An Approach for Cost-Efficient Grid Integration of Distributed Renewable Energy Sources

We describe a specific approach to capacity man a ge ment for distribution grids. Based on simulations, it has been found that by curtailing a maximum of 5% of the yearly energy production on a per-generator basis, distribution grid connection capacity can be doubled. We also present the setting and fi rst results of a fi eld test for validating the approach in a rural distribution grid in northern Germany.

Economic Factors in the Use of Renewable Energy Sources in Kazakhstan

The purpose of this research was to study economic incentives to use renewable energy sources in the Republic of Kazakhstan and to give suggestions for production and circulation of the ＂green＂ certificates as a new financial instrument. The author analyzed European Union and Kazakhstani experience of economic incentives to reduce emissions and introduction of renewable energy sources. As a result of conducted research, the proposal to produce and circulate new financial instruments in Kazakhstan is made; as well as economic and environmental factors of renewable energy sources in the Republic of Kazakhstan are defined.

Cost Optimization Modeling of Renewable Energy Sources in Smart-Grid Using SCADA

In recent times, renewable energy production from renewable energy sources is an alternative way to fulfill the increased energy demands. However, the increasing energy demand rate places more pressure, leading to the termination of conventional energy resources. However, the cost of power generation from coal-fired plants is higher than the power generation’s price from renewable energy sources. This experiment is focused on cost optimization during power generation through pumped storage power plant and wind power plant. The entire modeling of cost optimization has been conducted in two parts. The mathematical modeling was done using MATLAB simulation while the hydro and wind power plant’s emulation was performed using SCADA (Supervisory control and data acquisition) designer implementation. The experiment was conducted using ranges of generated power from both power sources. The optimum combination of output power and cost from both generators is determined via MATLAB simulation within the assumed generated output power range. Secondly, the hydro-generator and wind generator’s emulation were executed individually through synchronizing the grid to determine each generator’s specification using SCADA designer, which provided the optimum power generation from both generators with the specific speed, aligning with results generated through MATLAB. Finally, the operational power cost (with no losses consideration) from MATLAB was compared with the local energy provider to determine the cost-efficiency. This experiment has provided the operational cost optimization of the hydro-wind combined power system with stable wind power generation using SCADA, which will ultimately assist in operations of large-scale power systems, remotely minimizing multi-area dynamic issues while maximizing the system efficiency.

Renewable Energy Sources A Promising Opportunity for Remote Mine Sites

Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, secure and environment friendly energy sources becomes a key concern. At present, a great majority of remote mines relies heavily on diesel fuel that has to be transported over long distances. In this context, some of the renewable energy sources such as wind power or solar energy seem to provide potentially interesting and viable alternatives. Mine operations, however, have a very particular character, much different from other industries and from other potential applications of renewable power sources. This paper presents operational conditions of some mining operations, particularly those in remote regions, in the context of their energy needs. The authors analyse current and future capacities to decrease a reliance of remote mines on conventional fuels and energy. The paper also analyses and discusses the conditions to be met by alternative energy sources so that they might become a viable alternative for remote mining operations.

An Optimization Approach for Unit Commitment of a Power System Integrated with Renewable Energy Sources： A Case Study of Afghanistan

This paper focused on generation scheduling problem with consideration of wind, solar and PHES （pumped hydro energy storage） system. Wind, solar and PHES are being considered in the NEPS （northeast power system） of Afghanistan to schedule all units power output so as to minimize the total operation cost of thermal units plus aggregate imported power tariffs during the scheduling horizon, subject to the system and unit operation constraints. Apart from determining the optimal output power of each unit, this research also involves in deciding the on/off status of thermal units. In order to find the optimal values of the variables, GA （genetic algorithm） is proposed. The algorithm performs efficiently in various sized thermal power system with equivalent wind, solar and PHES and can produce a high-quality solution. Simulation results reveal that with wind, solar and PHES the system is the most-cost effective than the other combinations.

Accelerated Particle Swarm Optimization for Controlling Virtual Power Plant Consisting of Renewable Energy Sources

RES （renewable energy sources）, such as wind and photovoltaic power plants, suffer from their stochastic nature that is why their behavior on market is very delicate. In order to diversify risk, a concept of VPP （virtual power plant） has been developed. The VPP is composed of several RES, from which at least one of them is fully controllable. Because the production of noncontrollable RES can not be forecasted perfectly, therefore an optimal dispatch schedule within VPP is needed. To address this problem, an APSO （accelerated particle swarm optimization） is used to solve the constrained optimal dispatch problem within VPP. The experimental results show that the proposed optimization method provides high quality solutions while meeting constraints.

Exact Box-Constrained Economic Operating Region for Power Grids Considering Renewable Energy Sources

The growing integration of renewable energy sources manifests as an effective strategy for reducing carbon emissions. This paper strives to efficiently approximate the set of optimal scheduling plans(OSPs) to enhance the performance of the steady-state adaptive cruise method(SACM) of power grid, improving the ability of dealing with operational uncertainties. Initially, we provide a mathematical definition of the exact boxconstrained economic operating region(EBC-EOR) for the power grid and its dispatchable components. Following this, we introduce an EBC-EOR formulation algorithm and the corresponding bi-level optimization models designed to explore the economic operating boundaries. In addition, we propose an enhanced big-M method to expedite the computation of the EBCEOR. Finally, the effectiveness of the EBC-EOR formulation, its economic attributes, correlation with the scheduling plan underpinned by model predictive control, and the significant improvement in computational efficiency(over twelvefold) are verified through case studies conducted on two test systems..

Enhancing Renewable Energy Integration:A Gaussian-Bare-Bones Levy Cheetah Optimization Approach to Optimal Power Flow in Electrical Networks

In the contemporary era,the global expansion of electrical grids is propelled by various renewable energy sources(RESs).Efficient integration of stochastic RESs and optimal power flow(OPF)management are critical for network optimization.This study introduces an innovative solution,the Gaussian Bare-Bones Levy Cheetah Optimizer(GBBLCO),addressing OPF challenges in power generation systems with stochastic RESs.The primary objective is to minimize the total operating costs of RESs,considering four functions:overall operating costs,voltage deviation management,emissions reduction,voltage stability index(VSI)and power loss mitigation.Additionally,a carbon tax is included in the objective function to reduce carbon emissions.Thorough scrutiny,using modified IEEE 30-bus and IEEE 118-bus systems,validates GBBLCO’s superior performance in achieving optimal solutions.Simulation results demonstrate GBBLCO’s efficacy in six optimization scenarios:total cost with valve point effects,total cost with emission and carbon tax,total cost with prohibited operating zones,active power loss optimization,voltage deviation optimization and enhancing voltage stability index(VSI).GBBLCO outperforms conventional techniques in each scenario,showcasing rapid convergence and superior solution quality.Notably,GBBLCO navigates complexities introduced by valve point effects,adapts to environmental constraints,optimizes costs while considering prohibited operating zones,minimizes active power losses,and optimizes voltage deviation by enhancing the voltage stability index(VSI)effectively.This research significantly contributes to advancing OPF,emphasizing GBBLCO’s improved global search capabilities and ability to address challenges related to local minima.GBBLCO emerges as a versatile and robust optimization tool for diverse challenges in power systems,offering a promising solution for the evolving needs of renewable energy-integrated power grids.

Optimal Pricing Strategy for Data Center Considering Demand Response and Renewable Energy Source Accommodation

With the continuous development of information technology,data centers(DCs)consume significant and evergrowing amounts of electrical energy.Renewable energy sources(RESs)can act as clean solutions to meet this requirement without polluting the environment.Each DC serves numerous users for their data service demands,which are regarded as flexible loads.In this paper,the willingness to pay and time sensitivities of DC users are firstly explored,and the user-side demand response is then devised to improve the overall benefits of DC operation.Then,a Stackelberg game between a DC and its users is proposed.The upper-level model aims to maximize the profit of the DC,in which the time-varying pricing of data services is optimized,and the lower-level model addresses user’s optimal decisions for using data services while balancing their time and cost requirements.The original bi-level optimization problem is then transformed into a single-level problem using the Karush-Kuhn-Tucker optimality conditions and strong duality theory,which enables the problem to be solved efficiently.Finally,case studies are conducted to demonstrate the feasibility and effectiveness of the proposed method,as well as the effects of the time-varying data service price mechanism on the RES accommodation.

Frequency-based control of islanded microgrid with renewable energy sources and energy storage

When a microgrid is mainly supplied by renewable energy sources(RESs), the frequency deviations may deteriorate significantly the power quality delivered to the loads. This paper proposes a frequency-based control strategy, ensuring the frequency among the strict limits imposed by the Standard EN 50160. The frequency of the microgrid common AC bus is determined by the energy storage converter, implementing a proposed droop curve among the state of charge(SoC) of the battery and the frequency. Therefore, the information of the SoC becomes known to every distributed energy resource(DER) of the microgrid and determines the active power injection of the converter-interfaced DERs. The active power injection of the rotating generators remains unaffected, while any mismatch among the power generation and consumption is absorbed by the energy storage system. Finally, in case of a solid short-circuit within the microgrid, the energy storage system detects the severe voltage decrease and injects a large current in order to clear the fault by activating the protection device closer to the fault. The proposed control methodology is applied in a microgrid with PVs, wind generators and a battery, while its effectiveness is evaluated by detailed simulation tests.

KPI-based Real-time Situational Awareness for Power Systems with a High Proportion of Renewable Energy Sources

With the increasing complexity of power systems and the widespread penetration of renewable energy sources(RES),real-time situational awareness for power systems is of great significance for operational scheduling.Considering the impact of RES on power system operations,a situational awareness key performance index(KPI)system for power systems with a high proportion of RES is proposed in this paper,which consists of reserve capacity abundance,ramp resource abundance,center of inertia(COI)frequency deviation,interface power flow margin,synthesized voltage stability,and angle stability margin.Then,the KPIs are synthesized and visualized by the decision tree method and radar chart method,respectively,for monitoring the operation states(i.e,normal,alert,and emergency states)of power systems with a high proportion of RES.Numerical simulations are conducted in a revised New England 16-machine 68-bus power system and an actual CEPRI-RE power system in the northwest region of China with a high proportion of RES.The results show that the proposed KPI-based situational awareness method is able to accurately monitor the real-time state of power systems with a high proportion of RES,and can assist power dispatchers to make effective decisions.

Energy management of micro renewable energy source and electric vehicles at home level

As renewable energy source(RES)tend to be integrated more and more at home and electric vehicles(EVs)take a greater share in the personal automobile market,users see a chance to charge their EVs by microRES.In this context,this paper presents a review about opportunities and challenges needed to be overcome by the EV users to implement a vehicle to home system in their homes,as well as the integration of micro-RES.Several practical scenarios are presented,with different demand profiles,by integrating renewable energy that could be used to charge the EV.

Controlled Islanding Strategy Considering Uncertainty of Renewable Energy Sources Based on Chance-constrained Model

Controlled islanding plays an essential role in preventing the blackout of power systems.Although there are several studies on this topic in the past,no enough attention is paid to the uncertainty brought by renewable energy sources(RESs)that may cause unpredictable unbalanced power and the observabilit>T of power systems after islanding that is essential for back-up black-start measures.Therefore,a novel controlled islanding model based on mixed-integer second-order cone and chance-constrained programming(MISOCCP)is proposed to address these issues.First,the uncertainty of RESs is characterized by their possibility distribution models with chance constraints,and the requirements,e.g.,system observability,for rapid back-up black-start measures are also considered.Then,a law of large numbers(LLN)based method is em-ployed for converting the chance constraints into deterministic ones and reformulating the non-convex model into convex one.Finally,case studies on the revised IEEE 39-bus and 118-bus power systems as well as the comparisons among different models are given to demonstrate the effectiveness of the proposed model.The results show that the proposed model can result in less unbalanced power and better observability after islanding compared with other models.

Adaptive coordination control strategy of renewable energy sources,hydrogen production unit,and fuel celi for frequency regulation of a hybrid distributed power system

Owing to the significant number of hybrid generation systems(HGSs)containing various energy sources,coordina-tion between these sources plays a vital role in preserving frequency stability.In this paper,an adaptive coordination control strategy for renewable energy sources(RESs),an aqua electrolyzer(AE)for hydrogen production,and a fuel cell(FC)-based energy storage system(ESS)is proposed to enhance the frequency stability of an HGS.In the proposed system,the excess energy from RESs is used to power electrolysis via an AE for hydrogen energy storage in FCs.The proposed method is based on a proportional-integral(Pl)controller,which is optimally designed using a grey wolf optimization(GWO)algorithm to estimate the surplus energy from RESs(ie,a proportion of total power generation of RESs:Kn).The studied HGS contains various types of generation systems including a diesel generator,wind tur-bines,photovoltaic(PV)systems,AE with FCs,and ESSs(e.g.,battery and flywheel).The proposed method varies Kn with varying frequency deviation values to obtain the best benefits from RESs,while damping the frequency fluc-tuations.The proposed method is validated by considering different loading conditions and comparing with other existing studies that consider Kn as a constant value.The simulation results demonstrate that the proposed method,which changes Kn value and subsequently stores the power extracted from the RESs in hydrogen energy storage according to frequency deviation changes,performs better than those that use constant Kn.The statistical analysis for frequency deviation of HGS with the proposed method has the best values and achieves large improvements for minimum,maximum,difference between maximum and minimum,mean,and standard deviation compared to the existing method.

Review on Renewable Energy Source Fault Characteristics Analysis

The increase of renewable energy sources(RESs),especially wind power and photovoltaic,is bringing different fault features to the power system compared with the traditional syn-chronous generator,resulting in the urgent need for precise fault analysis.According to the sequentially activated fault features,the short circuit characteristics of RES can be divided into three fault stages.Within the staged framework of fault duration,the published research is reviewed to provide a systematic analysis of RES fault characteristics.It's concluded that the hardware parameter determines the sub-transient fault features of RES,whereas RES control begins to dominate during the following transient stage.However,the neglection of voltage transition and unavailable RES output phase shall impede the application of the analytical conclusions in protection design.To solve the existing problems,interaction among RES and networks must be figured out.Therefore,the fault calculation of the integral RES-grid system is offered as the research prospect.

Renewable Energy Seawater Desalination Technology and Application Analysis

This paper proposed a new technology way for seawater desalination which used renewable energy(wind energy and solar energy).The effects of practical application showed that remote islands and cage culture zones in the bay that lack electricity and water are very suitable for using small seawater desalination devices that do not require consumption of conventional energy.

Scenario Generations for Renewable Energy Sources and Loads Based on Implicit Maximum Likelihood Estimations

Scenario generations for renewable energy sources and loads play an important role in the stable operation and risk assessment of integrated energy systems.This paper proposes a deep generative network based method to model time-series curves,e.g.,power generation curves and load curves,of renewable energy sources and loads based on implicit maximum likelihood estimations(IMLEs),which can generate realistic scenarios with similar patterns as real ones.After training the model,any number of new scenarios can be obtained by simply inputting Gaussian noises into the data generator of IMLEs.The proposed approach does not require any model assumptions or prior knowledge of the form in the likelihood function being made during the training process,which leads to stronger applicability than explicit density model based methods.The extensive experiments show that the IMLEs accurately capture the complex shapes,frequency-domain characteristics,probability distributions,and correlations of renewable energy sources and loads.Moreover,the proposed approach can be easily generalized to scenario generation tasks of various renewable energy sources and loads by fine-tuning parameters and structures.

Deployment of wireless sensor network in dispersed renewable energy sources for increasing efficiency of power distribution networks

In this work,a novel performance analysis method for evaluating the robustness of emerging power distribution networks(PDNs),which involve deployable renewable energy sources,is proposed.This is realized with the aid of the outage probability(OP)criterion in the context of cooperative communications,which is widely considered in modern wireless communication systems.The main usefulness of this method is that it allows the involved components to communicate to each-other by means of a robust and flexible wireless sensor network architecture.In this context,any conventional medium voltage(MV)bus of the PDN is represented as a wireless relay node where data signals gathered from each MV bus can be forwarded reliably to a control station for the subsequent processing.The received signals at wireless nodes are decoded and then forwarded to ensure minimal errors and maximal robustness at the receiving site.The considered OP analysis denotes the probability that the power of a received information signal drops below a pre-defined threshold which satisfies the acceptable Quality of Service requirements of a reliable signal reception.To this end,simple closed-form expressions are proposed for the OP of a regenerative cooperative-based PDN in the presence of various multipath fading effects,which degrade information signals during wireless transmission.The offered results are rather simple and provide meaningful insights for the design and deployment of smart grid systems.

Real prospects for the development of power technologies based on renewable energy sources in Poland

In Poland more than 40% of the power units have been operating for over 40 years now and more than 10% are over 50 years old, which indicates a high degree of decrease in the value of the energy sector. An analysis of the energy market shows that every year a new power plant should be built with a capacity of 1000 MW to ensure the national energy security. An energy market research indicates that in Poland the structure of energy production is changing in recent years-the share of fossil (solid) fuels in electricity and heat production was approximately 88% in 2009, while in 2004 it reached 93%. According to the analysis of the market, it can be seen that conventional energy, mainly based on coal and lignite, has been the most important segment of the sector for a long time. In this paper the prospects for the development of power technologies based on renewable energy sources (RES) in Poland are presented.

Energy Storage Systems Technologies, Evolution and Applications

Energy in its varied forms and applications has become the main driver of today’s modern society. However, recent changes in power demand and climatic changes (decarbonization policy) has awakened the need to rethink through the current energy generating and distribution system. This led to the exploration of other energy sources of which renewable energy (like thermal, solar and wind energy) is fast becoming an integral part of most energy system. However, this innovative and promising energy source is highly unreliable in maintaining a constant peak power that matches demand. Energy storage systems have thus been highlighted as a solution in managing such imbalances and maintaining the stability of supply. Energy storage technologies absorb and store energy, and release it on demand. This includes gravitational potential energy (pumped hydroelectric), chemical energy (batteries), kinetic energy (flywheels or compressed air), and energy in the form of electrical (capacitors) and magnetic fields. This paper provides a detailed and comprehensive overview of some of the state-of-the-art energy storage technologies, its evolution, classification, and comparison along with various area of applications. Also highlighted in this paper is a plethora of power electronic Interface technologies that plays a significant role in enabling optimum performance and utilization of energy storage systems in different areas of application.