Strategy of AC-isolated island detecting and control mode switching over in Zhoushan Project

Author(s):  
Hu Xianlai Hu Xianlai ◽  
Dong Yunlong Dong Yunlong ◽  
Li Zhiguo Li Zhiguo

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7514
Author(s):  
S.M. Ferdous ◽  
Farhad Shahnia ◽  
GM Shafiullah

The two common mechanisms of load-shedding and renewable curtailment can prevent provisional overloading and excessive generation and the subsequent unacceptable voltage and frequency deviation in standalone microgrids (MGs), which makes MGs less resilient and reliable. However, instead of enabling load-shedding or renewable curtailment, such overloading or over-generation problems can be alleviated more efficiently and cost-effectively by provisionally interconnecting the neighboring MGs to exchange power amongst themselves. In such a scheme, the interconnected MGs can supply their local demand, as well as a portion of the demand of the adjacent MGs. In order to implement this strategy, a three-phase ac link can be used as the power exchange network, while each MG is coupled to the link through a back-to-back power electronics converter, in order to maintain the autonomy of each MG if they are eachoperated under different standards. This paper proposes a suitable decentralized power management strategy without a communication link between the MGs to achieve power-sharing amongst them and alleviate unacceptable voltage and frequency deviation along with the required control technique for the power electronic converters, which can be implemented at the primary level based on the measurement of the local parameters only. To this end, one of the converters should always regulate the dc link voltage while the other converter should operate in droop control mode when the MG is healthy and in constant PQ mode when overloaded or over-generating. Suitable status detection and mode transition algorithms and controllers were also developed and are proposed in this paper. The performance of the proposed power exchange and control mechanisms were evaluated and verified via PSIM®-based numerical simulation studies. The stability and sensitivity of the proposed power exchange topology are also analyzed against several critical design and operational parameters.







2012 ◽  
Vol 573-574 ◽  
pp. 797-800
Author(s):  
Miao Wang ◽  
Jing Fei Ren ◽  
Jing Li

There are many problems about the current management mode of the scenic spots in China with the contradiction between the economic development and environmental protection as the key problem. The study on the management and control mode of the low-carbon scenic spots can alleviate the overload operation in the scenic spots to a great extent and it can help increase the economic income as well as achieve a sustainable development of the scenic spots. The straight-matrix structure constructs a horizontal and vertical management coordination platform with the information technology as the support and it enables the management information to be processed and conveyed within the organization so as to realize a win-win development of economy and environmental protection in the scenic spots.



2011 ◽  
Vol 121-126 ◽  
pp. 4122-4126
Author(s):  
Yong Kui Man ◽  
Yu Yan Ma ◽  
Yu Shuang Zhao ◽  
Chang Cheng Xu ◽  
Wen Sheng Hao

In this paper, the mechanical structure of a novel two-phase hybrid stepping motor, which offers big transmission ratio and fast response characteristics, is proposed. Comparing with typical two-phase hybrid stepping motor, permanent magnet of the new model is placed on the stator, thus it has better utilization of space than conventional two-phase hybrid stepping motor. Furthermore, new two-phase hybrid stepping motor torque mathematical model is established. And the two-phase hybrid stepping motor torque vector analysis method we provide here provide you with an intuitive way of research on the new type two-phase hybrid stepping motor operation principle and control mode.



2013 ◽  
Vol 347-350 ◽  
pp. 768-771 ◽  
Author(s):  
Jian Jun Zhou ◽  
Xiao Fang Wang ◽  
Xiu Wang ◽  
Wei Zou ◽  
Ji Chen Cai

A greenhouse monitoring and control system based on Zigbee networks was developed. This system consists of greenhouse data acquisition controller and greenhouse remote monitoring and control software. The system could monitor temperature and humidity, soil water content and concentration of carbon dioxide in greenhouse and could save these greenhouse data to database. Greenhouse acquisition controller had two kinds of control modes, including local manual control mode and remote wireless control mode in monitoring center. Greenhouse remote monitoring and control software can collect, display and record the collected data, also can control greenhouse environment. According to the current indoor temperature, the target temperature and the offset temperature, PID control method is used for temperature control in greenhouse. The system is implemented using low power wireless components, and easy to be installed. A good wireless solution is provided by this system for centralized management of the greenhouse group.



2018 ◽  
Vol 4 (1) ◽  
pp. 143-157 ◽  
Author(s):  
D. E. Nicholson ◽  
O. Benafan ◽  
S. A. Padula ◽  
B. Clausen ◽  
R. Vaidyanathan


2018 ◽  
Vol 160 ◽  
pp. 04003
Author(s):  
Hanhong Jiang ◽  
Yao Lu ◽  
You Wu ◽  
Yi Wang

In order to realize the uninterruptible power supply in the master-slave independent micro-grid system, the micro-grid inverter needs to realize the mode switching of the grid-connection/grid-disconnection. How to reduce the transient oscillation during switching, so as to effectively achieve seamless mode switching is a key issue to be solved. In this paper, a typical master-slave control independent micro-grid is used as an example, the strategy of mode switching is improved in two aspects. On the one hand, the state-following algorithm is adopted to improve the switching strategy of the outer loop. On the other hand, the current inner loop is taken by the H∞ robust controller to improve the robustness of the controller. Compared with the traditional PI control mode switching, this paper illustrates the feasibility of the proposed strategy through the simulation and experiment verification. The improvement strategy in this paper can effectively reduce the voltage and current oscillation during mode switching.



2010 ◽  
Vol 4 (4) ◽  
Author(s):  
Basem Fayez Yousef ◽  
Rajni V. Patel ◽  
Mehrdad Moallem

An actuated robot arm is designed for use as a gross positioning macro-manipulator that can carry, appropriately orient, precisely position, and firmly “lock” in place different types of micro-robots and surgical tools necessary for applications in minimally invasive therapy. With a simple manipulation protocol, the clinician can easily operate the robot in manual mode. A remote control mode can also be enabled for teleoperation of the robot. The robot’s normally locked braking system and the simple quick-release joint enhance its safety features for emergencies and power shutdown. Robot workspace analysis showed that the singularity regions are outside the usable work envelope of the robot. Performance analysis showed that the robot operates with an average displacement accuracy of 0.58 mm and a roll, pitch, and yaw angular accuracies of 0.26 deg, 0.26 deg, and 0.38 deg, respectively. The sophisticated configuration and joint architecture of the arm enable it to perform and interact efficiently with the constrained and limited workspace of surgical environments. The special features of the proposed robot make it well suited for use with new surgical tools and micro-robots for a range of medical interventions.



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