Power flow algorithm for radial distribution system with voltage sensitive loads

Power flow in distribution networks with earth return

With rapid increase in wind power penetration into the power grid, unbalanced power flow in distribution network with distributed generators is becoming increasingly important to power sysytem. Due to the variability and uncertainty of wind, such traditional unbalanced power flow analysis method for distributed power supply limit the use of the existing tools for decision-making under uncertain conditions. As a result, unbalanced power flow analysis method, which provides information on uncertainty associated with wind power analysis, is gaining increased attention. This paper presents a novel hybrid intelligent algorithm for deterministic unbalanced power flow in distribution network with distributed generators that utilizes a combination of Cauchy particle swarm optimization(CPSO) and fuzzy ARTMAP (FA) network, which is optimized by using PSD-BPA. The performance of the proposed model is assessed utilizing wind power data from the Baolihua wind farm in Southern China. Unbalanced power flow in distribution network with distributed generators is researched. The typical static load model is established and the impact of distributed generators on feeder voltage profile is analyzed under unbalanced loads. The simulation results are given. References for the global planning of unbalance compensation in distribution network can be provided by the study.

The interline power flow controller (IPFC & UPFC) is one of the latest generation flexible AC transmission systems (FACTS) controller used to control power flows of multiple transmission lines. The main objective of this paper is detailed study about a new real and reactive power coordination controller for a interline power flow controller (IPFC & UPFC). The basic control for the IPFC is such that the series converter of the UPFC controls the transmission line real/reactive power flow and the shunt converter of the (IPFC & UPFC) controls the bus voltage/shunt reactive power and the DC link capacitor voltage. Because of the common link, any inverter within the (IPFC & UPFC) is able to transfer real power to any other and thereby facilitate real power transfer among the lines of the transmission system. Since each inverter is able to provide reactive compensation, the (IPFC & UPFC) is able to carry out an overall real and reactive power compensation of the total transmission system. This capability makes it possible to equalize both real and reactive power flow between the lines, transfer power from overloaded to under loaded lines, compensate against reactive voltage drops and corresponding reactive line power and to increase the effectiveness of the compensating system against dynamic disturbances. A simulation in MATLAB has been done in order to extend conventional algorithm based on this model.

A per-node granularity decentralized optimal power flow for radial distribution networks with PV and EV integration

The power grid has gradually changed its operation during the recent decades. These developments have encouraged a shift from centralized to decentralized power flow control. A research has been carried out to investigate the possibilities to control power flows using the Smart Power Router (SPR) in distribution networks, where a large share of distributed generation (DG) is present. In this paper, the possible applications of the SPR have been explored in a laboratory test network. In particular, the SPR's control capabilities for both active and reactive power flows were enhanced to improve the system performance. An overview of the control of the SPR is presented. The effect of the power flow management with reconfigurations in the distribution network is considered. Furthermore, the possibilities for decoupled control of the active and the reactive power flow are elaborated.

Day-ahead multi-period scheduling can provide reasonable operation plans for various power sources and energy storage systems in distribution networks, so as to reduce costs and improve energy utilization. In this paper, the dynamic power flow optimization model of radial distribution network with wind/PV/energy storage is established firstly. The model takes the output of various power sources and the charge-discharge power of energy storage systems as decision variables, which belongs to nonconvex nonlinear programming problems. Then the second-order cone relaxation is applied to the power flow equation, and the problem is transformed into a second-order cone programming model which can be solved strictly and efficiently. Finally, the extended IEEE 30-node system is simulated, and the software Gurobi is used to obtain the optimal scheduling scheme, which verifies the effectiveness of this method. Test results show that the operating cost is reduced by adding wind/PV/energy storage into networks, and the consumption of renewable energy is increased by considering the punishment for wind and PV abandonment.

5 - Networks with Disturbed Flows Dual Network Theorems for Networks with Disturbed Flows: Reoptimising the Power Flows in Active Power Networks in Real Time

While penetration of Distributed Generators (DGs) has been increasing with favorable government policies coupled with technological advances in portable deployment of DGs, the challenges of efficient network operations in secondary distribution networks have also become formidable. Among other issues, the real power penetration from PV and Wind generators causes imbalance between real and reactive power flows in low voltage distribution networks where phase unbalancing and variation in demand-supply have dominant effect on voltage profile, overloads, power factor and losses. This paper attempts to apply sequential time simulations approach by performing distribution power flow simulations for time-series data points of demand and generation over a period of one year at 15 minute intervals. This approach helps in capturing the diurnal and seasonal variability of intermittent power producing DGs and that of load profiles. It also helps in undertaking time integral studies for energy losses, number of switching operations by control devices such as shunt compensators and voltage regulators. The results of this exercise are used to propose different switching strategies to limit voltage limit violations while reducing annual energy losses.

The interline power flow controller (IPFC) proposed is a new concept for the compensation and effective power flow management of multi-line transmission systems. In its general form, the IPFC employs a number of inverters with a common DC link, each to provide series compensation for a selected line of the transmission system. Because of the common DC link, any inverter within the IPFC is able to transfer real power to any other and thereby facilitate real power transfer among the lines of the transmission system. Since each inverter is also able to provide reactive compensation, the IPFC is able to carry out an overall real and reactive power compensation of the total transmission system. This capability makes it possible to equalize both real and reactive power flow between the lines, transfer power from overloaded to underloaded lines, compensate against reactive voltage drops and the corresponding reactive line power, and to increase the effectiveness of the compensating system against dynamic disturbances. The paper explains the basic theory and operating characteristics of the IPFC with phasor diagrams, P-Q plots and simulated waveforms.

PurposeThe purpose of the paper is to develop a simple, efficient and robust power flow (PF) method for ill-conditioned distribution networks (DNs).Design/methodology/approachIt first formulates the PF problem as an optimization problem of minimizing the node power mismatches, while treating the corrections of node voltages as problem variables and then uses soccer game optimization (SGO), an artificial intelligent algorithm simulating the behavior of soccer game players in scoring goals, in solving the formulated PF problem.FindingsIt studies the performances of the developed method on four standard test DNs and exhibits that the method is superior in respect of accuracy, robustness and computational speed than those of existing methods.Originality/valueIt suggests a novel and new PF method using SGO and portrays that the proposed method is as accurate as any other PF method, robust like non-Newton type of PF methods and faster than Newton type of PF methods.

Distributed generators (DGs) are nowadays most commonly used in distribution networks to meet the rising demand. The distribution network power flow is altered as more distributed generations are integrated with the distribution network. Analyzing and researching the network's power flow with distributed generation is an essential element of analyzing the distributed generation's influence on the networks. This study proposed new sites in the test network for the purpose of connecting DGs. Good results were obtained in improving the necessary network elements. Firstly, applying a Newton-Raphson method to measure the distribution network's power flow without distributed generations. Then the optimal power flow approach with DGs is set up based on many goals such as minimizing fuel cost, minimizing losses, voltage deviation, increasing efficiency, and the incremental fuel cost in the network appeared. Eventually, applying Particle Swarm to overcome the optimization problems. In MATLAB software environment and programing MATPOWER version 6.0, the simulation is evaluated and validated using the IEEE30 node method. The test results indicate that optimal power flow analysis with distributed generation will accomplish many networks aims and boost system economy.

Bus voltage control and optimization strategies for power flow analyses using Petri net approach

The modern Distribution Systems (DS) require for accurate and fast Power Flow (PF) algorithms as a basis for other DS applications. Almost all decisions are taken based on accurate PF results and, possibly, they have to be taken in real time. In this paper, a new PF algorithm based on a linear programming approach is proposed. The graph theory is used for modeling the distribution network with some topological matrices. The proposed matrices are then utilized to develop a linear optimization model in rectangular form for PF in DS. Moreover, a linear load model is used for calculating the current injections in each system bus. This leads the PF equations to be linear with acceptable accuracy. In the paper the proposed PF algorithm is implemented on IEEE 18-bus and 33-bus test systems. The results show the accuracy and the performance of the proposed PF model compared to existing models. Since the optimization model is linear, the solution is global optimum. It facilitates the application of the accurate PF results in real-time optimization of DS.

A novel method to limit the short-circuit current in the distribution network is introduced in this study. The short-circuit limiter is a part of cascade H-bridge distribution-static synchronous series compensator (D-SSSC), which is placed in series with the line to manage the power flow in the loop distribution network. Hence, the short-circuit limitation and power flow management is achieved using only one power converter. During the fault, the D-SSSC inverter is changed to a rectifier by turning off the converter switches and using the anti parallel diodes. The transient thermal analysis of the converter verifies that the components operate within the safe operation area during the fault. The appropriate selection of the DC bus capacitors are discussed both, to limit the fault current below the diode surge current, and to prepare adequate reactive power for normal power flow control. Simulation studies are based on a model inspired by a part of the Tehran electrical distribution network. Moreover, a seven level cascade H-bridge is implemented to control the power flow and to limit the short-circuit in the simple line model.

With the increasing worldwide large-scale integration of green energy resources, their variable output will mostly be influenced by local environmental conditions. Therefore excess high generation penetration of intermittent output generation of these DERs during some specific peak generation hours in a day leads to create problem of reverse power flow and over voltage, which is always been an important concern for power energy engineers which eventually increase the dependency on energy storage units. In this paper six different C-Rate types of batteries namely 0.5C, 0.08C, O.25C, 0.33C, 0.l67C and lC are optimally placed and sized using Teacher Learner Based Optimization (TLBO), to minimize the reverse power flow impact due to high penetrating intermittent DG output on hourly peak load variation. The results shows that by optimal evaluating BESS, voltage profile gets improved with active power loss reduction in a day. With the optimal located and sized BESS in distribution side of grid will leads to have a reliable with efficient grid support and reduced power loss help to grid load power demand diversification. In this paper Reliability test system model is used for the reliability analysis per hour for Modified radial IEEE 33 bus distribution grid network, and results are verified and simulated in MATLAB 2019b software.