ADRC with SOPDT models

This paper presents a set of tuning rules for second-order reduced linear active disturbance rejection control for second-Order Plus-Dead-time (SOPDT) models. Rules are developed with a target to achieve a good compromise between tracking and disturbance rejection performances. Subsequently, it is formulated as a multi-objective optimization problem consisting of Integral Absolute tracking and regulatory errors as its objectives with a specified robustness level and a stability condition as constraints. The optimization problem is solved by a Multi-objective Quasi-Oppositional Rao-1 (MOQO-Rao-1) algorithm to generate the required Pareto optimal solutions. A compromised solution is chosen among these Pareto optimal solutions using Grey Relational Analysis (GRA). Finally, the resulting best solutions are used to fit a polynomial model using regression resulting in analytical tuning rules. Separate tuning rules are presented for lag-dominated and delay-dominated SOPDT models. The proposed tuning rules are validated through simulations on standard benchmark systems, power-system load frequency control problems, and experimentally on a temperature control system and DC motor control system. Furthermore, a condition on tuning parameters for closed-loop system stability is presented using the dual-locus method; the same is incorporated as one of the constraints in the proposed tuning framework.

Load frequency control under false data inject attacks based on multi-agent system method in multi-area power systems

This article considers the load frequency control of multi-area power system-based multi-agent system method under false data injection attacks. The research can provide better solutions for multi-area power system load frequency control under false data injection attacks. First, an event-triggered mechanism is introduced to decide which data should be transmitted in the controller to save the limited network bandwidth. Besides, a model of cyberattacks is built using the Bernoulli random variables. Then, conditions are given for maintaining the system asymptotic stability under attack. Finally, simulations are performed to demonstrate the validity of the theory proposed in this article.

Robust LFC of Power Systems With Wind Power Under Packet Losses and Communication Delays

Network-induced packet losses and communication delays, as well as load fluctuations and uncertain wind power have a negative effect on the frequency regulation of power system. This paper is concerned with designing a robust load frequency control (LFC) scheme for a multi-area power system penetrated by wind power via sampled-data control. Firstly, considering the effects of the inertia reduction, packet losses, communication delays and measurement noise, a decentralized aperiodic sampled-data LFC model with time delay is constructed, where the maximum sampling interval is characterized by limiting the maximum count of successive packet losses (MCSPL). Secondly, by applying Lyapunov theory and linear matrix inequality technique, a new exponential stability condition for the modeled LFC system with given controller is proposed based on a combination method of Lyapunov-Krasovskii functional and loop function, which is dependent on delay and MCSPL. It can be used to find the delay margin and allowable MCSPL of the LFC system. Thirdly, based on the <inline-formula> <tex-math notation="LaTeX">$\mathcal {L}_{2}$ </tex-math></inline-formula>-gain performance condition developed by the stability condition above, a design method of robust PI-type controller is proposed by maximizing an exponential decay rate (EDR). The larger EDR, the faster frequency response speed to cope with the effect of inertia reduction, but the worse robustness to load fluctuations, packet losses and delays, and vice versa. Finally, case studies are carried out by a one-area power system and a three-area power system with wind power. By comparing with the existing LFC schemes, simulation results show that the proposed LFC scheme for the tested system is more effective and has better robustness.

Decentralized LMI-based event-triggered integral sliding mode LFC of power systems with disturbance observer

In this paper, a disturbance observer (DO)-based event-triggered integral sliding mode control (DOETISMC) scheme for load frequency control (LFC) is presented in the presence of time varying uncertainties and disturbances. Firstly, the disturbance observer is designed to provide an online estimation of the unmatched load disturbance from the measurable variables. This estimation is being used as a feed-forward to the controller to attenuate the disturbance effect. Secondly, two types of integral sliding surfaces are proposed based on the estimated disturbances to eliminate the chattering effect of the integral sliding mode control (ISMC). Due to Lyapunov theory and utilization a decreasing triggering threshold, the ultimate boundedness stability of the system under the proposed controller is proved. Moreover, it is ensured that during the system process, the Zeno event as a basic obstacle in the ETISMC does not occur. The validity and advantages of the proposed method in oscillation suppression are well revealed through numerical simulations in different cases of single-area and multi-area power systems with time varying uncertainties and disturbances.

Observer-based dynamic event-triggered [formula omitted] LFC for power systems under actuator saturation and deception attack

This paper focuses on the observer-based H∞ load frequency control (LFC) of multi-area power systems with actuator saturation and deception attack. Firstly, a state observer is constructed to estimate the unmeasurable states and a time-delay model with the area control error is established. Secondly, a dynamic event triggering mechanism is developed, where dynamic parameter and a novel error-related exponential term are introduced to reduce the communication burden further in the network. Thirdly, considering time delays, data-packet losses and stochastic deception attack, a resilient LFC controller of power systems based on actuator saturation is designed and the security of the system is guaranteed with the condition of H∞ mean-square exponential stability. Sufficient conditions to co-design the event-triggered scheme, observer and desired controller gain are derived by Lyapunov functional analysis approach. Finally, simulation example is given to demonstrate the efficiency of the developed method.

The l1 Optimal State Estimator for Load Frequency Control of Power Systems: A Comparative and Extensive Study

This paper proposes fully decentralized <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> optimal dynamic state estimators (DSEs) for load frequency control (LFC) of interconnected power generating systems and provides its comparative and extensive study with respect to three other types of DSEs. To this end, we present the dynamic model of a single area of the power-generating unit occurring from the interconnected power systems. By noting the fact that each area is affected by the frequency deviations in other areas, and it is quite difficult to obtain any property of the load changes in power systems, we characterize the disturbances in the LFC of power systems as bounded persistent signals. As a candidate for DSEs for LFC of power systems, the unknown input observer (UIO), Kalman filter (KF), and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> optimal DSE are considered, and their limitations are analyzed in depth. In connection with this, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> optimal DSE, in which the maximum magnitude of estimation error for the worst bounded persistent disturbances is minimized, is proposed as the most effective state estimator. Finally, the practical validity and effectiveness of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> optimal DSE are demonstrated through some comparative simulations for a three-area power generating system.

Delay-Dependent Stability Analysis of Load Frequency Control for Power System With EV Aggregator

In this paper, the stability of load frequency control (LFC) for delayed power systems with an electric vehicle (EV) aggregator is studied based on Lyapunov theory and linear matrix inequalities (LMIs). Through mechanism analysis, the LFC of power systems with an EV aggregator based on a proportional–integral–differential (PID) controller is modeled. By constructing a delay interval information correlation functional and estimating its derivative using Wirtinger inequality and extended reciprocally convex matrix inequality, a new stability analysis criterion is proposed. Finally, in order to verify its advantage, the proposed method is used to discuss the influence of EV aggregator gains and PID controller gains on the delay margins for LFC of power systems with EV aggregator participation in frequency regulation.

Optimization and H∞ Performance Analysis for Load Frequency Control of Power Systems With Time-Varying Delays

With the development and expansion of the power grid, the load frequency control (LFC) scheme receives sensor signals and outputs control signals through an open communication network with a mass of data and extensive information exchange, which may introduce constant, and time-varying delays. This paper considers the optimization andH∞performance problem for LFC of power systems with time-varying delays. Some improved criteria for guaranteeing the stability andH∞performance of the closed-loop system with unknown external load disturbances via the Lyapunov stability theory application. An unique delay-dependent proportional-integral (PI) controller and an optimized PI controller are designed for a specifiedH∞performance index and set, respectively. The criteria proposed in this paper are based on linear matrix inequalities (LMIs), which can be easily solved by the MATLAB LMI-Toolbox. Finally, in case studies, the effectiveness of our method is demonstrated.

A novel observer-based approach to delay-dependent LFC of power systems with actuator faults and uncertain communications conditions

In this paper, a novel observer-based approach is proposed for the delay-distribution-dependent (DDD) load frequency control (LFC) of multi-area power systems with actuator faults and probabilistic communication conditions. LFC is designed considering missing data which obey the Bernoulli distribution and actuator faults. After that, an observer gain matrix is constructed for realizing Lyapunov stability, where delay-dependent stability criteria are derived under the consideration of different factors such as packet dropout during data transmission and faults in control. The stability conditions are derived in terms of linear matrix inequalities to achieve less conservative results in the communication delay and H∞ performance. Finally, the efficiency of the proposed observer-based DDD LFC is demonstrated and compared through time-domain simulations.

Robust Load Frequency Control Using Fractional-order TID-PD Approach Via Salp Swarm Algorithm

To preserve frequency and tie-line power flow within a tolerable range in modern intricate and renewable energy sources (RES) integrated power system, an intelligent, expert, and robust load frequency control (LFC) scheme is requisite. This paper proposes a new load frequency control (LFC) approach using a dual-stage controller composed of fractional-order tilted-integral-derivative (TID) and integer-order proportional-derivative (PD) controllers. The recently developed salp swarm algorithm has tuned the parameters of the controller. The proposed scheme exhibits robustness and fast disturbance rejection performance because the tilted-integral-derivative controller is structured in a fractional-order framework, and transient response is improved due to the proportional-derivative controller. The overall activity of the LFC has been further upgraded by incorporating the flexible AC transmission system (FACTS) device namely thyristor-controlled phase shifter (TCPS) unit and energy storage system called redox flow battery (RFB) units. The proposed control approach is applied to diverse types of multi-area multi-source power systems with thermal, hydro, and wind turbine units along with nonlinear functions namely generation rate constraint (GRC), governor dead band (GDB), and communication delay (CD). The simulation results yield improved frequency regulation activity with and without TCPS and RFB using the proposed control approach when compared with the recently developed LFC approaches. Sensitivity analysis also established the robustness of the proposed control approach.

Event-based secure [formula omitted] load frequency control for delayed power systems subject to deception attacks

This paper focuses on designing an H∞ load-frequency controller for power systems suffering from deception attacks based on the event-based secure control scheme. Firstly, to alleviate the occurrence of congestion phenomenon in the bandwidth-limited communication network, an event-triggered scheme is introduced into the sensor-to-controller channel. Subsequently, a mathematical model with regard to the event-triggered load frequency control is established under considering the existence of deception attacks. Then, in terms of Lyapunov stability theory and an improved inequality technique, some sufficient conditions that can ensure the mean-square asymptotic stability with a prescribed H∞ performance index of the closed-loop system are deduced. Besides, the corresponding controller gain is obtained by solving those conditions. Finally, two numerical examples are presented to verify the effectiveness of the proposed method.

Automatic Load Disconnection and Reconnection to Power System using Controllable Loads

Now a days, Renewable Energy Resources are playing a vital role in power system to meet the demand. As Renewable Resources includes solar power, Wind power generation they are eco-friendly in the aspect of power generation. It is progress a step forward to integrate the renewable power along with base load plants such as Thermal power plant. With the advancement in the network Technology, smart meters had became the key components in maintaining the power system to behave smartly by the demand side management. On the other hand, the sudden loss of Generation due to natural calamities like cyclones, will become a great burden on the power system. And thus the power system will try to be out of synchronization and leads to the problem of unstable. This is because of high penetration of Renewable power source like solar, wind etc...in to the Grid. Hence this type of scenario results in BLACKOUT of the power system which means the whole power system is going to be shut down and the whole world will remain in the darkness. To avoid the above situation, Demand Side Management is the best solution which is possible with controllable loads and load controller together called as Smart meter. This will play a key role is retaining the system frequency and LOAD FREQUENCYCONTROL will be improved further. In this project, we are going to simulate the simulink model of power system LOAD FREQUENCY CONTROL WITH CONTROLLABLE LOADS in MATLAB