Electromechanical Transient Modeling Analysis of Large-Scale New Energy Grid Connection

The synchronous virtual machine uses inverter power to imitate the performance of the conventional synchronous machine.It also has the same inertia,damping,frequency,voltage regulation,and other external performance as the generator.It is the key technology to realize new energy grid connections’stable and reliable operation.This project studies a dynamic simulation model of an extensive new energy power system based on the virtual synchronous motor.A new energy storage method is proposed.The mathematical energy storage model is established by combining the fixed rotor model of a synchronous virtual machine with the charge-discharge power,state of charge,operation efficiency,dead zone,and inverter constraint.The rapid conversion of energy storage devices absorbs the excess instantaneous kinetic energy caused by interference.The branch transient of the critical cut set in the system can be confined to a limited area.Thus,the virtual synchronizer’s kinetic and potential energy can be efficiently converted into an instantaneous state.The simulation of power system analysis software package(PSASP)verifies the correctness of the theory and algorithm in this paper.This paper provides a theoretical basis for improving the transient stability of new energy-connected power grids.

Research on the Application of New Energy Photovoltaic Power Generation Technology

With the rapid development of technology and economy,the demand for energy in society is increasing.People are gradually realizing that fossil energy is limited,and the development of new energy may also face situations where it cannot meet social needs.The problem of resource shortage is gradually exposed to people.Therefore,the development of usable new energy has become an urgent problem for society to solve.At present,electricity is the most widely used energy source worldwide and photovoltaic power generation technology is gradually becoming well-known.As an emerging industry,the development of photovoltaic power generation still requires continuous promotion by national and social policies to be extended to various industries and ensure the stability of its energy supply.This article mainly outlines the principles,characteristics,and advantages of photovoltaic power generation,and briefly explains the current technology types and application aspects of photovoltaic power generation to contribute to its promotion and better serve all aspects of social life with new energy.

Application of Power Electronics Converters in Renewable Energy

Against the backdrop of global energy shortages and increasingly severe environmental pollution,renewable energy is gradually becoming a significant direction for future energy development.Power electronics converters,as the core technology for energy conversion and control,play a crucial role in enhancing the efficiency and stability of renewable energy systems.This paper explores the basic principles and functions of power electronics converters and their specific applications in photovoltaic power generation,wind power generation,and energy storage systems.Additionally,it analyzes the current innovations in high-efficiency energy conversion,multilevel conversion technology,and the application of new materials and devices.By studying these technologies,the aim is to promote the widespread application of power electronics converters in renewable energy systems and provide theoretical and technical support for achieving sustainable energy development.

Steady-State Analysis of Grid-Connected New Energy Power Plants

In order to ease the fossil energy crunch,new energy sources need to be fully utilized.Clean energy sources such as wind,light,and nuclear energy are important tools to solve environmental and energy problems.However,in the process of researching new energy farms,there are some problems when they are integrated into the power system.In order to ensure the stability of new energy power plants,it is necessary to conduct an in-depth analysis of the grid connection technology of new energy farms.In the study,it is necessary to learn about the specific problems of the stability of the grid connection of new energy power plants,and to clarify the specific application of the grid connection technology of new energy power plants from the application principle and advantages of the grid connection technology of new energy power plants.Through simulation experiments,the positive effect of grid connection technology of new energy power plants in improving the stability of power systems was determined.

Assessment on Fault Diagnosis and State Evaluation of New Power Grid:AReview

1 Introduction The proposal of the concept of“New Power System”aims to illustrate the transform direction of the traditional power system,acting as the development core of the future new power grid.To achieve this,the proposed strategic targets of“carbon neutralization and carbon peaking”must be implemented and insisted[1].The core feature of the new power system is that renewable energy plays a leading role and becomes the main source of energy supply,meanwhile,the goal of green energy utilization has also been put forward on the agenda.Green energy utilization includes two aspects,one is the exploitation and promotion of various green energy technologies,and the other is the digitalization of energy management.Under this trend,stochastic and fluctuating energy sources such as wind power and photovoltaic power replace deterministic controllable power sources such as thermal power,bringing challenges to power grid regulation and dispatching,as well as flexible operation.The large-scale integration of renewable energy and increasingly high proportion of power electronic equipment tend to bring about fundamental changes in the operation characteristics,safety control,and production mode of the power system.

Difference between grid connections of large-scale wind power and conventional synchronous generation

In China, regions with abundant wind energy resources are generally located at the end of power grids. The power grid architecture in these regions is typically not sufficiently strong, and the energy structure is relatively simple. Thus, connecting large-capacity wind power units complicates the peak load regulation and stable operation of the power grids in these regions. Most wind turbines use power electronic converter technology, which affects the safety and stability of the power grid differently compared with conventional synchronous generators. Furthermore, fluctuations in wind power cause fluctuations in the output of wind farms, making it difficult to create and implement suitable power generation plans for wind farms. The generation technology and grid connection scheme for wind power and conventional thermal power generation differ considerably. Moreover, the active and reactive power control abilities of wind turbines are weaker than those of thermal power units, necessitating additional equipment to control wind turbines. Hence, to address the aforementioned issues with large-scale wind power generation, this study analyzes the differences between the grid connection and collection strategies for wind power bases and thermal power plants. Based on this analysis, the differences in the power control modes of wind power and thermal power are further investigated. Finally, the stability of different control modes is analyzed through simulation. The findings can be beneficial for the planning and development of large-scale wind power generation farms.

Life Cycle Assessment,Estimation and Comparison of Greenhouse Gas Mitigation Potential of New Energy Power Generation in China

From the perspective of life cycle assessment （LCA）, the development, construction, and operation of all kinds of new energy power generation technologies release greenhouse gas （GHG） emissions. This sparks concerns about the lowcarbon nature of the new energy power generation technologies. Based on national and international literature review, this paper estimates and compares the GHG emission factors of traditional thermal power generation and new energy power generation technologies in China with the LCA approach. The GHG mitigation potential of new energy power generation technologies as substitution for traditional thermal power generation in China was evaluated, according to the objectives of new energy power generation of the national development planning. The results show that the GHG emission factors of new energy power generation axe much lower than that of traditional thermal power generation even with LCA accounting, and the GHG mitigation potential of new energy substitution is huge.

Enhancing Autonomy Capability in Regional Power Grids:A Strategic Planning Approach with Multiple Autonomous Evaluation Indexes

After the integration of large-scale DistributedGeneration(DG)into the distribution network,the randomness and volatility of its output result in a reduction of spatiotemporal alignment between power generation and demand in the distribution network,exacerbating the phenomenon of wind and solar power wastage.As a novel power system model,the fundamental concept of Regional Autonomous Power Grids(RAPGs)is to achieve localized management and energy autonomy,thereby facilitating the effective consumption of DGs.Therefore,this paper proposes a distributed resource planning strategy that enhances the autonomy capabilities of regional power grids by considering multiple evaluation indexes for autonomy.First,a regional Energy Storage(ES)configuration strategy is proposed.This strategy can select a suitable reference value for the upper limit of ES configuration based on the regional load andDGoutput to maximize the elimination of source load deviations in the region as the upper limit constraint of ES capacity.Then,a control strategy for regional ES is proposed,the charging and discharging reference line of ES is set,and multiple autonomy and economic indexes are used as objective functions to select different proportions of ES to control the distributed resources of the regional power grid and establish evaluation indexes of the internal regional generation and load power ratio,the proportion of power supply matching hours,new energy consumption rate and tie line power imbalance outside the region to evaluate changes in the regional autonomy capabilities.The final simulation results showthat in the real regional grid example,the planning method in the planning year in the region of the overall power supply matching hour ratio and new energy consumption rate increased by 3.9%and 4.8%on average,and the power imbalance of the tie line decreased by 7.8%on average.The proposed planning approach enables the maximization of regional autonomy while effectively smoothing the fluctuation of power exchange between the regional grid and the higher-level grid.This presents a rational and effective planning solution for the regional grid,facilitating the coordinated development between the region and the distribution network.

Regulating cost for renewable energy integration in power grids

To address the issue of climate change caused by the use of polluting, non-renewable energy sources, the use of renewable energy has gained momentum worldwide. Consequently, the increased integration of renewable energy sources into power grids has necessitated the inclusion of flexible capacities in the power systems to solve problems of intermittent and fluctuating characteristics associated with renewable generation outputs. In this work, we study the regulating cost of a power system with high renewable penetration using an improved time-series system production simulation analysis method. The operational cost of the system is considered as the objective function. Three different methods to increase regulating capacities, including using interconnection lines, building additional flexible power capacities, and retrofitting existing thermal power plants, are adopted and simulated to compare the costs of accommodating renewable energy in the system in these cases. Our results indicate that increasing the flexibility of thermal power plants and developing crossregional connection lines are cost-effective methods of increasing renewable energy consumption.

An Improved Method of the Energy Loss Calculation Considering the Volatility of Wind Power Generation

The energy loss of the power grid is one of the key factors affecting the economic operation of power systems. How to calculate the electric energy consumption accurately will have a great influence on the planning, operation and management of the power grid. Currently there is a mountain of theoretical methods to calculate the line loss of the power system. However, these methods have some limitation, such as less considering the volatility of wind power resources. This paper presents an improved method to calculate the energy loss of wind power generation, considering the fluctuations of wind power generation. First, data are collected to obtain the curve of the typical daily expected output of wind farms for one month. Second, the curve of the typical daily expected output are corrected by the average electricity and the shape factor to obtain the curve of the typical daily equivalent output of wind farms for one month. Finally, the power flow is calculated by using typical daily equivalent output curve to describe the energy loss for one month. The results in the 110 kV main network show that the method is feasible.

Connection Technology of HPTO Type WECs and DC Nano Grid in Island

Wave energy fluctuating a great deal endangers the security of power grid especially micro grid in island. A DC nano grid supported by batteries is proposed to smooth the output power of wave energy converters（WECs）. Thus, renewable energy converters connected to DC grid is a new subject. The characteristics of WECs are very important to the connection technology of HPTO type WECs and DC nano grid. Hydraulic power take-off system（HPTO） is the core unit of the largest category of WECs, with the functions of supplying suitable damping for a WEC to absorb wave energy, and converting captured wave energy to electricity. The HPTO is divided into a hydraulic energy storage system（HESS） and a hydraulic power generation system（HPGS）. A primary numerical model for the HPGS is established in this paper. Three important basic characteristics of the HPGS are deduced, which reveal how the generator load determines the HPGS rotation rate. Therefore, the connector of HPTO type WEC and DC nano grid would be an uncontrollable rectifier with high reliability, also would be a controllable power converter with high efficiency, such as interleaved boost converter-IBC. The research shows that it is very flexible to connect to DC nano grid for WECs, but bypass resistance loads are indispensable for the security of WECs.

Towards Implementation of Smart Grid: An Updated Review on Electrical Energy Storage Systems

A smart grid will require, to greater or lesser degrees, advanced tools for planning and operation, broadly accepted communications platforms, smart sensors and controls, and real-time pricing. The smart grid has been described as something of an ecosystem with constantly communication, proactive, and virtually self-aware. The use of smart grid has a lot of economical and environmental advantages;however it has a downside of instability and unpredictability introduced by distributed generation (DG) from renewable energy into the public electric systems. Variable energies such as solar and wind power have a lack of stability and to avoid short-term fluctuations in power supplied to the grid, a local storage subsystem could be used to provide higher quality and stability in the fed energy. Energy storage systems (ESSs) would be a facilitator of smart grid deployment and a “small amount” of storage would have a “great impact” on the future power grid. The smart grid, with its various superior communications and control features, would make it possible to integrate the potential application of widely dispersed battery storage systems as well other ESSs. This work deals with a detailed updated review on available ESSs applications in future smart power grids. It also highlights latest projects carried out on different ESSs throughout all around the world.

Study on the Energy Dispatch Strategy of PV Power Plant

Now the energy efficiency of the PV power plant is low.For this case,this paper presents a PV power plant energy scheduling strategy.It includes new grid scheme and scheduling algorithm.Through the establishment of PV power station network model and the method of computer simulation of its scheduling algorithm,this paper describes its realization way,and then proves that the scheduling strat egy is correct and the effectiveness of improving energy conversion rate.At the same time,the PV power station scheduling strategy aslo re duces the environmental pollution,and alleviates the energy crisis and environmental crisis.

Research of Thermal Energy Storage Technology in the Solar Thermodynamic Power

Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and economy development. However, development pattern that excessively relies on the natural source is impossible to provide a sustainable development way for us. As a result, we should combine renewable energy with new energy technology as the aim of economy. It means that it is urgent to exploit new energy. Meanwhile, the ratio of energy waste cannot be ignored. How to decrease energy waste is also significant. Construction sector costs a lot of energy, which is mainly used for heating and refrigeration. In the new energy generation technology, thermal energy can be transformed to electricity with combination of BIPV and thermal energy storage technology. Photovoltaic generation has a great progress in the building construction. As a result, the thermal energy storage technology becomes the key link in the production chain. In this paper, feasibility of applying phase-change material (PCM) in the thermal energy storage will be analyzed. And analysis results are provided with a relative mathematical model.

Electronic Controlled Energy Storage Devices and Applications in Future Smart Grid

This paper discusses the future power system consisting of distributed generations connected to local loads in the form of micro-grid systems.The benefits of having energy storage systems and the role of power electronics in micro-grid systems are presented.This paper also examines how micro-grids have a key role to play in the development of the smart grid.

Feasibility Study of Smart Grid in Bangladesh

The agenda of this paper is to discuss about the significance and a detailed feasibility study of practical implementation of Smart Grid in Bangladesh. Smart grid refers to an electric power system that enhances grid reliability and efficiency by automatically responding to system disturbances. Power crisis is a major problem for a developing country like Bangladesh. Efficient transmission and distribution of electricity with essential energy resources is a fundamental requirement to provide citizens and economies. The paper analyzes the characteristics of Smart Grid and a comparative analysis with conventional grid system. It also discusses about the efficient transmission and distribution process which will integrate power system with renewable energy and information system.

Impact of Reactive Power in Power Evacuation from Wind Turbines

Application of Distributed Generation (DG) to supply the demands of a diverse customer base plays a vital role in the renewable energy environment. Various DG technologies are being integrated into power systems to provide alterna-tives to energy sources and to improve reliability of the system. Power Evacuation from these remotely located DG’s remains a major concern for the power utilities these days. The main cause of concern regarding evacuation is con-sumption of reactive power for excitation by Induction Generators (IG) used in wind power production which affects the power system in variety of ways. This paper deals with the issues related to reactive power consumption by Induc-tion generators during power evacuation. Induction generator based wind turbine model using MATLAB/SIMULINK is simulated and its impact on the grid is observed. The simulated results are analyzed and validated with the real time results for the system considered. A wind farm is also modeled and simulations are carried out to study the various im-pacts it has on the grid &nearby wind turbines during Islanding and system event especially on 3-Phase to ground fault.

Power Transfer of PV Inverter from DC to AC Voltage Source

This paper presents a simple approach of a topology already known in the literature, applied in active power transfer from direct current source to any alternating current voltage source, whether the utility power or a voltage inverter that is forming an isolated AC grid. The photovoltaic inverter works as current controlled voltage source inverter that provides a sinusoidal current to the AC grid. The inverter is insulated from the grid by a transformer. The system is discussed and modeled. Simulation results of this application are presented and experimental results validate this topology.

Distributed Generation Influence on Power Distribution System Development in Poland

A lot of individual electricity sources of small power common （called distributed generation） occurred in Polish power sector during the last period. Gradual increases of distributed generation will cover current and future demand of consumers as well as allow to keep essential reserves in distribution and transmission grids. Emphasizing on this problem can upgrade economic efficiency and grid significance of distributed generation for investors and distribution utilities in Poland.

新型电力系统主动构网机理与技术路径

随着新一代“双高”电力系统的发展,新能源并网变换系统逐渐由随网型向构网型演变,当新能源机组集群运行时,并网情况将更加复杂。变换器的构网能力需亟待研究,同时也是电力能源转型需承担的重要使命。该文立足并网系统内外形态的全局性和传统并网变换系统性能分析的局限性,对并网变换器的主动构网支撑机理进行再揭示。首先,对虚拟同步技术与构网机理进行简要评述;其次,就集群并网系统的建模问题、多机集群并网运行时的耦合交互问题、支撑构网能力的储能配置和运行边界等3个关键技术问题,进行深入研究;最后,针对上述3个关键技术问题,进行技术路径探索和研判。该文的思路为形成适用于未来新能源集群并网运行的系统化理论和实用化方法奠定一定基础。