reached during the **Load** **Flow** **Analysis**.
The Swing bus is the only bus at which the power is not specified. Net power flows cannot be fixed in The Swing bus is the only bus at which the power is not specified. Net power flows cannot be fixed in advance at every generating bus, since the network power losses are not known until the study has advance at every generating bus, since the network power losses are not known until the study has been completed. The Swing bus is therefore defined based solely on voltage and angle, leaving the been completed. The Swing bus is therefore defined based solely on voltage and angle, leaving the rest of the variables (kW & kVAR, including system losses) free to adjust (SWING) to the requirements rest of the variables (kW & kVAR, including system losses) free to adjust (SWING) to the requirements of the network. In other words, Active and Reactive Power are the unknown variables of the Swing of the network. In other words, Active and Reactive Power are the unknown variables of the Swing bus.

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power **flow** iterative algorithm and it is applied to a modified IEEE – 30 consisting of two wind farms in order to validate the model. [10] provides a novel method called Nonsy **load** **flow** in which the study has conducted **load** **flow** **analysis** using data that is unsynchronized and is obtained from diesel generators and the main substation in their network. Once this data is obtained other parameters of the network are solved using backward/forward sweep methods. This study makes a comparison of the performance of the methods using Matpower applied to two standard IEEE test bus cases.

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Rohit kumar verma 1 , S. N. singh 2
1 M.Tech student, 2 senior scientific officer, Alternate hydro energy centre, Indian Institute of Technology Roorkee Uttarakhand-247667
Abstract— This paper presents a **load** **flow** **analysis** of Mini- grid connected **load** by using MatLab programming of 13 and 33 **load** connected bus. Reactive power compensation is done by using switch shunt capacitor. This method gives the optimal placement of capacitor to inject reactive power in Mini-grid connected. The used program provides information of voltage at each **load** connected bus. This method helps in providing injection of reactive power at exact location of **load** bus. The MatLab program is very user friendly. This method of compensation is seen to be very effective for radial distribution system to make voltage profile flat.

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The principal information of **load** **flow** **analysis** is to measure the magnitude and phase angle of voltage at each bus and also to find the reactive
power and active power flowing in each of transmission lines. **Load** **flow** **analysis** is an involves numerical **analysis** and its application to a power system. In this **analysis**, we use various iterative techniques because there is no known mathematical method for solving the problem. It results in a number of nonlinear set of equations which are called as **load** **flow** equations.For this **analysis** there are various methods of numerical calculations which involvest many steps depending on the size of system. This process is difficult and takes very large time if performed by hand. So developing a toolbox for **load** **flow** **analysis** surely will help the **analysis** become easier.Load **flow** **analysis** software can help users to calculate the **load** **flow** problem. They are necessary for planning, operation, economic scheduling and exchange of power between different utilities. The basic information involves in **analysis** of power **flow** is to estimate the magnitude and phase angle of voltage at each bus and estimating the **flow** of real and reactive power through various transmission lines.

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The paper helps to know the basic of Optimal **Load** **Flow** **Analysis** of power system. **Load** **Flow** **Analysis** are used to validate that the power transfer from generators to consumers through the grid system is stable, reliable and economical. **Load** **flow** **analysis** is very useful for stabilityanalysis, future expansion planning and in determining the best economical operation for existing systems.

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ABSTRACT: Even though real world **analysis** is non-linear and uncertain, most of the power system network analyses are the approximation rather than the worst case results. One of the power system network **analysis** mechanisms which is based on deterministic input is a **load** **flow** **analysis**. Due to the penetration of renewable energy sources and the environmental temperature change, power system network inputs are no longer constant rather varies between upper and lower extremes constantly. The main **load** **flow** **analysis** constants considered to vary with the variation of input are the active and reactive power at the generator and the buses. In order to get a **load** **flow** solution for the varying input power a probabilistic **load** **flow** **analysis** based on complex affine arithmetic (CAA) is proposed and tested on standard IEEE 57 bus systems. The result is validated by its mid way conservation of the deterministic **load** **flow** **analysis** result and a probabilistic Monte Carlo approach.

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The importance of the problem and the aforementioned difficulties have produced a rich literature. Commonly used **analysis** model in power system is **load** **flow** **analysis**. The calculation of the **load** **flow** in the transmission lines and the transformers is called **load** **flow** **analysis**. It is necessary that not overloading of transmission lines and transformers in power systems, the voltages remain within certain limits for all buses and generator's reactive production to remain within acceptable limits.

Fig 2. Under voltage (kV) on the buses
Fig 3. Percentage of overload on transformers
V. C ONCLUSION
In this study, a comprehensive study for **load** **flow** **analysis** in distributed power system was presented. Besides, a case study of modelling, simulation, and **load** **flow** **analysis** of the actual distributed power system of Tehran metro (line 2) using ETAP is implemented. In this paper, a comparison of three common **load** **flow** techniques including Newton-Raphson, Fast Decoupled, and Accelerated Gauss-Seidel was presented; the numerical methods of **load** **flow** were compared; the theoretical and practical approaches of **load** **flow** have been learned, compared, and applied to solve the tasks given. The results of **load** **flow** assessment (total generation, loading, demand, and power losses) were obtained and analyzed. In addition, a **load** **flow** based simulation using ETAP were developed to find out the optimum location of distribution system unit for **load** profile improvement and minimizing power losses in the test distribution system. In order to improve speed performance and computational accuracy in power system **analysis**, using powerful software like ETAP is very practical and helpful, and it also offers a better view of the power network. Further research work can be done for finding more powerful methods to solve the power **flow** equations with more efficiency in terms of time, computer memory storage as well as robustness. In addition, understanding the best way of **load** **flow** is economical, and therefore which can be a hot topic for future studies of the power distribution system.

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[5] abhayengineer01@gmail.com
Abstract
This paper addresses the comparative **load** **flow** **analysis** with and without Unified Power **Flow** Controller (UPFC) for six buses, three phase transmission line under unsymmetrical faults (L-G, L-L and L-L-G) in simulation model. Unified Power **Flow** Controller (UPFC) is a typical Flexible AC Transmission System (FACTS) device playing a vital role as a stability aid for large transient disturbances in an interconnected power system. The main objective of this paper is to improve transient stability of the six bus system. Here active and reactive power on **load** bus of the system considered has been determined under different fault conditions. UPFC has been connected to the system and its effects on power **flow** and voltage profile of test system has been determined with various line data and bus data for six buses, three lines power system and simulation model by using simulation toolbox has been developed. In this work a versatile model is presented for UPFC inherent order to improve the transient stability and damp oscillation.

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S.Ghosh and D.Das [16] 1.58 1.45 1.93 Ranjan and D.Das [19] 1.79 1.63 2.10
VII. C ONCLUSION
A new method for **load**−**flow** **analysis** has been proposed in this paper for radial distribution networks that does not need the exhaustive line data preparation for branch number, sending−end node and receiving−end node. For sequential numbering scheme it needs the starting node of feeder, lateral(s) and sub lateral(s) only. Effectiveness of the proposed method has been tested by three examples (29−node, 33−node and 69−node radial distribution networks) with constant power **load**, constant current **load**, constant impedance **load**, composite **load** and exponential **load** for each of these examples where the voltage convergence has assured the satisfactory convergence in every case. The proposed method can handle arbitrary numbering scheme also. The superiority of the proposed method in terms of speed has been checked by comparing with the other methods proposed by Das et al. [15], Ghosh et al. [16] and Ranjan et al.

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Besides giving real and reactive power the **load** **flow** study provides information about line and transformer loading through Out the system and voltage at different point in the system for evaluation and regulation of the performance of the power systems. Growing demand of the power and complexity of the power system network, power system study is a signification tool for a power system operation in order to advent of digital computers, **load** **flow** solutions were obtained using network analysers **load** **flow** **analysis** used in different method [1]. Every method has got advantages as well as dis advantages. The objective of this papers is to develop an MATLAB Simulink model to perform **load** **flow** **analysis** for IEEE 30 bus system. In this bus system provided data form generation bus, shunt capacitor, transmission line, **load** on bus. But MATLAB Simulink model calculated data for series admittance (conductance and susceptance), value of inductor and capacitor.

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Given these valuable traits of OpenMDAO, the calculations needed for a hybrid AC-DC **load** **flow** capa- bility were implemented within the framework and will be described in the subsequent sections. While **load** **flow** **analysis** is typically only applied the AC systems, a hybrid AC-DC **load** **flow** method 11 was identified that enabled creation a system to capture both types of electrical systems. From this publication, a set of 10 objects which would be needed to model almost any electrical system were identified. These objects include AC and DC versions of the bus, line, generator, and **load**. In addition, components modeling an inverter and a rectifier are required to convert between the two different voltage sources. The sections below describe the AC versions of the bus, line, generator and **load** components as well as the converter which were developed in this research. The DC components are not described but are identical to their AC equivalents with the exception of the imaginary terms and phase angles in the equations. This separation of AC and DC components was made to maintain clarity in the use of these components and to simplify the computation of analytic derivatives in each of the developed components. In addition to the equations presented in each of the sections below, analytic expressions for partial derivatives of each output with respect to the each input were determined by symbolically differentiation and included in the code. These partial derivatives are key to enabling the rapid solution of the **load** **flow** problem as well as for multidisciplinary optimization around a **load** **flow** model.

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5. Stochastic Search Techniques 5.1. General Principles
Recent developments in **load** **flow** **analysis** have moved attention away from the iterative methods and towards so-called stochastic search methods. Two such methods – Genetic Algorithms and Simulated Annealing – are described here and are implemented in the Excel Workbook. Both approaches use a series of trial solutions to the problem and develop better solutions in the light of experience gained from these trials. The computational effort for each trial is kept as low as possible, so a very large number of trials can be conducted.

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Assistant Professor in ECE dept at Scient Engineering College ,Nadurgul, Hyderabad ,Telangana, India
Abstract: This paper presents the modeling of shunt Distribution FACT device in **load** **flow** **analysis** for the steady state voltage compensation and loss minimizations. For this purpose, Distribution STATCOM (D-STATCOM) is considered as shunt compensator. An accurate model for this device is derived to use in **load** **flow** **analysis**. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u) are derived and discussed analytically and mathematically using phasor diagrams. Since performance of D-STATCOM varies when it reach to the maximum capacity, modeling of this compensator in the maximum rating of reactive power injection are derived and discussed. The validity of proposed model for fixed compensation and compensation for fixed voltage is examined using MATLAB coding for two IEEE standard distribution systems consisting of 33 and 69 nodes respectively. The best location of D-STATCOM using Rate of under Voltage Mitigation node (RUVMN) in the distribution network is determined.

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Electrical loads of a system can be advised to contain different private, mechanical and metropolitan burdens.[1] For all intents and purposes the dynamic and receptive forces of heaps of an appropriation system are reliant on system voltage and recurrence varieties. Likewise, the dynamic and receptive power qualities of different sorts of **load** vary from each other. Recurrence deviation is viewed as unimportant in the event of static investigation like, **load** stream concentrates AN OVERVIEW OF **LOAD** **FLOW** **ANALYSIS**

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In this paper, distribution **load** **flow** **analysis** was done by using forward sweep through ladder network technique. The mathematical modeling of D-STATCOM was derived and optimal placement of D-STATCOM in a distribution network is identified. This paper is carried out with both fixed compensation and fixed voltage compensation D-STATCOM and comparison had made between them. This proposed model for D-STATCOM is applied to **load** **flow** calculations in IEEE 33 and 69 bus test systems. Moreover, the optimal placements of D- STATCOM for under voltage problem mitigation approach in the test systems are derived by using RUVMN.

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KEYWORDS:Load **Flow** Studies, Y-matrix and Z-matrix iteration, Newton-Raphson method, Fast Decoupled method, Fuzzy logic, Artificial Neural Network.
I.INTRODUCTION
Besides giving real and reactive power the **load** **flow** study provides information about line and transformer loading (as well as losses) throughout the system and voltages at different points in the system for evaluation and regulation of the performance of the power systems. Further study and **analysis** of future expansion, stability and reliability of the power system network can be easily analyzed through this study. Growing demand of the power and complexity of the power system network, power system study is an significant tool for an power system operator in order to take corrective actions in time. The advent of digital computers, **load**-**flow** solutions were obtained using network analyzers. The first practical automatic digital solution method appeared in the literature in 1956.

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INTRODUCTION
The **load**-**flow** problem models the nonlinear relationships among bus power injections, power demands, and bus voltages and angles, with the network constants providing the circuit parameters. It is the heart of most system-planning studies and also the starting point for transient and dynamic stability studies. This section provides a formulation of the **load**-**flow** problem and its associated solution strategies. An understanding of the fundamentals of three-phase systems is assumed, including per-unit calculations, complex power relationships, and circuit-**analysis** techniques.

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operation, fossil fuel emissions
3.1 IMPORTANCE OF **LOAD** MODELLING :
The choices regarding system reinforcements and system performance is mostly based on the results of power **flow** and stability simulation studies. For performing **analysis** of power system, models must be integrated to include all relevant system components, such as generating stations, sub stations, transmission and distribution peripherals and **load** devices. Much attention has been given to modelling of generation and transmission or distribution devices. But the modelling of loads have received much less attention and remains to be an unexplored frontier and carries much scope for future development. Recent studies have revealed that representation and modelling of **load** can have a great impact on **analysis** results. Efforts in the directions of improving **load**-models have been given prime importance.

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