Renewable Energy Power System Research Articles

Design and implementation of an intelligent multi-input multi-output Sugeno fuzzy logic controller for managing energy resources in a hybrid renewable energy power system based on Arduino boards

Design and implementation of an intelligent multi-input multi-output Sugeno fuzzy logic controller for managing energy resources in a hybrid renewable energy power system based on Arduino boards

Modeling State Transition and Head-Dependent Efficiency Curve for Pumped Storage Hydro in Look-Ahead Dispatch

As one of the most widely installed utility-scale storage facilities, pumped storage hydro (PSH) plays an essential role in providing flexibility for power systems worldwide. Thus, to accurately quantify the flexibility of PSH units in operational optimization problems is important. The conventional PSH models in the literature rarely consider detailed state transitions due to their hourly-based settings. However, it becomes imperative for operational optimization on short-term intervals, especially with increasing shares of renewable energy in power systems. To this end, this paper presents a novel deterministic PSH model that considers the transition time and trajectory between three states of PSH units in look-ahead dispatch. Moreover, to better characterize the varying efficiency of PSH units with water head and flow rate, this paper proposes to model detailed head-dependent efficiency curves (hereafter called input-output curves) in look-ahead dispatch, which encounters heavy computational burdens when short time intervals are applied. In this work, a zig-zag piece-wise linear approximation method is used for input-output curve modeling. This can enable an accurate quantification for variable efficiency and head dependence in a computationally effective manner. Numerical results are presented to show performances of the proposed PSH model in both flexibility quantification and computation time.

Multiobjective Scheduling of Hybrid Renewable Energy System Using Equilibrium Optimization

Due to increasing concern over global warming, the penetration of renewable energy in power systems is increasing day by day. Gencos that traditionally focused only on maximizing their profit in the competitive market are now also focusing on operation with the minimum pollution level. The paper proposes a multiobjective model capable of finding a set of trade-off solutions for the joint optimization problem, considering the cost of reserve and curtailment of power from renewable sources. Managing a hybrid power system is a challenging task due to its stochastic nature mixed with the objective function and complex practical constraints associated with it. A novel metaheuristic Equilibrium Optimizer (EO) algorithm incepted in the year 2020 utilizes the concept of control volume and mass balance for finding equilibrium state is proposed here for computing the optimal schedule and impact of renewable energy integration on profit and emission for different optimization objectives. In this paper, EO has shown dominant performance over well-established metaheuristic algorithms such as particle swarm optimizer (PSO) and artificial bee colony (ABC). In addition, EO produces well-distributed Pareto-optimal solutions and the fuzzy min-ranking is used as a decision maker to acquire the best compromise solution.

Enhanced TVI for Grid Forming VSC under Unbalanced Faults

With an increasing capacity of inverter-based generation and with a 100% renewable energy power system on the horizon, grid forming converters have the potential to become the prevalent control mode in the grid. Thus, the correct performance of these devices is going to be crucial for system stability and security of supply. Most research related to the grid-forming control is focused on normal operating conditions, although significant effort has been devoted to current limitation strategies to ensure Low Voltage Ride Through (LVRT) capability. However, most contributions usually consider only balanced faults. This paper, proposes a new current limiting method based on the well-known threshold virtual impedance (TVI) that keeps the voltage source behaviour associated to the grid forming (GFM) capability, even when the current limit is reached, while reducing the voltage unbalance according to user-defined settings.

Capacity expansion planning for wind power and energy storage considering hourly robust transmission constrained unit commitment

The installed capacity of renewable energy in power systems is rising rapidly in recent years due to environmental pressure. And as the main asset of mitigating renewable output fluctuations, energy storage (ES) also has been greatly developed with the increase of renewable capacity. To this end, the capacity planning of renewables and ESs has drawn much attention and many methods have been proposed. In the formulations of capacity planning problems, more detailed and complicated operation constraints mean more accurate planning results, which is the consensus of many researchers. However, to guarantee the problem formulation tractable, the actual multistage operation process of power system is not properly considered in existing planning methods. Therefore, in this paper, a new capacity expansion planning method for wind power and ESs is proposed considering the actual multistage operation process of power system. Specially, the hourly robust transmission constrained unit commitment (TCUC) and economic dispatch (ED) are involved in this planning method and thus, it could accurately evaluate the operational cost under certain planning decision. Besides, to guarantee the solvability and computational efficiency of planning method, a parallel horizon-splitting method is improved to solve the long-time-horizon hourly robust TCUC problem, and a genetic algorithm nested gradient descent method is established to accelerate the solving of planning problem. With the actual multistage operation process, a more reasonable expansion planning decision is obtained and the computational efficiency is greatly improved by the proposed acceleration algorithm. Numerical tests verify the efficacy of proposed method.

Expansion Planning of Renewable Energy Power System Considering Flexibility and Economy

Expansion Planning of Renewable Energy Power System Considering Flexibility and Economy

Performance of Hybrid Renewable Energy Power System for a Residential Building

Abstract Using fossil fuels as the primary way to generate electricity causes a significant effect on the environment. In 2019, more than 64% of the electricity in the United States of America was generated using fossil-fuel resources, while renewable energy (RE) resources contributed to only 17% of the U.S. electricity generation for the same year. Due to the complex terrain distribution of many states in the U.S., a massive opportunity of utilizing RE resources in rural and remote areas can reduce the cost of electrical grid installation for such areas. In this study, a typical residential building with an average energy utilization of 30.25 kWh/day with a demand peak of 5.34 kW was considered a case study in each state to optimize a hybrid RE system and find the best alternative electrical grid system. This study presents the best configuration between solar and wind energy with different types of energy storage. It was discovered the photovoltaic (PV) solar panels—diesel generators with battery best services in all states. The daily radiation and diesel prices substantially affect the levelized cost of energy (COE) values in each state.

Optimal Combination Control Technology of Demand Side Resources of Distributed Renewable Energy Power Generation

The paper proposes a new unit commitment model that can promote car-bon emission reduction in distributed renewable energy power systems. Themodel first comprehensively considers the optimal combination of low-carbon demand-side resources such as supply-side resources and demandresponse, electric vehicles, and distributed renewable energy power gener-ation. Secondly, the model unit scheduling rules fully consider the carbonemission target and the economic target and propose a fuzzy dual-objectiveoptimization method that can consider the relative priority of the target. Whensolving the optimization model, we improved the particle swarm optimizationalgorithm. We introduced the “cross” and “mutation” operators in the geneticalgorithm to improve the particle swarm algorithm’s global optimizationcapability. The paper verifies the effectiveness of the model and algorithmthrough the analysis of a ten computer system.

Quantifying the challenge of reaching a 100% renewable energy power system for the United States

Quantifying the challenge of reaching a 100% renewable energy power system for the United States

Book Reviews [7 books reviewed

The following seven books are reviewed: Handbook of Large Hydro Generators: Operation and Maintenance (Mottershead, G., et al; 2021); Heat Transfer—Principles and Applications (Forsberg, C.H.; 2021); Renewable Energy in Power Systems (Infield, D. and Freris, L.; 2020); Noise in Radio-Frequency Electronics and Its Measurement (Fouquet, F.; 2020); Polymers in Organic Electronics (Khalifeh, S.; 2020); Transient Analysis of Power Systems (Martinez-Velasco, J.A., ed.; 2020); and Lens Design Basics—Optical Design Problem-Solving in Theory and Practice (Gerhard, C.; 2020).

Matching renewable energy and conservation targets for a sustainable future

Renewable energy facilitates emission reductions, but its deployment also presents challenges. Recently in <i>Joule</i>, Cole et al. examined barriers to establishing a 100% renewable energy power system in the United States, but land-use-change impacts of renewable energy deployment on biodiversity conservation were unexplored and warrant interdisciplinary investigation.

Analysis on Several Blackouts Caused by Extreme Weather and its Enlightenment

In recent years, blackouts caused by extreme weather show a trend of frequent occurrence. This paper analyses the external causes of blackouts, summarizes the evolution process of blackouts, discusses the internal causes of blackouts in power system, analyses the challenges faced by power system under the superposition of extreme weather and renewable energy, and finally puts forward some suggestions for the planning of high proportion renewable energy power system.

Study on the flexibility enhancement of China’s power system with renewable energy

At present, China’s renewable energy utilization scale has ranked first in the world. By the end of 2019, China’s cumulative installed capacity of solar power had reached 204.3 million kW, and that of wind power had reached 210 million kW. Some parts of China already have a high proportion of renewable energy power systems. However, the lack of flexibility in China’s power system has become a constraint to the development of renewable energy. This paper analyzes the current situation of the flexibility of China’s power system and the problems facing the development of high proportion of renewable energy. It is proposed that the flexibility of China’s power system should be improved by retrofitting the existing coal power system, controlling the scale of newly installed coal power plant, establishing the demand side resource utilization system, planning the energy storage application of the power system, and implementing the reform of the power market.

Series Loss-Free Resistor: Analysis, Realization, and Applications

An analysis of the transient behavior of dc networks consisting of voltage sources, capacitors, and series loss-free resistors (SLFRs) is presented. The realization of an SLFR was achieved by means of a topological variation of the positive output voltage buck-boost converter operated in discontinuous-conduction mode. It is demonstrated that even simple RC circuits containing SLFRs exhibit behavior that is described by Abel nonlinear differential equations, which do not have an exact analytical solution. Some possible applications of the SLFRs in power electronics, dc microgrids, and renewable energy power systems include loss-free charge and discharge of capacitor banks, voltage equalization of capacitors, and loss-free voltage clamping circuits. The concept of the SLFR can also be applied for voltage control in dc microgrids, employing the droop voltage technique, equalization of power and current in voltage sources associated in parallel (including batteries and dc-dc converters), and also input and output voltage natural balance in input-series output-series association of dc converters. The theoretical analysis results are validated via numerical examples and computer simulation.

A Voltage Control Strategy of VSG Based on Self-Adaptive Inertia Coefficient and Droop Coefficient

With the increasing penetration rate of distributed renewable energy in power systems, the control strategy of virtual synchronous generator (VSG) is widely used for several years. Some existing VSG control strategies have been able to solve the stability problems caused by the abnormal grid voltage, but the effects of the inertia coefficient and the droop coefficient on the voltage stability are not taken into account. In order to further improve the voltage stability of the microgrid system, a voltage control strategy of VSG based on self-adaptive inertia coefficient and droop coefficient is proposed in this paper. When the voltage is far from the steady state, the increase of the inertia coefficient can decrease the voltage deviation. On the contrary, when it is close to the steady state, the decrease of the inertia coefficient can make the system response speed accelerate. According to the real-time voltage deviation, the droop coefficient can change adaptively to decrease the adjusting time and the voltage deviation during the disturbance. Finally, the simulation model of VSG is built by MATLAB/Simulink for conducting simulation experiments. Compared with other strategies, the correctness and effectiveness of the proposed control strategy are validated.

Modeling and assessment of economic viability of grid-connected photovoltaic system for rural electrification

ABSTRACT Renewable energy resources are an adequate substitute for a conventional power system that can deliver greener, consistent quality power with low network congestion and losses. The output of a renewable energy power system effected by the intermittency of resources. The storage system plays a vital role in overcoming intermittency and provides a reliable and smooth power supply to the demand. In the present work, a grid-connected solar PV with a battery storage system is proposed for the rural population in India’s hilly state. The complete resource assessment of the solar system carried out for the grid-connected mode of operation. The total load of the system shared by PV and battery system investigated. Techno-economic analysis and feasibility study carried for the suggested model. The study indicates that the annual saving of a grid-connected system with storage is $3923394.00, with a net present value is $37433.87. The energy cost reduced to $0.21/kWh compared to $0.30/kWh for standalone operation.

Analysis on Response Characteristics of Two-Level VSC to Disturbances and Its Oscillation Suppression Strategy

To improve the stability of renewable energy power systems, the response characteristics of two-level voltage-source converter (VSC) to disturbances are analyzed, and some suppression strategies for oscillation problems are further proposed in this paper. Based on the balance principle of frequency components, the response characteristics of two-level VSC to its AC-side disturbances are investigated in detail, considering its complete control system. Specially, the coupling effect among disturbances with different frequencies are illustrated by the time-domain phasor and space vector analysis. Subsequently, the impedance model describing the port-characteristics of two-level VSC is established and verified through electro-magnetic transient simulation in PSCAD/EMTDC. On the basis, the conditions about oscillation problems caused by negative-resistance effect are concluded and verified in a two-level VSC test system. Finally, by analyzing the influence of controller parameters on impedance characteristics, the controller parameters adjustment based suppression strategy is proposed and verified. From case studies, it indicates that the oscillation instability is related to the resonance frequency and the negative-resistance effect of two-level VSC, and it could be improved by adjusting controller parameters.

Synchronous measurement technology of source-grid-load in renewable energy power system

In this paper, the technology of synchronous phasor measurement and its application in power system transient stability prediction and control, state estimation and dynamic monitoring, fault location is introduced. The construction method of wide area measurement system based on synchronous phasor measurement technology is puts forwarded. The important role of synchronous phasor measurement technology in these fields and its significance to power system security are analysed.

Economic analysis of distribution network planning considering decentralized energy storage system

The rapid development of renewable energy makes the power grid gradually change from traditional power system to high proportion renewable energy power system. The rapid development of electric vehicles, energy storage and controllable load increases the uncertainty of load. The flexible adjustable load is less, which can not meet the consumption demand of large wind and solar power generation, and can not support the power valley filling demand when the wind power output is insufficient. Energy storage system is very important for the safe and stable operation of renewable energy internet. How to consider the reliability and economy, this paper proposes a distribution network planning scheme considering energy storage system.

Techno-economic sizing of renewable energy power system case study Dhofar Region-Oman

ABSTRACT In this paper, the sizing of an electrical power system for the Dhofar region in the southern of Oman is proposed and discussed through an optimization of the net project cost of different configurations of power sources. Both stand-alone and grid-connected cases are studied and discussed. The generated electrical power from renewable energy sources depends mainly on solar radiations, temperature, and wind speed. The incomes depend on the electrical power produced from renewable energy sources and the initial cost of investment as well as the operation and maintenance cost of renewable energy equipment. The analysis of different cases is performed using HOMER Software. The comparison of different configurations shows that the hybrid grid-connected system is the optimum solution to produce 1046807 kWh of electrical power from renewable energy sources with a minimum net project cost of 186 751 €. The utilization of electrical power from the power grid is the most expensive solution with a net project cost of 5.07 million €. The hybrid photovoltaic wind grid-connected system allows reducing of the cost of energy to 0.0117 € per kWh with an optimum initial investment cost of 386 648 €. The detailed analysis of proposed renewable energy solutions based on accurate informations gives every confidence in its reliability for future energy requirements of Oman. The proposed solutions hold good for this region in Oman in the long term. Indeed, installing renewable energy systems allows reducing electricity bills and participating in the national development plan related to green energy policy.