scholarly journals Algorithm for optimization of power system short-term mode in conditions of partial uncertainty of initial information taking into account the frequency change

2020 ◽  
Vol 216 ◽  
pp. 01100
Author(s):  
Tulkin Gayibov
Keyword(s):  
Power Systems ◽  
Power System ◽  
Economic Effect ◽  
Active Power ◽  
Computational Experiments ◽  
Frequency Change ◽  
Short Term ◽  
Initial Information ◽  
The Real ◽  
System Mode

Many existing methods and algorithms for optimization of short-term modes of power systems provide in calculations the introduction of a slack bus station, which ensures the balance of active power and, accordingly, the permissible frequency. In cases where the real load deviates from the planned one, determined by forecasting, the power system mode may turn out to be not optimal, and sometimes even not acceptable. This factor is especially noticeable in conditions of partial uncertainty of initial information about loads of nodes. To overcome this problem, planning of power system mode should be carried out taking into account the frequency change and, accordingly, the regulatory capabilities of all stations. This paper proposes an algorithm for optimization of modes of power systems in terms of partial uncertainty of initial information about loads, taking into account the frequency change. On the basis of computational experiments using the proposed algorithm, it is shown that taking into account the frequency change when planning modes of power systems with partially undefined loads of nodes can give a significant economic effect.

scholarly journals Consideration of limitations in the form of inequalities in optimal planning of power systems regimes under uncertainty initial information

2021 ◽  
Vol 289 ◽  
pp. 07005
Author(s):  
Sh.Sh. Latipov ◽  
A.E. Shanazarov ◽  
I.B. Ikramdjanov
Keyword(s):  
Power Systems ◽  
Efficient Algorithm ◽  
Computational Experiments ◽  
Optimal Planning ◽  
Short Term ◽  
Initial Information

In the article the issues of taking into account of constraints in the form of inequality in optimal planning of short-term modes of power systems are considered. An efficient algorithm for solving of the problem is offered. On the basis of computational experiments for specific problems of optimal planning of modes of power systems the efficiency of the proposed algorithm is revealed.

Under Frequency Load Shedding Techniques for Future Smart Power Systems

2019 ◽  
pp. 188-202
Author(s):  
H. H. Alhelou
Keyword(s):  
Power Systems ◽  
Power System ◽  
Active Power ◽  
Load Shedding ◽  
System Stability ◽  
Special Focus ◽  
Power Demand ◽  
Synchronous Generators ◽  
Smart Power ◽  
System Frequency

It is critical for today's power system to remain in a state of equilibrium under normal conditions and severe disturbances. Power imbalance between the load and the generation can severely affect system stability. Therefore, it is necessary that these imbalance conditions be addressed in the minimum time possible. It is well known that power system frequency is directly proportional to the speed of rotation of synchronous machines and is also a function of the active power demand. As a consequence, when active power demand is greater than the generation, synchronous generators tends to slow down and the frequency decreases to even below threshold if not quickly addressed. One of the most common methods of restoring frequency is the use of under frequency load shedding (UFLS) techniques. In this chapter, load shedding techniques are presented in general but with special focus on UFLS.

scholarly journals Optimization of Short-term Modes of Hydrothermal Power System

2020 ◽  
Vol 209 ◽  
pp. 07014
Author(s):  
Tulkin Gayibov ◽  
Bekzod Pulatov
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Plants ◽  
Optimal Planning ◽  
Hydroelectric Power ◽  
Short Term ◽  
Planning Period ◽  
Time Intervals ◽  
Large Power ◽  
Integral Constraints

Optimal planning of short-term modes of power systems is a complex nonlinear programming problem with many simple, functional and integral constraints in the form of equalities and inequalities. Especially, the presence of integral constraints causes significant difficulties in solving of such problem. Since, under such constraints, the modes of power system in separate time intervals of the considered planning period become dependent on the values of the parameters in other intervals. Accordingly, it becomes impossible to obtain the optimal mode plan as the results of separate optimization for individual time intervals of the period under consideration. And the simultaneous solution of the problem for all time intervals of the planning period in the conditions of large power systems is associated with additional difficulties in ensuring the reliability of convergence of the iterative computational process. In this regard, the issues of improving the methods and algorithms for optimization of short-term modes of power systems containing thermal and large hydroelectric power plants with reservoirs, in which water consumption is regulated in the short-term planning period, remains as an important task. In this paper, we propose the effective algorithm for solving the problem under consideration, which makes it possible to quickly and reliably determine the optimal operating modes of the power system for the planned period. The results of research of effectiveness of this algorithm are presented on the example of optimal planning of daily mode of the power system, which contains two thermal and three hydraulic power plants..

scholarly journals Examples of changes in Romania power systems towards the achievement of the modern objective of the UE

2020 ◽  
Vol 305 ◽  
pp. 00032
Author(s):  
Maria Daniela Stochitoiu ◽  
Ilie Utu
Keyword(s):  
Power Systems ◽  
Power System ◽  
Digital Data ◽  
Power Electronic ◽  
Electronic Technology ◽  
The Real ◽  
Intelligent Planning ◽  
Power Electronic Technology

One of the main scopes for power systems is the ensuring adequate and secure electricity service through intelligent planning, operation and reliability. In order to benefit today from the advantages of the intelligent production of tomorrow, the connection between the real production and the processes based on digital data is necessary. The devices using power electronic technology become a vital solution in many power system applications. Nowadays technologies are generating solutions various increasingly for the energetically management.

scholarly journals Security Constrained Stochastic Power System Scheduling Algorithms - With Wind Electric Generators

2021 ◽  
Author(s):  
Yu Peng
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Output ◽  
Unit Commitment ◽  
System Security ◽  
Transmission System ◽  
Short Term ◽  
Transmission Systems ◽  
Probabilistic Distribution ◽  
Ac Transmission

Power systems worldwide are embracing diverse supply mixes that incorporate a significant portion from renewables such as wind and solar energy. Wind energy is characterised by reliable equipment, but with an output that is uncertain and intermittent. In addition to equipment unreliability (system N-1 criterion), output uncertainties of wind electric generators (WEGs) introduce risk into daily power system schedules. This risk from the uncertainty of output from WEGs can be quantified as expected energy not served (EENS). Furthermore, the introduction of new forms of generation changes the methods of operating transmission systems, further necessitating the use of transmission security constraints in power systems optimization algorithms. This dissertation explores new approaches to stochastically model the real power output of WEGs and to efficiently tackle AC transmission system security constraints for power system optimization algorithms such as optimal power flow (OPF) and day-ahead unit commitment (UC). Usually, normal probabilistic distribution is used to model uncertainty in short-term wind power output forecast and compute EENS. In this dissertation, a new triangular approximate distribution (TAD) model is proposed which is a linear approximation of normal probabilistic distribution to model short-term wind power output forecast and compute EENS. This TAD model is used to formulate a practical risk-constrained fast OPF for transmission systems to simultaneously minimize: 1) risk due to uncertainties in power output from WEGs, and 2) the total operating cost. The integration of new energy resources causes transmission systems to operate in new, challenging, and often unforeseen operating states. Thus, it is imperative that UC algorithms incorporate AC transmission system security constraints and stochastically model output of WEGs to ensure reliable operation of transmission systems. As a first step, a successive mixed integer linear programming (MILP) method is proposed for AC transmission system security constrained unit commitment (SCUC) challenge. Fuzzy sets theory is used to model infeasible constraints in this MILP formulation. As a next step, the TAD model of WEGs is integrated into the MILP formulation of SCUC to create a fast security and risk constrained probabilistic UC algorithm. The two UC algorithms are tested on large systems.

scholarly journals Mathematical Models and Algorithms of Optimal Load Management of Electricity Consumers

2019 ◽  
Vol 62 (6) ◽  
pp. 528-535 ◽  
Author(s):  
I. U. Rakhmonov ◽  
K. M. Reymov
Keyword(s):  
Mathematical Model ◽  
Power Systems ◽  
Power System ◽  
Experimental Studies ◽  
Optimal Planning ◽  
Short Term ◽  
Planning Period ◽  
Efficient Operation ◽  
Load Profile ◽  
Optimal Load

Load profile alignment based on optimal power consumption management is considered to be one of the main ways to ensure efficient operation of energy systems in the short-term planning. Alignment load profile with a view to reducing costs can be implemented with the aid of consumers’ involvement by administrative and economic measures. Administrative measures are associated with the forced restriction of consumer loads in certain intervals of the planning period. On one hand, these measures provide benefits to the power system by alignment load profile, and on the other hand, they cause detriment to consumers. Ultimately, in some cases, for the whole power system, the detriment may be greater than the benefits. Therefore, it is advisable to use administrative measures in conditions of shortage of power and electricity in the power system. Optimal planning of short-term regimes of power systems according to rigid load profile received after alignment can be carried out by traditional methods. The solution of such a problem ought to be initially carried out under conditions of non-rigid load profile resulting from the directive use of administrative and economic measures carried out with the help of specially developed models. In this regard, the paper proposes a mathematical model of the problem of optimizing load profile of regulated electricity consumers to be used for optimal planning of shortterm power system modes, an algorithm for optimal planning of a short-term power system mode with optimizing load profile of regulated power consumers. Also, algorithms are proposed for accounting for simple and functional constraints in the form of equalities and inequalities when optimizing load profile. The effectiveness of the described algorithm for optimizing the short-term mode of the power system, taking into account the optimal load control of adjustable electricity consumers, has been studied using the example of optimal coverage of the load profile of power system, which contains two consumers with adjustable load profile, and two TPPs. Based on the calculated-and-experimental studies, it was determined that the proposed mathematical model of the problem is adequate, while the developed algorithms for optimal planning of short-term power system modes with optimization of load profile of regulated electricity consumers and taking into account various types of limitations are of high computational qualities.

scholarly journals ANN-Based Day-Ahead Short Term Load Forecasting

2021 ◽  
Author(s):  
Heng Zhao
Keyword(s):  
Power Systems ◽  
Power System ◽  
Meteorological Data ◽  
Load Forecasting ◽  
Automatic Generation ◽  
Training Algorithms ◽  
Security Assessment ◽  
Short Term ◽  
Short Term Load Forecasting ◽  
And Performance

Load forecasting (LF) is of great significance for effective operation, utilization, safety and reliability of the modern electric power systems. Load forecasting can be categorized into very short term, short-term, medium-term, and long-term forecasts, depending on which time scale is concerned. The short term load forecasting (STLF) plays an increasingly important role in achieving a more efficient, reliable and safe power system. Its outputs are the indispensable inputs of generating scheduling, power system security assessment and power dispatch. In the era of smart grid (SG), STLF is the basic building block to imply Demand Side Management (DSM) in areas such as automatic generation control, load estimation, energy purchasing, and contract evaluation, etc. The accuracy of STLF is of essential importance for both economic and reliability. In the last few decades, various methods have been devised and applied to perform STLF. Due to its superior capability of handling the nonlinearity, Artificial Intelligence (AI) based techniques are gaining more popularity in a variety of applications. The objective of this study is to review, categorize, evaluate, and analyze the principle, application, and performance of STLF techniques. It builds up several feed forward Artificial Neural Networks (ANN) models with different configurations, and studies the mechanism of ANN for effective STLF. With 12 years of hourly load and meteorological data sets of a section of the City of Toronto, the configurations are built up with different hidden layers, activating function, training algorithms and both un-normalized and normalized data to predict the day ahead STLF with satisfactory result achieved.

scholarly journals ON THE SIMULATION OF MODES ОF ELECTRIC POWER SYSTEMS WITH FACTS

2017 ◽  
Vol 60 (4) ◽  
pp. 341-351
Author(s):  
E. D. Halilov
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Power Flow ◽  
Power Transmission ◽  
Electric Power Systems ◽  
Active Power ◽  
Operating Conditions ◽  
Electrical Networks ◽  
Facts Devices

Power flow control is an important task of development of electric power systems. It is necessary to reduce the power loss, improve the reliability and quality of power supply and increase the power transmission. Currently, on the basis of modern power electronics effective FАСТS devices for flexible control of power system operation modes have been developed. FАСТS devices are able to simultaneously influence the voltage, the reactance, the angle between the voltages. As it is known, the calculations of the established modes of electric systems are the most frequently performed tasks at all the territorial and time levels of control and planning operations. These calculations are significant by themselves, being also an integral part of software systems of calculation of losses of power and energy in electrical networks, calculation of optimal modes and also sustainability. The need for multiple mode calculation imposes high requirements to the methods of calculation of the established modes in real time in terms of performance and reliability of the results of the solution being obtained under operating conditions of electric power systems. In traditional calculations of the established modes of electrical networks, shunt reactors, current-limiting reactors, capacitor banks, longitudinal compensation devices were accounted in the simulation as passive elements. In regard with the introduction of FACTS devices in power systems, there is an arising need to develop appropriate algorithms and implement them in the form of software for analyzing and controlling the established modes of power systems. The methodology and software for calculation of the established modes of electric networks with consideration of FACTS devices have been developed. The software makes it possible to obtain practically acceptable solutions in three outer iterations. Based on the results of numerical simulation of modes of the power system of the “Azerenergy” JSC it was determined that the application of FACTS devices can significantly increase the transmission line active power, improve voltage levels and reduce losses of active power. The dependences of flows and power losses on the control parameter of FACTS devices have been derived. 

scholarly journals The problem of active power measurement in the case of distorted waveforms

2019 ◽  
Vol 24 (6) ◽  
pp. 139-143
Author(s):  
Agata Bandrowska-Kaim ◽  
Krzysztof Kratiuk
Keyword(s):  
Power System ◽  
Active Power ◽  
Power Measurement ◽  
The Real ◽  
Fundamental Component ◽  
Harmonic Content ◽  
Energy Measure ◽  
Higher Harmonic

The article discusses the influence of deformed waveforms on the accuracy of power measurement in the energy meters installed by the distributors of the power system. The basic sub-logical and reliability aspects of the real energy measure are presented. The discussed issue is presented based on the analysis of two cases: deformed waveforms with a fundamental component and higher harmonic content and distorted waveforms with subharmonic and interharmonic contents.

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