Large Electric Power Systems Research Articles

Methodological Proposal: First Steps for the Implementation of Demand Management Programs in Colombia

The electrification of isolated or rural areas brings with it technical, economic, and social challenges that differentiate the operation of these networks compared to the traditional operation of large electrical power systems, such as the dependence of air or river transport on fuel for the supply of generation plants, the absence of individual measurement and the obsolete infrastructure of the distribution networks. Therefore, this paper proposes a hybrid methodology for studying a Colombian case, analyzing the development of programs for rational electricity use and energy efficiency in isolated areas. These first steps are related to the diagnosis of the current conditions of the power network, the identification of actors that can influence the regulation of the electricity service in the area, and the proposal of mechanisms that allow promoting the rational and efficient use of the electricity.

Modeling and Simulating Wind Energy Generation Systems by Means of Co-Simulation Techniques

This paper presents the development of a wind energy conversion system co-simulation based on the Functional Mock-up Interface standard aiming at contributing to the development of co-simulation of large electrical power systems by means of open-source and standardized computational tools. Co-simulation enables the computational burden of a monolithic simulation to be shared among several processing units, significantly reducing processing time. Through the Functional Mock-up Interface standard, developed models are encapsulated into Functional Mock-up Unit, providing an extra means for the protection of intellectual property, a very appealing feature for end users, both in industry and academia. To achieve the decoupling of the subsystems, the Bergeron ideal transmission line model will be used, with travel time equal to the simulation time-step. The computational performance and effectiveness of the proposed co-simulation technique was evaluated with a wind power plant with 50 wind turbines. The system digital models were developed into Modelica language, while co-simulation was implemented in Python.

Simulating a Strong Magnetic Storm Impact on Russia’s Interconnected Power System of Center

Studying of a negative impact of the space weather and magnetic storms as its special case, on the performance of a critical technological infrastructure, with development of methods and means for protecting it is a relevant but difficult task. Many advanced countries, primarily the United States, are dealing with this problem. The article presents the results of elaborating a methodology for computational simulation of the impact of geomagnetically induced currents on large electric power systems. The developed methodology makes it possible to take into account the influence of changes in the reactive power and temperature of power transformer structural elements caused by magnetic biasing of their core, as well as the operation of relay protection. The impact of the geomagnetically induced currents expected during a strong magnetic storm on Russia’s Interconnected Power System of Center, including the power systems of Moscow, Leningrad and other major administrative and industrial regions of the country has been simulated for the first time. It is shown that such impact gives rise to a set of factors that can cause the development of a system-wide accident: a significant decrease in voltage at a number of power system facilities, mass-scale disconnection of power lines by their relay protections, and unacceptable heating of structural elements of some power transformers.

Electrical Event Detection and Monitoring Data Storage from Wide Area Measurement System

Synchronized phasor measurement systems are being widely used around the world and have become essential elements in the evolution of the operation of large electrical power systems (EPS). These systems, called Phasor Measurement Units (PMUs), are capable of recording and communicating dynamic data from the EPSs in a synchronized way by GPS and with a high sampling rate, generate a huge set of data that, among many applications, has the capacity to detect events. In this way, this work presents a data management system architecture applied to a real PMU system located in the state of Paraná, Brazil that detects and storages events using principal component analysis and Pearson correlation. This method can detect and store electrical events that occurred during the operation of the national interconnected system of Brazil with good results.

Simplified model of battery energy-stored quasi-Z-source inverter-based photovoltaic power plant with Twofold energy management system

The use of a battery energy-stored quasi-Z-source inverter (BES-qZSI) for large-scale PV power plants exhibits promising features due to the combination of qZSI and battery as energy storage system, such as single-stage power conversion (without additional DC/DC boost converter), improvements in the output waveform quality (due to the elimination of switching dead time), and continuous and smooth delivery of energy to the grid (through the battery energy storage system). This paper presents a new simplified model of a BES-qZSI to represent the converter dynamics with sufficient accuracy while using a less complex model than the detailed model (including the modelling of all switches and switching pulses). It is based on averaged values of the variables, voltage/current sources, and the same control circuit than the detailed model, except for the switching pulses generation. The simplified model enables faster time-domain simulation and is useful for control design and dynamic analysis purposes. Additionally, an energy management system has been developed to govern the power supply to grid under two possible scenarios: 1) System operator command following; or 2) economic dispatch of the stored energy. The results obtained from simulations and experimental hardware-in-the-loop (HIL) setup for different operating conditions of the grid-connected large-scale PV power plant with battery energy storage under study demonstrate the validity of the proposed simplified model to represent the dynamics of the converter and PV power plant for steady-state stability studies, long-term simulations, or large electric power systems.

Integral Models Based on Volterra Equations with Prehistory and Their Applications in Energy

The paper addresses the application of Volterra integral equations of the first kind for modeling dynamic power systems. We study the problem of forecasting the commissioning of capacities of the electric power system, taking into account various hypotheses about the dynamics of equipment aging, and the known prehistory. The numerical results of the application of two models to the problem of the development of a large electric power system using the example of the Unified Energy System of Russia are presented. Theoretical results were formulated for a two-dimensional Volterra integral equation of the first kind with variable limits of integration. This class of equations arises when solving the actual problem of identifying variable characteristics of a nonlinear dynamic system of the “input-output” type.

Averaged Dynamic Modeling and Control of a Quasi-Z-Source Inverter for Wind Power Applications

Typically, permanent magnet synchronous generator (PMSG)-driven wind turbines (WTs) present a two-stage power converter topology based on a DC/DC boost converter and voltage source inverter. In this study, this configuration is substituted by a quasi-Z-source inverter (qZSI), which is an attractive solution for boosting and converting the voltage from DC to AC in a single stage. A 2 MW PMSG WT with qZSI was studied herein. A switched dynamic model (SDM) of the qZSI (including the modeling of all switches and firing pulses) is not recommended for steady-state stability studies, long-term simulations, or large electric power systems. For such studies, two averaged dynamic models are proposed in this work. Both models present the same control system as the SDM, except for the generation of firing pulses, which is not necessary in the averaged models. The two proposed models were evaluated and compared with the SDM in the large-scale WT under different operating conditions, such as wind speed fluctuations, variable power references, and grid disturbances (voltage sag and 3rd and 5th order harmonics injection), in order to demonstrate their adequacy to represent the system response with a high reduction in the simulation time and computational efforts.

Optimization Problem for the Integral Model of Developing Systems

This paper addresses an integral model of development a large electric power system using the example of the Unified Energy System of Russia. The model takes account of the age structure of the plants main equipment. Besides, generating equipment is divided into components depending on the types of energy resources used. The mathematical model is presented by a system of nonclassical Volterra integral equations of the first kind. One of the equations describes the balance between the total available capacity of the electric power system, commissioning of new equipment, and dismantling of obsolete one. The other equations define the shares of different types of power plants in the total composition of the electric power system equipment. Based on the considered model, we set a problem that searches the optimal lifetimes of electric power system capacities for a given demand for electricity. The optimality criterion is a functional reflecting cost of commissioning and operating the capacities. The specifics of the optimization problem are that the optimization parameter is in the lower limit of integration. An algorithm for solving of this optimal control problem numerically is developed. The influence of economic indices on the solution to the optimal control problem is studied. Calculations of the optimal development of the Unified Energy System of Russia until 2050 are carried out using real-life data.

Unified Fast Decoupled Load Flow in a Parallel Distributed Computation Framework

This research proposes a parallel and distributed computation approach for the fast decoupled load flow (FDLF) analysis applicable to both transmission and distribution networks of large electrical power systems. In this approach, the overall repetitive FDLF computations are performed by the respective control centers identified for each sub-system, the sub-systems being formed by partitioning the system through a network tearing procedure splitting the identified buses. The data of each subsystem are stored at their own control centers and hence the subsystems are solved using message passing distributed memory architecture. The computations performed by the control centers in various sub-systems are coordinated from a regional control center. The investigations on IEEE 118 bus standard test system indicate that the proposed approach provides faster solution than the conventional approach, without affecting the solution accuracy. The effectiveness of the proposed technique over the conventional approach become more visible when it is applied for the load flow analysis of large scale systems spread over a wide geographical area.

От плана ГОЭЛРО к глобальному электроэнергетическому интернету

The GOELRO Plan adopted 100 years ago is briefly characterized, and the importance and necessity of its adoption under the conditions of post-revolution devastation and foreign intervention are substantiated. It is pointed out that the scales of the modern electric power industry are incommensurable with those the plan developers imagined in their dreams. The article tells about the establishment of large state, interstate, and intercontinental electric power systems and pools that make it possible to usefully utilize the system effects, which are profitable to all participants of the pools. It is pointed out that radical changes have occurred in the technology of energy generation, transmission, distribution, storage, and consumption, and also that transformations have occurred in the structure and properties of the systems. Digitalization of the systems implies improvement in the efficiency of production processes and development of new software products to perform control of substations, regional networks, etc. The future electric power systems will acquire the response of well-developed intelligent cyber-physical systems operating on the principles of electric power internet.

От плана ГОЭЛРО к глобальному электроэнергетическому интернету

The GOELRO Plan adopted 100 years ago is briefly characterized, and the importance and necessity of its adoption under the conditions of post-revolution devastation and foreign intervention are substantiated. It is pointed out that the scales of the modern electric power industry are incommensurable with those the plan developers imagined in their dreams. The article tells about the establishment of large state, interstate, and intercontinental electric power systems and pools that make it possible to usefully utilize the system effects, which are profitable to all participants of the pools. It is pointed out that radical changes have occurred in the technology of energy generation, transmission, distribution, storage, and consumption, and also that transformations have occurred in the structure and properties of the systems. Digitalization of the systems implies improvement in the efficiency of production processes and development of new software products to perform control of substations, regional networks, etc. The future electric power systems will acquire the response of well-developed intelligent cyber-physical systems operating on the principles of electric power internet.

Bases Conceptuales para la Utilización del Análisis de Contingencias en Tiempo Real con Criterios de Consciencia Situacional, Caso Centro de Control de CENACE-Ecuador

La operación segura de sistemas eléctricos requiere que los Operadores, sobre los cuales recae esta gran responsabilidad, reconozcan de forma permanente el estado en que se encuentra la red supervisada y dispongan de los recursos para identificar amenazas probables, que le permitan anticipar y reaccionar de manera segura frente a eventos fortuitos de consecuencias predecibles, como ocurren cuando hay la salida de equipos durante la operación. En el ámbito de la Consciencia Situacional se dispone de una metodología que adecuadamente integrada con herramientas como el Análisis de Contingencias, posibilitan capacidades avanzadas de supervisión. Esto solo es posible, si se desarrollan a cabalidad tres fases de implementación, que se proponen conceptualmente en este trabajo como son; Modelación – Sintonización y Personalización. Siendo la Personalización la extensión metodológica clave para el logro de la integración planteada en este trabajo basado en años de experiencia de los autores en sistemas SCADA-GMS-EMS.

The hybrid model of VSC HVDC

The trend in semiconductor developments has made the high-voltage direct current (HVDC) technologies based on voltage source converters feasible. This type of convertor has a number of potential advantages compared with “classic” HVDC, but deep analysis should be carried out before its integration in electric power system. In this paper, the results of realization of the VSC HVDC model based on a concept of hybrid simulation of electric power system are presented. Hybrid concept combines three approaches of simulation: analog, digital and physical, combination of which allows to achieve a maximum efficiency. The obtained simulation results have confirmed an adequacy of the model and possibility to integrate it to the hybrid real-time simulator for carrying out various researches and analyses of the operation of large electric power system, including HVDC technologies, in real time without any decompositions and limitations.

Numerical solution of the age structure optimization problem for basic types of power plants

Our paper addresses an integral model of the large electric power system optimal development. The model takes into account the age structure of the main equipment, which is divided into several types regarding its technical characteristics. This mathematical model is a system of Volterra type integral equations with variable integration limits. The system describes the balance between the given demand for electricity, the commissioning of new equipment and the dismantling of obsolete equipment, as well as the shares of different types of power plants in the total composition of the electric power system equipment. Based on the developed model, we got numerical solution to the problem of finding the optimal strategy for replacing equipment with a minimum of the cost functional. The case study is the Unified Electric Power System of Russia. Calculations of the forecast for development of the electric power system of Russia until 2050 were made using real-life data.

Ameliorated grey wolf optimization for economic load dispatch problem

Owing to no free lunch theorem, meta-heuristic search algorithms, behaviour and performance are different for solving specific class of optimization problems than another. Further, search algorithms are conceptualized of exploration and exploitation aspects. Ameliorated grey wolf optimization algorithm is proposed to solve economic power load dispatch problem that synergizes between exploration and exploitation aspects. Ameliorated grey wolf optimization procedure coordinates the behaviour of grey wolves, random exploratory search, local random search and opposition learning heuristics. Grey wolf optimization algorithm is considered to perform global search and random exploratory search applied to perform a search in the neighbourhood of already visited search locations. To maintain good solutions and diversity among solutions, opposition based learning has been implemented. The practical aspects i.e. value-point loading effect, avoidance of prohibited operating zones and ramp rate limits, generation limits of generators and satisfaction of power demand constraint are undertaken to solve economic power load dispatch problem. Heuristic search is exploited to handle equality constraints. The proposed algorithm is validated on standard benchmark functions and medium to large electric power systems. Results reveal that proposed technique is a potential method to solve economic load dispatch problems as it competes with recent algorithms undertaken for comparison.

Fast calculation of modal interaction in large power systems using spectral decompositions of Gramians

Abstract The solutions of Lyapunov and Sylvester equations can be represented as a sum of Hermitian matrices or sub-Gramians corresponding either to individual eigenvalues of the system or their pairwise combinations. The sub-Gramians corresponding to a given part of the spectrum of dynamical system can be used to estimate the modal interaction in this part of the spectrum. In this paper we propose an algorithm for the fast calculation of sub-Gramians for large electric power systems. Our numerical tests demonstrate that the sub-Gramians corresponding to the selected part of the spectrum can be calculated much faster than all sub-Gramians of the system. Therefore, the proposed algorithm can serve as a basis for the fast calculation of modal interactions in large-scale power systems in real time.

Fast network restoration by partitioning of parallel black start zones

The restoration of large electrical power systems after a blackout is often a challenging task. A typical restoration process includes the partitioning of the power systems into subsystems and the successive booting of large non-black start (NBS) units by black start (BS) units. A proper partitioning of the starting zone can reduce the restoration time significantly. This paper investigates a novel network partitioning algorithm to improve the restoration time and ratio of generation and load in each subsystem. The proposed algorithm consists of three stages. In the first stage, the number of subsystems is determined by the number of available BS units and their electrical distance. In the second stage, NBS units are assigned to each subsystem in the way that the rebooting time difference among subsystems is minimised. In the third stage, the substations are assigned to one of the subsystems to achieve the optimal ratio of generation and load in each subsystem. With the proposed algorithm, the switching transient and steady-state over-voltages at the receiving end of unload lines are kept within acceptable ranges and the self-excitation phenomenon does not occur in the subsystems. Furthermore, the start-up sequence of NBS units in each subsystem is determined simultaneously. The proposed algorithm is flexible and can be adjusted very easily according to the real status of the power system. The validity and performance of the proposed approach is demonstrated through simulations using a New England 39 Nodes network and a real network from south China.

Assessing the economic feasibility of the gradual decarbonization of a large electric power system

The decarbonization of power systems is among the primary actions to fight air pollution and climate change. In this study, we evaluate the costs of a gradual transition towards a new power system in which the oldest coal plants are replaced with low-carbon power plants. We developed the Wind Energy Integration Cost Advisor Model (WEICAM) to analyze different strategies for this energy transition and determine the most cost-effective roadmap, with and without externalities. The test case is the PJM Interconnection, one of the power systems in the United States with the largest fraction of coal. Different strategies to replace coal plants are evaluated: 1) installing only new, high-efficiency, natural-gas combined-cycle plants (control case), 2) installing new wind farms in combination with natural-gas combined-cycle plants used as spinning reserves (wind case), and 3) same as the wind case but boosting up the production of existing baseload plants that work with a capacity factor between 50% and 60%–80% before installing new wind farms. All three strategies have similar costs (∼54 $/MWh), but the latter is slightly more cost-effective, with a total of 19 GW of coal capacity decommissioned and an increase in the levelized cost of electricity from 49.1 to 53.6 $/MWh (without externalities). In addition, selecting the windiest sites – even far away from the PJM region – is cheaper than selecting local but less windy sites. When externalities due to human health and environmental pollution are accounted for, the two wind-based strategies become the most advantageous, reducing the levelized cost below 104 $/MWh from the initial 110 $/MWh. We conclude that adding new wind farms from the windiest locations, accompanied by a better management of existing plants and a small addition of new natural-gas reserve capacity, is the most economic and the most environmentally responsible pathway to replace retiring coal-fired power plants in PJM.

PowSysGUI: A new educational software package for power system stability studies using MATLAB/Simulink

Graphical user interfaces have been progressively used in the classrooms to provide users of computer simulations with a friendly and visual approach to specify all input parameters with enhanced configuration flexibility. In this paper, an educational software package called PowSysGUI (Power System GUI), which runs on MATLAB and uses graphical user interfaces, has been developed for analysis and simulation of small to large size electric power systems. PowSysGUI is open-source software and anyone can see the inner structure of the program to figure out how to code a power engineering problem. It is designed as a simulation tool for researchers and educators, as it is simple to use and modify. PowSysGUI has algorithms for solving power flow, small signal stability analysis, and time-domain simulation. In the case studies, IEEE 16-machine 68-bus test system is given to show the features of the developed software tool. Moreover, classroom experience has shown that the developed software package helps in consolidating a better understanding of power system stability phenomena.

Voltage Stability in Large Marine-Integrated Electrical and Electronic Power Systems

Offshore oil and gas vessels operating in deep and ultra-deep waters demand larger and more sophisticated power and control systems. This tendency brings new challenges in integrated power system’s design, especially for platforms/vessels requiring both dynamic positioning and high levels of redundancy. Voltage stability is essential in such systems, being in islanded operation (with related limited power generation) and with continuously changing load demands. In particular, voltage stability issues can arise due to the increasing amount of power electronic converters installed onboard, used to feed variable frequency drives and other electronic loads. Indeed, most of these have a controlled front-end, whose control can affect network voltage with a destabilizing effect named constant power loads (CPLs) instability. Such a behavior deserves special attention in islanded power systems, mostly if the quota of power electronics loads on the total installed power reaches very high values (up to the 85% for new large all electric ships). This paper initially focuses on the CPL voltage instability. Two different models to assess voltage stability in marine systems with high penetration of electronic power conversion are given, focusing on a design-stage assessment. Using the conditions obtained by such models, a practical stability analysis methodology is proposed, to help assessing voltage stability already at design stage, to avoid equipment retrofits during vessel building or commissioning. Finally, some practical case studies are discussed, and solutions to overcome the CPL instability are suggested.