External Surges Research Articles

87‐1: A Study on the Optimal Design of ESD Protection Circuit in OLED Panel Using Electromagnetic Simulation

In the display industry, in line with the high performance and miniaturization of products, the fine patterning and the increase in integration in the backplane process are becoming very important. It is the Electrostatic Discharge (ESD) issue that is increased importance in such a display panel development environment. Careful ESD management is very important because various types of electrostatic issues arising from the panel production process are directly connected to the decline in product quality and productivity. In this paper, we introduce the case of ESD defects in the ESD diode protection circuit of display panels being developed. The ESD failure caused by plasma ions and external surges during fabrication process was identified, and the charge and current path were verified through static and transient simulation to determine how it affects the actual display OLED panel. In addition, the design of ESD diode protection circuits optimized for ESD to robust layout was proposed. As a result, it was possible to reduce electric‐field, an insulating breakdown factor, by more than 80%.

Design of Destruction Protection and Sustainability Low-Dropout Regulator Using an Electrostatic Discharge Protection Circuit

In terms of sustainable power semiconductors, the embedding of an electrostatic discharge (ESD) protection circuit in an integrated circuit (IC) is an important aspect. In order for the semiconductor circuit to operate continuously or stably, a sufficient protection circuit against external surges must be configured. The purpose of this thesis is not only to effectively operate the low-dropout (LDO) regulator according to the load current, but to also secure high reliability against ESD situations by embedding an ESD protection circuit at the IC level. Moreover, the existence and nonexistence of an ESD protection circuit at the IC level is directly related to reliability. The proposed LDO regulator has high reliability against ESD situations using an embedded silicon controlled rectifier (SCR)-based ESD protection circuit in the I/O clamp and power clamp. The results revealed that the LDO regulator can not only effectively control the output voltage according to the load current, but it can also stably maintain the output voltage against the ESD surge. Moreover, the proposed LDO regulator with an embedded ESD protection circuit implemented in a 0.13 μm BCD process maintained an undershoot voltage of 21 mV and overshoot voltage of 19 mV for a load current of 300 mA.

Improvements to the detection and analysis of external surges in the North Sea

Abstract. External surges are a key component of extreme water levels in the North Sea. Caused by low-pressure cells over the North Atlantic and amplified at the continental shelf, they can drive water-level changes of more than 1 m at the British, Dutch and German coasts. This work describes an improved and semi-automated method to detect external surges in sea surface time histories. The method is used to analyse tide gauge and meteorological records from 1995 to 2020 and to supplement an existing dataset of external surges, which is used in the determination of design heights of coastal protection facilities. Furthermore, external surges are analysed with regard to their annual and decadal variability, corresponding weather conditions, and their interaction with storm surges in the North Sea. A total of 33 % of the 101 external surges occur within close succession of each other, leading to the definition of serial external surges, in which one or more external surges follow less than 72 h after the previous external surge. These serial events tend to occur more often during wind-induced storm surges. Moreover, the co-occurrence with a storm surge increases the height of an external surge by 15 % on average, highlighting the importance of the consideration of combined events in coastal protection strategies. The improved dataset and knowledge about serial external surges extend the available basis for coastal protection in the North Sea region.

Self‐capacitance grading approach to suppress winding resonance in EHV transformers under oscillatory terminal disturbances

Interleaving of the high-voltage winding turns is a widely-accepted method for restraining the surge voltage stresses in extra high voltage (EHV) transformers. Reduction of voltage stresses under external surge is attributed by the increase in the self-capacitance of the interleaved winding disks. However, the apparent benefit of interleaving may be counterpoised by a significant decrease of natural frequency of windings, which in turn, may force a winding to resonate under external surges. Winding resonance is particularly noticeable when uniform interleaving is adopted for the whole winding, uniform interleaving attributes a unique natural frequency to all interleaved coils and consequently, the collective resonance of the winding disks is plausible. Uniform interleaving in large EHV transformers therefore leads to complications and the windings reportedly exhibit an unexpectedly poor surge voltage response because of such internal resonances. This study describes a novel concept termed as ‘graded interleaving’ for EHV transformer windings to overcome resonance and to achieve an improved response against surge voltage. The performance of the proposed winding was tested on a 132/33 kV two-winding transformer with a tap changer using EMTP(ATP) simulations with encouraging results. Manufacturing and real-time implementation feasibility of the winding were verified with transformer manufacturers.

Identification of extreme storm surges with high-impact potential along the German North Sea coastline

Planning and design of coastal protection rely on information about the probabilities of very severe storm tides and the possible changes that may occur in the course of climate change. So far, this information is mostly provided in the form of high percentiles obtained from frequency distributions or return values. More detailed information and assessments of events that may cause extreme damages or have extreme consequences at the coast are so far still unavailable. We describe and compare two different approaches that may be used to identify highly unlikely but still physically possible and plausible events from model simulations. Firstly, in the case when consistent wind and tide-surge data are available, different metrics such as the height of the storm surge can be derived directly from the simulated water levels. Secondly, in cases where only atmospheric data are available, the so called effective wind may be used. The latter is the projection of the horizontal wind vector on that direction which is most effective in producing surges at the coast. Comparison of events identified by both methods show that they can identify extreme events but that knowledge of the effective wind alone does not provide sufficient information to identify the highest storm surges. Tracks of the low-pressure systems over the North Sea need to be investigated to find those cases, where the duration of the high wind is too short to induce extreme storm tides. On the other hand, factors such as external surges or variability in mean sea level may enhance surge heights and are not accounted for in estimates based on effective winds only. Results from the analysis of an extended data set suggest that unprecedented storm surges at the German North Sea coast are possible even without taking effects from rising mean sea level into account. The work presented is part of the ongoing project “Extreme North Sea Storm Surges and Their Consequences” (EXTREMENESS) and represents the first step towards an impact assessment for very severe storm surges which will serve as a basis for development of adaptation options and evaluation criteria.

EXTREME SCENARIOS AT THE GERMAN NORTH SEA COAST A NUMERICAL MODEL STUDY

A procedure, based on numerical models is proposed to investigate the processes involved during conditions of extreme water levels within the outer Elbe estuary at the German North Sea coast. Nonlinear interactions between the different processes are analyzed and adverse combinations are simulated yielding new scenarios. Various conditions in the astronomical tide, three major storm events over the North Sea, several external surges and an increase in the mean sea level are analyzed. Techniques for the modeling of each of the isolated processes are developed and individually verified. The isolated processes are temporally shifted relative to each other and superimposed in various combinations. The results obtained from the present method, provide new insights into the nonlinear interactions between the involved processes. Generally, the effects of the processes seem to be reduced in superpositions with high absolute water levels. However, due to the large scatter of the results no general relations are found. New extreme scenarios are determined by iterative maximizations of the peak water level of different superpositions around spring high tide.

Storms and surges in Irish coastal waters

Abstract Mechanisms of storm surge formation and severity on the north European continental shelf and, in particular, in the Irish coastal waters are examined in this paper. A numerical surge model was developed and used in combination with meteorological forcing and hydrographic records to analysis aspects of surge mechanics. An attempt is made to estimate sea level response to meteorology and to quantify pressure and wind contributions as a driving force. Results show that the inverted barometer term contributes to more than 80% of surge residual in the Celtic Sea and to approximately 55% along the British coast in the Irish Sea. Local winds on the Irish Sea have less of an impact on storm surge heights than previously reported; the Irish Sea surges are predominantly caused by the propagation of external surges into the basin from the north and south channels. An analysis of sea level variability due to wind or pressure was undertaken to select regions of positive and negative interactions. Negative correlation between wind and pressure-driven surges found in the Celtic Sea explains generally low magnitudes of surges in this region, while medium level correlation coefficients could be responsible for generally high surges in the eastern Irish Sea and coast of Scotland. Following a regression analysis, it was determined that in these regions a drop of atmospheric pressure by 1 mbar implies a rise of sea level by 1.2 cm. Non-linear tide–surge interactions are also investigated. Relationships between surge and tidal phase are determined at numerous locations in the Irish coastal waters. Analysis shows that interaction characteristics vary from site to site due to shallow water dynamics and variations in topography. The regional pattern of tide–surge interactions is quite remarkable. Finally, a characterisation of the statistical properties of extreme surges is given. An efficient approach is adopted considering statistics of extremes. A hybrid GEV-EV1 statistical solution was used to estimate the 10, 50 and 200-years extreme surge in the Irish coastal waters.

Sea-level fluctuations in the fleet, an English tidal lagoon

Tidal elevation data are presented for places along the length of the Fleet, which is a tidal lagoon behind Chesil Beach on the south coast of England. Harmonic analysis of the data is not able to represent the observations adequately, particularly at the inner end of the lagoon. However, careful inspection of the data shows that the tidal regime is capable of being understood in terms of the non-linear propagation of long waves in very shallow water. Distortion of the tidal wave by unequal progression speeds of high and low water, and the set-up of mean level by frictional effects, are shown to be the important physical mechanisms controlling the observed water level fluctuations. A one-dimensional numerical model which incorporates these processes is able to reproduce the observations satisfactorily. Whilst the model predicts strong effects of wind stress, the meteorological influences in the observed data appear to be largely due to external surges in the English Channel which propagate into the lagoon through its entrance.

On the importance of atmospheric pressure gradients for the generation of external surges in the North Sea

On the importance of atmospheric pressure gradients for the generation of external surges in the North Sea

Chain and inductive charging system as a charge-carrying element of the electrostatic generator

A charge-carrying element or chain, for the electrostatic generator, which can be charged or discharged by the electric induction method, has been developed and used in the generator of the Kyushu University with excellent performance. High stability and durability of this system has been well tested through the operation in the last few years. This charge-carrying system is particularly suitable for use in an insulation gas, like freon-12 or SF 6, which has a high dielectric strength but is easily decomposed by corona discharge. Fluctuation of the charge carried by the chain, or that of the generated voltage, is extraordinarily small. The chain is well protected against the external surges since the series of metal rings of the chain serves as spark gaps to prevent damage of the internal insulator. The highest voltage so far obtained with this charging system was 8.9 MV (the height of the stack is 5 m).

Surge Voltages in Residential and Industrial Power Circuits

Special instrumentation was developed for monitoring the magnitude and frequency of occurrence of surge voltages in residential and industrial circuits. Over a period of 2 years, more than 400 locations in 20 cities were surveyed. Monitoring was accomplished by automatic recording cathode-ray oscilloscopes and simple surge counters. In residential circuits, two significant sources of surge voltages were identified: load switching within the house, and external surges, most likely associated with lightning, coming through the service drop. In industrial circuits, the levels of surges are lower than in residential circuits. However, switching surges on the load side of the switch can be severe. Internally generated surges as high as 2500 volts were recorded during this test program, and surges due to lightning reaching 5600 volts have been recorded on a 120-volt overhead distribution line.

Research on methods of forecasting storm surges on the east and south coasts of Great Britain

AbstractRecent work at the Tidal Institute has provided means of predicting storm surges at the River Tyne entrance, Immingham, King's Lynn, Lowestoft and Southend in the North Sea and Newhaven in the English Channel, from meteorological forecasts.An investigation of surges at Aberdeen has not resulted in a completely satisfactory method of predicting external surges, which are generated outside the North Sea, so that their effects at ports further south have been allowed for by observing their magnitude at Aberdeen and applying an empirical rule which governs their amplification and rate of travel, after Corkan (1948). The disturbances generated inside the North Sea proper, at all the other North Sea ports except King's Lynn, have been correlated at intervals of 6 hr with quantities representing the tractive force of the gradient winds at chosen points in the sea, assuming a quadratic law of friction. The success of the formulae so produced is fully illustrated. For King's Lynn, tide and surge have been treated as an entity, and high‐ and low‐water heights have been expressed as functions of the corresponding heights at the River Tyne and the local wind strength and direction.The propagation of North Sea surges through the Straits of Dover has been studied using Newhaven observations, and it is shown that they travel from Lowestoft as free progressive waves, being attenuated by half. Depressions in the western approaches to the English Channel are also shown to be responsible for disturbances at Newhaven.