Single-area System Research Articles

Scheduling and assessment of multi-area virtual power plant including flexible resources using swarm intelligence technique

A virtual power plant (VPP) makes the distributed energy resources (DERs) visible to support grid services, promoting clean energy use by offering an alternative to reduce reliance on conventional sources. This paper proposes optimized operation and scheduling of VPP by forming a group of flexible resources that includes renewables i.e., solar, wind power, fuel cell, and co-generation units along with storage facilities to form a holistic network in a multi-area interconnected system framework. Initially, the scheduling is performed for a single area system in which a comparison is made with the available work relevant to the proposed formulation. In addition, the scheduling is further extended to the proposed multi-area based virtual power plant (MAVPP) performed on a day-ahead (DA) basis and the target objective(s) i.e., net profit and emission are optimized. Furthermore, a recently developed marine predator optimization algorithm (MPOA) is employed to solve the proposed problem formulation and the results are compared and discussed extensively with conventional techniques. Also, the analysis pertaining to MAVPP is carried out which is beneficial in terms of economic and environmental perspective. The result reveals that the maximum value of net profit for MAVPP is converging to an optimum value of 59,351.88 $ followed by the attained value of minimum emission of 51,700.73 Kg by consuming an elapsed time of 92.96 and 104.76 s., respectively in 200 iterations. The outcomes are promising and upon comparison with the available literature work, the superiority of the selected technique is evident in terms of computational time, improvement of net profit and reduction in emission followed by the ease of convergence behaviour in fewer iterations.

Load Frequency Control of a Single Area System Using Fuzzy Logic Controller and Comparison with Integral and PID Controller

Load Frequency Control of a Single Area System Using Fuzzy Logic Controller and Comparison with Integral and PID Controller

Load Frequency Control of a Single Area System Using Fuzzy Logic Controller and Comparison with Integral and PID Controller

Load Frequency Control of a Single Area System Using Fuzzy Logic Controller and Comparison with Integral and PID Controller

Estimated Flatness-Based Active Disturbance Rejection Control for Load Frequency Control of Power Systems

An estimated flatness-based active disturbance rejection control (EF-ADRC) is proposed for the load frequency control (LFC) of power systems in this paper. Different from the traditional ADRC design, the selections of the order and the gain of the flatness-based ADRC controller are based on the flatness output, which is a linear combination of the system states, rather than the nominal integral cascade model. In addition, an extra extended state observer (ESO) is adopted to estimate the system states and the unknown external disturbance. The former is used to replace the actual system states in the flat output, and the latter is used in trajectory planning of the estimated flat output to achieve the unbiased tracking. The proposed method is applied to single-area systems with reheat turbine and hydro turbine, as well as a four-area system, and the simulation results show that the proposed method can achieve satisfactory performance.

Fuzzy Logic Controller Equilibrium Base to Enhance AGC System Performance with Renewable Energy Disturbances

Owing to the various sources of complexity in the electrical power system, such as integrating intermittent renewable energy resources and widely spread nonlinear power system components, which result in sudden changes in the power system operating conditions, the conventional PID controller fails to track such dynamic challenges to mitigate the frequency deviation problem. Thus, in this paper, a fuzzy PI controller is proposed to enhance the automatic generation control system (AGC) against step disturbance, dynamic disturbance, and wind energy disturbance in a single area system. The proposed controller is initialized by using Equilibrium Optimization and proved its superiority through comparison with a classical PI optimized base. Results show that the fuzzy PI controller can reduce the peak-to-peak deviation in the frequency by 30–59% under wind disturbance, compared to a classical PI optimized base. Moreover, a fuzzy PID controller is also proposed and EO initialized in this paper to compare with the PIDA optimized by several techniques in the two-area system. Results show that the fuzzy PID controller can reduce the peak-to-peak deviation in the frequency of area 1 by 30–50% and the deviation of frequency in area 2 by 13–48% under wave disturbance, compared to the classical PIDA optimized base.

Design of Load Frequency Controller for Multi-area System Using AI Techniques

The paper presents an adaptive Load Frequency Controller (LFC) based on a neural network for the interconnected multi-area systems. When there is an imbalance between active power generation and demand there will deviation in the frequency from the reference value. Major disturbances that lead to the variation in frequency beyond the allowable limits are variation in load demand and faults, etc. Initially PID based LFC which is a conventional controller is used to bring back the variations in frequency when there is a disturbance. But these conventional controllers will operate certain operating points only, very slow and, are less efficient for nonlinear systems. To avoid the flaws in the conventional controller the artificial intelligent controllers such as neural network and fuzzy logic controllers are designed. The three, two area, and single area systems are considered as the test systems. The response of all the test systems is observed without and with PI, fuzzy, and neural network controllers. It was observed that the neural network controller is outperforming in damping the variation in the frequency due to the disturbances.

A FO-PID Controlled Automatic Generation Control of Multi Area Power Systems Tuned by Harmony Search

Background: Power system stability demands minimum variation in frequency, so that loadgeneration balance is maintained throughout the operation period. An Automatic Generation Control (AGC) monitors the frequency and varies the generation to maintain the balance. A system with multiple energy sources and use of a fractional controller for efficient control of stability is presented in the paper. At the outset a 2-area thermal system with governor dead band, generation rate constraint and boiler dynamics have been applied. Methods: A variation of load is deliberated for the study of the considered system with Harmony Search (HS) algorithm, applied for providing optimization of controller parameters. Integral Square Time Square Error (ISTSE) is chosen as objective function for handling the process of tuning controller parameters. : A study of similar system with various lately available techniques such as TLBO, hFA-PS and BFOA applied to PID, IDD and PIDD being compared to HS tuned fractional controller is presented under step and dynamic load change. The effort extended to a single area system with reheat thermal plant, hydel plant and a unit of wind plant is tested with the fractional controller scheme. Results: The simulation results provide a clear idea of the superiority of the combination of HS algorithm and FO-PID controller, under dynamically changing load. The variation of load is taken from 1% to 5% of the connected load. Conclusion: Finally, system robustness is shown by modifying essential factors by ± 30%.

Performance Evaluation of Neuro Fuzzy Clustering for Hydro Thermal Power System

To meet increasing power demands and reduce carbon emission additional renewable sources of power are added to existing thermal unit. Even network frequency change by 1% due to change in speed, may result in loss of synchronization with the rest of power system and finally resulting in power system black-out. Inter-connection of hydro units to existing thermal system can allow to transmission system to operate at full capacity. The paper investigates LFC by adding non-linearity’s to the thermal and hydro-thermal systems. Further PID and Neuro-Fuzzy Controllers are compared for these systems . A multi section steam turbine with re-heater was used for a single area system modeled in MATLAB, later two single area systems were combined to create a two area system, and its dynamics are studied by creating load perturbations. Form simulation studies it is shown that the proposed Neuro-Fuzzy controller was able to attain a setting time of 10 Sec which is comparatively lower than other existing speed controllers. The time domain response result of hydropower system proves that it provides more rapid output response and minimal overshoot.

Model Predictive Control for load frequency stabilizer

This paper deals with the importance of load frequency control (LFC) for single and interconnected power system. It is important to keep the frequency of the system and the inter area tie power stable. The goal of LFC is to maintain the frequency, the desired power output and to control the change in tie line power between control areas in an interconnected power system. Two different techniques have been implemented in this paper which are model predictive controller MPC and conventional proportional plus integral controller PI for LFC of single area power system as well as two area system. To investigate the powerful and robustness of model predictive control (MPC) technique for LFC problems in electric power system, time simulations is performed. The obtained results indicate that the MPC provide better damping to the single area system as well as two-area system in case of load disturbance compared with conventional PI controller. The studied single-area and two-area systems are modelled and simulated using Simulink/Matlab software.

Load Frequency Control of Single Area System Using Ziegler-Nichols and Genetic Algorithm

In this paper, determining the optimal proportional-integral-derivative (PID) controller gains of load frequency control (LFC) system using Ziegler-Nichols (ZN) and Genetic algorithm (GA) is presented. The conventional tuning of PID is difficult as the system and the load parameters change constantly. It is for this reason tuning strategies has been applied. Comparative studies of both the techniques are presented. The simulation has been conducted in MATLAB Simulink package for single area power system.

Optimal Design of Load Frequency Control of Single Area System

In a single-area power system, if a load demand changes randomly, the frequency varies. The main aim of load frequency control (LFC) is to minimize the transient variations and to make sure that the steady state error is zero. Many modern and robust control techniques are used to implement an authentic controller. The objective of these control techniques is to produce and deliver power reliably by maintaining both frequency and voltage within the threshold range. As real power changes, system frequency gets affected and reactive power is dependent on variation in voltage level. Hence real power and reactive power are controlled separately. The role of automatic generation control (AGC) in power system operations under normal operating conditions is analysed. To study the reliability of various control techniques of LFC of the proposed system through simulation in MATLAB-Simulink.

A novel operating strategy for unscheduled interchange price-based automatic generation control

In order to maintain grid discipline and bring about more responsibility and accountability among the participants in the system, the availability-based tariff (ABT) mechanism was introduced in Indian power sector. Though there is a considerable improvement, it is further required to maintain the system with greater frequency stability and reduced fuel cost for power generation. This paper presents a control scheme for unscheduled interchange (UI) price-based automatic generation control (AGC) to nullify the deviations in frequency following a disturbance in the system. This scheme gives the system operator flexibility to schedule the generations in a desired manner on various units by which the merit order dispatch can be maintained. The proposed scheme is tested on a single area system with four generating units and is compared with an existing system and found effective. The results indicate that the frequency is maintained at normal value following a disturbance and the increased load can be shared among the generators in a desired manner.

Resonance Attacks on Load Frequency Control of Smart Grids

Load frequency control (LFC) is widely employed to regulate power plants in modern power generation systems of smart grids. This paper presents a simple and yet powerful type of attacks, referred to as resonance attacks, on LFC power generation systems. Specifically, in a resonance attack, an adversary craftily modifies the input of a power plant according to a resonance source (e.g., rate of change of frequency) to produce a feedback on LFC power generation system, such that the state of the power plant quickly becomes instable. Extensive computer simulations on popular LFC power generation system models which consist of linear, non-linear, and/or high-order items clearly demonstrate the effectiveness of the proposed attacks. As the attack has very low computational cost and communication overhead, it is easy to launch in resource-limited devices such as intelligent electronic devices. In our simulations, the attacker keeps modified input within the normal operating range so as to invade plausibility and consistency based attack detection methods and yet the modifications can quickly drive the system beyond the admissible boundary. Another interesting finding is that by maliciously modifying the input such as power load and tie-line signal over multi-area interconnection channels, a multi-area LFC power generation system could become unreliable more quickly than a single-area system. Finally, we propose countermeasures on the proposed attacks.

Price based fuzzy automatic generation control for Indian tariff system

In order to maintain grid discipline and bring about more responsibility and accountability among the participants in the system, the availability based tariff (ABT) mechanism was introduced in Indian power sector. Though there is a considerable improvement, it is further required to maintain the system with greater frequency stability and reduced fuel cost for power generation. This paper presents a new control scheme for price based automatic generation control (AGC) to minimize the unscheduled interchange (UI) charge through nullifying the deviations in frequency and to maintain the generation at various units economically following a disturbance. This scheme also gives the system operator flexibility to schedule the generation in a desired manner. A two input single output Mamdani type fuzzy PID (FPID) controller is used in the proposed scheme to improve the system dynamic response. The proposed scheme is tested on a single area system with four generating units and is compared with an existing control scheme and found effective. The results indicate that the UI charges are considerably minimized by maintaining frequency at normal value and the load perturbations can be adjusted among the generators in a desired manner following a disturbance.

Assessment of the Effectiveness of Energy Storage Resources in the Frequency Regulation of a Single-Area Power System

An energy storage resource (ESR) has outstanding ramping capability, but its limited energy disables the provision of regulation service around the clock. As a comparison, a conventional generator (CG) is not restricted by the released energy, but the ramp rate is limited. In this paper, a method is proposed to evaluate the effectiveness of ESRs providing frequency regulation service in a single-area system. We measure the performance of frequency regulation by the standard deviation of system frequency excursions, and define the regulation requirement of an isolated power system as the minimum regulation capacity which satisfies the desired regulation performance. By analyzing the regulation requirements under different combinations of regulation resources, we can quantitatively compare the effectiveness of CGs and ESRs. Case studies show that ESRs can reduce regulation requirements, indicating that they are more effective than CGs in frequency regulation. However, they become less effective and even outperformed by CGs when they constitute a larger portion of the system regulation capacity.

Load Frequency Control in Single Area System Using Model Predictive Control and Linear Quadratic Gaussian Techniques

Load Frequency Control in Single Area System Using Model Predictive Control and Linear Quadratic Gaussian Techniques

Comparative performance analysis of teaching learning based optimization for automatic load frequency control of multi-source power systems

• Application of teaching learning based optimization to AGC problems. • PID controller gains have been optimized by teaching learning based optimization. • Dynamic performance is analyzed for single area system and multi area with HVDC link. • Dynamic performances of TLBO based PID controller are better than DE-PID controller. • Sensitivity analysis is done to load changes and different cost functions. This paper presents a new population based parameter free optimization algorithm as teaching learning based optimization (TLBO) and its application to automatic load frequency control (ALFC) of multi-source power system having thermal, hydro and gas power plants. The proposed method is based on the effect of the influence of teacher on the output of learners and the learners can enhance their knowledge by interactions among themselves in a class. In this extensive study, the algorithm is applied in multi area and multi-source realistic power system without and with DC link between two areas in order to tune the PID controller which is used for automatic generation control (AGC). The potential and effectiveness of the proposed algorithm is compared with that of differential evolution algorithm (DE) and optimal output feedback controller tuning performance for the same power systems. The dynamic performance of proposed controller is investigated by different cost functions like integral of absolute error (IAE), integral of squared error (ISE), integral of time weighted squared error (ITSE) and integral of time multiplied absolute error (ITAE) and the robustness of the optimized controller is verified by its response toward changing in load and system parameters. It is found that the dynamic performance of the proposed controller is better than that of recently published DE optimized controller and optimal output feedback controller and also the proposed system is more robust and stable to wide changes in system loading, parameters, size and locations of step load perturbation and different cost functions.

A Genetic Algorithm Optimised Fuzzy Logic Controller for Automatic Generation Control for Single Area System

This paper presents a genetic algorithm (GA)-based design and optimization of fuzzy logic controller (FLC) for automatic generation control (AGC) for a single area. FLCs are characterized by a set of parameters, which are optimized using GA to improve their performance. The design of input and output membership functions (mfs) of an FLC is carried out by automatically tuning (off-line) the parameters of the membership functions. Tuning is based on maximization of a comprehensive fitness function constructed as inverse of a weighted average of three performance indices, i.e., integral square deviation (ISD), the integral of square of the frequency deviation and peak overshoot (Mp), and settling time (ts). The GA-optimized FLC (GAFLC) shows better performance as compared to a conventional proportional integral (PI) and a hand-designed fuzzy logic controller not only for a standard system (displaying frequency deviations) but also under parametric and load disturbances.

Automatic generation control of single area power system with multi-source power generation

In the current paper, automatic generation control (AGC) of a more realistic single area power system with multi-source power generation is studied. The system transfer function model comprises hydro, thermal, and gas power generations with speed governor models and system load for studying the dynamic response for small load disturbances. A proportional plus integral load frequency control scheme is applied only to thermal and gas power generations and hydro is allowed to operate at its scheduled generation level with only speed governor control. Genetic algorithm (GA) is used to optimize the conventional proportional—integral controller gains. Integral squared error (ISE) and integral time absolute error (ITAE) performance indices are used to obtain optimal AGC parameters. The effects on transient performance of the system are investigated for common and individual AGC controller gains of thermal and gas power generations. It is shown that the optimum values of the AGC controller parameters for a single area power system obtained by assuming single source plant dynamics (hydro or thermal) are considerably different than that of a multi-source single area system. The study is also conducted by considering generation rate constraint (GRC) on thermal and hydro generating units. Finally, transient responses are shown for different scheduled loading conditions.

Role of the Support in Determining the Vibrational Properties of Carbonyls Formed on Pd Supported on SiO2−Al2O3, Al2O3, and MgO

The vibrational properties of adsorbed carbonyls on heterogeneous Pd/oxide systems (SiO2−Al2O3, Al2O3, and MgO) are compared and discussed. On the basis of the surface science literature, the complex IR spectra of carbonyls formed on Pd particles are interpreted in terms of what occurs on well-defined Pd(111) and Pd(100) faces and on edge/corner defects, typical of metal nanoparticles, thus bridging the gap between single crystals and high surface area systems. Furthermore, the influence of the electronic properties of the support (i.e., surface acidity/basicity) in determining the spectral features of carbonyls formed on Pd particles is clearly demonstrated.