Renewable Energy Grid Integration Research Articles

A Comprehensive Study of Degradation Characteristics and Mechanisms of Commercial Li(NiMnCo)O2 EV Batteries under Vehicle-To-Grid (V2G) Services

Lithium-ion batteries on electric vehicles have been increasingly deployed for the enhancement of grid reliability and integration of renewable energy, while users are concerned about extra battery degradation caused by vehicle-to-grid (V2G) operations. This paper details a multi-year cycling study of commercial 24 Ah pouch batteries with Li(NiMnCo)O2 (NCM) cathode, varying the average state of charge (SOC), depth of discharge (DOD), and charging rate by 33 groups of experiment matrix. Based on the reduced freedom voltage parameter reconstruction (RF-VPR), a more efficient non-intrusive diagnosis is combined with incremental capacity (IC) analysis to evaluate the aging mechanisms including loss of lithium-ion inventory and loss of active material on the cathode and anode. By analyzing the evolution of indicator parameters and the cumulative degradation function (CDF) of the battery capacity, a non-linear degradation model with calendar and cyclic aging is established to evaluate the battery aging cost under different unmanaged charging (V0G) and V2G scenarios. The result shows that, although the extra energy throughput would cause cyclic degradation, discharging from SOC 90 to 65% by V2G will surprisingly alleviate the battery decaying by 0.95% compared to the EV charged within 90–100% SOC, due to the improvement of calendar life. By optimal charging strategies, the connection to the smart grid can potentially extend the EV battery life beyond the scenarios without V2G.

A Review of Control Techniques and Energy Storage for Inverter-Based Dynamic Voltage Restorer in Grid-Integrated Renewable Sources

Power quality (PQ) is a key issue, particularly for technologically advanced process equipment, whose performance mainly depends on the quality of supply. Problems with PQ such as voltage swells/sags, interruptions, and harmonics are defined by any voltage, current, or frequency abnormalities causing damage or failure of the end-user equipment. Outages and interruptions lead to malfunctioning of end-user equipment or sensitive loads, such as diagnostic equipment in healthcare facilities, clinics, educational institutions, and detention centers, while further increasing significant economic losses. Custom power devices (CPDs) are recommended for enhancing power quality, and the best and most economical solution is considered to be the dynamic voltage restorer (DVR). Several methods are suggested to improve the PQ by using the dynamic voltage restorer; among them, most encouraging ways are to use a multilevel inverter (MLI) in the dynamic voltage restorer. This article combines the latest work of the literature, as well as a detailed discussion on PQ issues of the grid-integrated renewable energy sources (RESs), DVR principle with its operating procedures, system components, energy storage-based DVR topologies, DVR control unit, and DVR power converter-based topologies. In addition, synthesis of energy storage, control strategies, and multilevel inverters for DVR. This review benefits those interested in investigating DVR as a relevant and comprehensive reference.

Adaptive Multi-Parameter-Tuning for Online Stabilization Control of Grid-Tied VSC: An Artificial Neural Network-Based Method

Voltage Source Converter (VSC) for grid integration of renewable energies are prone to have small-signal stability issues when connected to weak AC grids. Such stability issues largely arise from the lack of VSC control adaptivity to the varying grid condition (e.g., grid impedance). To address this issue, this letter presents an adaptive multi-parameter tuning method using the Artificial Neural Network. Innovative aspect of the proposal lies in that it enables the VSC to simultaneously tune multiple controller parameters online, which brings about a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pole-tracking</i> -based stabilization control feature for the VSC. Experimental results demonstrate that the proposed method can effectively and adaptively stabilize the VSC when the grid impedance is varied.

Dynamic energy flow analysis of the heat-electricity integrated energy systems with a novel decomposition-iteration algorithm

Simulation and operation optimization studies on the integrated energy system have received extensive attention recently for its potential in improving energy efficiency and increasing grid integration of renewable energy, where the task of energy flow calculation serves as a fundamental tool to determine the network states. This paper investigates the models and methods for dynamic energy flow analysis of two strongly coupled networks in the integrated energy systems — the power grid and the heating network. First, the complicated coupling mechanisms of power grid and heating network are thoroughly analyzed and classified into four representative coupling modes. On this basis, the detailed dynamic energy flow analysis method for each coupling mode is developed. Second, a refined difference scheme is applied to discretize the partial differential equations describing the long-lasting temperature dynamics in the heating network. The high-dimensional dicretized model is then solved by a novel decomposition-iteration algorithm. Compared with existing methods, this algorithm avoids deriving the gigantic coefficient matrix of network equations and can improve the accuracy of energy flow results. Finally, considering the systematical error caused by neglecting the inertial and adjusting constraints of heat sources, a revision stage is firstly introduced to correct the heat power output of the slack source and help obtain more accurate energy flow results. Case study shows that the proposed methods take 3.21 s to obtain the dynamic energy flows of a coupled system consisting of a 118-node power grid and eight 35-node district heating networks over a 300-minutes simulation course, which is qualified to provide support for simulation and optimization related applications in practice.

Hybrid protection algorithm for power system with renewable energy generation using Stockwell transform and Wigner distribution function

Rapid technological development in grid integration of renewable energy (RE) plants has increased the RE penetration level in power utility network. This dramatic change in power scenario challenges the protection and stability of grid. Therefore, this work proposed a protection scheme algorithm (PSA) for the RE integrated hybrid power system. This PSA is implemented in the following steps: (1) calculate Wigner distribution function powered fault index (WFI), (2) calculate Stockwell transform powered combined FI (SCFI), (3) calculate hybrid FI (HFI) using WFI and SCFI, (4) classify the faults using number of faulty phases and fault ground index. Proposed hybrid fault index is used for the identification of faults. It also considers the change in magnitude and waveform distortions of current signals. The proposed PSA effectively identifies and classifies the faulty events such as single phase to ground, two phase, two phase to ground and all phases to ground. PSA is successfully tested for the recognition of faults under various operating scenarios like noisy scenario, different magnitudes of fault impedance, fault location node and fault incidence angle, lines comprising of overhead section and underground cable with availability of transformer. This PSA is effective to discriminate the operational switching events compared to faulty events. It is concluded that performance of the introduced PSA is better and fault detection time is less compared to wavelet energy spectrum entropy based PSA, discrete wavelet transform (DWT) based PSA and Stockwell transform supported PSA.

Synthetic inertia and frequency support assessment from renewable plants in low carbon grids

Increasing grid integration of uncertain Renewable Energy (RE) sources reduces system’s inherent Frequency Response (FR) and restricts System Operators’(SOs) ability to maintain frequency stability. This condition further aggravates as existing operational practices do not consider FR from RE based generation. Technical feasibility of RE generation to facilitate synthetic inertia and Primary Frequency Response (PFR) is well established. However, FR support from RE plants must be integrated in scheduling decisions to ensure inertial and PFR adequacy in operational time frame. Further, unlike conventional units, RE plants’ output is volatile due to inherent variability and uncertainty. Hence, the uncertainty of RE generation needs to be considered in scheduling horizon to accurately assess system-wide FR requirement and RE Plants’ potential in its’ contribution. In this context, the paper proposes a novel day-ahead stochastic security-constrained unit commitment framework to incorporate synthetic inertia and PFR support from wind and PV plants, and ensure frequency response adequacy. RE generation is forecasted using long-short-term memory, a deep learning approach. A machine learning-based Bayesian inference statistics is used to characterize RE power uncertainty. Simulations are carried out on New England test system for various RE integration levels. Numerical results demonstrate the effectiveness of frequency support from RE plants in terms of improvement in frequency security parameters. Operating cost and RE curtailment are reduced 11% and 68%, respectively with PFR support from RE plants.

Grid integration of renewables: challenges and solutions

Exponential growth in the energy demand on account of rising population and economic growth, increasing apprehensions of energy security coupled with climate change and global warming concerns are some of the major drivers for pushing the renewable energy (RE) to the top of the energy portfolio. Among various renewable energy resources, wind and solar PV systems are experiencing rapid growth since 2010. By the end of 2016, the world total capacity of wind power generation was 487 GW and that of solar PV was 303 GW, aggregating to a penetration level of 4.0% and 1.5% respectively. Global renewable energy penetration till December 2016, excluding conventional hydro share (of 16.6%) was only around 8.0%. However, many countries have set target of 30% RE based electricity generation by 2030. India has an ambitious target of achieving 175 GW of RE power by 2022, with 100 GW from solar, 60 GW from wind, 10 GW from biomass and 5 GW from small hydro. Power generation from renewables often takes place through distributed generation (DG). These units, mostly located in remote locations, are not centrally planned or dispatched, and are usually connected to distribution grids at LV or MV levels. In few cases, large capacity RE generation are also connected to transmission networks. As a result, the power generation structure is moving from the large, centralized plants to a mixed generation pool consisting of traditional large plants and many smaller DG units. Most of the RE generators have electrical characteristics that are different from the synchronous machines. Since a large group of DG technologies use power electronics converters for grid connectivity, they introduce many technical issues related to the operation, control and protection of the power system, impacting generators, transmission system and consumer devices. This paper presents some of the technical issues and challenges that need to be addressed for the effective grid integration of RE based power generators so that eventually our reliance on polluting and expensive fossil based hydrocarbon driven power generation can be reduced substantially.

Extreme weather and electricity markets: Key lessons from the February 2021 Texas crisis

Todd Levin is a principal energy systems engineer in the Center for Energy, Environmental and Economic Systems Analysis (CEEESA) at Argonne National Laboratory. His research interests focus on utilizing advanced optimization and simulation methodologies to model complex interactions in electricity markets and quantify the implications of domestic energy policies and regulations. He also maintains a strong interest in international energy development, examining optimal centralized and decentralized rural electrification strategies and a range of global energy security issues. Dr. Levin holds a BA in physics from Northwestern University and a PhD in industrial engineering from the Georgia Institute of Technology. Audun Botterud is a principal energy systems engineer in CEEESA at Argonne National Laboratory with a co-appointment in Laboratory for Information and Decision Systems at Massachusetts Institute of Technology. He analyzes the complex interactions between engineering, economics, and policy in electricity markets, in support of the transition toward a cost-efficient and reliable low-carbon energy system. He is particularly interested in grid integration of renewable energy and energy storage. Audun holds an MSc (industrial engineering) and PhD (electrical power engineering) from the Norwegian University of Science and Technology and was previously with SINTEF Energy Research in Trondheim, Norway. W. Neal Mann is a postdoctoral appointee in CEEESA and the Nuclear Science and Engineering Division at Argonne National Laboratory. His research interests include energy system modeling and design, nuclear energy, and energy storage for climate change mitigation and adaptation. He holds a BA in physics and music from Southwestern University and an MSE and PhD in mechanical engineering (nuclear and radiation engineering focus) from the University of Texas at Austin. Jonghwan Kwon is an energy systems engineer in CEEESA at Argonne National Laboratory. His research interests include operations research applied to electric power systems, power systems operations and planning, management of distributed energy resources, and market design and pricing. Dr. Kwon holds a PhD in electrical engineering power system from Arizona State University. Zhi Zhou is a principal computational scientist in CEEESA at Argonne National Laboratory. His research interests include optimization, machine-learning-based forecasting, decision making under uncertainty, and applications to power grid, electricity markets, renewable energy, and the interdependency between power grids and other infrastructure systems. Zhi Zhou received his BE in computer sciences from Wuhan University, MS in operations research and statistics, and PhD in decision sciences and engineering systems from Rensselaer Polytechnic Institute.

Control and Automation of Hybrid Renewable Energy Harvesting System

The hybrid renewable energy harvesting and grid integration system has been proposed and validated in this work. The proposed system uses a Wind Energy Conversion System (WECS) and a Solar Photo Voltaic Energy Conversion System (SPVECS). The WECS uses Permanent Magnet Synchronous Generator (PMSG) driven by a wind turbine. The variable frequency and variable voltage output of PMSG is rectified by Diode Bridge Rectifier (DBR) and stepped up by Super Lift Luo Converter (SLLC 1), and finally, the harvested wind energy is delivered to the Direct Current (DC) link of a Distributed Static Synchronous Compensator (DSTATCOM). Further, SPV energy is harvested by using PV modules and voltage is stepped up by another SLLC (SSLC 2), and the harvested PV energy is brought to the DC link of DSTATCOM. The DSTATCOM extends real and reactive power support to the load. The various subsystems of the proposed system have been modelled in Matrix Laboratory (MATLAB) Simulink environment and analyzed their performance.

Separation of Lithium Ion Cathode Material for Direct Recycling

In recent years there has been an acceleration in the use of lithium ion batteries (LiBs) in applications ranging from automotive to wearable technology. This means it is now more key than ever to be able to extract maximum use and then to recycle these batteries in a safe sustainable manner as they not only contain rare and critical elements but many of these elements are expensive and environmetaly damaging to extract and make into batteries and thus can cause a large amount of environmental damage1. A good way to prolong the life of some LiBs is to utilise them in 2nd life applications without any chemical treatment. 2nd life applications vary and can range from electric vehicle fast charger support2,3 to back up power4 and grid balancing support2,5, these 2nd life applications can extend the life of a battery by anywhere between 6 and 30 years2.Some batteries may not be re-used directly in second life applications due to capacity loss through degradation. Degradation can occur through a number of mechanisms including: electrolyte decomposition6, Loss of active lithium, and loss of active material porosity and interconectivity7, all of which lead to an increased impedance and losses in efficiencies. For these batteries a disposal route must be found. Currently for End of Life (EoL) batteries the disposal routes most commonly consist of either stock piling, which may be a potential environmental hazard, or pyrometallurgical processes that are not as environmentally friendly and do not necessarily recover the maximum value from the product. For quality control rejects no dedicated commercial recycling process is known about. One of the main hurdles to direct recycling of LiBs is the difficulty in separating active material from casing and current collector.In this work we investigate how two different commercial cathode chemistries are affected by two separation methods and compare these to their untreated equivalents. The first method comprises of an acid and ultrasonic agitation and the second comprises of the green solvent DMSO and ultrasonic agitation. We present data to investigate how particle morphology, crystal structure and metal content varies between the three methods. We then go on to remanufacture the materials into half cells and examine the capacity, electrochemical performance, and cycle life of the two processes. Harper, G. et al. Recycling lithium-ion batteries from electric vehicles. Nature 575, 75–86 (2019).Casals, L. C., Amante García, B. & Canal, C. Second life batteries lifespan: Rest of useful life and environmental analysis. J. Environ. Manage. (2019). doi:10.1016/j.jenvman.2018.11.046Sebastian, S. S. et al. Adaptive fast charging methodology for commercial Li‐ion batteries based on the internal resistance spectrum. Energy Storage 1–16 (2020). doi:10.1002/est2.141Pagliaro, M. & Meneguzzo, F. Lithium battery reusing and recycling: A circular economy insight. Heliyon 5, e01866 (2019).Gohla-Neudecker, B., Bowler, M. & Mohr, S. Battery 2nd life: Leveraging the sustainability potential of EVs and renewable energy grid integration. 5th Int. Conf. Clean Electr. Power Renew. Energy Resour. Impact, ICCEP 2015 311–318 (2015). doi:10.1109/ICCEP.2015.7177641An, S. J. et al. Correlation of electrolyte volume and electrochemical performance in lithium-ion pouch cells with graphite anodes and NMC532 cathodes. J. Electrochem. Soc. 164, A1195–A1202 (2017).Birkl, C. R., Roberts, M. R., McTurk, E., Bruce, P. G. & Howey, D. A. Degradation diagnostics for lithium ion cells. J. Power Sources 341, 373–386 (2017).

Electrochemical Control for Corrosion in Molten Chloride Salts

Concentrated solar power (CSP) with thermal energy storage (TES) has the ability to help solve the renewable energy grid integration challenge with its electricity dispatch capability. However, utility-scale adaption of CSP-TES has been slow due to the high levelized cost of electricity (LCOE). One avenue for cost reduction is the increase in operating temperature of the CSP plant to increase the thermal efficiency of the Carnot cycle. This requires finding a new salt blend with higher thermal stability up to 800 ℃. A ternary MgNaK chloride salt is a prime candidate with its low cost, high thermal stability, and good heat transfer properties. However, its commercial deployment is challenged by the high corrosion rates, leading to the use of expensive alloys; thus, increasing the capital cost and maintenance cost of the CSP plant.A corrosion control system in MgNaK chloride salts using active metals such as Mg has been demonstrated under laboratory conditions. This mitigation strategy involves controlling the corrosive impurities, such as MgOHCl, by using liquid Mg. The elemental Mg scavenges oxygen and water derived impurities and provides redox reaction control by shifting the electrochemical potential of the alloys towards cathodic protection while Mg acts as the sacrificial oxidant. However, employment of Mg is challenged in the cold temperature section of the CSP plant (400 – 550 ℃) due to its slow dissolution kinetics in the solid state (melting point of 650 ℃).Here, we propose an electrochemical approach using bulk Mg anodes and W cathodes to provide corrosion control. We used electrolysis to enhance dissolution kinetics of solid Mg to the molten salt at temperatures relevant to the cold section of the CSP plant (500 ℃). Our data suggests electrolysis of Mg effectively enhances the rates of removal of corrosive impurities from molten chloride salts. Preliminary results indicate significant opportunity for the electrochemical process to be scaled up commercially. The novel approach eliminates impurities in-situ from oxygen and moisture ingress in the CSP plant, in turn reducing corrosion rates and therefore reducing capital and maintenance cost of the CSP plant.

Time-of-Use feature based clustering of spatiotemporal wind power profiles

The global drive towards a sustainable energy future is giving rise to rapidly increasing penetration of variable renewable energy into modern power grids. This creates a need for the assessment, characterization and classification of renewable energy resources in the context of the operational challenges posed by large-scale grid integration of renewable energy. This investigation explores a methodology for classifying wind energy resources, using feature vectors defined in terms of the statistical properties of the wind resource for Time-of-Use energy demand periods. Results are presented for the geographic areas associated with the South African Renewable Energy Development Zones, using a mesoscale wind atlas dataset as the resource input. The cluster formations obtained with the Time-of-Use feature vector approach are compared with results obtained by clustering the temporal power profiles using the k-means algorithm. It is shown that cluster formations obtained with the respective inputs exhibit distinct differences, especially with reference to the spatial granularity and geographical dispersion of the clusters. It is concluded that the proposed Time-of-Use feature vector approach offers advantages for application as a classification and data partitioning methodology for spatiotemporal wind profiles.

Grid integration of renewable energy in Qatar: Potentials and limitations

This study presents an analysis of the current electricity supply grid in Qatar and investigates the potential of integrating various renewable energy sources (RES) into the grid. The hourly demand profile for electricity, cooling, and freshwater is used to investigate the impact of wind turbines, photovoltaics, and concentrated solar power integration on the environmental emissions and total annual cost of the systems. A one-year dynamic analysis based on an hourly time step is conducted using the EnergyPLAN tool. The results show that large-scale installations of renewable energy technologies can decrease the emission rate from electricity production at a relatively lower cost. A reference case scenario representing the current state of affairs along with six other cases representing various single and hybrid renewable energy combinations for integration into the electricity supply is presented in terms of their ability to avoid excess electricity production. The eighth case scenario presents a hypothetical electricity demand for the year 2025. The results show that increasing the share of RES in electricity production is possible by as much as 80%. The optimum cases for the deployment of wind, photovoltaic (PV), and concentrated solar power (CSP) with storage technologies presented a 28.3%, 23.4%, and 38.2% share to electricity produced, respectively. The market economic simulation shows that the total annual cost for some of the scenarios that integrated renewable energy was lower than that of the reference case currently deployed in the country.

On Converter Topology, Control, and Modeling [About This Issue

Power electronic converters are the new workhorses of the upcoming age. Converters are ubiquitous in electric vehicles (EVs), electric ships, aircraft, railways, solar photovoltaics (PVs), batteries, and wind farms. In this issue of IEEE Electrification Magazine, we present seven feature articles on converter topology, control, and modeling, along with “Technology Leaders” and “Viewpoint” columns. The converters discussed in this issue include dc-dc converters used in transportation electrification, ac-dc converters used in EV chargers, and dc-ac converters used in renewable energy grid integration. Converters used in various applications aim for different functionalities; thus, they vary in topology and control methods. This issue offers a picture of two types of applications (EVs and grid integration) and their respective challenges in circuit design, control, and modeling

Synthesis, Characterization and Electrochemical Evaluation of Layered Vanadium Phosphates as Cathode Material for Aqueous Rechargeable Zn-ion Batteries

The potential application of rechargeable multivalent ion batteries in portable devices and renewable energy grid integration have gained substantial research interest in aqueous Zn-ion batteries (ZIBs). Compared to Li-based batteries, ZIBs offer lower costs, higher energy density, and safety that make them more attractive for energy storage in grid integration applications. Currently, more research is required to find a suitable cathode material for ZIBs with high capacity and structural stability during charge/discharge cycling. Vanadium phosphate (VOP) compounds as cathode material for ZIBs have been of particular interest, owing to vanadium’s diverse oxidation states. In this present work, two VOP compounds, [H0.6(VO)3(PO4)3(H2O)3].4H2O and VOPO4.2H2O, were synthesized from phosphoric acid and different sources of vanadium via a simple hydrothermal method. Various characterization techniques were carried out, revealing the layered structure of both products and high purity of [H0.6(VO)3(PO4)3(H2O)3].4H2O. Zn/VOP batteries were prepared using Zn metal as counter and reference electrode and 3 M ZnSO4.7H2O as electrolyte. Electrochemical tests were conducted to evaluate the cycling performance of VOPs as cathode material for aqueous Zn-ion batteries. Based on the results, both compounds have shown highly reversible Zn-ion intercalation and deintercalation. VOPO4.2H2O achieved a higher specific capacity of up to 85 mAh/g during discharging, as opposed to 65 mAh/g for the hydrated VOP complex. However, [H0.6(VO)3(PO4)3(H2O)3].4H2O is more stable with higher reproducibility than VOPO4.2H2O during cycling. Nevertheless, more research is still required to enhance the specific capacity and improve the cycling performance of VOP-based cathodes for their prospective use in aqueous ZIBs.

Multilevel Converter Applications in the Area of Renewable Energy, More-Electric Propulsion, Electric Vehicles and Power Grid Integration

The papers in this special section focus on Multilevel converter applications in the area of renewable energy, electric propulsion, electric vehicles and power grid integration. Today, power electronics converters have shifted into a decisive part of our ways of living, noticeably for the profitable utilization of renewable energy sources (RESs). Electric network grid, even standalone type, “more-electric” propulsion, electric vehicles, space applications, military, medical, process/heavy industries, etc., are all affected by converters. In the last few years, we have seen a rising demand for the grid-connected multilevel converter (MC) structures, precisely with RES integration.

The curtailment paradox in the transition to high solar power systems

Summary Rising penetrations of variable renewable energy (VRE) in power systems are expected to increase the curtailment of these resources because of oversupply and operational constraints. We evaluate the effect on curtailment from various flexibility approaches, including storage, thermal generator flexibility, operating reserve eligibility rules, transmission constraints, and temporal resolution, by using a highly resolved realistic system. Results reveal two aspects of a curtailment paradox as the system evolves to higher solar penetration levels. First, thermal generator parameters, especially in restricting minimum operating levels and ramp rates, affect VRE curtailment more in mid-PV penetration levels (∼25%–40%) but much less at lower (∼20%) or higher (∼45%) PV penetration levels. Second, although allowing VRE and storage to provide operating reserve results in significant operating costs and curtailment benefits, the price suppression effect from these resources reduces incentives for PV to provide operating reserves with curtailed energy.

Simulation of a microgrid for a non-interconnected zone that integrates renewable energies

This paper develops a simulation of a small electrical network (Microgid) that integrates renewable energies, the model of the micro network is made up of a solar energy source, a wind energy source, an energy storage element, a non-renewable source such as a diesel generator. The model of the microgrid represent a non-interconnected area from the electrical network in Colombia. The non-interconnected areas sometimes depend on unreliable connections to the grid integration of renewable energies could be the best option to guarantee energy in these sectors and allow generating projects with social impact. A possible solution to this deficit of energy is to supplement the production of energy with renewable energy plants from resources as sun or wind. The simulated model allowed to study the effects of the network in island mode and in interconnected mode, showing the imbalances that can be obtained by integrating renewable energies and storage systems. It is verified that with an inclusion of more than 30% of power in renewable energies there is the possibility of having load imbalances, which affect the frequency and cause instability in the network. It also verifies how a control system can regulate the load balance but must interact with the other energy sources.

Research on new transmission network planning considering adjustable comprehensive resources

With the large-scale renewable energy grid integration, the problems of traditional transmission network planning methods, such as high investment, low utilization rate and difficulty in implementation, have gradually emerged. Therefore, in order to improve the level of new energy consumption, effectively improve the operation efficiency of power grid and optimize the investment benefit, this paper proposes a new mode of power grid planning based on adjustable integrated resources. This paper focuses on two key planning methods: new energy confidence capacity assessment methods and load forecasting methods considering demand side resources.Then the paper takes a city-level 220 KV power grid as an example, applies a new power grid planning method to carry out planning, and verifies the effectiveness of the proposed planning model and method.

A New High Voltage Gain DC to DC Converter with Low Voltage Stress for Energy Storage System Application

Increasing energy demand globally has led to exploring ways of utilizing renewable resources for sustainable development. More recently, the integration of renewable distributed resources in small- and large-scale grid has been seriously researched. Development in renewable power sources and its integration with the grid require voltage level conversion to match the grid/micro-grid level. The voltage level conversion is brought about by employing Direct Current-Direct Current (DC-DC) converters with boosting features. The paper presents a wide gain range DC-DC boost converter with a low-stress on switching devices. The proposed converter’s voltage gain is high compared with the conventional quadratic boost converter and other recently developed high gain boost converters. The topology has been compared with recently proposed topologies, and comparative analysis based on various performance parameters has shown that the topology is suitable for renewable and sustainable energy storage and grid integration. The power loss analysis has been done by incorporating the switching and conduction losses. A hardware prototype of 150 W has been developed to validate the converter’s performance in steady-state as well as in dynamic conditions.