Advantage And Disadvantage Of Hvc

A Power system is an connection of generators to load centres. Through H.V. electrical lines & in general is controlled mechanically. It can be divided into 3 subsystems: Generation, X’mission and Distribution-systems. The electric power demand is Growing and building of new generating units & transmission circuits is becoming difficult because of environmental & economic reasons. So, power utilities are forced to depend on utilization of existing generating units and to load existing lines close to their heating limits.

It is observed that the power factor is maintained closer to unity when the input voltage is reduced from 230V to 110Vrms. Figure 11 (a) and (b) shows the power factor correction of controller for various load condition such as 20% (60W) and 75% (230W). The power factor for the system is found to be 0.84 for light load condition and 0.99 for full load condition. The THD of input current at full load with predominant third and fifth harmonic components are shown in Figure 12(a) and (b).Third harmonics is found to be 4.8% and fifth harmonic component is 4.9% which are well within IEC 61000-3-2 standard during wide range of load variations. The variation in power factor with load is shown graphically in Figure 13(a). It can be inferred from the graph that improved resettable control operates at high power factor for all load condition whereas the conventional PI control has poor power factor under light load conditions. Figure 13(b) shows the comparison between the efficiency of the converter for varying load conditions with the conventional control method and the resettable integrator control. The converter’s efficiency is maintained at 92% for light load conditions and 96% for fully loaded condition with integrator control technique. Thus the improved resettable integrator controller provides a very simple and reliable solution for power factor correction and

Fig. 5.12. Control of the dc–dc converter with FLC to produce less power under voltage sag: grid voltages, related grid currents, related dc-link

The DVR is one of the most common and effective solutions for protecting critical load against voltage sags [10] [11]. The DVR is a power electronic device used to inject three-phase voltages in series and in synchronism with the distribution feeder voltages in order to compensate for voltage sags. Moreover, it can be efficiently used to augment the fault ride through capability in wind applications. Detection time is an important factor in the voltage restitution process. Fast detection

The problem of the reactive power compensation in the conventional HVDC LCC transmission is a nagging issue in the subject of the Line Commutated Converter tech-nique of HVDC transmission

D.C Motor is used for variable speed operation because in dc motor torque and flux that can be control independently and that is achieved by armature and field current control respectively. D.C motor has many advantages delivering high starting torque, ease of control and non linear performance. But due to certain disadvantage of dc machine such as mechanical commutator and brush holder required time to time maintenance [1] .So cost of the drive system is increases. But now D.C Motor is less used in industrial applications. Because of low cost, better performance and the requirement of maintenance is less as compared to D.C Motor it make the asynchronous motor advantageous in many industrial applications. SCIM are most widely used than all the rest of the electric motor as they have all the advantages of A.C Motors and are cheaper in cost as compared to slip ring induction motor. Because of absence of slip rings, brush maintenance duration and cost associated with the wear and tear of brush are minimized. Because of these advantages, the induction motor is used in element of most of the electrical drive system for all the conditions like starting, braking, change in speed and speed reversal. To achieve the maximum efficiency of the induction motor drive, so many techniques are developed in the last few years. Now a day’s high switching frequency converters are used for changing the frequency, phase and amplitude of the input to an A.C. Motor can be changed, hence the speed and motor torque can be controlled. With the help of power electronic it is possible to

The combined economic and technical benefits of HVDC transmission can make it a suitable choice for connecting electricity sources that are located far away from the main

This chapter proposes a hybrid stability assessment method, i.e., combine both time-domain and direct methods, for detection, classification and assessment of the transient and small signal dynamic stability. The proposed energy function in chapter 3 is used to calculate the system energy. Then, the overall system energy is compared to the sum of the critical energies of the critical series components which can be determined using the proposed time-to-instability index. The HVDC system impact on the system stability assessment technique is also discussed. A termination criterion for stable cases is proposed to expand the proposed method capability to the dynamic security

A few recent papers [53]-[56] have demonstrated a virtual synchronous machine (VSM) concept, particularly for microgrid applications and usually for distributed generators utilizing the same ac-dc-ac conversion stages. The same concept applied on flywheel based energy storage is discussed in [57]. Given the similarities existed in the MEA power grid and motor controlled thermal storage, it is deemed feasible to implement the VSM concept in this research. A high-level description is shown in Fig. 3. For a synchronous machine in the rotating reference frame, the d-q voltage and current relationship is shown in (1a-b), where vg is the grid voltage, R is the stator resistance, M is the magnetizing, and Ld = Lq = L is assumed. On the other hand, the active front end (i.e., the hex-bridge converter connected to the gird) follows (2a-b) in d-q reference frame at ωc rotating speed, where Rg and Lg are grid tied resistance and inductance, and vc is the output voltage at the converter controlled by modulation index from the dc voltage bus []. The analogy between (1a-b) and (2a-b) is straightforward. By equating the first three terms and varying the modulation indices, md and mq, the active front end mimics the VSM proposed in [ZhongQC]. The purpose of the ac motor-tied inverter (i.e., the left hex-bridge converter in Fig. 3) is to main a constant 270 V dc bus by adjusting the motor speed and torque using conventional vector controls. Given the limited

In the industrial sector the various motoring loads are continuously running and generating the inductive load. So the power factor in this system gets reduced due to the inductive reactive power. But the electricity board has a standard limits regarding the power factor values and if the power factor goes below the specified limit; the electricity company charges the penalty to the industrial consumers. The automatic power factor correction panel provides the required compensation to overcome the inductive reactance by using the power capacitors. The microcontroller PIC receives current signal from current transformer and simultaneously gives the signals to the various contactors to connect the capacitors in the line for the compensation. Thus by adding the capacitor to the line will compensate the reactive power and maintains the power factor near to unity. This will avoids the penalty to the industrial consumers and may get the incentives. In the conventional methods we were using the fixed capacitor for compensation. But these were leading to excessive charging of the capacitors causes the voltage surges. Thus it becomes difficult to main power factor near unity by on and off operation of fixed capacitor. The contactor switched capacitors are connected and disconnected automatically eliminating the previous problem.

A microgrid refers to a small electricity power system that is connected to the utility grid through the point of common coupling (PCC) and uses on-site Distributed Energy Resources (DERs) for the supply of all or part of local demands. Microgrids comprise of a low voltage (approximately ≤ 1kV) or medium-voltage (range 1-69 kV) locally controlled cluster of distributed energy resources that behave, from the grids perspective, as a single load both electrically and in energy markets. Fig. 1 shows the interaction between the two types of electrical systems and their corresponding components interlinked by the power converters. [4] From this figure, it can be revealed that the AC MGs can be connected to the bulk AC system via power transformers and require an AC/DC power converter to interconnect with the bulk DC system.

Abstract— The purpose of this paper is to analyse the impact of three different Flexible Alternating Current Transmission System (FACTS) devices on a power system and to analyse their capabilities with respect to various disturbances. FACTS devices discussed in this paper are Static Var Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC) and Unified Power Flow Controller (UPFC). The impact on power-flow and Power Oscillation Damping due to these devices is analysed in detail. Simulations based on different choices of Power Oscillation Damping (POD) signal are simulated for small and large disturbance incurred on the system. Effect of Linear (residue method) and Non-linear (CLF) based POD signals on the system is shown in the paper. Impact of each device is considered separately followed by a comparative study between them. All simulations are done with the help of SIMPOW© and all figures are plotted in MATLAB©.

Abstract—Different converter topologies have been introduced for high power applications in recent years. This paper shows Permanent Magnet Synchronous Motor in Hybrid electrical vehicle is proposed by an interface of boost converter, interleaved converter and inverter as an integrated circuit. An inverter/converter circuit is designed in such a way so as to operate or control the HEV during different modes of operation. The integrated circuit in HEV will operate as a boost converter or interleaved converter depending on the load condition. The proposed integrated circuit will reduce the current ripple and voltage ripple hence it will leads to reduction in switching, conduction losses, and thermal stress on the motor. The effectiveness of proposed integrated circuit is simulated in MATLAB/ Simulink. The simulation shows that the integrated circuit have a high efficiency and can be used at high power application.

IN RENEWABLE dc-supply systems, batteries area unit usually required to back-up power for electronic equipment. Their voltage levels are generally abundant under the dc-bus voltage. Bidirectional converters for charging/discharging the batteries area unit thus needed. For high-powered applications, bridge-type bidirectional converters have become a very important analysis topic over the past decade. For raising power level, a dual full-bridge configuration is sometimes adopted

Abstract: DC microgrid is the high quality electric power system focused on the development of renewable energy resources. The dc distribution system is connected to AC grid, Photovoltaic system and synchronous generator. Moreover, the power is transmitted through dc distribution line and is converted to required AC or DC voltages by load side converters. Those converters do not require transformers by choosing proper DC distribution voltage. The DC power line is 400V. This distributed design of load side converters also contributes to provide supplying high quality power. In this research, the configuration of DC microgrid system, control methods of distributed generation will be presented. Moreover, stand-alone system and grid connected system of DC microgrid will also be expressed. The model of DC microgrid system will be constructed with MATLAB/SIMULINK. Simulation results will be described.