Control Of Interconnected Power Systems Research Articles

Improved model predictive load frequency control of interconnected power system with synchronized automatic generation control loops

BackgroundAutomatic generation control (AGC) of multi-area interconnected power system (IPS) is often designed with negligible cross-coupling between the load frequency control (LFC) and automatic voltage regulation (AVR) loops. This is because the AVR loop is considerably faster than that of LFC. However, with the introduction of slow optimal control action on the AVR, positive damping effect can be achieved on the LFC loop thereby improving the frequency control. In this paper, LFC synchronized with AVR in three-area IPS is proposed. Model predictive controller (MPC) configured in a dense distributed pattern, due to its online set-point tacking is used as the supplementary controller. The dynamics of the IPS subjected to multi-area step and random load disturbances are studied. The efficacy of the developed scheme is ascertained by simulating the disturbed system in MATLAB/Simulink.ResultsBased on the comparative analysis on the system responses, it is established that by cross-coupling the LFC loop with AVR, reductions of 66.45% and 59.09% in the frequency and tie-line power maximum deviations respectively are observed, while the respective settling times are found to be reduced by 29.68% and 22.77% when compared with the uncoordinated control scheme. In addition, the standard deviation and variance of the integral time absolute error of the system’s responses have reduced by 23.21% and 20.83% respectively compared to those obtained in a similar study.ConclusionsThe reduction in the maximum deviations and settling times in the system states indicates that introducing the voltage control via AVR loop has improved the frequency control significantly. While the lower standard deviation and variance of the integral time absolute error signify improvement in the robustness of the developed algorithm. However, this improvement is at the detriment of the controller size and computational complexity. In the uncoordinated control scheme, the control vector is one-dimensional, while in the coordinated scheme, the control vector is two-dimensional for each CA.

Quasi-oppositional JAYA optimized 2-degree-of-freedom PID controller for load-frequency control of interconnected power systems

ABSTRACT An effort is given in this paper, for the first time, to discuss the load-frequency control (LFC) problem of an interconnected power system by implementing a novel heuristic optimization method called quasi-oppositional-based JAYA (QOJAYA). The proposed algorithm houses the knowledge of quasi-oppositional-based learning to enhance convergence speed and find the best solutions to the LFC problem. To show the effectiveness, the proposed QOJAYA scheme is, individually, applied to a two-area multi-unit multi-source power plant and a three-area hydrothermal power plant considering the system nonlinearities. The structural simplicity and performance adequacy of the well-known proportional-integral (PI) controller enforces to optimally design it as a secondary controller at the first instant. Afterward, the dynamic stability of the concerned power systems is increased with a 2DOF-PID controller. The proposed algorithm is employed to search the optimal settings of the said controllers by minimizing the time-based single-valued fitness functions. Simulation results validate the success of the proposed QOJAYA scheme and demonstrate its dominance over original JAYA, teaching-learning-based optimization (TLBO), and other recently introduced optimization techniques in the state-of-the-art for the same power system. Finally, the robustness of the designed controller is established by performing sensitivity analysis considering parameters and loading uncertainties.

Equilibrium optimization algorithm for automatic generation control of interconnected power systems

Equilibrium optimization algorithm for automatic generation control of interconnected power systems

Robust State Estimation Method for Adaptive Load Frequency Control of Interconnected Power System in a Restructured Environment

Handling varying uncertainties in renewable energy generation and load demands are major challenges to the restructured power system environment. This article proposes the design of a novel control methodology using a robust UIO for dynamic state estimation and an interval type-2 fuzzy logic controller for adaptive LFC of interconnected power systems with high penetration of renewable energy in a restructured power system environment. The capability of the proposed robust UIO to independently estimate the true state of the power system regardless of unknown inputs or disturbances that impact the frequency stability in real time is demonstrated by the asymptotic zero property of the state estimation error. This is supported by using an interval type-2 fuzzy logic controller in the LFC loop of each area of the interconnected system to efficiently damp frequency oscillations, thereby improving power system stability and resilience. The performance of the proposed methodology is evaluated using a modified two-area power system in the restructured environment. The results obtained from the stability and LFC analyses during severe operating conditions demonstrated the robustness of the proposed control framework to unknown inputs and unprecedented variations that can affect the frequency stability of the system.

Optimal PID Controller Design by Enhanced Class Topper Optimization Algorithm for Load Frequency Control of Interconnected Power Systems

ABSTRACT In this paper, a new ranking-based enhanced Class Topper Optimization (e-CTO) algorithm is proposed. It is an advanced version of Class Topper Optimization (CTO) algorithm. The CTO algorithm is based upon the learning behavior of students in a class. The learning behavior of the students from the topper of a class is a source of motivation for both the existing CTO and the proposed e-CTO. The exploration, exploitation, and global convergence ability of the proposed algorithm are validated using benchmark functions. Next, the learning ability of students is upgraded to provide a better solution. The proposed algorithm is verified by implementing a Load Frequency Control (LFC) problem for an interconnected power system with a parallel alternating current-high voltage direct current (AC-HVDC) tie-line. A PID controller with filter frequency component structure and PI controller is designed using the proposed algorithm. To check the performance of the e-CTO-based PID controllers, transient analysis of the power system with a fixed load perturbation is carried out. A comparative analysis with some existing results is done to prove the superiority of the proposed method. After this, the sensitivity of the proposed PID control design is tested by analyzing the controller performance during different system parameter variations.

Model-Based Secure Load Frequency Control of Smart Grids Against Data Integrity Attack

In this paper, a cyber-physical digital signature creation method and a resilient load frequency control approach are proposed to improve the security of the existing SCADA protocols used in the load frequency control of interconnected power systems. In specific, the dynamic model of the power system is used to predict the future states of the system and the statistics of a number of future states are calculated and used as the dynamic hash to determine the integrity of the data communicated between remote telemetry units and the power system SCADA control center. The proposed algorithm has inherently the cyber-physical characteristics and enhanced robustness to collisions without adding a larger overhead to the message frame of the packets in current SCADA protocols. To compensate for the possible performance degradation and instability of the power system caused by corrupted data, a model-based resilient load frequency controller is designed for the smart grid. The maximum interval between two consecutive feedback updates in the model-based control scheme is obtained for securing the stability of the power system. The investigation of three types of integrity attacks on a two-area power system shows that the proposed model-based digital signature attack detection scheme is able to detect even a little inconsistency of the communicated data. By using the designed resilient load frequency controller, the stability and dynamic performance of the smart grid are guaranteed.

Improved Automatic Generation Control of Interconnected Power System

In present day manage frameworks situation, the most intense significance is given to interconnection of different frameworks on the way to meet the dynamical modifications in burdens additionally energy movements via specific elements. it's miles essential to manipulate the framework recurrence and tie-line streams of an interconnected electricity framework. Albeit, normal controllers are applied to meet the ones conditions, yet on the same time a a success controller is required for powerful manage. in this paper, an progressed programmed age manipulate (AGC) with fluffy cause for a -zone heat hydro manage framework is exhibited. Contingent on the factors of burden, required suggestions are completed to improve enduring us of a and dynamic reaction of two-place manage framework. The adequacy of proposed controller is stated via making use of MATLAB/Simulink programming.

Cooperation-Based Distributed Economic MPC for Economic Load Dispatch and Load Frequency Control of Interconnected Power Systems

In this letter, a distributed economic model predictive control (EMPC) strategy is proposed for economic load dispatch and load frequency control of interconnected power systems. A general economic cost function is used in the EMPC to calculate the control sequence directly optimizes the economic performance of the system without using a hierarchical control structure, thus achieving both the real-time optimization and transient optimization. A cooperation-based distributed EMPC algorithm is proposed and the asymptotic stability is proven. Simulation results reveal the advantages of the proposed method.

RETRACTED ARTICLE: Analysis of antlion optimizer-based ABT for automatic generation control of an interconnected power system

In this paper, a novel ant lion optimization algorithm is proposed for the recent availability-based tariff (ABT) pricing scheme for the automatic generation control of a three-area interconnected power system (IPS). The innovative ant lion optimizer (ALO) process is performed in conjunction with ABT. The real frequency and load variation are realistic to the input of ALO and minimize the objective function area control error, generation costs and marginal cost of the system. Based on the output of the ALO, the ABT is resolute and assumed as the input of the proposed controller. The dynamic performance of the three-area IPS values including hydrothermal, wind turbine and photovoltaic power systems are evaluated on the basis of limits such as frequency deviation, generation power and tie-line power. Based on these limits, the frequency deviation is controlled and the parameters of the multi-resolution PID (MRPID) controller are regulated. The proposed MRPID controller is modified with the proposed ABT-based ALO to increase the optimal resolution. A three-area IPS is modeled under numerous loads to improve the efficiency of the proposed algorithm. The performance of the this method is demonstrated and compared with existing methods including particle swarm optimization and gravitational search algorithm.

Maiden application of SSA‐optimised CC‐TID controller for load frequency control of power systems

This study describes a maiden application of salp swarm algorithm (SSA) optimised cascade tilt-integral-derivative controller (CC-TID) for frequency and tie-line power control of interconnected power systems (IPSs). The proposed controller includes both the merit of the cascade control algorithm and fractional-order calculus. In the proposed CC-TID controller, TID controller is used as a slave controller and a proportional-integral (PI) controller served the role of master controller. To elucidate the effectiveness, the designed controller has employed to, initially, two-area IPS followed by four-area IPS. SSA is used to pursue the optimum settings of the CC-TID controller via the minimisation of area control error. Performances of CC-TID controller is obtained and compared with I-, PI-, PI-derivative-, cascade PI-PD, and TID controllers. Simulation results, apparently, show that SSA: CC-TID controller exhibits superior performance compared with other controllers described above. Moreover, the performance of SSA is evaluated and compared with differential evolution and flower pollination algorithm in terms of convergence profile, power density, and statistical results. Finally, time-varying step load perturbation and random load perturbation are applied to confirm the robust behaviour of SSA: CC-TID controller.

Implementation of Frequency Aware Distributed Power Flow Simulation and Analysis System for Interconnected Power System based on Multi-Agent System

With the diversified development of power source, power grid and electric load, power system is characterized by integrated transmission & distribution system, hybrid AC/DC transmission and bidirectional power flow, which could be a big challenge for operation and control of interconnected power system. According to the design ideas of Java Agent Development Framework (JADE), a frequency aware distributed power flow simulation and analysis system is implemented based on multi-agent system. The techniques of reactive power-voltage sensitivity analysis and dynamic power flow asynchronous iteration are applied for the proposed system to reflect the voltage support incidence relation of interconnected power system. Frequency regulation characteristics of generations and loads are considered to characterize the frequency change caused by fluctuation of renewable generations and disturbance of loads. Timing simulation of interconnected system is achieved to illustrate the spatial and temporal distribution of energy flow, which can provide an important support for power system operation and control. The validity and effectiveness of the proposed techniques for power flow calculation are tested in the modified IEEE 118-bus system and Shandong provincial power grid of China. The test results verify the applicability and the effectiveness of the proposed system

Model Predictive Based Load Frequency Control of Interconnected Power Systems

Model Predictive Based Load Frequency Control of Interconnected Power Systems

Novel application of integral‐tilt‐derivative controller for performance evaluation of load frequency control of interconnected power system

The primary aim of load frequency control (LFC) is to provide a good quality of electrical power to the consumers within a prescribed limit of frequency and scheduled tie-line power deviation. To achieve this objective, LFC needs highly efficient and intelligent control mechanism. Subsequently, here, a novel integral-tilt-derivative (I-TD) controller, fine-tuned by a powerful heuristic optimisation technique [called as water cycle algorithm (WCA)], is proposed for the LFC study of a two-area interconnected thermal-hydro-nuclear generating units. The studied system involves non-linearities like generation rate constraints, governor dead band, and boiler dynamics. To explore the effectiveness of the proposed controller, dynamic responses of the studied system, as obtained using I-TD controller, are compared to those yielded by other controllers such as tilt-integral-derivative and conventional proportional–integral–derivative controllers. The investigation demonstrates that the proposed I-TD controller delivers better performance in comparison to the other counterparts. Furthermore, sensitivity analysis is carried out to show robustness of the WCA tuned proposed I-TD controller by varying system parameters and loading condition. It is perceived that the proposed I-TD controller is robust and offers better transient response under varying operating conditions.

Particle Swarm Optimization based Automatic Generation Control of Interconnected Power System incorporating Battery Energy Storage System

This paper deals with Automatic Generation Control (AGC) of three area multi source interconnected power system assimilating Battery Energy Storage System (BESS). The plant is designed with Particle Swarm Optimization (PSO)tuned Integral controller (IC) which is carried out on three different sources, thermal, gas and hydro interconnected power system with and without BESS. Further computational intelligent technique, has been used to optimize the parameters of IC for different area by considering the objective function as integral square error (ISE). BESS provides fast active power compensation and manage sudden demand of power requirement in load, thus effectively dampening the frequency oscillations due to large disturbances in load. Dynamic performances of the system and objective function are analysed and compared for considered model. Analysis reveals that with the use of BESS, there is effective improvement in deviation of frequency of load disturbances.

Comparative performance analysis of one rank cuckoo search technique based optimization for automatic generation control of interconnected power systems

This paper presents a one rank cuckoo search optimization technique is proposed to design classical PID Controllers for Automatic Generation Control (AGC) of interconnected power systems. This method is proposed based on the original cuckoo search method. It was found in original cuckoo search the convergence speed is comparative lesser in reaching optimal solutions. To overcome the above mentioned problem one rank cuckoo search algorithm has been proposed which uses a bound by best solution technique to get the valid dimension so as to improve the system performance and rate of convergence. The proposed approach is applied to a four area hydro-thermal system in which area-1 and area-2 are steam reheat power plant and area-3 and area-4 are hydro power plant. The controller gains are derived using original cuckoo search and one rank cuckoo search methods. The superiority of the proposed approach is compared with the results obtained with original cuckoo search algorithm.

Accurate modelling of discrete AGC controllers for interconnected power systems

This paper deals with the modeling of discrete automatic gain control (AGC) controllers for an interconnected power system. The AGC supplementary controllers continuously try to reduce the ACE signal to zero by sending control commands/signals to the speed governor set points. Typically, control signals are sent in the form of discrete control pulses to adjust the generating unit outputs in discrete steps. However, in the preceding AGC studies, ZOH circuit has been misplaced in discrete supplementary controller models. Therefore, control signals feed to the speed governor set points no longer remains in discrete mode or in other words, controller action no longer remains in discrete steps. Therefore, the results and inferences drawn in these studies are erroneous and unrealistic. This paper presents the realistic model of discrete AGC controllers and removes the anomaly in existing works. Furthermore, it is also discovered that inappropriate selection of sampling period of ACE signal degrades the system dynamic performance or even cause system instability. Surprisingly, no proper guidelines/method has been provided yet to select the appropriate sampling period of ACE signals for discrete AGC operation. Here, a maiden attempt has been made to obtain the suitable values of ACE signal&s sampling periods using Shannon&s sampling theorem.

Load Frequency Control of Interconnected Power System via Multi-Agent System Method

For the load frequency control (LFC) of the interconnected power system, a two-level coordinated control frame based on multi-agent system is proposed to improve the frequency control performance of the power system. In the control frame, the upper-level agent, in a centralized manner, coordinates the lower-level LFC agents to deal with the conflict between narrowing the area control error and stabilizing the system frequency. The lower-level LFC agents, in the distributed cooperative manner, realize the mutual power support among the neighboring areas to guarantee the frequency stability in an emergency. To verify the validity of the proposed method, the numerical simulations are performed on the three-area interconnected power systems.

Model Predictive Load Frequency Control of two-area Interconnected Time Delay Power System with TCSC

In order to reduce the influence of non-linear constraint and time delay on load frequency control of interconnected power system, this paper, based on Model Predictive Control (MPC), designed a load frequency control scheme for two-area interconnected power system with TCSC device. First, considering the Generation Rate Constraint (GRC) and time delay, this paper builds the dynamics model of two-area interconnected power system with Thyristor Controlled Series Compensation device (TCSC). Then the whole system is decomposed into two subsystems. And each subsystem has its own local area MPC controller. Second, collaborative control is implemented by integrating the control information (measurement value, predictive value, etc.) of subsystems’ MPC controllers into the local control goal. In the end, under consideration of physical constraints, the Matlab simulation is conducted. The calculation results showed that the MPC strategy has better dynamic performance and robustness compared to the traditional PI control.

Distributed coordination regulation marginal cost control strategy for automatic generation control of interconnected power system

The area-level coordination of regulation capacity by automatic generation control (AGC) is an effective approach to mitigate wind power fluctuations in interconnected power system with high wind penetration. However, the applicability of this method is restricted by the existing AGC strategy. For this reason, power systems in China are experiencing serious wind curtailments to meet the power balance. In this study, a distributed coordination AGC strategy based on regulation marginal cost (RMC) is proposed for coordinating regulation capacity in different areas to remove frequency deviations. Detailed regulating characteristics of the AGC strategy in the existing power systems are discussed. Based on the above analysis, a distributed coordination RMC controller is designed to meet the proposed multi-area coordination rule using a partial primal-dual sub-gradient algorithm. In this proposed controller, the coordination signal containing RMC is exchanged with adjacent controllers through communication networks. The simulation results prove that the distributed coordination RMC strategy can economically coordinate the regulation capacity of an interconnected power system and satisfy the frequency control performance standard.

Symbiotic organisms search algorithm for automatic generation control of interconnected power systems including wind farms

Automatic generation control (AGC) plays an important role in power systems, where it maintains the system frequency and tie-line power flow at their desired values. This study presents a novel symbiotic organisms search (SOS) algorithm in order to optimally design the proportional–integral–derivative (PID) controllers in the AGC of interconnected multiple-area power systems including wind farms uncertainty and system non-linearity. The PID controllers’ parameters define the design variables of the optimisation problem. The SOS algorithm is applied to different objective functions such as integral square error and integral absolute of error. The efficacy of the proposed controller is compared with other competing evolutionary algorithms-based proportional–integral or PID controller. The system performance is evaluated under different operating conditions such as different loading, variation of system parameters, and an addition of wind energy uncertainty. For obtaining realistic responses, real wind speed data that extracted from Zafarana location in Egypt is used in this study. The validity of the proposed controller is extensively confirmed using the simulation results. With the SOS-based PID controllers, the dynamic responses for the AGC of interconnected power systems, including wind farms uncertainty can be further enhanced.