DVR is of great importance in present day’s power system. DVR is used to protect sensitive loads against voltage disturbance can occurs into two forms either voltage or voltage swell. it is a type of forceful or solution of power system application fault at either the transmission or distribution level may cause voltage sag and swell in the entire system or a large part of it. Voltage sag occurs at any time in the system. The ratio of the amplitude is 10-90% and the time duration can take a half cycle of one minute .
In recent years, lack of new generation and with the increased loading of transmission and distribution lines, transmission networks have forced power transmission and distribution systems to operate closer to their security limits. Voltage instability problem has become a concern and serious issue for power system planners and operators. The main challenge of this problem is to narrow down the locations where voltage instability could be initiated and to understand the origin of the problem. As a result some voltage stability indices have been proposed to identify weak nodes for protective measures, which helps proper placement of reactive power compensator and distributed generators for enhancement of system stability.
ABSTRACT:An electric energy is an essential ingredient for the industrial and all around development of any country. An electrical power system consists of generators, transformers, transmission lines distribution lines etc. Short circuits and other abnormal conditions often occur on power system. The heavy current associated with short circuits is likely to cause damage to equipment, if suitable protective relays and circuit breakers are not provided for the protection of each section of power system. The aim of this paper is to design a real time visualization, monitoring and controlling of electrical distribution system using MATLAB. All the equipment must be visible, all the parameters must be measured and if any fault or abnormal condition occurs in distributed feeders then it should be discriminate from healthy part of power system. It increase reliability of power system. The goal of this paper is to provide a better understanding of the design challenges of electric distribution line monitoring system and identify important research in this increasing important field.
SVC has been examined. In that paper, increase in real power flow and progress in a bus voltage profile are noticed after using the SVC. It is noticed that the bus voltage profiles of the network are also improved. In paper , the uses of series compensation in the transmission system and shunt reactors has been presented. The paper gives focus on design and also the implementation of series compensation to solve the problem of working with reactive power and voltage collapse in transmission lines by simulation methods. In paper , the author discussed series compensation in which a synchronous source is used to implement series compensation. To compensate for the transmission line, this paper show focuses on Static synchronous series compensator(SSSC). In paper , the author did a work on the south-Eastern part of Romanian power grid (Dobrogea - a peninsular area), to increase the transfer capacity to the rest of the grid. The situation considered the present topology and also future developments of the transmission network. Paper  works with AC power transmission system and shows the benefits of using FACTS devices on it. The overall process for this system studies and analysis with FACTS installation projects and the paper also discussed the necessity of FACTS devices. Here have an introduction to the elemental circuits of different types of FACTS devices with a focus on system performance characteristics. The reactance value of the transmission and distribution system changes with Series compensation; however, shunt compensation give variation to the corresponding load impedance.
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In present-day dynamic security assessment of a large-scale power system, it is common to represent the bulk generation and higher voltage (transmission) levels accurately, while the lower voltage (distribution) levels are equivalenced. On the other hand, when concentrating on a DN, the TN is often repre- sented by a Thévenin equivalent. The prime motivation behind this practice has been the lack of computational resources. Indeed, fully representing the entire power system network was historically impossible given the available computing equipment (memory capacity, processing speed, etc.) . Even with current computational resources, handling the entire, detailed model with hundreds of thousands of Differential and Algebraic Equations (DAE) is extremely challenging , . As modern DNs are evolving with power-electronics inter- faces, DGUs, active loads, and control schemes, more detailed
In smart grid system use small distributed generators that both make electricity and produce usable heat energy. They make more efficient use of the energy of the fuel that is used; they can relieve stresses on transmission and distribution systems; and, they can increase the reliability of power supply to local customers. In an emergency, it would sometimes be desirable to be able to disconnect a distribution feeder from the main power system. How- ever, with the right technology, control systems, and regulatory environment, there is no reason why we could not do this in a safe and efficient manner. Changes are needed to allow the development and wider use of dis- tributed generation and small micro-grids [6, 8].
Abstract: The smart grid is the integration of electrical and information infrastructures. Here to improve the power communication between generation, transmission, distribution and consumer we required advanced information technology based smart energy monitoring system (SEMS). Hence the advanced information technology need fast and reliable communication protocol i.e. Zigbee, Internet of Things (IoT) and Cloud Computing. These are the communication devices which are used to develop the smart energy monitoring system (SEMS). In future using SEMS easily we can obtain the closed loop communication for developing smart grid. This paper presents the comparison among these three types of SEMS and also get the final solution in which communication protocol suitable for implementation of closed loop communication. The concept of smart grid is combination of smart energy monitoring system, smart energy management system and smart energy control system. In this aspect smart energy monitoring system is the important tool which is interface with the energy management system and energy control system respectively. Hence the SEMS provide the electrical information in real time to energy management system without any delay time; we can obtain the efficient energy management system.
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In present-day dynamic security assessment of a large-scale power system, it is common to represent the bulk generation and higher voltage (transmission) levels accurately, while the lower voltage (distribution) levels are equivalenced. On the other hand, when concentrating on a DN, the TN is often repre- sented by a Thévenin equivalent. The prime motivation behind this practice has been the lack of computational resources. Indeed, fully representing the entire power system network was historically impossible given the available computing equipment (memory capacity, processing speed, etc.) . Even with current computational resources, handling the entire, detailed model with hundreds of thousands of Differential and Algebraic Equations (DAE) is extremely challenging , . As modern DNs are evolving with power-electronics inter- faces, DGUs, active loads, and control schemes, more detailed and elaborate equivalent models would be needed to encom- pass the dynamics of DNs and their impact on global system
Within the transmission and distribution integrated monitoring and analysis system, the transmission data is acquired from the SCADA system and the distribution data through DAS. The DAS system monitors power facilities installed on distribution systems and their operational status in real time, swiftly identifies any functional failure, shortens the time of failure through remote control, and reduces malfunctioning parts to support and ensure a stable power supply. Figure 3 shows the algorithm of the distribution system’s data acquisition in DAS. The data acquired by DAS and SCADA converge in the transmission and distribution integrated analysis and monitoring system, and are combined at the connection point between the distribution and transmission systems. The data conversion program selects a power system subjected to the integrated analysis to perform data merging of the selected distribution systems.
36 | P a g e Figure 1 shows a schematic diagram of a grid-connected PV system which typically consists of a PV array, a DC link capacitor, an inverter with filter, a step-up transformer, and a power grid . The DC power generated from the PV array charges the DC link capacitor. The inverter converts the DC power into AC power, which has a sinusoidal voltage and frequency similar to the utility grid. The diode blocks the reverse current flow through the PV array. The transformer steps up the inverter voltage to the nominal value of the grid voltage and provides electrical isolation between the PV system and the grid. The harmonic filter eliminates the harmonic components other than the fundamental electrical frequency. Figure 2-4 shows two basic storage architectures commonly found with grid-connected PV systems. This arrangement leaves the inverter to provide backup battery charge control from the utility power grid when insufficient PV power is available, but does not allow efficient extraction of excess PV power for supply to the grid when the batteries are fully charged.
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Abstract: The energy transition towards renewable and more distributed power production triggers the need for grid and storage expansion on all voltage levels. Today’s power system planning focuses on certain voltage levels or spatial resolutions. In this work we present an open source software tool eGo which is able to optimize grid and storage expansion throughout all voltage levels in a developed top-down approach. Operation and investment costs are minimized by applying a multi-period linear optimal power flow considering the grid infrastructure of the extra-high and high-voltage (380 to 110 kV) level. Hence, the common differentiation of transmission and distribution grid is partly dissolved, integrating the high-voltage level into the optimization problem. Consecutively, optimized curtailment and storage units are allocated in the medium voltage grid in order to lower medium and low voltage grid expansion needs, that are consequently determined. Here, heuristic optimization methods using the non-linear power flow were d eveloped. Applying the tool on future scenarios we derived cost-efficient grid and storage expansion for all voltage levels in G ermany. Due to the integrated approach storage expansion and curtailment can significantly lower grid expansion costs in medium and low voltage grids and at the same time serve the optimal functioning of the overall system. Nevertheless, the cost-reducing effect for the whole of Germany was marginal. Instead, the consideration of realistic, spatially differentiated time series lead to substantial overall savings. Keywords: power grid modelling; transmission grid planning; distribution grid planning; optimization; linear optimal power flow; power flow; grid expansion; storage expansion; renewable energy
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The power distribution system is made up of sub- transmission lines, power transformers, 33kV lines, 15kV lines, distribution transformers, LV Lines, etc. Currently Ethiopian Electric Power system has 400kV, 230kV, 132 kV primary transmission systems and 66kV, 45kV as sub transmission system and 33kV and 15kV as distribution system. At all the 66 or 45kV substations power transformers of various ratings like 25 /12 /6.3/3MVA are installed for step down of voltage to 15kV for feeding to Distribution Transformers. Once the voltage has been lowered at the distribution substation, the electricity flows to industrial, commercial, and residential centers through the distribution system. Conductors called feeders reach out from the distribution substation to carry electricity to customers. Customers require higher quality service due to more sensitive electrical and electronic equipment. The effectiveness of a power distribution system is measured in terms of efficiency, service continuity or reliability, service quality in terms of voltage profile and stability and power distribution system performance .
In bulk power transmission system planning and ope- ration, the present practice is to carry out an N-1 con- tingency analysis . Occasionally, an N-2 security ana- lysis is employed in some stringent cases. However, it is implemented not via an exhaustive search but rather via a partial assessment of the system reserves over a small portion of the transmission network. An N-k security analysis for k > 1 is perceived as being impossible to achieve due to the huge number of cases that need to be investigated. In fact, under the assumption of independ- ence between successive events, it would require check- ing the impact on the system reserve margins of the loss of every k out of N pieces of equipment, which yields a number of cases to be tested that grow exponentially with N. However, it is clear that this chain of contingencies is dependent on each other due to the protection-system interactions, either directly or indirectly via the changes in the distribution of power through the network or due to the possible multiple impacts of a triggering event, such as lightning or other natural hazards. Consequently, the probability of the occurrence of cascading failures is much higher than the probability of a random (i.e. inde- pendent) tripping of k out of N components of the sys- tem.
The Unified Power Flow Controller (UPFC) is a typical FACTS (Flexible AC Transmission Systems) device that is the most sophisticated and complex power electronic equipment and has emerged for the control and optimization of power flow and also to regulate the voltage in electrical power transmission system. This paper propose the real, reactive power and voltage control through a transmission line by placing UPFC at the sending end using computer simulation. The L index is the y is concerned with the ability of a under normal conditions and after being s also become more complicated due dealt with performance analysis of e collapse point and enhancement of
Abstract: Congestion is severe problem that affects the power system security as it violates the various operating limits of the power system so congestion management is an important task for independent system operator. For managing congestion, smart wire module has been used in series with transmission line. When smart wire is connected in series with most congested line, there is improvement in voltage profile, reduction in transmission line loading and losses. Transmission Congestion Distribution Factor (TCDF) is calculated to know congestion in lines and congestion is managed with the help of smart wire module. It is observed that value of TCDF also reduced when smart wire is connected. Work has been carried out on IEEE 15 bus system on MATLAB.
ABSTRACT:This paper proposes a simulink model of wind turbine using induction generator and performance analysis of high voltage direct current power converter station. This paper also shows how wind power can easily be generated with help of induction generator. The need of developing such a system promoted the utilization of non- conventional energy resources like wind power. For a developing country like India the electrical energy much mire required to achieve the estimated targets within the specified period of time. Since the power generation is not only our concern but also power transmission have great importance to transport the electrical energy over long distance easily and efficienctly, which ensures uninterrupted and regulated power supply at load end. Hence this paper also proposes a model to transmit electrical power in DC form. Since it is difficult to load long extra high voltage (EHV) ac lines to their thermal limits as a sufficient margin is kept against transient instability. With the model proposed in this thesis, it will be possible to load these lines close to their thermal limits. The transmission lines are allowed to carry usual ac along with dc superimposed on it.
Nowadays, wireless sensor nodes have played significant roles in the monitoring and control system for various industrial applications to achieve automation, self-awareness and real- time control with great flexibility. The smart grid presents flexible and reliable energy distribution between the supplier control centre and the smart meters on the user-side. In addition to the main power supplier, additional energy generation sources (that may also comprise green energy) are included in smart grid, such as batteries, backup devices, plug- in hybrid electric vehicles (PHEVs), solar cells, and so forth. This aspect of the smart grid is expected to contribute to a quite complicated real-time consumer power demand management. A smart grid would help the utilities get information about the electricity use by the consumers and can potentially adapt its distribution process with respect to the time and quantum of power demand. The smart grid, which uses smart meters could potentially be used for detecting power theft. In addition, the information that the consumers would have access through the smart meters would possibly help them manage their energy use in a better and more efficient way.
ABSTRACT:A high-voltage direct current (HVDC) electric power transmission system uses direct current for the bulk transmission of electrical power over a long distance and our basic requirement of transmitting large amount of power over a long distance with minimum losses. The converter transformer is an integral part of an HVDC system. The major loss in the converter transformer is a harmonic loss. This paper presents review in literature of converter transformer based on HVDC system. Traditional converter transformer produces more harmonic current. So to overcome the existing problem of the traditional converter transformer, new converter transformer and an inductive filtering method are presented in this paper.
The inﬂuence of the distance on the ultrasonic energy is shown in Fig. 7. In Fig. 7, the horizontal axis represents the distance from the receiving transducer to the transducer of the transmitting end, and the vertical axis represents the power after normalization. It can be seen from Table 2 and Fig. 7 that when the frequency is 20 kHz and the distance 1.8 cm, the maximum transmission power is 1.60 W. As the distance increases, the power received by the receiving end gradually decreases. At diﬀerent frequencies, when the frequency is 28 kHz, the maximum power of 1.92 W is obtained at 1.8 cm, and at 40 kHz, the maximum power of 3.31 W is obtained at 1.8 cm. At the same time, it can be seen that the simulation and experiment are consistent from the normalized simulation data and experimental data trends in Fig. 7.
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Modern electric drive has many advantages over competing mechanical systems. The advantages include redundancy, reliability, better fuel economy and reserve power when needed, better use of internal space allowing revenue producing space, quietness, easier maintenance and improved ship safety. A conceptual design has been developed under an Office of naval Research contract for a 25MW, 120rpm, HTS motor for ship propulsion. In order to demonstrate the key technologies employed for the 25MW motor, a 5MW motor preliminary design has been completed.
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