Distributed Power Station Research Articles

Integrated Two-Level New Energy Monitoring and Big Data Centers: A Comprehensive Approach for Urban Sustainability

This study examines the transition to green energy in Wenzhou City and suggests a novel plan for integrating an energy monitoring and data center. The aim is to improve the city's sustainability through the building of a large-scale wind-solar integrated energy monitoring system by a group in Wenzhou City. The solution uses the Internet of Things and intelligent data analysis technology to realize real-time data collection, processing and operation and maintenance decision support for distributed power stations. The system adopts storage-computer separation and data encryption technology to ensure data security and system stability and improves data processing efficiency through containerization and microservice architecture. In addition, the study also explores the application potential of this technical scheme in regional energy planning, which provides a new idea for Wenzhou to achieve green energy transformation and low-carbon development.

Conditional Style-Based Generative Adversarial Networks for Renewable Scenario Generation

Day-ahead scenario generationof renewable power plays an important role in short-term power system operations due to considerable output uncertainty included. In this paper, a deep renewable scenario generation model using style-based generative adversarial networks followed by a sequence encoder network, is developed to generate accurate and reliable day-ahead scenarios directly from historical data through different-level scenario style controlling and mixing, thus achieving better characterization of renewable spatial-temporal dynamics. Meanwhile, the integration of meteorological information serving as conditions enables our model to precisely capture the complex diurnal pattern and seasonality difference of renewable power. From wind and photovoltaic power perspectives, the effectiveness of the proposed model is validated on two real-world datasets reflecting region aggregation level and distributed power station level respectively. Numerical results demonstrate the superiority of model performance through both the statistical and power system scheduling analysis, compared to three benchmarks.

Data Quality Evaluation of Photovoltaic Power Station based on Entropy Weight Method and Grey Comprehensive Evaluation Method

The increasing necessity of renewable energy utilization has fueled the successful development of photovoltaic power generation technology. Distributed photovoltaic power stations have been rapidly promoted because of their small installed capacity and low initial investment costs. Scientific and comprehensive data evaluation of distributed PV is conducive to improving the operational efficiency of the power station. An index evaluation system is constructed for distributed power station data in each province. The entropy weighting method is used to determine the weights of different dimensions. Then, the data quality evaluation level is contrasted with the help of the gray evaluation method. Simulations of the proposed method were conducted. Finally, the results showed that the data of the tested distributed PV were at an excellent level, which verified the applicability of the method. In addition, the causes of data quality deficiencies are preliminarily explored.

Insertion of High Frequency Solid State Transformer to Electric Power System And Analysis of its performance

The spread of distributed power stations, especially small power stations that use renewable energy sources, as well as the connection of a large number of distributed power stations to the network led to the necessity of making some changes in the electrical distribution system. Therefore, the Solid State Transformer (SST) has recently emerged as a suitable alternative to the traditional transformer. SST is characterized by its small size and weight, and as the possibility of controlling the direction and amount of power flow, improving the quality of power, the possibility of controlling voltage, compensating reactive power and other advantages that are not available in the traditional transformer that can be of paramount importance to the development of the power system. This paper reviews solid state transformers in terms of their components, working method, mathematical analysis, design steps, and control process. ANSYS Maxwell 3D software was used to design and model the high frequency isolation transformer and a working model of the core-type high frequency isolation transformer was presented. It was found through the results of the study and analysis of the solid-state transformer that it would be a suitable alternative to the traditional transformer that works at high frequencies.

Fault Diagnosis Knowledge Reasoning of Switching Network in Distributed Generation Based on Petri Net

Telephone network based on IMS technology has been widely applied inpower production and dispatching communication, especially in distributedpower stations. Analysis and positioning failure of IMS network is arduous,because it’s dependent on IP data communication network. In this paper,we first introduced IMS switching network architecture and distributed gen-eration communication network architecture, analyzed and summarized allkinds of network malfunction. Combining typical IMS network fault con-nection relations, we introduced an improved Petri net fault handling modeland reasoning method. The diagnosis and positioning results could reflectthe defects of equipment logic functions. This method on fault diagnosisand location of substation network has been proved to be effective throughpractical application.

Discussion on Problems and operation and maintenance of distributed photovoltaic power stations in Tibet

Due to the vast area of Tibet, where farmers and herdsmen live scattered, and the construction sites of solar distributed photovoltaic power stations are relatively scattered, which makes the operation and maintenance of the system more difficult. At the same time, due to the lack of practical experience of technical personnel, even if there are problems in photovoltaic power stations, they can not get timely feedback and solution. Over time, many distributed photovoltaic power stations are forced to be abandoned because of no maintenance and repair. These phenomena also restrict the application of photovoltaic power in Tibet to a certain extent. Based on the field investigation of distributed photovoltaic power stations in Tibet, this paper finds out the common faults and existing problems of photovoltaic power stations, analyzes the causes of the failures, and puts forward suggestions for operation and maintenance. The purpose of this paper is to build a solar distributed photovoltaic power station with high reliability and easy maintenance in Tibet, so as to provide a certain scientific basis for the existing photovoltaic power station and the later construction of photovoltaic power station.

Combined Multi-Layer Feature Fusion and Edge Detection Method for Distributed Photovoltaic Power Station Identification

Distributed photovoltaic power stations are an effective way to develop and utilize solar energy resources. Using high-resolution remote sensing images to obtain the locations, distribution, and areas of distributed photovoltaic power stations over a large region is important to energy companies, government departments, and investors. In this paper, a deep convolutional neural network was used to extract distributed photovoltaic power stations from high-resolution remote sensing images automatically, accurately, and efficiently. Based on a semantic segmentation model with an encoder-decoder structure, a gated fusion module was introduced to address the problem that small photovoltaic panels are difficult to identify. Further, to solve the problems of blurred edges in the segmentation results and that adjacent photovoltaic panels can easily be adhered, this work combines an edge detection network and a semantic segmentation network for multi-task learning to extract the boundaries of photovoltaic panels in a refined manner. Comparative experiments conducted on the Duke California Solar Array data set and a self-constructed Shanghai Distributed Photovoltaic Power Station data set show that, compared with SegNet, LinkNet, UNet, and FPN, the proposed method obtained the highest identification accuracy on both data sets, and its F1-scores reached 84.79% and 94.03%, respectively. These results indicate that effectively combining multi-layer features with a gated fusion module and introducing an edge detection network to refine the segmentation improves the accuracy of distributed photovoltaic power station identification.

Experimental investigation of a novel micro gas turbine with flexible switching function for distributed power system

Micro gas turbine (MGT) is widely used in small-scale distributed power systems because of its low emissions and fuel flexibility. However, the under-utilization of its exhaust heat and the low electric efficiency are the main bottlenecks that restrict its application. Additionally, the flexible switching between the power generated by the MGT and the power grid is also a key factor for keeping the secure operation of a distributed power station. Therefore, this paper conducted some experimental investigations of a 30 kW MGT to provide reference solutions for the above issues. This MGT is located at Shanghai Jiao Tong University (SJTU), which is designed by the Gas Turbine Research Institute of SJTU, and is manufactured by a turbo-machinery factory in Chongqing, China. The demonstration prototype is mainly composed of a single stage centrifugal compressor, a radial turbine, a combustor, a high-speed permanent magnet generator, and a control system. The results show that the MGT can achieve steady operation at a low rotational speed from 10000 r/min to 34000 r/min in the case of using oil lubricated bearings, which can greatly reduce the economic cost compared with the use of air bearings. At the same time, the ignition success rate of combustion chamber (CC) reaches 98% at a low rotational speed, and a wide range of stable combustion area can be obtained, because of the novel design method of combustor by referencing the way applied in an axial flow aero-engine. The MGT generating set can achieve functions, such as starting up, ignition, stable operation, loaded operation, grid-connection and stopping. This system also can realize flexibly switching from the start motor mode to the generator mode, and from grid-connected mode to off-grid mode, because the innovative multi-state switching control system is adopted. The above research work can make our state master independent intellectual property rights of micro gas turbine, rather than continue to be subject to the technological monopoly of the developed states, which can provide theoretical and experimental support for the industrialization of MGT in China.

Fault diagnosis of photovoltaic system based on machine learning model fusion

With the reduction of non-renewable resources, the energy issues become more and more important and urgent. Distributed photovoltaic power stations not only provides more energy with flexible deployment, but also proposes a possibility of how to fully use the solar energy with a better efficiency. Although a distributed photovoltaic power station has many advantages and great potential, it is not easy to be operated and maintained. In recent years, the applications of machine learning in multiple fields make it possible to do the fault diagnosis of photovoltaic systems more efficiently. This paper designs a full processing system to realize the function of real-time fault diagnosis specially for distributed photovoltaic power stations, which includes the data processing, an online system to give the result of real-time diagnosis, an offline system to retrain models, and a fusion model of several machine learning algorithms. The data processing and performances of different models in this problem are introduced in detail. The fusion model that proposed in this paper acts much better than single models. Hence, the fault diagnosis system could be used in the operation and maintenance of distributed power stations.

Application of Phase-Shifting Transformer in the Volga Hydroelectric Station Power Distribution System

The paper presents the results of studying the effectiveness of using a phase-shifting transformer (PST) at the Volga Hydroelectric Station. It is shown that PST can be effectively used at the Volga Hydroelectric Station to ensure the distribution of the entire available power using advanced power modes while considering the implementation of the program of updating the power generating equipment and improving the adjacent electrical grid system.

Effect of fuel composition fluctuation on the safety performance of an IT-SOFC/GT hybrid system

Fuel composition fluctuation could result in operation performance degradation caused by a potential failure of component or system. Therefore, this work elaborated the safe characteristic and load performance of an intermediate-temperature solid oxide fuel cell (IT-SOFC) and gas turbine (GT) hybrid system using gasified biomass gas when the composition fluctuates. The malfunction restrictions of components (such as fuel cell thermal crack, compressor surge, reformer carbon deposition) were considered in this research. Results show that the hybrid system has a high efficiency 60.78% at the design point using gasified wood chip gas, which is a useful reference for small distributed power stations. H2 concentration variation is the most influential factor to the hybrid system output power and efficiency, followed by CH4, and then CO. System efficiency increases significantly with H2 concentration increase, while decrease slightly with CO and CH4 increase. For the system safety operation: ⅰ) when the H2 and CH4 fluctuates to relative proportion 90% and 97%, respectively, the reformer will suffer from the potential failure of carbon deposition; ⅱ) when H2 increases to 116%, the TIT exceeds the upper limit 1223 K, which causes the turbine blade to burn down because of over temperature. For the effect of water variation, the system output power and efficiency will be improved with water reduction, and the efficiency can even reach up to 64.85%. However, the reformer can't work safely due to the severe shortage of water for the reforming reactions.

Performance analysis of island energy system of SOFC and GT with gasified biomass fuel

The integration of solid oxide fuel cell (SOFC), gas turbine (GT), and biomass gasification is presented in this paper to form an island energy system to provide power to users as needed. In order to insight the safe characteristics of the main components in the various operating conditions, the safety constraint factors are considered. The system thermal-electric performance is analyzed by conducting the mathematic models of SOFC, GT and other components with wood chip gasified gas. The effects of changes of H2, CH4 and CO on the system performance are analyzed to research the component fluctuation. Results show that the energy system has a high efficiency 60.78% at the design point using gasified wood chip gas, which is a useful reference for small distributed power stations. H2 concentration variation is the most influential factor to the energy system output power and efficiency, followed by CH4, and then CO. System efficiency increases significantly with H2 concentration increase, while decrease slightly with CO and CH4 increase. For the system safety operation, when the H2 and CH4 fluctuates to relative proportion 90% and 97%, respectively, the reformer will suffer from the potential failure of carbon deposition.

A rolling prediction optimization strategy for the optimal design of grid connected integrated CCHP system with renewable energy and energy storage

Integrated Combined Cooling Heating and Power (CCHP) system with renewable energy (RE) and energy storage (ES), short as RE-CCHP-ES, is the distributed power station supply electricity, heating, cooling, and hot water by solar, wind power, and natural gas for a specific customer, such as campus, hospital, or commercial palace. Following electric load (FEL) and following the thermal load (FTL) are the traditional operation strategies for CCHP system. But for the system with gas boiler and electricity storage, their performances are not satisfied. Therefore, FLB-RPO operation strategy is designed and contracted with FEL-ECR, and FLB. The result of case study shows that the system designed under FLB-RPO strategy reducing more carbon emission, energy consumption, and system cost than the systems designed under other operation strategy or power supply.

Design of an Online Monitoring System of Lithium Ion Energy Storage Batteries for a Distributed Power Station

Aiming at the online monitoring of real-time operating of lithium-ion energy storage batteries for distributed power station, this paper studies the online monitoring system of lithium-ion energy storage batteries based on B/S network structure. The system consists of a battery status information collection unit, a centralized control unit, and a remote monitoring center. The battery status information collection unit detects the current, voltage, temperature and other parameters of the lithium ion energy storage battery in real time, transmits the data to the centralized control unit for data processing and real-time estimation of the SOC of the battery, and then the centralized control unit transmits the measurement parameters through the Internet network. The remote monitoring center monitors and analyzes the battery real-time status data, accurately calculates the battery SOC, realizes the online real-time monitoring of the lithium ion battery, prevents the lithium ion battery from overcharging, over-discharging, overheating, and promotes the safe and stable operation of the lithium-ion energy storage battery.

A novel centralized charging station planning strategy considering urban power network structure strength

Considering detrimental impact on grid by sizeable and unpredictable electric vehicles (EVs) loads, establishing centralized charging stations through swapping batteries can be the future competitive development orientations in EV industry. Optimal centralized charging station planning is not only pervasive enough to meet the requirement of EV charging, but also has the potential to improve the rationality of power grid structure as a distributed power station. In this paper, a novel centralized charging station strategy considering urban power network structure strength is proposed. Based on the analysis of time-space characteristic of load shifting in normal urban life, power supply moment balance index is defined to represent fluctuation of supply capability between peak and valley under certain structure. Meanwhile, the investment of charging stations and network loss are considered as part of objective function with moment balance index, aiming at improving urban power network structure with minimal economic cost. Case study on IEEE 123-bus test distribution system illustrates the validity of the strategy proposed.

Determination of safe operation zone for an intermediate-temperature solid oxide fuel cell and gas turbine hybrid system

This paper proposes a novel approach to determine the safe zone for an intermediate-temperature solid oxide fuel cell and gas turbine hybrid system. The approach first ensures the compressor safety and then determines the overall system safe zone by analyzing the unsafe characteristics of main components. Safe performance of the hybrid system fueled with biomass gas at all operations is analyzed. Finally, the map of safe zone is obtained to avoid component malfunctions and system performance deterioration. Results show that the hybrid system can achieve a high efficiency 60.78%, which is an interesting reference for distributed power stations. Under all operations, two unbalanced energy zones exist, which may cause the short supply of O2 or fuel for electrochemical reaction. The lower the rotational speed of gas turbine, the narrower the zone of carbon deposition takes place in the reformer or turbine inoperation caused by too low inlet temperature. However, the phenomenon of fuel cell thermal cracking due to over-temperature will be exacerbated. System layout also affects component safety especially for the fuel cell. In the safe zone, the system has a characteristic of high efficiency and low load with low rotational speed, vice versa. In other words, the powers and load adjustment ranges both decrease with decreasing rotational speed whereas the efficiency increases, which peaks at 63.43%.

Study on Access System of Low Voltage Distributed Photovoltaic Power Station

Due to the actual situation, when carrying out research on the principle of low-voltage distributed PV power station, we should make research on the process of survey and the determination of measurement program. And the working-out process of the connection scheme to the first distributed PV power station in Liaoning region is stated. After the discussing the difficult problem on the development of the connection scheme, the next phase of research direction is proposed.