Development of a quick-response superconducting generator model for electromagnetic transient analysis of power systems

Superconducting generators (SCGs) can improve power system stability in steady state and also in transient state with a high response excitation. The authors designed and made an experimental 100 kVA SCG with high response excitation and carried out several experiments for power system stability using an artificial transmission line. In this paper, a high response excitation control of SCG considering stability of the superconducting field winding is discussed and tested. A proposed control system has limiter (over excitation limiter) functions for not only the field current but also for its differential value (voltage). These factors affect a design of the field windings. Transient stability tests were performed by using the test generator and the artificial transmission lines with and without the proposed excitation control. The effects of the proposed control on the transient stability were studied.

In this paper we present the wavelet analysis technique, a powerful tool for the detection and analysis of power system transients. Traditional Fourier analysis techniques are suitable for periodic signals whereas aperiodic signals such as transients on a power system would require a more robust analysis technique such as the wavelet analysis technique. The basic idea of this technique is to decompose the transient signal into a number of levels, which basically contain the high and low-frequency components of the signal. By analyzing the decomposed transient signal at different levels, not only do we get information regarding the frequency content of the transient but also the time at which each of these transients occurred, which helps in distinguishing transients occurring due to different reasons.

By means of field investigation, this paper found the factors that restricting the development of Qinhuangdao port logistics low carbonization. The factors are: the planning layout port is not reasonable; related policies and regulations of low carbon lag; port infrastructure is weak and low carbon logistics technology level need to be improved; the lack of talented person for port of low carbon logistics. This paper put forward the measures and suggestions on Qinhuangdao port logistics low carbonization: striving to optimize the layout; enhancement of infrastructure capacity; the introduction of technology to reduce emissions, improvement of the level of low carbon development; enhancement of port operation management and operation ability; improvement of low carbon consciousness of port industry practitioners; government and industry play an active role in Qinhuangdao port logistics low carbonization.

A s environmental problem has drawn the focus of people's attention; low carbonization has become the trend of world's economic development. In this background, low carbon tourism is becoming a new traveling fashion and tourism attitude. So, low carbon tourism will become the new development direction of the tourism industry in the near future. This article begins with the low carbon economy and low carbon tourism concept, and then introduces the basic concept system of low carbon tourism. In the second part of the paper, using the concept of low carbon, it puts forward the development strategies of tourism scenic spots, hotels, travel agencies and tourism transportation.

Addressing the complexity of transient evolution and the difficulty of rapid risk quantification in high-penetration renewable energy receiving-end grids under short-circuit faults, this paper proposes a rapid risk assessment method based on the fault transient evolution process. The method first constructs a directed weighted graph model to characterize the fault transient evolution process. It then integrates mechanism analysis with data-driven approaches to establish state transition models and temporal feature models, which are used to generate the fault evolution path. Based on the transient evolution path, this paper defines the equivalent active power loss as the risk index and rapidly quantifies it through a phased simplified calculation approach. Finally, validation using a provincial power grid case study confirms the efficacy of the method and successfully achieves reliable predictions of fault evolution scenarios, as well as rapid and effective assessment of power loss during the transient process.

Nowadays, there is quite high demand for electromagnetic transient (EMT) analysis programs and real-time simulators for power systems. In addition to the conventional demand such as overvoltage, over-current and oscillation simulations, the new demand that includes simulations of power-electronics circuits and power quality is increasing. With this background, development groups of EMT programs and real-time simulators have made progress in terms of computational performance and user experience. In Japan, Central Research Institute of Electric Power Industry has newly developed an EMT analysis program called XTAP (eXpandable Transient Analysis Program). This article overviews these international and domestic development trends of EMT analysis programs and real-time simulators.

Because of the superconducting field winding of superconducting generators (SCGs), the resistance and voltage drop of the field circuit are extremely low. Therefore, machine constants concerning the field circuit are different from those of conventional machines. In this paper, a method for obtaining these constants is proposed. By the use of this method, the constants are given experimentally. In SCGs with high response excitation, which can improve transient power system stability, the characteristics of high response excitation are discussed both theoretically and experimentally.

In the literature, wavelet techniques are proposed for the analysis of power system transients. Many mother wavelets have been used for this analysis such as Haar, Daubechies (db), Symlets, and Coiflets. This paper describes a strategy to choose a suitable mother wavelet for this analysis. It also shows the deviation between Matlab and theoretical (mathematically calculated) db-wavelets when they are used for the analysis of power system transient. The simulation study is carried out using PSCAD simulation program and Matlab wavelet toolbox. The simulation results show that the theoretical db wavelet is more suitable for analyzing power system fault transients than the Matlab db wavelet.

Amicrogrid is a combination of clusters of distributed generators connected to fulfill the requirement of dedicated load. A microgrid can be operated with standalone or grid connected mode. A microgrid when operated in standalone mode with a limited voltage and power rating is more likely prone to a serious damage due to its unpredictable faults. Load flow, voltage stability & short circuit analysis of a micro-grid is essential for both design and performance monitoring and to ensure reliable microgrid operations. The faults with a continuously varying in nature affects the normal operation of buses and so to the peripherals associated to the micro-grid. The cause and severity of such faults plays a vital role while designing protection scheme in standalone micro-grid as standalone mode has confined generation. In this paper, electrical model of a 52.3 kW Photo-voltaic based micro-grid is developed on Electrical Transient Analysis Program (ETAP) and various transient conditions such as load flow, loss of DG & short circuit analyses are performed. A detailed short circuit analysis puts light on various short circuit conditions and provides useful analysis. ETAP is the most comprehensive analysis platform for the design, simulation, operation, and automation of generation, distribution, and industrial power systems. ETAP also provides the industry leading transient analysis of power system and micro-grid so chosen for this transient analysis study. A short circuit analysis is calculated based onIEC Std. 60909 using ETAP. This paper presents a simulated model of micro-grid with actual system oriented results and analyzes responses of system during fault conditions and various contingencies.

Electromagnetic transients are the tidal waves of electric power systems. These momentary voltage surges generally lasting only fractions of a second can be powerful enough to disrupt normal operations and even cause serious damage to major pieces of equipment, such as transformers. Created by lightning, line faults, substation switching functions, and other sudden events along a utility network, transients must be taken into account both in choosing equipment ratings for a power system and in setting its operating parameters. Like the builders of a seawall that must withstand the highest expected waves from the ocean, engineers trying to guard against damage from transients face an extraordinary design task. Most of the huge computer simulation codes related to power systems either model steady-state conditions or deal with system stability problems. The analysis of electromagnetic transients, on the other hand, requires a much more detailed examination of how some critical portion of a power system will react to conditions that can change greatly in microseconds. For many years, simulation of transient effects was performed by special-purpose analog computers called transient network analyzers (TNAs). These machines, which are still in use, recreate a portion of the power system in miniature, complete with voltage sources representing generators and various kinds of capacitive or inductive loads. TNAs are generally adequate but relatively inflexible, tedious to set up, and cumbersome to use. Once a system configuration is modeled, many simulations can be performed. Given the need to manually reconfigure TNA circuits to represent changes in a system, however, the analyzers can also be quite expensive to use. During the late 1960s, Herman Dommel of the Bonneville

Presents a review of a frequency domain technique for power system transient analysis. Frequency domain analysis represents the power system voltage and current equations as a function of the complex frequency. The system of equations is then solved using a numerical inverse Laplace transform technique, which yields the system voltages and currents. The technique is compared with a time domain method. The Electromagnetic Transients Program (EMTP) is a time domain analysis program that allows the user to model the power system components to determine the response of the system to a variety of transient phenomena. The user inputs the system data to the program via a data file. The data file specifies the type of source, different models for the transmission lines, motors, transformers, and loads, as well as analog functions and time varying parameters. The program output includes system voltages, currents, and power flows. >

This paper considers a unified approach to the analysis of electromechanical and electromagnetic transients in the electric power system and to the analysis of functioning of phasor measurement units (PMU).

China’s low carbon economy has been established and developed under the regional non-equilibrium development state. There’s great difference between regions in economic development stage, resources endowment, industry structure and technology level. The difference inordinately restricts the development of regional low carbon technology, and influences the development of regional low carbon economy and the whole country’s low carbon economy. From the viewpoint of applied research, this paper uses systematic science method. Based on classification of different types of low carbon technology, it positions and analyzes the constraints in the process of regional low carbon technology development. The study shows that low carbon technology has the public product attributes, and regional synergetic development is the necessary channel to promote the overall and sustainable development of low carbon technology. We can achieve the regional technological synergies through perfecting technology sharing system, advocating multi-side participation, enhancing promotion and utilization.

Catalysis: The Technology Enabler for New, Low Carbon Energy Technologies

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