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Conventional control techniques such as proportional integral (PI) control and proportional integral derivative (PID) control are widely used as the load frequency controller in power system control applications; however, the increase in complexity of the power system is degrading the performance of classical control. Therefore, in this paper a new control approach using fractional calculus has been proposed for the load frequency control problem of two-area hydro-thermal power system. The paper presents an interconnected hydro-thermal power system working under different operating conditions introduced in the form of various nonlinearities. Four case studies have been presented in this paper considering transient analysis with (i) different loading conditions, (ii) parameter variations, (iii) different nonlinearities (governor dead band nonlinearity, time delay and generation rate constraints), and (iv) superconducting magnetic energy storage (SMES) device. A tilt integral derivative (TID) control has been presented as a secondary controller to stabilize the frequency deviations occurring in the two-area power system with the above-mentioned different operating conditions. The parameters of TID controller have been optimized using a differential evolution algorithm which solves an optimization problem formulated using the integral of time-weighted absolute error (ITAE) performance index. In addition, a comparison of dynamic system response obtained using TID control and PID control has been presented, which focusses on the better performance of TID control over PID control in an interconnected power system.

Advances in power electronics have improved grid support functions such as tie-line power control and frequency control, making renewable generation and High Voltage DC (HVDC) links more common in power system applications. Load Frequency Control (LFC) systems handle the complex interactions between the distributed generator and the control area with the HVDC link. In this work, LFC of a two-zone system including parallel AC/DC transmission links has been analysed. The parameters of this system are optimised using advanced genetic algorithm resulting in improved performance of system in terms of reduction in peak overshoots and settling time of frequency measurement, tie line power flow and area control error signals in an interconnected power system. The advantage of having parallel HVDC links is also demonstrated when performance is compared to system interconnected with only AC tie line.

This paper introduces a tilt integral derivative controller as the supplementary controller for load frequency control of a two-area interconnected power system. The optimal value of parameters of the tilt integral derivative controller is evaluated using constrained nonlinear optimization by means of a performance index-based method. The proposed tilt integral derivative control offers superior properties such as simple parameter tuning and its performance does not compromise the occurrence of any parameter variations in the system. To verify these features of the controller, the test system is subjected to step load disturbance and parameter variations that ensure the robustness of the tilt integral derivative controller. Comparative analysis with previously published work indicates that the proposed tilt integral derivative controller gives better performance and holds the property of robustness. Simulations have been performed using Matlab®.

With the advent of smart grid, which exhibits the up and coming age of electrical power systems, residents have a chance to manage their energy expenditure. This paper presents Smart Homes Energy Management System (SHEMS) in order to support the grid and optimal operation of a smart home in terms of minimizing the total energy cost. Such kinds of home comprise of roof top PV, electric vehicle (EV), smart appliances and energy storage system (ESS). The EV battery can be charged during low demand period and stored power can be fed to home as well as grid during peak load hours. The energy exchanges are valued in view of net metering standards considering a dynamic pricing scheme. Finally, case studies are carrying out to validate the result.

Incorporation of wind energy into power systems has gathered substantial momentum globally due to its abundant supply and environmental benefits. Despite its numerous benefits, wind power in grid integration poses many challenges. The non-dispatchable and inherent intermittent qualities of wind energy not only insert additional fluctuations to the existing frequency deviation, they also reduce frequency stability by decreasing the regulation capability and the inertia. This paper presents the significance of these effects, which causes a larger frequency deviation in the proposed system. In this paper optimization algorithm used to optimize PID controller is Harmony Search Algorithm (HSA). The simulation and analytical results represented here provide guidance on calculating maximum wind power penetration level using frequency deviation limit.

In this paper, a non-integer (fractional) order controller namely tilt integral derivative controller has been introduced as supplementary controller in automatic generation control (AGC) of a two-area power system. Generally, classical control approach such as PI control and PID control has been most widely used in AGC scheme, but due to increase in complexity of the power system, the performance of classical control approach has been lagged behind. To study the effectiveness of tilt integral derivative (TID) controller in AGC scheme, two case studies presenting different non-linearities have been presented in the paper. Non-linearities in the form of step load perturbations and generation rate constraint (GRC) have been introduced in the system. For such operating conditions, an optimization problem using ITAE performance index has been formulated and a differential evolution algorithm has been used to optimize and determine the parameters of PI, PID and TID controller. Further, a comparison between PI, PID and TID control approach has been presented in the paper which shows the robustness property of TID controller and its superiority over PI and PID controller in an interconnected power system.

The power system is prone to many emergency conditions which may lead to emergency state of operation with decay in the system frequency. The dramatic change in the frequency can result in cascaded failure of the system. In order to avoid power system collapse, load shedding (LS) schemes are adopted with the optimal amount of load shed. This paper proposed a methodology in a two-area thermal-thermal system for finding the required amount of load to be shed for setting the frequency of the system within minimum allowable limits. The LS steps have been obtained based on the rate of change of frequency with the increase in load in steps. A systematic study has been conducted for three scenarios: the scheme with a conventional integral controller; the scheme with a linear quadratic regulator (LQR); and the scheme with an LQR and superconducting magnetic energy storage devices (SMES). A comparison of the results has been presented on the two-area system.

This paper presents a fractional order proportional integral derivative order controller, popularly known as FOPID controller for load frequency control problem of a two-area hydro-thermal power system. The objective of this study is to present a non-conventional way of robust control for the load frequency control problem. In this study, a performance index — Integral of absolute error has been used to formulate a cost function which is later minimized using differential evolution algorithm. The algorithm solves the optimization problem and determines the optimal value of parameters of FOPID controller. The FOPID controller has been tested under different operating conditions to verify its superiority over proportional integral (PI) controller. The system response obtained through simulation studies using FOPID controller has been compared with PI controller and the obtained response of system displays the effectiveness of FOPID control over PI control.

Phenomenal increase in load and cost of electricity has raised many challenges ranging from security of the system to the economics of generation. For economic operation of power system, the solution to Unit Commitment problem is necessary. Unit Commitment aims to schedule the generation to meet the load demands at the most economical rate for the next few hours. It decides that which unit should be operated in that particular period of study and which should not. On time horizon basis, it can be varied from few hours to one week. In this paper, the solution to unit commitment problem is achieved using Lagrangian relaxation and modified Mendel's GA approach for standard 10 unit system for 24 hours with 1-hour time interval. The Lagrangian Relaxation (LR) method provides a good optimal solution but it sometimes suffers from numerical convergence and problems related to solution quality. The proposed Lagrangian Relaxation and Mendel's Genetic Algorithms (LRMGA) include Mendel's Genetic Algorithm into Lagrangian Relaxation method to update the Lagrangian multipliers and improve the performance in solving problems like Unit Commitment (UC) problem. Results so obtained are compared with those obtained with various other methods. Solutions obtained show better convergence and highly optimal solution by LRMGA.

Phenomenal increase in load and cost of electricity has raised many challenges ranging from security of the system to the economics of generation. For economic operation of power system, the solution to Unit Commitment problem is necessary. Unit Commitment aims to schedule the power generation to meet the load demands at the most economical rate for the next few hours. It decides that which unit should be operated in that particular period of study and which should not. On time horizon basis, it can be varied from few hours to one week. In this paper unit commitment problem is solved using modified Mendel's GA approach for standard 4 unit system scheduled for 8 hours with 1-hour time interval. The results obtained show that the proposed technique is able to achieve the solution of unit commitment problem in lesser number of trials and in minimum cost as compared to the conventional approach.

The frequency of the power system varies based on the load pattern of the consumers. With continuous increase in the load, the frequency of the system keeps decreasing and may reach its minimum allowable limits. Further increase in the load will result in more frequency drop leading to the need of load shedding, if excess generation is not available to cater the need. This paper proposed a methodology in a hybrid thermal-hydro system for finding the required amount of load to be shed for setting the frequency of the system within its minimum allowable limits. The load shedding steps were obtained based on the rate of change of frequency with the increase in the load in both areas. The impact of superconducting magnetic energy storage (SMES) was obtained on load shedding scheme. The comparison of the results was presented on the two-area system.

The essential point of the Automatic Generation Control (AGC) is to keep up the system frequency and tie-line power interchange within the limits by controlling the electrical power generated, whenever the fluctuations in the power system occur due to change in load demand. This paper proposes few online smart control techniques to understand the Load Frequency Control (LFC) of multi area system. The main reason to develop smart control techniques to improve the transient response of the power system by reducing the overshoot, undershoot and settling time of the multi area system. The proposed method in this paper is combination of Bacterial Foraging Algorithm (BFA) and Particle Swarm Optimization (PSO) we call it as Hybrid-PSO (H-PSO). The modelling of multi area power system and tuning of the controller are carried out in MATLAB/Simulink environment. After the analysis of results it is observed that H-PSO is better as compare to BFA and PSO.

The paper is concerned with the improvement in load frequency control of multi area power systems, so that the deviation in frequency and tie line powers due to change in load are restored to its initial state for stable operation. A comprehensive digital computer model of the interconnected multi area system including the thermal, thermal reheated and hydro system with superconducting magnetic energy storage (SMES) unit is developed. Time domain solutions are used to study the performance of the power system and control logic. The effect of introducing superconducting magnetic energy storage unit for improvement of stability and system dynamic response is studied. The simulation results have been compared and analyzed to evaluate the performance of the system with SMES and different controllers using MATLAB/SIMULINK package.

This paper presents operation and control of a hybrid Photovoltiac Power, Diesel-Engine Generator (DEG) - Battery energy storage system (BESS) connected to an isolated power system. A case study on the impact of BESS operations on the frequency stability of the hybrid system has been carried out. The limits on state of charge (SOC) due to limited storage capacity have also been incorporated. Simulation of a hybrid system model has been carried out in two cases, steady state analysis of hybrid system using step load response with PI controller and other real time performance analysis for a typical day with random variation in load demand. Parameters of controllers are optimized with Genetic Algorithm. Simulation of a hybrid system model is done with the Matlab/Simulink environment. Simulation results indicate that BESS system can contribute to frequency stability in both cases when the load increases and when the load drops. This feature of BESS system will be helpful if it is operated along with a hybrid Wind-PV System.

Due to the fast response of superconducting energy storage system, it may improve the stability of system frequency. This paper proposed the modeling and control of a hybrid Wind Power, Diesel-Engine Generator (DEG) - Superconducting Magnetic Energy Storage system connected to an Isolated power system. A case study on the impact of SMES operations on the frequency stability of Hybrid System has been carried out. The limits on the inductor (coil) current due to the possibilities of discontinuous conduction in the presence of large disturbances and limited storage capacity have also been incorporated. The modeling of wind power is also presented and analyzed for a time period of 24-hours with varying wind velocity. Hybrid system has analyzed in the Matlab Simulink environment. Simulation results indicate that SMES system can contribute to frequency stability in both cases when the load increases and also when the load drops. This feature of SMES system will be helpful if it is operated along with a hybrid Wind-PV System.

This paper presents modeling and control of a hybrid Wind Power, Diesel-Engine Generator (DEG) - Battery energy storage system (BESS) system connected to an electric Micro grid. A case study on the impact of BESS operations on the frequency stability of electric grid has been carried out. The limits on state of charge (SOC) due to limited storage capacity have also been incorporated. The modeling of wind power is also presented and analyzed for a time period of 24-hours with varying wind velocity. Simulation results indicate that BESS system can contribute to frequency stability in both cases when the load increases and also when the load drops. This feature of BESS system will be helpful if it is operated along with a hybrid Wind-PV System.

Excess load may cause the frequency to drop to a level that may result in permanent damage to steam turbines. Since an isolated power system possesses a lower inertia with limited reserves, load shedding becomes a critical solution to restore system frequency. This paper presents a load shedding scheme determining the slope calculation based on the initial frequency variation based on [10]. The steps are determined with initial rate of change of the frequency considering the impact of proportional, integral, and derivative controller. The load shedding scheme has been implemented with different step load changes in the system. The comparison of the results of load shedding without and with controller has been obtained. The impact of the parametric variation has also been studied for deciding the parameters for minimum values of the load shed to maintain the frequency within the limits.

This paper presents modeling and control of a hybrid Photovoltaic (PV), Diesel-Engine Generator (DEG) — Fuel Cell (FC) system connected to electric grid. A case study on impact of FC operation on the frequency stability of electric grid has been carried out. The model of fuel cell system includes a fuel cell generator, electrolyzer and a hydrogen storage facility. The limits on hydrogen volume due to limited storage capacity have also been incorporated. The modeling of photovoltaic is also presented and analyzed for a time period of 24-hours with varying solar radiation and temperature. Results of simulation indicate that FC system can contribute to frequency stability in both cases when the load increases and also when the load drops. This feature of FC system will be helpful if it is operated along with a hybrid Wind-PV System.

Transmission outage occurs more frequently in deregulated power systems and congestion management has become a major issue in the emerging electricity market environment. In many operating electricity markets, a hybrid trading mode with pool and bilateral contract trade inclusive is employed. Coupling exists between these two kinds of trade as both are implemented in the same system. Therefore, the problem of effectively coordinating the congestion management is very important. In this paper, a model for optimal load curtailment for congestion management is presented for pool plus bilateral electricity market model. The effect of FACTS devices for optimal load curtailment has been obtained locating these devices based on the congestion distribution factors. Case studies with multi-line congestion of transmission system of the IEEE-RTS are presented for demonstrating the proposed method.