Future Electric Power Systems Research Articles

Grid sense multiple access: A decentralized control algorithm for DC grids

Due to the distributed nature of future electrical power systems, decentralized control is essential for these grids. This paper shows that converters that have identical voltage thresholds switch off simultaneously even if some could have remained operational. Therefore, inadequate system and energy utilization can occur when decentralized demand or supply response is utilized. The Grid Sense Multiple Acces (GSMA) algorithm proposed in this paper ensures that, after a change occurs in the system, a subset of the converters remains connected to the grid, without the need of utilizing any form of communication. This is achieved by introducing an exponential backoff time between failed connection attempts. Furthermore, several simulations and experiments are conducted to illustrate and validate the behavior of the GSMA algorithm, showing that it can be applied to dc grids in order to improve system and energy utilization.

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.

Analytics and Optimization for Renewable Energy Integration [Book News

The book illustrates the application of stochastic mathematical methods and tools to power systems with renewable energy integration to improve analytics and decision making, benefiting both security and the economy. The book is divided in four parts. Part I presents the background of stochastic mathematical concepts. Part II focuses on modeling for longand short-term renewable energy uncertainties, dependencies among multiple renewable power plants, renewable energy generation, and the time series analysis. Part III deals with methods to handle the uncertainty of renewable energy in power system operation, including fast and efficient algorithms for probabilistic power flow, risk-based stochastic models to compute the optimal generation schedule under uncertainty, and efficient operation strategies for renewable power plants in electricity markets, handling tie-line scheduling under uncertainty. Part IV introduces computationally efficient approaches to simulate long-term power system operation; estimate the capacity credit of renewable energy; optimize the location, capacity, and sequence of renewable investments; and to optimize the long-term planning of generation and transmission in power systems with renewable energy penetration. Most of the sixteen chapters include case studies as well as summaries and references. The book is of paramount importance to graduate students, engineers, and researchers who are willing to increase the penetration of renewable energy in electrical networks. The book is also a valuable tool for graduate-level teachers and practicing power systems professionals who need to understand and master the planning and operation of future electrical power systems with increased renewable energy penetration.

Building conflict uncertainty into electricity planning: A South Sudan case study

This paper explores electricity planning strategies in South Sudan under future conflict uncertainty. A stochastic energy system optimization model that explicitly considers the possibility of armed conflict leading to electric power generator damage is presented. Strategies that hedge against future conflict have the greatest economic value in moderate conflict-related damage scenarios by avoiding expensive near-term investments in infrastructure that may be subsequently damaged. Model results show that solar photovoltaics can play a critical role in South Sudan's future electric power system. In addition to mitigating greenhouse gas emissions and increasing access to electricity, this analysis suggests that solar can be used to hedge against economic losses incurred by conflict. While this analysis focuses on South Sudan, the analytical framework can be applied to other conflict-prone countries.

Extracting Novel Relations Between Economic and Electrical Variables in DC Electric Power Systems

DC electric power systems, including HVDC, HVDC light, dc distribution systems, and dc microgrids, have a significant position in present and, especially, future electric power systems, namely, smart grids. One of the most significant issues of electric power systems, including dc electric power systems, is the calculation of accurate and fair energy costs of the consumers. In this paper, novel, simple, practical, and precise relations between economic and electrical variables in dc electric power systems are extracted. The novel relations prove that there are interesting relations between voltages of nodes, as electrical variables, and prices of nodes, as economic variables, in dc electric power systems. Applying the extracted novel relations in this paper, a new, fair, precise, practical nodal price, i.e., the fair nodal price, is determined to calculate the energy costs of consumers in dc electric power systems, including dc distribution systems and microgrids. Moreover, as an application of the extracted novel relations, a practical method to determine the fair nodal prices of all nodes and, as a result, the real energy cost of each consumer at each node of dc electric power systems is presented. The analyses results demonstrate the mentioned significant characteristics.

Techno-economic analysis of the lithium-ion and lead-acid battery in microgrid systems

Microgrids are a beneficial alternative to the conventional generation system that can provide greener, reliable and high quality power with reduced losses, and lower network congestion. However, the performance of renewable energy resource (RER) based generators in a microgrid is hindered by their intermittent nature. The energy storage system plays a key role in overcoming the intermittency of renewable sources by balancing the power demand against variable generation. Energy storage using batteries is accepted as one of the most important and efficient ways for retaining reliable energy supply whilst incorporating RERs into the electricity grid. Lead-acid (LA) batteries have been the most commonly used electrochemical energy storage technology for grid-based applications till date, but many other competing technologies are also being used such as lithium-ion (Li-ion), Sodium-Sulphur and flow batteries. This paper carries out the techno-economic analysis of the battery storage system under different configurations of the microgrid system. The design of an optimal model of standalone as well as grid-connected microgrid systems having PV-wind-diesel and biodiesel energy resources in the presence of Li-ion (LiFeSO4 type) and LA batteries have been studied. The performance of the two types of batteries has been compared in the proposed microgrid systems considering realistic load profiles, real resource data, and real prices of the components. Load profiles of two rural villages, a business organization and an urban residential building have been used. On the basis of these load profiles and available resources, different microgrid configurations with generation from PV, wind turbine, diesel and biodiesel generators have been considered to study the performances of the batteries. The results include the cost of optimal system configuration under the given scenarios, electricity generation by various generating sources, detail comparison between various components, emissions, and various batteries performance assessment parameters. The study reveals that Li-ion batteries as energy storage are techno-economically more viable compared to LA batteries and they are expected to play a significant role in various applications of future electric power systems.

Selecting the Optimal Micro-Grid Planning Program Using a Novel Multi-Criteria Decision Making Model Based on Grey Cumulative Prospect Theory

As useful supplements and effective support for large-scale electric power networks, micro-grid systems are the development tendency of future electric power systems. The planning performance of a micro-grid not only affects its security, reliability and economy, but also has a profound influence on the stable operation of large-scale electric power networks with the increasing penetration of micro-grids. Hence, studies related to micro-grid planning program evaluation are of great significance. This paper established a novel multi-criteria decision making (MCDM) model combining the best-worst method (BWM), the entropy weighting approach, and grey cumulative prospect theory for optimum selection of micro-grid planning programs. Firstly, an evaluation index system containing 18 sub-criteria was built from the perspectives of economy, electricity supply reliability and environmental protection. Secondly, the weights of sub-criteria were calculated integrating the subjective weights judged by the BWM and the objective weights computed by the entropy weighting method. Then, the cumulative prospect theory (CPT) combined with grey theory was employed to select the optimal micro-grid planning program. The empirical result indicates that the program with 100 kWp photovoltaic power generation unit, 200 kW wind power generation unit and 600 kWh NaS battery energy storage system is the optimal micro-grid planning program. To verify the robustness of obtained result, a sensitivity analysis related to values change of parameters under different risk preferences was conducted, and the result indicates that the selected optimal micro-grid planning program will not be influenced by various risk preferences of decision makers (DMs) and investors. The novel MCDM proposed in this paper is applicable and feasible in the micro-grid planning programs evaluation and selection.

Impacts of Demand-Side Management on Electrical Power Systems: A Review

Electricity demand has grown over the past few years and will continue to grow in the future. The increase in electricity demand is mainly due to industrialization and the shift from a conventional to a smart-grid paradigm. The number of microgrids, renewable energy sources, plug-in electric vehicles and energy storage systems have also risen in recent years. As a result, future electricity grids have to be revamped and adapt to increasing load levels. Thus, new complications associated with future electrical power systems and technologies must be considered. Demand-side management (DSM) programs offer promising solutions to these issues and can considerably improve the reliability and financial performances of electrical power systems. This paper presents a review of various initiatives, techniques, impacts and recent developments of the DSM of electrical power systems. The potential benefits derived by implementing DSM in electrical power networks are presented. An extensive literature survey on the impacts of DSM on the reliability of electrical power systems is also provided for the first time. The research gaps within the broad field of DSM are also identified to provide directions for future work.

Fast Frequency Response from MMC-HVDC with Varying Dead Band Implementation

Abstract Future electrical power systems will have an increased percentage of renewable generation which will reduce the amount of synchronously connected rotating kinetic energy and inertia. With reduced levels of inertia, the system frequency will be prone to a faster rate of deviation from its nominal value. As traditional frequency containment may be too slow under low inertia conditions, it is expected that systems will require renewable sources of generation to provide some additional frequency containment response (FCR) in suitably fast timeframes. Of particular interest in this research is how the use of modular multilevel converter (MMC) based HVDC interconnectors could be operated to provide FCR. To avoid excessive operation of MMC-based FCR, dead bands around nominal frequency are often suggested. Here, the implementation of the dead band is revisited to investigate how different variants of implementations (namely, continuous and discontinuous), could improve frequency response from an MMC. A continuous implementation with a variable controller gain value that is dependent on dead band size is shown to reduce frequency nadir. The discontinuous implementation is shown to reduce frequency nadir further and when modified with latching behavior also improves frequency recovery. This research highlights that alternative dead band implementation for MMCs, particularly a discontinuous dead band with latching behavior could improve frequency response in future power systems.

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

A Learning Scheme for Microgrid Reconnection

This paper introduces a potential learning scheme that can dynamically predict the stability of the reconnection of subnetworks to a main grid. As the future electrical power systems tend toward smarter and greener technology, the deployment of self sufficient networks, or microgrids, becomes more likely. Microgrids may operate on their own or synchronized with the main grid, thus control methods need to take into account islanding and reconnecting of said networks. The ability to optimally and safely reconnect a portion of the grid is not well understood and, as of now, limited to raw synchronization between interconnection points. A support vector machine (SVM) leveraging real-time data from phasor measurement units is proposed to predict in real time whether the reconnection of a subnetwork to the main grid would lead to stability or instability. A dynamics simulator fed with preacquired system parameters is used to create training data for the SVM in various operating states. The classifier was tested on a variety of cases and operating points to ensure diversity. Accuracies of approximately 85% were observed throughout most conditions when making dynamic predictions of a given network.

Analysis and Design of a 1200 V All-SiC Planar Interconnection Power Module for Next Generation More Electrical Aircraft Power Electronic Building Blocks

Compact, light weight and efficient Power Electronic Building Blocks are seen as fundamental components of future More Electric Power Systems, e.g. More Electrical Aircraft. Core elements supporting the trend are power modules employing solely SiC MOSFETs. In order to take advantage of the high switching speed enabled by SiC, novel modules concepts must be investigated. For example, low inductance planar interconnection technologies, integrated buffer capacitors and damping networks are possible solutions to mitigate switching overvoltages and oscillations at the switching node occurring for conventional modules. In this paper, the analysis and the design of a novel ultra-low inductance 1200 V SiC power module featuring an integrated buffer-damping network are discussed. The power module is first described and characterized with impedance measurements. Afterwards, a general optimization procedure for the sizing and the selection of the integrated components is presented and measurements are performed to verify the analysis and to highlight the improvements of the proposed solution.

Engineering Support for Handling Controller Conflicts in Energy Storage Systems Applications

Energy storage systems will play a major role in the decarbonization of future sustainable electric power systems, allowing a high penetration of distributed renewable energy sources and contributing to the distribution network stability and reliability. To accomplish this, a storage system is required to provide multiple services such as self-consumption, grid support, peak-shaving, etc. The simultaneous activation of controllers operation may lead to conflicts, as a consequence the execution of committed services is not guaranteed. This paper presents and discusses a solution to the exposed issue by developing an engineering support approach to semi-automatically detect and handle conflicts for multi-usage storage systems applications. To accomplish that an ontology is developed and exploited by model-driven engineering mechanisms. The proposed approach is evaluated by implementing a use case example, where detection of conflicts is automatically done at an early design stage. Besides this, exploitable source code for conflicts resolution is generated and used during the design and prototype stages of controllers development. Thus, the proposed engineering support enhances the design and development of storage system controllers, especially for multi-usage applications.

A Z-Source-Based Bidirectional DC Circuit Breaker With Fault Current Limitation and Interruption Capabilities

DC microgrids have some attractive characteristics, which have being investigated to utilize in future electrical power systems. However, they have several essential challenges, such as limiting and interrupting fault current, which should be rectified to have high-performance dc microgrids. In this paper, an efficient dc bidirectional fault current limiter and interrupter (FCLI) based on Z-source topology is proposed to overcome some of the challenges in dc microgrids. The FCLI is a multifunction device, by which power flow direction control, circuit breaking, fault current limiting, and interrupting in a dc system can be handled. Analytical analysis of the FCLI is discussed in detail for different operation modes. Performance of the proposed FCLI in the different operation modes is evaluated using some simulations and experiments. The results confirm high capability of the device to realize appropriate operation in dc systems. Fast response time of fault current limitation and interruption, simple and reliable structure, and negligible conduction loss are the main features of the proposed FCLI.

Analysis of Microgrid Contributing to Hour-ahead market operation through Marginal Day-ahead market Price-Based Demand Response

Abstract: In Japan, 53 GW Photovoltaic (PV) systems will be introduced in future electric power system in 2030 year. It will raise issues of insufficient supply capability and reserve capacity to utility operator to ensure supply-demand balance. On the other hand, Microgrid that located in demand side will be expecting to actively response the incentive signal sent by the utility operator so as to contributing to demand-supply adjustment. In this paper, based on revised IEEJ-EAST-10 Generators simulation model that included of 22GW PV generations and 5GW Microgrids, we analyzed the effect and potential contribution capability of microgrid to electric power system demand-supply adjustment in hour-ahead electricity market through Price-Based Demand Response. Firstly, we analyzed the impact of day-ahead market marginal price on optimal scheduling of Micorgrid. Secondly, we analyzed the impact of optimal scheduling of Micorgrid on Utility operator in Hour-ahead market operation. Lastly, we evaluated the contribution capability of microgrid to electric power system demand-supply adjustment in hour-ahead electricity market that included the improvement of partial-load operation of coal thermal power plant, Utility side load-leveling, and reserve capacity provided by Microgrid.

Frequency response services designed for energy storage

Energy Storage Systems (ESS) are expected to play a significant role in regulating the frequency of future electric power systems. Increased penetration of renewable generation, and reduction in the inertia provided by large synchronous generators, are likely to increase the severity and regularity of frequency events in synchronous AC power systems. By supplying or absorbing power in response to deviations from the nominal frequency and imbalances between supply and demand, the rapid response of ESS will provide a form of stability which cannot be matched by conventional network assets. However, the increased complexity of ESS operational requirements and design specifications introduces challenges when it comes to the realisation of their full potential through existing frequency response service markets: new service markets will need to be designed to take advantage of the capabilities of ESS. This paper provides new methods to analyse and assessing the performance of ESS within existing service frameworks, using real-time network simulation and power hardware in the loop. These methods can be used to introduce improvements in existing services and potentially create new ones. Novel statistical techniques have been devised to quantify the design and operational requirements of ESS providing frequency regulation services. These new techniques are demonstrated via an illustrative service design and high-resolution frequency data from the Great Britain transmission system.

A New Approach for Soft Synchronization of Microgrid Using Robust Control Theory

Microgrid is the main part of future electrical power systems, called “smart grids”. In this context, the synchronization of a microgrid with utility or other microgrids will be a crucial and commonplace task during power system operation. Based on robust control principles, a new approach for synchronizing microgrids with utility was presented in this paper. Uncertainties of the dynamic model of microgrids were considered as multiplicative perturbations. Based on the uncertain model, a robust controller was designed by means of $\mu$ synthesis analysis so that the robust stability and performance of the system could be maximized. The simulation results confirmed the effectiveness of the proposed control strategy.

Future energy and electric power systems and smart technologies

In this paper, we describe, first, the present status and the tasks toward the future of energy systems in Japan from the viewpoint of 3E+S. 3E+S means energy security, environmental conservation, economic efficiency, and safety. Second, we describe the future energy society in 2030 and 2050, respectively. We introduce a large picture of the total energy system considering the energy resources, conversion, transportation, storage, consumption, control, and system architecture. For the image of 2030, the Japanese government has already announced the middle‐term (2030) energy demand and supply on July 16, 2015. For 2050, we assume three cases regarding the renewable energy installations: the status quo of 2030 covering 22–24% of the total consumption, and 50 and 100% of the total consumption. In the last section, we describe smart technologies to support the envisioned society in 2030 and 2050. We also introduce the reference architecture model. To achieve 80% reduction of greenhouse gas (GHG) emission in 2050, the innovations at the consumer side, such as the large‐scale renewable energy resources and storage installations, utilization of electrified vehicles, distributed energy management systems including virtual power plants, and system integration, will become very important in addition to innovations at the supply side. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Role of pump hydro in electric power systems

This paper provides an overview of the expected role that variable speed hydro power plants can have in future electric power systems characterized by a massive integration of highly variable sources. Therefore, it is discussed the development of a methodology for optimising the operation of hydropower plants under increasing contribution from new renewable energy sources, addressing the participation of a hydropower plant with variable speed pumping in reserve markets. Complementarily, it is also discussed the active role variable speed generators can have in the provision of advanced frequency regulation services.