Estimation of Real-Time Equivalent of Power System for Distribution System

2009 ◽  
Vol 10 (1) ◽  
Author(s):  
Kasi Viswanadha Raju G ◽  
Pradeep R. Bijwe
Keyword(s):  
Power System ◽  
Real Time ◽  
Distribution System ◽  
Power Flow ◽  
Computational Effort ◽  
Equivalent Model ◽  
Equivalent Representation ◽  
Proposed Model ◽  
Three Phase

Distribution power flow methods by and large consider the substation voltage to be known and fixed. This type of model is not suitable for stressed system conditions. Although some power flow software may allow an equivalent representation of the transmission and sub-transmission system, the procedure for the determination of such an equivalent is not available in literature. Hence, this paper presents a very simple three-phase power system equivalent model, which can be obtained with negligible computational effort from real time measurements, for an unbalanced operating system. The validity of the proposed model is demonstrated through studies for two sample systems.

scholarly journals Modeling of Doubly Fed Induction Generators for Distribution System Power Flow Analysis

2021 ◽  
Author(s):  
Amitkumar Dadhania
Keyword(s):  
Wind Turbine ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Green Energy ◽  
Flow Method ◽  
Proposed Model ◽  
Three Phase ◽  
Doubly Fed ◽  
Power Flow Method

Large-scale integration of Wind Generators (WGs) with distribution systems is underway right across the globe in a drive to harness green energy. The Doubly Fed Induction Generator (DFIG) is an important type of WG due to its robustness and versatility. Its accurate and efficient modeling is very important in distribution systems planning and analysis studies, as the older approximate representation method (the constant PQ model) is no longer sufficient given the scale of integration of WGs. This thesis proposes a new three-phase model for the DFIG, compatible with unbalanced three-phase distribution systems, by deriving an analytical representation of its three major components, namely the wind turbine, the voltage source converter, and the wound-rotor induction machine. The proposed model has a set of nonlinear equations that yields the total three-phase active and reactive powers injected into the grid by the DFIG as a function of the grid voltage and wind turbine parameters. This proposed model is integrated with a three-phased unbalanced power flow method and reported in this thesis. The proposed method opens up a new way to conduct power flow studies on unbalanced distribution systems with WGs. The proposed DFIG model is verified using Matlab-Simulink. IEEE 37-bus test system data from the IEEE Distribution System sub-committee is used to benchmark the results of the power flow method.

scholarly journals Modeling of Doubly Fed Induction Generators for Distribution System Power Flow Analysis

2021 ◽  
Author(s):  
Amitkumar Dadhania
Keyword(s):  
Wind Turbine ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Green Energy ◽  
Flow Method ◽  
Proposed Model ◽  
Three Phase ◽  
Doubly Fed ◽  
Power Flow Method

Large-scale integration of Wind Generators (WGs) with distribution systems is underway right across the globe in a drive to harness green energy. The Doubly Fed Induction Generator (DFIG) is an important type of WG due to its robustness and versatility. Its accurate and efficient modeling is very important in distribution systems planning and analysis studies, as the older approximate representation method (the constant PQ model) is no longer sufficient given the scale of integration of WGs. This thesis proposes a new three-phase model for the DFIG, compatible with unbalanced three-phase distribution systems, by deriving an analytical representation of its three major components, namely the wind turbine, the voltage source converter, and the wound-rotor induction machine. The proposed model has a set of nonlinear equations that yields the total three-phase active and reactive powers injected into the grid by the DFIG as a function of the grid voltage and wind turbine parameters. This proposed model is integrated with a three-phased unbalanced power flow method and reported in this thesis. The proposed method opens up a new way to conduct power flow studies on unbalanced distribution systems with WGs. The proposed DFIG model is verified using Matlab-Simulink. IEEE 37-bus test system data from the IEEE Distribution System sub-committee is used to benchmark the results of the power flow method.

scholarly journals A Comprehensive Three-Phase Step Voltage Regulator Model with Efficient Implementation in the Z-Bus Power Flow

2021 ◽  
Author(s):  
Evangelos Pompodakis ◽  
Georgios C. Kryonidis ◽  
Minas Alexiadis
Keyword(s):  
Power Flow ◽  
Equivalent Circuit Model ◽  
Computation Time ◽  
Voltage Regulators ◽  
Equivalent Model ◽  
Voltage Regulator ◽  
Phase Step ◽  
Step Voltage ◽  
Proposed Model ◽  
Three Phase

<p>This paper presents a comprehensive three-bus equivalent circuit model of three-phase step voltage regulators. The proposed model can be efficiently integrated in the Z-bus power flow method and can accurately simulate any configuration of step voltage regulators. In contrast to the conventional step voltage regulator models that include the tap variables inside the Y<sub>BUS</sub> matrix of the network, the proposed model simulates them in the form of current sources, outside the Y<sub>BUS</sub> matrix. As a result, the re-factorization of the Y<sub>BUS</sub> matrix is avoided after every tap change reducing significantly the computational burden of the power flow. Furthermore, possible convergence issues caused by the low impedance of step voltage regulators are addressed by introducing fictitious impedances, without, however, affecting the accuracy of the model. The results of the proposed step voltage regulator model are compared against well-known commercial softwares such as Simulink and OpenDSS using the IEEE 4-Bus and an 8-Bus network. According to the simulations, the proposed model outputs almost identical results with Simulink and OpenDSS confirming its high accuracy. Furthermore, the proposed 3-bus equivalent model is compared against a recently published conventional step voltage regulator model in the IEEE 8500-Node test feeder. Simulation results indicate that the proposed step voltage regulator model produces as accurate results as the conventional one, while its computation time is significantly lower. More specifically, in the large IEEE 8500-node network consisting of four SVRs, the proposed model can reduce the computation time of power flow around one minute for every tap variation. Therefore, the proposed step voltage regulator model can constitute an efficient simulation tool in applications where subsequent tap variations are required. </p>

scholarly journals Hybrid Control for Power System Based on STATCOM and UPFC with Two 3-level 48-pulse under Different Conditions

2021 ◽  
Vol 19 ◽  
pp. 277-288
Author(s):  
Osama Elbaksawi
Keyword(s):  
Power System ◽  
Power Flow ◽  
Hybrid Control ◽  
Unified Power Flow Controller ◽  
First Case ◽  
Proposed Model ◽  
Current Voltage ◽  
Three Phase ◽  
Fault Clearance ◽  
Power Flow Controller

This research presents the proposed model, to control the power flow in the transmission power system by applying Unified Power Flow Controller (UPFC), STATCOM and two 3-level 48-puls converter. This hybrid has been used to improve performance and reduce the maximum over shoot which is obtained from proposed model when the fault is occurring or suddenly system changes. The behavior of the system is analyzed under different three cases. The first case, the model is applied to plus load at bus 3. The second case, the model is operating at normal work and the third case, the three phase fault is occurred at bus4. In this research, the performance of system is studied under applied all cases of the current, voltage and power for the system. The numerical results of the proposed model are introduced to show the maximum over shoot and RMS values after applied proposed control at three different cases to prove the suggested model gave a good performance especially, during three phases fault and after fault clearance.

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

scholarly journals Photovoltaic Maximum Penetration Limits on Medium Voltage Overhead and Underground Cable Distribution Feeders: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3843
Author(s):  
Sultan Sh. Alanzi ◽  
Rashad M. Kamel
Keyword(s):  
Power System ◽  
Power Factor ◽  
Distribution System ◽  
Power Flow ◽  
Underground Cables ◽  
Overhead Lines ◽  
Medium Voltage ◽  
Load Power ◽  
Bus Voltage ◽  
Pv Penetration

This paper investigates the maximum photovoltaic (PV) penetration limits on both overhead lines and underground cables medium voltage radial distribution system. The maximum PV penetration limit is estimated considering both bus voltage limit (1.05 p.u.) and feeder current ampacity (1 p.u.). All factors affect the max PV penetration limit are investigated in detail. Substation voltage, load percentage, load power factor, and power system frequency (50 Hz or 60 Hz) are analyzed. The maximum PV penetration limit associated with overhead lines is usually higher than the value associated with the underground cables for high substation voltage (substation voltage = 1.05 and 1.04 p.u.). The maximum PV penetration limit decreases dramatically with low load percentage for both feeder types but still the overhead lines accept PV plant higher than the underground cables. Conversely, the maximum PV penetration increases with load power factor decreasing and the overhead lines capability for hosting PV plant remains higher than the capability of the underground cables. This paper proved that the capability of the 60-Hz power system for hosting the PV plant is higher than the capability of 50 Hz power system. MATLAB software has been employed to obtain all results in this paper. The Newton-Raphson iterative method was the used method to solve the power flow of the investigated systems.

scholarly journals Local Market for TSO and DSO Reactive Power Provision Using DSO Grid Resources

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3442
Author(s):  
Fábio Retorta ◽  
João Aguiar ◽  
Igor Rezende ◽  
José Villar ◽  
Bernardo Silva
Keyword(s):  
Real Time ◽  
Distribution System ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Reactive Power ◽  
Time Interval ◽  
Local Market ◽  
Distribution Grid ◽  
Power Profile ◽  
System Operator

This paper proposes a near to real-time local market to provide reactive power to the transmission system operator (TSO), using the resources connected to a distribution grid managed by a distribution system operator (DSO). The TSO publishes a requested reactive power profile at the TSO-DSO interface for each time-interval of the next delivery period, so that market agents (managing resources of the distribution grid) can prepare and send their bids accordingly. DSO resources are the first to be mobilized, and the remaining residual reactive power is supplied by the reactive power flexibility offered in the local reactive market. Complex bids (with non-curtailability conditions) are supported to provide flexible ways of bidding fewer flexible assets (such as capacitor banks). An alternating current (AC) optimal power flow (OPF) is used to clear the bids by maximizing the social welfare to supply the TSO required reactive power profile, subject to the DSO grid constraints. A rolling window mechanism allows a continuous dispatching of reactive power, and the possibility of adapting assigned schedules to real time constraints. A simplified TSO-DSO cost assignment of the flexible reactive power used is proposed to share for settlement purposes.

Integration of Power System Real-Time Digital Simulator and Optimal Power Flow

2012 ◽  
Vol 590 ◽  
pp. 195-200
Author(s):  
Meng Jen Chen ◽  
Yu Chi Wu ◽  
Wen Shiush Chen ◽  
Pei Wei Huang ◽  
Tsung Wei Tsai
Keyword(s):  
Steady State ◽  
Power System ◽  
Real Time ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Optimal Power ◽  
Communication Architectures ◽  
Analog Channels ◽  
Real Time Digital Simulator ◽  
Steady State Performance

In this paper, a framework for integrating a real-time digital simulator and EMS-OPF program is proposed and addressed, through two different communication architectures: asynchronous and synchronous. Validation of these communication architectures is carried out by Ethernet UDP/IP (asynchronous) and analog channels of IO card (synchronous). With this framework, both dynamic and steady-state performance of a power system can be studied easily in real-time mode.

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