In this paper, a novel and effective tidal pitch system is proposed in which hydraulic servo and bevel geared transmission are employed to highly enhance the pitch control accuracy. The tidal pitch system has compact and stable structure, and is readily sized and installed into the front inner narrow space of the turbine hub. The excellent characteristic of the bevel geared transmission can also guarantee smooth and direct pitch actions. The dynamic characteristics of the pitch system is modelled and analyzed, and external loads and disturbances are also considered and integrated into the overall system model. An efficient and robust UDE based pitch control scheme is then designed. The UDE control has been successfully applied to a wide class of linear, nonlinear uncertain systems and is easy to be implemented and tuned while offering better robust performances than the traditional control schemes . It includes 3 inherent design freedoms: a reference model, an error feedback gain and a filter, which enables high decoupling between reference tracking and disturbance rejection . The UDE based robust control is also able to achieve good robust performance by estimating and compensating the unknown dynamics and disturbances in a system with a filter having the appropriate frequency characteristics . The UDE based pitch control scheme is designed in a composite hierarchical manner that includes an upper level generator power smoothing controller and a low level pitch angle tracking controller. The main contributions and novelty of this paper are highlighted as follows.
multilevel of genes as demonstrated in Figure 2 showing the HGA chromosome representation with one-level control genes and parametric genes. With this configuration, the control genes are analogous to the PSS locations. The control gene signified as “0” in the corresponding site, is not being activated meaning that the PSS at the corresponding location will not be installed into the powersystem during the simulation. Parametric genes are analogous to the PSS parameters to be optimized. Using the HGA concept, locations and PSS parameters can be simultaneously tuned. Fig. 2 illustrates the interface system of HGA chromosome structure and simulation package for calculating the fitness value. In many cases, other scenarios may be added arbitrarily by users depending on the critical events in powersystem operation. By HGA, it provides more flexibility and assures us that the optimal solution will always exist without biasing from the initial location determination.
The paper introduces the proposal of the hierarchical expert system which evaluates the impact of economic entities on the social environment. The system core was described in detail – the concept of the corporate social responsibility (level one – see Fig. 1). Four main fields were mentioned – the pillars of the corporate social responsibility; they undoubtedly have an influence on their surrounding environment and the life standard of the society. Individual economic entities fulfil their social activities just within the frame of these pillars, even though they very often do not realize the positive impacts of their behaviour on the society or do not know about them. But if we want to achieve positive changes in the society, it is necessary to begin with every individual, every particular entity in harmony with the idea „think globally, act locally“. We all realize that we are a part of the global world and that acts of each individual can have a worldwide dimension. That is why it is necessary that economic entities (small and medium‑sized enterprises of a local character) realize the same thing and, at the same time, do not get distant from local current events. They should also be solidary and helpful in their activities, more responsible and frugal towards human resources and nature in general. However, turning the attention to local markets does not mean establishing protectionism or cutting off from the world production. Economic entities of small and medium size have a huge power to contribute to rising basic economic indicators, the local employment and economic growth in particular.
In this contribution, standard hierarchical T-splines and truncated hierarchical T-splines have been considered in a unified framework, see Equation (23). Explicit basis function operations are avoided, as only matrix manipulations have to be carried out. Hence, the efficiency of the proposed approach is superior to that of recent implementations of hierarchical T-splines . We note that, in particular, truncated hierarchical T-splines can be applied without explicit truncation of the basis functions. Therefore, the innovative aspect of this work is the multi-level implementation of hierarchical T-splines by using Bézier extraction in an efficient way without basis function operations. The extension of the method to three dimensions case is straightforward by employing Bézier extraction to analyse cases as in [31, 32].
dc power into ac power. Since the output voltage of solar cell array is low, dc/dc power converter is used in small capacity solar power generation system to boost the output voltage so it can match the dc bus voltage of the inverter. A filter inductor is used to process the switching harmonics of an inverter, so the power loss is proportional to the amount of switching harmonics. The control circuit not only provides PWM signals to switches of two power stages, but also traces maximum PV module energy as well as real time grid detection and protection. The efficiency of conventional boost converter is restricted by duty ratio for higher output voltage. Theoretically, when duty ratio is closed to unity the voltage gain will be infinity.
Abstract. In the domain of many relevant classification problems, classes are organized in hierarchies, representing specialization relationships between them. These are the so-called hierarchical classification problems. Methods based on different approaches have been used to solve them, trying to achieve better predictive performance. In this work, we propose two local per levelhierarchical classifiers, which contain distinct strategies to solve inconsistent predictions, common to the local per level approach. We have compared the proposed methods with traditional strategies from different paradigms. The computational experiments, conducted over 18 hierarchical classification data sets, showed that the proposed ideas were able to reach competitive and robust results in terms of prediction accuracy.
ABSTRACT: This paper proposes a seven-level inverter for a solar power generation system. The new solar power generation system is composed of a dc/dc power converter and a new seven-level inverter. The dc/dc power converter converts the output voltage of the solar cell array into two independent voltage sources with multiple relationships. This new seven-level inverter is configured using a capacitor selection circuit and a full-bridge power converter, connected in cascade. The capacitor selection circuit converts the two output voltage sources of dc-dc power converter into a three-level dc voltage, and the full-bridge power converter further converts this three-level dc voltage into a seven-level ac voltage. The salient features of the inverter are that only six power electronic switches are used, and only one power electronic switch is switched at high frequency at any time
Abstract— With the advent of complex systems the need for large data storage with less space utility & high performance have become the vital features. Another important concern of the data is the security which is assured via the cryptographic techniques implemented at all levels of data storage. In this survey paper we introduce the concept of security between two hierarchical data accesses and propose the concept of hierarchical cryptography between data of different classes of different hierarchies. Keywords— Hierarchical inheritance, cryptree, cryptographic file system, Elliptical curve, Dual level key management, Chinese Remainder Theorem, cipher text policy attribute based encryption, Two level based Encryption construction.
The operation of mode 4 is shown in Fig. 4.3(d). Both SS1 and SS2 of the capacitor selection circuit are off. The output voltage of the capacitor selection circuit is Vdc/3. Only S4 of the full-bridge power converter is on. Since the output current of the seven- level inverter is positive and passes through the filter inductor, it forces the anti-parallel diode of S2 to be switched on for continuous conduction of the filter inductor current. At this point, the output voltage of the seven- level inverter is zero. Therefore, in the positive half cycle, the output voltage of the seven-level inverter has four levels: Vdc, 2Vdc/3, Vdc/3 and 0.
Since it is difficult to create an asymmetric voltage technology in both the diode-clamped and the flying capacitor topologies, the power circuit is complicated by the increase in the voltage levels and H-bridge inverter to allow more levels of output voltage in this eight power electronic switches are used more recently various topologies for seven level inverters has been proposed. This seven-level grid-connected inverter contains six power electronic switches. However, three dc capacitors are used to construct the three voltage levels, which results in that balancing the voltages of the capacitors is more complex. In a seven-level inverter topology, configured by a level generation part and a polarity generation part, is proposed. There, only power electronic switches of the level generation part switch in high frequency, but ten power electronic switches and three dc capacitors are used. In a modular multilevel inverter with a new modulation method is applied to the photovoltaic grid-connected generator.
This section provides a brief review of accident causation models (Figure 1). The earliest accident causation models which came from industry safety (called occupational safety) placed an emphasis on the factors connected to workers protection from injury, illness, and death. The focus was on unsafe conditions and technological development in industrial accident prevention, such as open blades and unprotected belts. As a result, the most obvious workplace hazards were eliminated and the injuries started to diminish while technology became increasingly reliable. The focus then shifted from unsafe conditions to unsafe acts (human error). Accidents began to be considered as someone’s mistake rather than a condition that could have been prevented by applying hazard removal in the workplace (Leveson, 2011; Hollnagel, 2004). Thus, accident records guided our attention to human error analysis. The researchers moved into studies of the management’s role organizing the work place for operators. It was found that it is necessary to look at the decision errors at the management level. Figure 1 shows the development in the type of accident causes during the last century. According to this, the main models of accident
As seen in Fig. 4, the utility current is detected and sent to an RMS detection circuit. The output of the RMS detection circuit is sent to a hysteresis comparator that contains a low threshold value and a high threshold value. If the RMS value of the utility current is smaller than the low threshold value, the output of the hysteresis comparator is high, meaning the condition of islanding operation or power balance occurs. On the contrary, the output of the hysteresis comparator is low when the RMS value of the utility current is larger than the high threshold value, meaning the utility is normal. The output of the hysteresis comparator is sent to a signal generator. The output signal of the signal generator is an islanding control signal S a . The islanding control signal is a dc signal with unity amplitude if the output
round to the base station. The constrained load on the elected cluster heads during the 400 round of simulation drastically reduced the CHs’ energy over a short period. Unlike the non-hierarchical formation, the proposed hierarchical routing technique in which cluster hierarchy takes precedence in cluster formation and evaluate the residual energy for selection of cluster head, we observed that this technique offers a better life span for individual nodes and even the entire network. With optimization in energy usage, we observed that the lifetime in our proposed hierarchical technique extends to an impressive range when compared to non-hierarchical technique. The impressive increment in life span of the network from our proposed hierarchical technique is seen as a result of efficient routing decision and optimization of energy in cluster head selection of each cluster formed. Since the sensor nodes in each cluster send data to the cluster head within its cluster range and then the aggregated data is sent to the cluster head closer to the base station, which further aggregates data of its own cluster and that of the incoming data, from cluster head whose distance is farther to the BS, before sending the data to the base station. Thus, a considerable amount of energy is saved which indicate improved network lifetime in the case of first level hierarchy when compared to non hierarchical technique. From Fig. 6, we observed that the Non-hierarchical technique had an estimated lifetime of 20 rounds, First level had an estimated lifetime of 30 rounds and Second level had an estimated lifetime of 40 rounds. The progressive increase of network lifetime employed by our proposed technique offers efficient energy usage for each node in the entire network
The demand of static compensator(STATCOM) and static synchronous series compensator(SSSC) is increasing day by day because these are the flexible ac transmission systems(FACTS) controllers for high power applications. The reason for increasing demand is, these improve the power quality(PQ) is distributed systems and ability to stabilise the transmission systems. Conventional var compensators are replaced with STATCOM as it is reliable for reactive power controller. Some of static var compensators are like thyristor controlled reactor(TCR) and thyristor switched capacitor(TSC). STATCOM provides active power oscillation damping, reactive power compensation, voltage regulation, flicker attenuation etc.
The IPC is not a new technology but almost unknown among power engineers. Its working mechanisms, flexibility and speed of response put this technology in the category of the FACTS devices. It is a series connected device, which the major components in each of the phases are a reactor and a capacitor subjected to individual phase shifted voltages provided by two phase shifting transformers (PST). There are many IPC formations, depending on specific application requirements and on the method used to implement the internal consist of only passive elements including inductors, capacitors and PST (Chitra Selvi, 2008). An IPC with electronically switched phase shifting devices add dynamic regulation capabilities to the powersystem. As a consequence, not only the steady state stability properties but also the transient stability performance of the powersystem is enhanced, remarkably. After disturbances such as line outages, electronically based IPC can quickly redistribute the power INTERNATIONAL JOURNAL OF CURRENT RESEARCH
This paper presents a configuration with structure electrical converter with six-phase induction motor, this configuration proposes force management of 2 pole induction motor in rotating system. The model is simulated in Simulink atmosphere to guage its performance beneath load and no-load conditions. The results show reliable and smart performance of the motor. Total circuit is simulated in MATLAB simulink.
There are a large number of publications on integration of renewable energy systems into power systems. A list of com- plete publications on FACTS applications for grid integration of wind and solar energy was presented in . In , new commercial wind energy converters with FACTS capabilities are introduced without any detailed information regarding the efficiency or the topology used for the converters. In , a complete list of the most important multilevel inverters was reviewed. Also, different modulation methods such as sinusoidal pulsewidth modulation (PWM), selective harmonic elimination, optimized harmonic stepped waveform tech- nique, and space vector modulation were discussed and com- pared. Among all multilevel topologies –, the cascaded H-bridge multilevel converter is very well known for STATCOM applications for several reasons –. The main reason is that it is simple to obtain a high number of levels, which can help to connect STATCOM directly to medium voltage grids. The modular multilevel converter (MMC) was introduced in the early 2000s , . Refer- ence  describes a MMC converter for high voltage DC (HVDC) applications. This paper mostly looks at the main circuit components. Also, it compares two different types of MMC, including H-bridge and full-bridge submodules. In  and , a new single-phase inverter using hybrid- clamped topology for renewable energy systems is presented. The proposed inverter is placed between the renewable energy source and the main grid. The main drawback of the proposed inverter is that the output current has significant fluctuations that are not compatible with IEEE standards. The authors believe that the problem is related to the snubber circuit design. Several other applications of custom power electronics in renewable energy systems exist, including  an application of a custom power interface where two modes of operation, including an active power filter and a renewable energy STATCOM. Another application  looks at the current- source inverter, which controls reactive power and regulates voltage at the point of common coupling (PCC). Varma et al.
In this paper, we propose a methodology for systemlevelpower model extraction of the NoC router based on heterogeneous macro-models. The systemlevelpower model is built by power macro-models of each component according to their different characteristics: Linear regression is used to obtain the power macro-models for the input buffer, the routing calculation unit and the crossbar switch due to their single data flow state (linear characteristics). The power macro-model for the arbiter is established based on BP neural network because of its multiple states (nonlinear characteristics). Experiment results show that our systemlevelpower model demonstrates less than 5.0% average error as compared with the gate level analysis with 600 times speed up. As can be seen, the model can accurately and efficiently evaluate the average power consumption in NoC router, and provide reliable and fast power simulation to designers at systemlevel. In order to demonstrate the utility of our power
ABSTRACT: Consumer electronics, domestic appliances and a large range of industrial applications, namely power electronics based, can cause high disturbances in the supplied electricity. Normally soft starts are used for avoiding this problem and to achieve smooth starting of large capacity induction motors. A 3- phase AC voltage controller is employed as a soft-start. But, this takes harmonic-rich current especially while operating at large firing angles. In this paper, the effect of inserting a shunt active filter to provide harmonic and reactive power compensation in a soft-start has been studied. The shunt active filter has been inserted between the AC voltage controller and power supply to take care of the reactive power requirement of the motor and AC voltage controller and also to provide harmonic compensation. Therefore, as a result of theses harmonics, a traditional passive filters are used to suppressed the integer multiple fundamental frequencies, but due to the passive filter draws back in producing series or parallel impedance with the supply impedance and heavy in sized, its limitations in service becomes an old scheme. The application of shunt active power filter in mitigating these harmonics problems supersedes the used of passive filter.
Domino CMOS has become a prevailing logic family for 20 many high performance CMOS applications and is used in many state-of-the-art processors due to its high speed capabilities. A decoder is a multiple-input, multiple-output logic circuit that converts coded inputs into coded outputs, where the input and output codes are different. The generation, distribution, and dissipation of power are at the forefront of current problems faced by the integrated circuit industry .