Power Flow In Transmission Line Research Articles

Analysis of Reactive Power Flow in an Electric Power System

Optimal power flow analysis is a calculation to minimize an objective function, namely generation costs or transmission losses by regulating the active power and reactive power generation of each interconnected power system generator by taking into account certain limits. The growth of industrial loads which are dominated by inductive loads requires a fairly large reactive power supply. This reactive power requirement will of course reduce the available power that can be transmitted to the load. Reactive power flow in transmission lines will reduce the active power distribution capacity required by the load. Reactive power flow that is too large can also cause losses. However, this reactive power is also an important component in the stability of the electric power system. For this reason, the flow of active and reactive power in transmission lines needs to be regulated so that the capacity and stability of the electric power transmission system is maintained.

Integration of optimal power flow with combined heat and power dispatch of renewable wind energy based power system using chaotic driving training based optimization

Combined heat and power economic dispatch (CHPED) based optimal power flow (OPF) problem has been studied in this article using a new, practical approach based on chaotic driving training optimization (DTBO) (CDTBO). In the proposed technique (CDTBO), the chaotic based learning is integrated with DTBO to overcome the local optimal problem and inferior convergence speed of the existing algorithms. OPF is an important concern to retain the power system running effectively. In order to meet the demand for reasonably priced power generation with optimal power flow in transmission lines, the authors combined CHPED and OPF. Since fuel is changing daily in the current environment, using renewable energy sources to generate electricity economically is crucial. The renewable energy source like wind energy is integrated with thermal units for economic power generation with reducing the thermal fuel consumption of CHPED-based OPF system. The proposed technique implemented on CHPED based IEEE-30 bus system for renewable and without renewable energy sources with considering different cases. The suggested problem considering with valve point loading of thermal units, transmission losses and uncertainties of wind speed to address the non-linearity of the renewable-based CHPED-OPF system. Cost minimization, voltage deviation control, transmission losses minimization and stability index are the single objectives of the prospective system. Furthermore tested on multi-objective functions for simultaneously minimization of cost with emission and simultaneously minimization of active power loss with voltage profile. It is observed that the proposed CDTBO technique helps to reduce the cost by 2% and 12.8% for renewable based system as compared to non-renewable system for multi-objective function. The robustness of the proposed solution has been verified by implementing the statistical analysis on two systems with least variation of mean and optimal values of cost with the tolerance of less than 0.0035%. A comparison has been made with recent well known optimization techniques to address the superiority of the suggested CDTBO algorithm.

A Methodology for Rating Electricity Transmission Lines to Assess the Most Important or Critical Lines

The proposed method, based on three combined criteria—Sn—design capacity of the power line, LF, (line flow)—power flow in an electric transmission line, MVA, and the ratio of LF/Sn—allows for ranking electric transmission lines when calculations are performed in normal/pre-emergency modes. A combined set of criteria used to study critical/post-emergency N-k modes is developed. The simulations were performed on the real Baltic 330 kV electricity transmission system. The results reveal that when the power system operates in different load modes, most of the critical power lines determined by our method fall into the actual set of important/“critical” power transmission lines. This allows us to significantly reduce the number of simulated combinations and shorten the calculation time required for it. During the study of the Baltic electricity system, it was found that the developed method was accurate and efficient and suitable for the assessment of the reliability of real electricity transmission networks when planning operational and perspective work modes. The simulations results revealed the high reliability of the Baltic electricity system. The 330 kV electricity transmission network of the Baltic countries fully meets the N-2 criterion (usually, electricity transmission networks are designed to meet the N-1 criterion).

A Brief Review on Power Quality Improvement using UPFC

Abstract: Load demand is rising rapidly these days, necessitating an increase in generation capacity. Voltage instability arises as a result of external and internal imbalance, causing the bus voltage to vary. The FACTS device Unified Power Flow Controller (UPFC) is used to maintain stable voltage and improve power flow in transmission lines. This study examines the comparison of different FACTS devices as well as the analysis of UPFC to control both. In comparison to other FACTS devices such as STATCOM, which regulates only voltage, TCSC, and SVC, which controls only impedance, UPFC is one of the most promising FACTS devices since it can manage phase angle, voltage magnitude, impedance, and many line parameters selectively or concurrently

A Novel Improved Manta Ray Foraging Optimization Approach for Mitigating Power System Congestion in Transmission Network

This research manuscript proposes an Improved Manta Ray Foraging Optimization (IMRFO) algorithm for the power system congestion cost problem. The goal of the proposed Congestion Management (CM) strategy is twofold: firstly, the Generator Sensitivity Factors (GSF) is determined to select and involve the most influential power system generators that will reschedule their real power to alleviate the excess power flow in congested transmission lines. Secondly, the IMRFO has been developed and applied to attain the minimum possible congestion cost. The IMRFO has been formulated with the inclusion of correction factors in the exploration and exploitation phases to improve the coordination between these phases. The effectiveness of IMRFO has been measured considering its effective performance on the 23 conventional benchmark functions. 39 bus New England and IEEE-118 bus test system has been utilized to authenticate the effectiveness of the CM approach with the application of IMRFO. The outcomes highlight that the congestion cost achieved with IMRFO has been reduced by, of 16.08%, 13.73%, 11.78%, and 4.48 % for the 39-bus system and 14.84%, 12.97%, 9.63%, and 6.85% for 118 bus system when compared to the Bacteria Forge Optimization (BFO), Grey Wolf Optimization (GWO), Sine-Cosine Algorithm (SCA), and Original MRFO. The results gained with the implementation of IMRFO on the CM problem portrays appreciable minimization in the congestion cost, enhancement in the system voltage and losses, generates better convergence profile and computational time when contrasted with the recent optimization methods.

Performance and security enhancement using generalized optimal unified power flow controller under contingency conditions and renewable energy penetrations

In this paper, a novel flexible AC transmission system (FACTS) device named generalized optimal unified power flow controller (GOUPFC) is introduced to control the power flows in multi transmission lines and to regulate the voltages and angles at the load buses. The detailed power injection modeling of GOUPFC is presented in this paper. The optimal location of GOUPFC is determined based on line collapse proximity indicator (LCPI). A multi-objective function is framed in terms of average voltage deviation (AVDI), real power loss (Ploss) and average line collapse proximity indicator (LCPIavg) to test the effectiveness of the proposed device. The simulation studies are performed on standard IEEE 57-bus test system under single line contingency and considering various renewable energy source (RES) penetrations. The control parameters of GOUPFC are optimized by using whale optimization (WO-BAT) algorithm, by hybridizing WOA and BAT algorithms, and the superiority of WO-BAT is observed in minimizing the proposed objective function and enhancing the voltage profile.

VSC-HVDC Incorporated Corrective Security-Constrained Optimal Power Flow

With the rapid development and diverse engineering applications of VSC-HVDC technology, development in power industry has put forward higher economic and security requirements for the security-constrained optimal power flow. Under these circumstances, this paper proposes a security-constrained optimal power flow model for hybrid AC/DC power grids that incorporates the VSC-HVDC corrective control. The linear relationship between the pre-contingency state power flow and post-contingency state power flow is established based on the shift factor and the reliability constraints are described as the linear inequality constraints of the post-contingency state active power flow which is expressed by the pre-contingency state branch power flow. With the inherent ability of the VSC-HVDC converter station (short as VSC station) to rapidly regulate active power taken into account, this paper utilizes the linear relationship between the active power adjustment of the VSC station and the power flows of transmission lines and electrical equipment and corrects the reliability constraints with the sensitivity coefficient. Hence the correction of the post-contingency state power flow is reflected in the constraints. By solving the proposed model with the primal-dual interior-point method, the pre-contingency state optimal security operating point that considers the corrective capability of the VSC stations is obtained. Finally, the correctness and validity of the proposed model is verified based on a VSC-HVDC modified IEEE 14-bus system.

Impact of stealthy false data injection attacks on power flow of power transmission lines—A mathematical verification

Stealthy False Data Injection (SFDI) attacks in power systems can lead to a large-scale cascading failure, if not detected and eliminated quickly. The impact of such attacks can be minimized by using advanced control and protection mechanisms. This paper aims to provide mathematical proof for validation of the impact of SFDI attacks on power flow changes of power transmission lines equipped with metering devices based on graph theory, regardless of the network topology. In particular, it is assumed that an adversary attack targets a set of power transmission lines that are highly vulnerable to SFDI attacks, and corrupts the measurements, thus, changing the power flow of the entire power transmission system, leading to wrong power dispatches. Subsequently, an index is defined to show the power flow changes in case of SFDI attacks considering full and partial knowledge of true values of the system information. In addition, the valid boundaries of possible values for the defined index are determined. The proposed theorem can show how a controller can take protective measures to enhance the safety and reliability of power systems.

Active Power Flow Control Using Phase Shifting Transformer and UPFC in AC Transmission Line

Electrical power system is huge interconnected power system to meet the consumer demand without interruption and to maintain the stability, to utilize existing system to their maximum limit within stability limit of the system, to solve the congestion problem and improve the power flow in the line. Phase shifting transformer (PST) is used to control the active power flow in transmission line. This active flow control is obtained by adjusting phase angle of voltages at PST terminal. Unified power flow controller (UPFC) is facts device, it can control both the active and reactive power in transmission line by controlling the line parameter like voltage, phase angle and line impedance there by adjusting the line reactance in real time. The power system simulation model for PST and UPFC are developed in MATLAB. By simulating the model without PST and UPFC and then model with PST and UPFC is simulated to obtain the results. Results are compared for different loading condition to analyze the performance of the system with both the model. Keyword – PST, UPFC, Power flow control, active and reactive power, MATLAB/SIMULINK

Smart Load Flow Analysis using Conventional method and modern method

The optimal power flow for networked microgrids with different renewable energy sources (PV panels and wind turbines), storage systems, generators, and load is investigated in this study. A conventional method and an Artificial Intelligence method are applied to solve the OPF problem. The performance of MGs system with renewable energy integration was investigated in this study, with a focus on power flow studies. The power flow is calculated using the well-known Newton-Raphson method and the Neural Network method. The power flow calculation is used to assess grid performance parameters like voltage bus magnitude, angle, and real and reactive power flow in system transmission lines. under given load conditions. The standard test system used was a benchmark test system for Networked MGs with four MGs and 40 buses. The data for the entire system has been chosen as per the IEEE Standard 1547-2018. The results showed minimumlosses and higher efficiency when performing OPF using NN than the Newton-Raphson method. The efficiency of the power system for the networked MG is 99.3% using Neural Network and 97% using the Newton- Raphson method. The Neural Network method, which mimics how the human brain works based on AI technologies, gave the best results and better efficiency in both cases (Battery as Load/Battery as Source) than the conventional method.

Day-ahead stochastic scheduling of integrated electricity and heat system considering reserve provision by large-scale heat pumps

Integrating power and heat sectors can increase the flexibility of wind power integration. Power-to-heat devices powered by renewables can promote the electrification and decarbonization of the heat sector. This paper explores the feasibility and benefits of using large-scale heat pumps for reserve provision. A two-stage stochastic optimization model is proposed for the day-ahead centralized scheduling of the integrated electricity and heat system considering wind power uncertainties, with reserve provision of large-scale heat pumps, combined heat and power units, and thermal power units. The model co-optimizes energy, following reserve, regulating reserve, and heat regulation to handle wind power uncertainties. To reduce the computational complexity of the scenario-based stochastic optimization problem, inactive transmission line constraints are identified and removed based on an analytical calculation method, which considers the influence of power consumption of large-scale heat pumps on the power flow of transmission lines. The benefits of using reserves from large-scale heat pumps are tested on the modified IEEE-118 bus integrated electricity and heat system. The simulation results show that using large-scale heat pumps to provide the following reserve and regulating reserve show similar impacts on saving cost and reducing wind energy curtailment, and the acceleration algorithm can save computation time by approximately 64%.

Research on Emergency Power Support Method after Distributed Energy Storage System Blocking UHV DC

In order to explore the emergency support effect of distributed energy storage on reducing the peak power flow of AC transmission lines and improving the operating power of DC transmission lines after UHV DC locking fault, based on the analysis of UHV DC locking fault, the active power is provided according to the distributed energy storage system. A mathematical model is established to reduce the peak power flow of AC transmission lines by distributed energy storage after DC locking. According to the relationship between power gap and frequency variation, a mathematical model of distributed energy storage to improve UHV DC operating power is established. Based on frequency variation and inertial response time, a mathematical model of dynamic response time of energy storage output on system support effect was established. Taking Henan Power Grid of UHV AC/DC hybrid operation as an example, the simulation analysis of distributed energy storage system response in two ways is carried out, which verifies the effectiveness of distributed energy storage system for emergency power support method after UHV DC locking.

Energy Monitoring and Control Using New Linearized Power Flow Technique.(Dept.E)

The paper presents a proposed technique with linearized formula for computing the transmission line power flow in terms of injected power due to any change in power system loading conditions. The formula relates the line power flows to both loads and power generation directly for a transmission network configuration. Being in an integral form, new power flows on the lines can be obtained directly without running a complete load flow programs when the total system generation changes. This formula is a fairly general one as it is suitable for various energy monitoring and control applications such as generation shifts to alleviate the line overloads, the generation redispatch for an incremental change in loading conditions and the on-line load shedding programs as well as the fast contingency analysis.

Reliability Evaluation of Bulk Power Systems Incorporating UPFC

Unified power flow controller (UPFC) is one of the most advanced flexible AC transmission system (FACTS) devices that can simultaneously and independently control both the real and reactive power flow in a transmission line. The utilization of UPFC can result in significant reliability benefits in modern power systems. This paper proposes a novel reliability network model for a UPFC, which incorporates the logical structure and the distinct operating modes of a UPFC. Two-state or three-state models have been used for UPFC by previous researchers. The proposed model divides the UPFC operating modes into four states, namely the UPFC up state, STATCOM state, SSSC state and UPFC down state, in order to improve the accuracy of the model by recognizing the practical operating states of a UPFC. The new model also incorporates an AC flow-based optimal load shedding approach to assess the impact of bus voltages and reactive power flow on UPFC in order to decide appropriate load curtailment in the reliability evaluation process. The performance of the proposed model is verified using a test system, and compared with different reliability models of UPFC. Various operating schemes, such as different placement locations of UPFC, and different capacities of UPFC are used to illustrate the advantages of the developed models, and to examine the impacts of UPFC on the system reliability.

Power flow control of power systems based on a simple TCSC model

Thyristor-Controlled Series Capacitor (TCSC) is used to control the active power flow in transmission lines in the power system to specific values. This paper proposes a simple modeling of TCSC into Newton-Raphson load flow algorithm in order to reduce the complexity and enhance the reusability of the original load flow code. TCSC is represented by two injected loads at the sending and auxiliary buses. These loads are calculated based on the specified active power while the reactive power is calculated based on the systems. The reactive loads are updated during the iterative process until the convergence is achieved. TCSC parameters are calculated based on the voltages of connected buses and the specified active power. This model solves the problem associated with the selection of proper initial values of the TCSC control parameter. The proposed TCSC model is validated using the standard IEEE 14-bus, IEEE 30-bus and IEEE 118-bus test systems.

SSSC to control Power flow in the Line

FACTS controller is the Power Electronics based static controller which enhance power transfer capability and increase controllability of the power system network. Static Synchronous Series Compensator (SSSC) is VSC based controller which is used in transmission network with the aim of utilization of existing line upto its fullest extent. This paper demonstrates transmission line power flow control with the help of SSSC. A control scheme of SSSC is presented to control active power flow in the line. Increase in the power flow in the line is realized with SSSC operation in capacitive mode of operation and decrease in the power flow is realized with SSSC operated in inductive mode of operation. MATLAB simulation studies are demonstrated to validate the SSSC operation.

Optimal Power Flow Solution Using Levy Spiral Flight Equilibrium Optimizer With Incorporating CUPFC

Centre Node Unified Power Flow Controller (CUPFC) is a developed member of Flexible Alternating Current Transmission System (FACTS) connected at midpoint of transmission line. It has ability to control the power flow in transmission line (TL) as well as the voltage of the midpoint of TL. Solving the optimal power flow (OPF) problem is crucial task, and it became a difficult problem in case of integration FACTS devices into the system. Therefore, in this paper an efficient optimizer, namely Levy Spiral Flight Equilibrium Optimizer (LSFEO), is proposed for solving the OPF problem and determining the optimal allocation of CUPFC. The proposed algorithm is based on developing the Equilibrium Optimizer (EO) to enhance its searching capabilities. In this technique, two searching strategies are applied to enhance the exploration and exploitation processes of the traditional EO. The first strategy is based on Levy Flight Distribution to enable the optimizer to jump to new search areas for avoiding the stagnation of the traditional EO while the second strategy is based on spiral motion of the particles around the sorted best solution to boost the exploitation. The considered objective functions include fuel cost, fuel cost with valve point effect, emission, voltage deviations and the power losses. The validity and applicability of the proposed algorithm is demonstrated using the IEEE 30-bus system. The simulations verify the superiority of the proposed algorithm over the other reported algorithms. In addition, optimal inclusion of the CUPFC can reduce the cost, VD, losses, and emission considerably.

Congestion management with improved real power transfer using TCSC in 30 bus system

Secure operation and reliable utilisation of transmission lines is a challenging issue in deregulated power system. The scheduled power transactions are difficult due to the overloading of transmission lines in restructured power system as the electricity market has become more competitive. Due to congestion of transmission lines, the transfer of real power and the power system voltage profile are greatly affected in the power system. The aim of this research work is to increase the real power and the reactive power flowing in the lines of multibus system using thyristor controlled series compensator (TCSC). Real power transfer with reduced losses and improved voltage stability is an important factor in the present global scenario. This paper deals with the improvement of power flow in power transmission lines by series compensation device in 30 bus system with reduced congestion. The 30 bus system without and with thyristor controlled series compensation device (TCSC) is modelled and simulated and the results are presented. The simulation studies indicate a significant improvement in the real and the reactive power flow with the introduction of TCSC. The advantages of the proposed system include the smooth variations of the real and the reactive powers.

Online Non-Iterative Estimation of Transmission Line and Transformer Parameters by SCADA Data

Utilization of abundant measurements provided by supervisory control and data acquisition (SCADA) system has attracted increasing attention. Real-time estimation of transmission line parameters, utilizing voltage and power flow measurements provided by remote terminal units (RTUs) located at two substations across the line, has been investigated, recently. This paper improves this approach by introducing a novel exact linear reformulation of the problem, which can be solved in closed form. The distributed-parameter model of long transmission lines is considered and its parameters are estimated in a non-iterative manner using RTU measurements. The method is also extended to estimate transformer series impedance and tap position by SCADA measurements, linearly. As such, the disadvantages associated with the previous iterative approach, e.g. concern over convergence, for transmission line parameters are avoided. Moreover, the novel technique for estimating transformer parameters allows to determine the tap position as well as updated transformer series impedance. Furthermore, a thorough analysis is presented to take the measurement accuracy into account. Simulation results for different transmission lines and transformers in the IEEE 118-bus test system are reported, where the result indicate successful performance of the proposed algorithms.

Optimal Power Flow Models With Probabilistic Guarantees: A Boolean Approach

The legacy Optimal Power Flow (OPF) dispatch in electric power grids with high proliferation of renewables can be at risk due to the lack of awareness on major uncertainties, and sudden changes in renewable outputs. This may, in turn, result in conditions where transmission line power flows are significantly exceeded, and subsequent automatic protective actions take place. This letter presents a new generalized joint chance-constrained model for the OPF problem that effectively captures the stochasticity in renewable power generation in the system. In dealing with the complexity, and non-convexity of the proposed optimization model with probabilistic guarantees, we propose a novel tractable Boolean method to transform the model into an equivalent deterministic mixed-integer linear problem, which can be solved quickly, and efficiently by off-the-shelf solvers. Numerical results verify the effectiveness of the proposed model, and the suggested Boolean methodology.