Stability Of Distribution Network Research Articles

STABILITY ENHANCEMENT BASED ON DISTRIBUTED GENERATION UNITS IN AL-NAJAF AL-ASHRAF ELECTRICAL NETWORK

The operation and structure of distribution system are changing with the integration of Distributed Generation (DG) units, where these units may have effect on power losses, stability, voltage profile, power quality and other quantities. Therefore the optimum location, size and number of DG units are necessary to avoid the negative impacts on electric power system. In this work, the Particle Swarm Optimization (PSO) technique is used to find the optimal number and locations of DG in order to minimize the active power losses. The thermal limit of transmission lines and transformers was studied to detect the lines or transformers which exceed the limit in order to process it. The voltage stability of distribution network has been investigated, using L index method.Â

Effect of distributed generations on reconfiguration and voltage stability of distribution networks considering average hourly load data

Effect of distributed generations on reconfiguration and voltage stability of distribution networks considering average hourly load data

Effect of distributed generations on reconfiguration and voltage stability of distribution networks considering average hourly load data

Distributed generation (DG) sources are becoming more popular nowadays and they are inevitable in modern large interconnected power systems to meet enormous demands of electrical energy. Such sources could be photovoltaic cells, wind generation, biomass, combined heat power, fuel cells etc. The location and size of distributed generations (DGs) have more impact on energy losses, voltage stability and other benefits also. A method has been proposed in this paper for the placement of DGs in a distribution network. The best nodes once identified, power injection by DGs is optimised using genetic algorithm and particle swarm optimisation methods to reduce power losses, maintain node voltages and branch currents within specified limits. The methods are also compared for getting the best penetration level of DGs at different load levels. It is observed that reconfiguration with DGs at their locations have great impact on power loss reduction and voltage stability improvement. The effect of power injection by DGs and reconfiguration with DGs to the voltage stability of distribution network is examined using a voltage stability index. The proposed technique is demonstrated through an example of 69 node distribution network.

Distributed Generation Placement in Distribution Network Based on Power-Flow Relations

Installing Distributed Generation (DG) influences distribution network stability and losses. The aim of the Distributed Generation placement (DGP) is to provide the best locations and sizes of DG units to optimize electrical distribution network operation and planning taking into account DG capacity constraints. In this paper a really formula based on Power flow for obtaining DGP and sizing to improve the performance of the distribution network is offered. The aim of this really formula is to eliminate complex and time-consuming algorithms in solving DGP problems. Using the proposed method, one can easily and without complex calculations obtains the size and location of DG units on the network. The proposed method has been tested on several networks and the test results show its effectiveness. The benefit of the proposed method is its low computational burden as well as its simplicity of implementation.

Optimal selection of distributed generating units and its placement for voltage stability enhancement and energy loss minimization

Abstract The integration of distributed generation (DG) in distribution network may significantly affect its performance. Transmission networks are no longer accountable solely for voltage security issues in distribution networks with penetration of DGs. The reactive power support from the DG sources greatly varies with the type of DG units and may potentially distress the larger portion of the network from the voltage stability aspects. This paper presents the analysis for the selection of the best type of DG unit among different categories and its optimal location that can enhance the voltage stability of distribution network with simultaneous improvement in voltage profile. Voltage sensitivity index and bus participation factors derived from continuation power flow and Modal Analysis, respectively, are used together for voltage stability assessment and placement of DGs. Changes in mode shapes and participation factors with the placement of DGs are comprehensively analyzed for 33 and 136 nodes radial distribution network.

Research of the Voltage Stability of Distribution Network Connected Induction Machines

There are a lot of wind power plants based on double feed induction machine technology which are connected to electrical network. These usually don’t consider reactive power (even reactive power consumption), so they generally affect the entire network voltage stability and can cause instability in themselves and become no longer balanced by the torque. This paper presents a method to study the relationship between the active power and voltage at the point of common coupling (PCC) connected wind power plant to identify the voltage stability limit. It is a fundament to define a permitted operation region in complying with the voltage stability limit at the PCC connected wind power.DOI: http://dx.doi.org/10.5755/j01.eee.21.1.9804

Steady‐state and transient voltage stability analysis of a weak distribution system with a remote doubly fed induction generator‐based wind farm

AbstractIn modern, stressed distribution system, voltage stability is a major concern from planning and operation perspectives. Remote wind farm connected to a weak distribution system through a long line could adversely affect the voltage stability of the respective distribution network. This paper investigates the transient and steady‐state voltage issues of a distribution network with a distant doubly fed induction generator (DFIG)‐based wind farm. Results show that a distant DFIG‐based wind farm could improve the voltage stability of a distribution network with a large motor load in steady‐state operating condition as well as following disturbances, like three‐phase faults, sudden load tripping, and motor starting.

The Research for the Voltage of Distribution Network Including Distributed Generation

There is a challenge to the voltage stability of distribution network when DG is added to the distribution network. By means of theoretical derivation, three conclusions had been got. The amplitudes of node voltage would rise including DG. The more capacity of DG, the higher node voltages. The same capacity of DG met different nodes would have different effects on the node voltages. The farther away from the equilibrium node, the higher voltages. Through a case, the correctness of theoretical analysis had been proved.

Analytical method of the impact of distributed generation on static voltage stability of distribution network and its development

It can’t be ignored that the impact of distribution network to the static voltage stability of the distributed generation. In this paper, we first introduce the stability indices of the traditional grid on static voltage and the analytical method, in the mean time, we put forward the corresponding advantages and disadvantages and applicable scope. Then, we present a summary of the current research on the impact of distribution network to the static voltage stability of the distributed generation at home and abroad from the two aspects of the static voltage stability indices and analytical methods. In the end, the paper points out a new way to improve the distribution network static voltage stability that with the consistency theory to achieve coordinated control of distributed generation, microgrid, as well as virtual power plants, which will be more advantage. This article has a reference value for the analysis of the impact of distributed generation on static voltage stability of the distribution network, as well as researches the measures to improve the static stability. DOI: http://dx.doi.org/10.11591/telkomnika.v11i9.2255

Distributed Generation Allocation to Improve Steady state Voltage Stability of Distribution Networks using Imperialist Competitive Algorithm

Distributed Generation Allocation to Improve Steady state Voltage Stability of Distribution Networks using Imperialist Competitive Algorithm

Research on Intelligent Reactive Power Optimization Method for Distribution Network with DFIG Wind Farm

In order to ensure the voltage stability of distribution network with doubly fed induction generator, it is more significant to determine the reactive power distribution of the grid reasonably except installation of on load tap changing transformer and shunt capacitor bank. However, the reactive power control capability of doubly fed induction generator is not fully implemented in the reactive power optimization of distribution network. In this paper, on the premise of utilizing wind energy maximally, the wind farm with doubly fed induction generator is considered as a continuous reactive power source to participate in the reactive power optimization. Then the constructed reactive power optimization problem is converted to a nonlinear mixed integer optimization problem which is solved by intelligent genetic algorithm. Finally, the IEEE 16 node system is chosen as an example for simulation, the computation results verify the effectiveness of the proposed algorithm.

Reactive power management of distribution networks with wind generation for improving voltage stability

This paper proposes static and dynamic VAR planning based on the reactive power margin for enhancing dynamic voltage stability of distribution networks with distributed wind generation. Firstly, the impact of high wind penetration on the static voltage stability of the system is analysed and then the effect of composite loads on system dynamics is presented through an accurate time-domain analysis. A new index, reactive power loadability (Q-loadability), is used to measure the vulnerability of the network to voltage collapse. Compensating devices are located using Q-loadability to increase the system voltage stability limit. Finally, a cost-effective combination of shunt capacitor bank and distribution static compensator (D-STATCOM) is determined through static and dynamic analyses to ensure voltage stability of the system after a sudden disturbance for different wind penetration levels. This study takes into account the induction motor dynamic characteristics which influence the transient voltage recovery phenomenon. The results show that the proposed approach can reduce the required sizes of compensating devices which, in turn, reduces costs. It also reduces power losses and improves the voltage regulation of the system.

Using Hybrid Genetic-Particle Swarm (HGPSO) Optimization to Distributed Generation Allocation to Improve Steady State Voltage Stability of Distribution Networks

Using Hybrid Genetic-Particle Swarm (HGPSO) Optimization to Distributed Generation Allocation to Improve Steady State Voltage Stability of Distribution Networks

Determination of Voltage Stabilityin Distribution Network Using ANN Technique

Voltage stability condition, reliability and service quality are the important parameters of a distribution system which need to be satisfied from the customer point of view.To measure voltage stability of distribution network a voltage stability index is presented in this paper. Voltage stability improvement of network is facilated by network reconfiguration and voltage stability level is quantified by voltage stability index. Network reconfiguration is a process which alters the feeder topological structure by changing the open/close status of the sectionalizing (normally closed) and ties switches (normally open) in the system. In this work, a two stage search of switching option i.e. local search and global search is implemented to achieve desired network configuration. A multilayer ANN model with Error Back Propagation Learning (EBPL) algorithm is simulated for global search to obtained optimal set of candidate switching. The proposed scheme is tested on an 11 kV practical radial distribution system consisting of 52 buses. After reconfiguration, better voltage stable condition of the system is attained. Active power loss of the system is reduced from 0.854 MW to 0.485 MW and reactive power loss of the system is reduced from 0.355MVar to 0.199MVar after achieving optimal configuration.

Voltage Stability of Medium and Low Voltage Distribution Networks with Wind Generation Based on Hilbert-Huang Transform

Nowadays the voltage instability problems occur in the distribution grid due to the integration of more and more fluctuant distributed generators. This paper focuses on voltage stability of distribution networks with wind generation. A voltage stability index is presented, and calculated by an expanding Newton-Raphson power flow method in which the wind power generation nodes are modified according to the P-Q(V) character. In order to obtain the key components of fluctuant wind power, the Hilbert-Huang transform algorithm is utilized to reveal the inherent characteristics of wind power. The extrema extending method based on the mirror periodic is used in the empirical mode decomposition and can handle the end effects. According to the Hilbert spectrum and instantaneous energy of each intrinsic mode functions, the components with lower instantaneous frequency are selected to rebuild the wind power. The new rebuilt series consist of stationary and monotonic components which are smoother, and the rebuilt series can reflect the main fluctuant characteristic of the initial wind power data by comparing the index.

05/00130 Biomass based micro-turbine plant and distribution network stability: Jurado, F. et al. Energy Conversion and Management, 2004, 45, (17), 2713–2727

Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pHT ([H+]T in moles per kg of solution) is given as:and R(25)=R(t){1+0.00909(25−t)}, where 29⩽S⩽37,13°C⩽t⩽32°C, and R(t) is the absorbance ratio (A616/A444) at temperature t and salinity S. Using bromocresol purple, the solution pHT is given as pHT=5.8182+0.00129(35−S)+log((R(25)−0.00381)/(2.8729−0.05104R(25))) and R(25)=R(t){1+0.01869(25−t)}, where 29⩽S⩽37,13°C⩽t⩽32°C, and R(t)=A589/A432. Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg-1 and were within 0.3–0.9 μmol kg-1 of the alkalinities of certified seawater reference materials.

Biomass based micro-turbine plant and distribution network stability

Abstract Micro-turbine systems that enable the use of biomass are important for future technologies for electricity production. These distributed resources are dynamic devices, and when connected to the distribution system, they will affect its dynamic behavior. The micro-turbine is capable of providing effective load following service in the distribution system. However, the results also show that the micro-turbine system is not an uninterruptible power supply and does not protect the load from voltage instability while in a grid connect mode.