Area automatic generation control by multi-pass dynamic programming

Smith L.M., Fink L.H., Schulz R.P.

This paper describes the development, validation and use of a non-linear dynamic model developed for the study of automatic generation control and economic dispatch structures within a large multi-company interconnected electric power system. The model constitutes a unique tool for the realistic evaluation of the dynamic performance of newly developed system control and dispatch strategies. The improvements obtainable with these strategies and the determination of sufficient response reserves are demonstrated.

Kwatny H., Bechert T.

Static optimization techniques have been used by the electric power industry for several years to solve the problem of economic load allocation. Experience has shown that difficulties frequently arise when these solutions are incorporated in the feedback control of dynamic electric power networks. In a recent paper, economic load allocation was formulated as a dynamic optimal control problem in an effort to overcome the disadvantages of controllers currently used. At the heart of that problem is the area control problem that is treated in detail in this paper. An unusual feature of the area control problem is that it contains kinks. The maximal principle is modified for this situation. Necessary conditions for an optimal controller are obtained for the general case of n generators. The optimal feedback controller is synthesized for the case of two-generator load sharing.

Bechert T., Kwatny H.

Electric utilities presently use static optimization techniques to solve the economic load allocation problem. Experience has shown that a number of difficulties arise when these solutions are incorporated in the feedback control of dynamic electric power networks. This research attempts to overcome the disadvantages of such controllers by combining economic load allocation and supplementary control action into a single dynamic optimal control problem.

Ross C.

The error adaptive control computer (EACC) permits new and different degrees of freedom for automatic control. It is a logic computer which monitors the control error signal and makes logical decisions on how much, if any, control action should be taken depending on the characteristics of the error signal. Control action may be reduced to any judiciously chosen minimum by adjusting the EACC to discriminate against certain classes of disturbance, e.g., statistical, deterministic, and periodic. Fast control action may still be taken for large and/or sustained disturbances. Certain compromises may be necessary when the EACC is used; in particular, the error signal may be slightly increased. However, the EACC tends to hold the integrated error within a specified value by the action of its integrating circuit. The EACC lends itself to execution by either a special-purpose analog device or a digital computer program. An analog version of the EACC has been constructed and tested both in the field and by simulation.

Rasolomampionona D.D., Połecki M., Zagrajek K., Wróblewski W., Januszewski M.

Load frequency control (LFC) is one of the most important tools in power system control. LFC is an auxiliary service related to the short-term balance of energy and frequency of power systems. As such, it allows the acquisition of a central role in enabling electricity exchanges and providing better conditions. The classification of LFC can be carried out from different angles: we can enumerate, among others, the type of control used. The following types of control are presented in this review: classical, optimal, and robust control. More advanced controls can also be used for classification: fuzzy logic control, ANN control, genetic algorithms, PSO control, etc. The influence of renewables and power control tools like FACTS is also considered as a category to be analyzed. The last classifications are related to two important subjects—the influence of DC links on LFC efficiency and the dangers of cyberattacks on the LFC.

Wadi M., Shobole A., Elmasry W., Kucuk I.

This study provides a comprehensive and fresh review of load frequency control (LFC) in multi-area interconnected power systems (MAIPSs). The central tasks of LFC are to keep frequency variations as minimum as possible to achieve an acceptable level of stability. This research provides a complete view, from early classical control to recent technologies and modern techniques considering strategies, robust, optimal, self-tuning, and adaptive controllers for LFC in MAIPSs. Fuzzy control and earlier and recent optimization algorithms also are analyzed. The linearity, nonlinearity, and uncertainty of LFC models are also investigated. This review emphasizes recent technological advances and novel control strategies. LFC is also considered with the integration of wind, photovoltaic, electric vehicles, and storage devices. Besides, the utilization of machine learning and reinforcement techniques is examined. Further, LFC in smart grids and modern complex power systems concerning limited communication bandwidth, communication failure, and cyber-attacks are also investigated. This review provides an in-depth and detailed diagnosis of the challenges associated with LFC in modern and complex power systems. This work may be valuable for studies and practitioners interested in LFC. It, in detail, investigates future efforts and directions to enhance LFC performance, stability, and reliability in the face of increasing complexity and uncertainty.

Ali I., Askir A.N., Nazlibilek S.

Singh S.R., Kumar Bhagat S., Saikia L.C., Kumar Behera M., Kalita A., Gogoi S.

Saikia N., Das N.K., Patowary M., Buragohain M.

It is seen that there is a direct relation between the generation and demand of electrical energy in a power system. Any disturbance in the coordination between the two is highly undesirable and may result in unsatisfactory operations of power system structures. A sudden change in the real power demand in any area has a great impact on the system frequency. Whenever there is an increase in real power demand, the system frequency decreases, and when the real power demand decreases, the frequency increases. The fluctuations in the system frequency are highly undesirable and may even result in power system failures. Thus, the load frequency control provides the control strategies to maintain the system frequency and tie-line power deviation within allowable limits. In this paper, the different aspects of load frequency control (LFC) is discussed in details, considering various configurations of power system models and different control schemes. Also a comparative study is made between these approaches outlining the major advantages and disadvantages.

Peddakapu K., Mohamed M.R., Srinivasarao P., Arya Y., Leung P.K., Kishore D.J.

• Reviewed on AGC challenges with various control approaches in power systems. • A detailed survey presented on AGC with renewable energy sources. • AGC problems with integration of energy storage devices & FACTS have addressed. • Research gaps and directions for future power systems is presented. This paper presents a comprehensive literature review and an up-to-date bibliography on automatic generation control (AGC)/load frequency control (LFC) of interconnected power systems integrated with conventional, renewable and sustainable energy sources. The objective of AGC is to quickly stabilize the deviations in frequency and tie-line power following load fluctuations. Various state-of-the-art AGC strategies have not been reviewed so far, hence, an appropriate review on recent AGC mechanism is indispensable. Salient points discussed and highlighted in this survey include different power system models with/without renewable sources, and integration of sophisticated concepts such as microgrids (MGs), smart grids (SGs), distributed generations (DGs), high voltage direct current (HVDC) links, and power system after liberalization. Furthermore, various examined control approaches like traditional controllers, intelligent methods, adaptive, robust, optimal, variable, soft computing, centralized and decentralized methods with their advantages and disadvantages have been pondered and compared. Further, AGC challenges with incorporation of flexible AC transmission systems (FACTS), energy storage devices and high penetration of renewable sources for modern and future power systems have been addressed. This review concludes the new control schemes namely, electrical vehicles (EVs), fractional-order (FO) based controllers, fuzzy aided controllers, and cascaded controllers with case studies. Research gaps and directions for future developments AGC of power systems are also discussed.

Ram Babu N., Bhagat S.K., Saikia L.C., Chiranjeevi T., Devarapalli R., García Márquez F.P.

This review article aims to provide an in-depth analysis of the literature along with comprehensive bibliography on automatic generation control (AGC)/load frequency control investigations. Different control perspectives concerning frequency and power control have been featured. Diverse linear, non-linear power system models are discussed under conventional and deregulated environments considering various power generation sources, including conventional, renewable energy sources (RES), and realistic RES. Moreover, AGC literature briefly explains various secondary controllers like integer order, fractional order, intelligent, cascade, and some recently used controllers. To obtain the optimum values of secondary controllers, various optimization strategies such as numerical approach, heuristic, and meta-heuristic techniques for AGC issues are mentioned. Also, AGC studies concerning power transmission, considering inertia and phase-locked loops in high voltage direct current (HVDC) and accurate HVDC models are discussed. Further, AGC literature integrated with flexible alternating current transmission system devices in loaded transmission lines and energy storage devices due to intermittent power generation in RES is deliberated. Furthermore, various performance index criteria (PIC) such as standard PIC and hybrid peak area (HPA)–PIC for controller optimization with algorithms are also conferred.

Hu Z., Dai C., Su Q.

Dynamic economic dispatch with valve-point effect (DED_vpe) is a dynamic nonlinear high-dimensional optimization problem with non-smooth and non-convex characteristics. Meta-heuristic methods have become the mainstream for solving the DED_vpe problem. However, most of these methods only focus on minimizing the generation costs and ignore the algorithmic robustness. In this paper, an adaptive backtracking search optimization algorithm with a dual-learning strategy (DABSA) is proposed for solving the DED_vpe problem. In DABSA, a dual-learning strategy (DL) based on the current and historical optimal individuals is developed to update each individual. This updating strategy helps DABSA improve solution accuracy and overcome premature convergence. In addition, an adaptive parameter control mechanism (APC), which can automatically adjust parameter ‘mixrate’ value according to the current iteration number, is presented. To handle the system constraints, a ‘repair + penalty’ constraints-handling approach is employed to lead non-feasible solutions towards the feasible region quickly. The performance of DABSA is assessed by testing on four DED problems containing 5, 10 and 30 units. The experimental results show that DABSA is very competitive compared with reported representative methods in yielding low fuel costs along with high robustness. • A new method DABSA is proposed for solving DED problem with valve-point effects. • The core innovation of DABSA lies in the design of a dual learning strategy (DL). • BSA is the first attempt in solving DED problem with valve-point effects. • Results on 5, 10 and 30 units show that DABSA is competitive in terms of solution accuracy and robustness.

Dai C., Hu Z., Su Q.

Dynamic economic dispatch with valve-point effects (DED_ vpe ) is a high-dimensional constrained optimization problem with non-convex and non-smooth characteristics. Hybrid methods are one of the most advanced methods to solve the problem. However, most of these methods improve the solution accuracy at the expense of algorithm robustness. This paper proposes an adaptive hybrid backtracking search optimization algorithm (AHBSA) for solving the DED_ vpe . The core idea of AHBSA lies in designing a suitable coupling structure based on the current best individual (called optimal partial coupling). The structure hybridizes an improved BSA mutation operator and the DE/best/1 operator with equal probability. The improved BSA mutation operator uses the current best individual and the historical population to update individual position, called BSA/best/old. It is also the first research work of extending BSA to the problem. In addition, an adaptive parameter control mechanism is proposed to select an appropriate ‘mixrate’ value for achieving better coupling. The performance of AHBSA is validated on six DED test cases of three systems. Experimental results demonstrate that, compared with some representative methods, AHBSA not only reduces the fuel cost but also ensures the robustness of the algorithm. • A hybrid method AHBSA is proposed to solve DED problem with valve-point effects. • An optimal partial coupling structure is designed in AHBSA. • BSA is the first attempt at solving DED problem. • Results on six benchmark DED test cases show AHBSA is competitive.

Abdeen M., Emran A., Moustafa A., Kamal D., Hassan R., Hassan E., Ahmed F., Mahmoud M., Kamel S., Jurado F.

The most common method to increase the transmittable power is to insert a fixed series capacitor into a transmission line. But unfortunately, it was noted that the system stability is inversely proportional to the compensation level. This phenomenon is called a sub-synchronous resonance (SSR). SSR has a detrimental influence on the system's safety and stability. Thyristor controlled series capacitor (TCSC) is one of the most methods used for damping SSR and improving system stability. In this paper, appropriate values of TCSC parameters are identified. The ratio of TCSC inductive reactance to the TCSC capacitive reactance, TCSC impedance characteristic, the ratio of the TCSC capacitive reactance to the capacitive reactance of the fixed series capacitor, and different synchronization signals are studied. Additionally, the TCSC constant power control based on the P and PI controllers are compared. In order to analyze the SSR phenomenon in a doubly fed induction generator (DFIG)-based wind farm connected to TCSC, IEEE first benchmark model (FBM) is modified. MATLAB software is utilized to demonstrate the results.

Lin W., Li C.

With the worsen of environmental problems, the carbon emission of the energy system has quickly become the spotlight. However, Most of the existing works focus on the economic dispatch without carbon emission constraints. In this paper, we focus on the economic dispatch with carbon emission constraints. First, a novel mathematical model which characterizes the economic dispatch with carbon emission constraints is given. Then it is followed by the distributed carbon-aware dispatch strategy design based on the singular perturbation system.

Peddakapu K., Mohamed M.R., Srinivasarao P., Veerendra A.S., Kishore D.J., Leung P.K.

This paper reviews on the function of Automatic Generation Control (AGC) as an intelligent mechanism in enhancing electrical power systems dynamic performance at various perturbations; by sustainin...

Dev A., Sarkar M.K.

The chapter focuses on load frequency control (LFC) problems in multi area power systems using nonlinear second order sliding mode control (NL-SOSMC) under load disturbances and parameter uncertainties. A sudden load disturbance can causes deviation in frequency and tie line power from their schedule value. The main objective of the chapter is to give knowledge about the application of robust control technique mainly sliding mode control (SMC) for load frequency problems. The designed controller ensures finite time convergence of frequency and tie line power deviations with chattering free control signal. The proposed controller confirms better transient and steady state behavior. Furthermore, the controller is validated under matched uncertainty, random step load disturbances, parameter uncertainties, and with nonlinearities in power system like generation rate constraints (GRC) and governor dead band (GDB). The stability of the controller is theoretically proved using Lyapunov candidate function and verified using simulations in MATLAB R2015a.

Shen X., Zou D., Duan N., Zhang Q.

In this paper, an efficient fitness-based differential evolution (EFDE) algorithm and a constraint handling technique for dynamic economic emission dispatch (DEED) are proposed. In EFDE, there are three improvements compared to the standard differential evolution (DE) algorithm. First, an archive containing the current and previous population is established to provide more candidate solutions. Second, two mutation strategies are used to generate mutant individuals, where the population similarity is introduced to choose a suitable one between DE/rand/1 and DE/best/1. The fitness-based mutation operation is efficient to balance the exploration and exploitation ability of EFDE. Third, EFDE adopts a random-based mutation factor, and the crossover rate with the learning ability is developed to produce more excellent solutions. In addition, the infeasible solutions can be effectively avoided by the proposed repair technique. Four cases are selected to judge the performance of the proposed EFDE and constraint handling technique. For the fuel cost and emission minimizations of four DEED cases, a normalized approach (NA) is used to help EFDE to find the best compromise solutions in the evolution process. According to the simulation results, EFDE exhibits a huge advantage in comparison with the other approaches for the single-objective and multi-objective optimization problems.

Zheng Z., Li J., Han Y.

In this study, an improved invasive weed optimisation (CMIWO) algorithm is investigated to solve the dynamic economic dispatch (DED) problem with valve-point effects. In the proposed algorithm, a h...