Method For Distributed Systems Research Articles

A novel single sensor based fault/branch location method in distribution systems based on combination of game theory and Dijkstra's algorithm

This paper proposes a branch and fault locating method based on traveling wave theory. This method requires only one sensor in the system to detect the fault location. In this method, the distribution system is assumed to be an undirected graph, with the edges and vertices representing the transmission lines and buses. In addition, the weight of each edge equals the length of the line in the system. Dijkstra's algorithm graph determines all the point candidates for fault at that distance as the fault waves enter the sensor. Subsequently, using the game theory, the fault location and branch of the system are identified out the candidate points. The proposed method is compared with other methods, and it has been proved superior in reducing costs, as well as the lack of dependency on the system's structure, the polarity of the fault wave, and the fault type.

Distributed Arduino for Communication Agriculture

The needs of human life today, are felt to require the help of technology. Utilization of information technology has reached the countryside and all regions, beaches, mountains and cities. Information on agricultural or plantation products is very important for rural and urban communities, where yields and their development are indicators of decision-making and policy. Currently this information is very difficult to obtain, let alone collided with the complexity of problems in life. The method used is a distributed system method where the information produced by farmers regarding their harvest is distributed host to host (distributed system) via Arduino Uno. The use of Arduino Uno devices means the use of minimalist devices or embedded systems to minimize resources, and save energy

Aggregation of Radial Distribution System Bus with Volt-Var Control

The high penetration of the distributed energy resources (DERs) encourages themselves to implement grid-supporting functions, such as volt-var control. The quasi-static time-series (QSTS) simulation is an essential technique to evaluate the impact of active DERs on the grid. Meanwhile, the increase of complexity on the circuit model causes a heavy computational burden of QSTS simulation. Although circuit reduction methods have been proposed, there have been few methods that can appropriately handle the distribution system (DS) with multiple voltage control devices, such as DERs implementing volt-var control. To address the remaining issues, this paper proposes an offline bus aggregation method for DS with volt-var control. The method determines the volt-var curve for the aggregated bus on the basis of historical data to reduce error in the aggregated model, and its offline process solves the computational convergence issue concerned in the online one. The effectiveness of the proposed method is validated in the simulation using a Japanese low-voltage DS model. The simulation results show that the proposed method can reduce the voltage error and computational time. Furthermore, the versatility of the proposed method is verified to show the performance does not heavily depend on how to select historical data for model-building.

Research on Fault Waveform Recording Testing of Single Phase to Earth for Distribution Line Fault Indicator

To evaluate the recognitional capacity of single-phase grounding fault based on transient recording method in distribution system, the corresponding test method about fault waveform recording is presented for distribution line fault indication. The principle and implementation process of transient recording method is introduced. Ten 10 key indexes are selected from typical characteristic signals of earth fault, and a similarity comparison method of fault waveforms is designed. The proposed method is verified by laboratory tests, which shows its feasibility and effectiveness for test of the recognitional capacity of single phase to earth fault.

A Voltage Control Method for Distribution System by Coordinating LRT and DG Power Factors

A Voltage Control Method for Distribution System by Coordinating LRT and DG Power Factors

Detection of electricity theft using data processing and LSTM method in distribution systems

Electricity theft is a big problem faced by all energy distribution services and continues to rising. Therefore, studies on electricity theft detection techniques have increased in recent years. Unsuitable calibration and illegal calibration of energy meters during production may cause non-technical losses. Non-technical losses have been a major concern for the resulting security risks and the immeasurable loss of income. In most of the meter tampered locations, damaged meter terminals and/or illegal applications cannot be distinguishable during checking. In fact, electric distribution companies will never be able to eliminate electricity theft. But it is possible to take measure to detect, prevent and reduce it. In this paper, we developed by using deep learning methods on real daily electricity consumption data (Electricity consumption dataset of State Grid Corporation of China). Data reduction has been made by developing a new method to make the dataset more usable and to extract meaningful results. A Long Short-Term Memory (LSTM) based deep learning method has been developed for the dataset to be able to recognize the actual daily electricity consumption data of 2016. In order to evaluate the performance of the proposed method, the accuracy, prediction and recall metric was used by considering the five cross-fold technique. Performance of the proposed methods were found to be better than previously reported results.

A power quality evaluation method for distribution system with renewable energy

ABSTRACTPower quality evaluation data are heterogeneous and fluctuating, and there are large subjective factors in the evaluation process. To solve this problem, a power quality evaluation method based on incentive punishment factor and the ordered weighted aggregation (OWA) operators was proposed. The integrity and fairness of the evaluation information were guaranteed, through the homogenisation of the evaluation data. And using incentive and penalty factors to calculate the single index evaluation value without considering the time factor. By introducing the time weights and adopting the linear target programming model and ordered the weighted averaging operator to get the primary evaluation values of the indices in the inspection period. Then, the minimum variance method was used to get index weights, and the ordered weighted geometric averaging (OWGA) operator was applied to obtain the comprehensive evaluation value of the power quality. Finally, the power quality of a distribution system with photovoltaic generation under different load conditions is analysed as an example. The results showed that the method proposed in this paper distinguishes the power quality level under various load conditions significantly, which verify the feasibility and effectiveness of the model.

Sequence Component-Based Improved Passive Islanding Detection Method for Distribution System with Distributed Generations

Abstract In distributed generation (DG) systems, the rate of change of voltage and the rate of change of frequency are the two most common and widely used simple and low-cost passive islanding detection schemes. Unfortunately, these passive islanding detection schemes find limitation for detecting the islandings that cause very small power imbalance. In this paper, an improved passive islanding detection scheme is proposed by using the two newly derived indices from the sequence components of the current signal with the conventional voltage and frequency parameters. The performance of the proposed scheme is tested for numerous islanding and non-islanding cases generated on IEEE Std 399–1997 and IEC microgrid model distribution system integrated with both inverter-interfaced and synchronous DGs through PSCAD/EMTDC. The obtained results confirm the effectiveness of the proposed scheme.

New reclosing scheme of distribution system for utilization of BESS using wavelet transform

This paper proposed the reclosing method in distribution system with battery energy storage system (BESS) using wavelet transform (WT). The proposed method performs the WT of load current and then calculates the absolute value of slope of detail coefficient. The mother wavelet used is db4 of level 6. The fault clearing is detected using the rapid increase of this value. After the detection of fault clearing, the reclosing is performed. To verify the proposed method, various simulations according to the fault clearing times, fault resistances, and fault lengths are performed using EMTP. The simulation results show that fault clearing can be detected using proposed absolute value of slope of detail coefficient and hence the reclosing can be performed successfully.

Accuracy improvement of impedance-based fault locating method in distribution systems with DGs considering loss of laterals and load variations

Accuracy improvement of impedance-based fault locating method in distribution systems with DGs considering loss of laterals and load variations

PQ decoupled 3-phase numerical observability analysis and critical data identification for distribution systems

Summary Emerging active distribution systems are operated under more complicated and uncertain conditions. Because of frequent topology changes or temporary malfunctions of data acquisition, the network may lose observability and in turn may lead to the failure of distribution system state estimation. Without distribution system state estimation, the distribution system operator may not be able to make secure decisions, and the system may face with risk of serious damages. In this paper, a new real/reactive (PQ) decoupled 3-phase numerical observability analysis method and a new critical data identification method for distribution systems are proposed. The methods can efficiently identify all unobservable branches and critical data in a non-iterative manner. In addition to the 3-phase decoupling, the normal equation is also PQ decoupled, and the computation burden is greatly reduced. Furthermore, all entries in the Jacobian matrix are non-negative integers and the proposed methods present good numerical performance. Strict theoretical proofs on the performance of the proposed methods are provided and numerical results on different scales of test systems illustrate their validities.

Stochastic LMP (Locational marginal price) calculation method in distribution systems to minimize loss and emission based on Shapley value and two-point estimate method

LMP (Locational marginal price) calculation is a serious impediment in distribution operation when private DG (distributed generation) units are connected to the network. A novel policy is developed in this study to guide distribution company (DISCO) to exert its control over the private units when power loss and green-house gases emissions are minimized. LMP at each DG bus is calculated according to the contribution of the DG to the reduced amount of loss and emission. An iterative algorithm which is based on the Shapley value method is proposed to allocate loss and emission reduction. The proposed algorithm will provide a robust state estimation tool for DISCOs in the next step of operation. The state estimation tool provides the decision maker with the ability to exert its control over private DG units when loss and emission are minimized. Also, a stochastic approach based on the PEM (point estimate method) is employed to capture uncertainty in the market price and load demand. The proposed methodology is applied to a realistic distribution network, and efficiency and accuracy of the method are verified.

배전계통의 전압안정화를 위한 선로전압조정장치와 전지전력저장장치의 협조제어 알고리즘에 관한 연구

In order to maintain customer voltages within allowable limit() as much as possible, tap operation strategy of SVR(Step Voltage Regulator) installed in distribution system is very important, considering the scheduled delay time(30 sec) of SVR. However, the compensation of BESS(Battery Energy Storage System) during the delay time of SVR is being required because the customer voltages in distribution system interconnected with PV(Photovoltaic) system have a difficultly to be kept within allowable limit. Therefore, this paper presents the optimal voltage stabilization method in distribution system by using coordination operation algorithm between BESS and SVR. It is confirmed that customer voltage in distribution system can be maintained within allowable limit().

Power Flow Method for Distribution Systems Based on the Current Network Equation

Proposed general distribution power flow algorithm based on the current network equation. The power flow equations of the algorithm based on the node current balance, and the Jacobian matrix is a constant coefficient matrix compared to the conventional Newton method. It has the characteristics of easy programming, and the method has universality at the same time. It can be used for radial distribution network and systems with loops. The example shows that the method is superior to conventional Newton method on speed and convergence.

A Heuristic Analysis Method for the Impact of DGs to Power System Reliability

With high penetration of distributed generation connected to the grid, distribution system will have some huge impacts, and system reliability calculation models and assessment methods are changing. Based on Monte-Carlo method, a heuristic reliability analysis method for distribution system with distributed generations was proposed in the paper, which focuses on the mode of distributed generation in parallel to system power supply. Functional role of distributed generation in the power distribution system failure and distributed power adapter with load strategies were analyzed in this method. Cases simulation analysis was used to verify its effectiveness.

Distribution System Fault Recovery with Undispatchable Distributed Generations

Considering the probabilistic of the wind power and the solar power, a fault recovery method for distribution systems with the wind power and the solar power is presented in this paper. For the wind power, a simplified steady-state equivalent model of an asynchronous wind generator is added into the Jacobian matrix to consider the impact of the wind power on systems. For the solar power, its output is considered as an injected power which is related with solar irradiance. Three-point estimate is employed to solve the probabilistic power flow of distribution systems with the wind power and the solar power. The restoration is described as a multi-objective problem with the mean of the system loss and the number of switch operations. Fast elitist non-dominated sorting partheno-genetic algorithm is used to solve this multi-objective problem. IEEE 33-bus system is used as an example and the results show that the models and algorithms in this paper are efficient.

대용량 태양광발전이 연계된 배전계통의 수용가 전압 특성해석에 관한 연구

This paper deals with the analysis of the customer voltage characteristic in distribution system interconnected with large scale PV system. There would be many power quality issues which are caused by reverse power flow of PV system interconnected with distribution system. In order to analyze the effect of PV system on the customer voltage, detailed modeling method of distribution system and modified modelling method of PV system are proposed using PSCAD/EMTDC in this paper. So far, less than dozens KW of PV system can be simulated with the existing modelling method. Therefore, a new modeling method which can simulate the large scale PV system is proposed by considering the relationship equation on the phase and voltage in the current control algorithm. From the simulation result of proposed modelling method, it is confirmed that an optimal operation method in distribution system is suggested by analyzing the effect of PV system on customer voltage.

Effect of advanced water treatment on behaviour of residual chlorine and development of chlorine control method in distribution systems

The behaviour of residual chlorine concentration in drinking water treated by the mid-chlorination or the advanced water treatment (AWT) was investigated. The AWT removes dissolved organic matter more than the mid-chlorination, thus the rate of residual chlorine reduction is decreased. The analysis of chlorine concentration data measured by automated continuous monitoring devices revealed that the introduction of AWT reduced the maximum and mean chlorine concentration by 0.33 mg L−1 and 0.21 mg L−1 compared to the mid-chlorination respectively, while the minimum concentration was maintained at around 0.3 mg L−1 in the whole city. The overall chlorine reduction rate coefficient in the AWT was reduced to approximately half of that in the mid-chlorination. Volatilization of chlorine from a water surface could be expressed by the zero-order rate of reaction from laboratory experiments. The rate of volatilization increases with increasing water temperature and shallower water depth. The residual chlorine prediction models were developed based on the results of data monitoring and laboratory experiments. The accuracy of simulated values is good and almost all of the predicted concentrations are in the range of±0.1 mg L−1 of measured concentrations. The models are very effective to control residual chlorine concentration at predetermined target value.

Decentralised control of voltage in distribution systems by distributed generators

Recently, renewable energy such as wind turbine generators and photovoltaic systems are introduced as distributed generators (DGs). Connection of a large amount of DG causes voltage deviation beyond the statutory range in distribution systems. Reactive power control of inverters interfaced with DGs is one of the solutions against this problem. Additionally, reactive power control has a possibility to contribute to the reduction of distribution loss. In this study, the authors propose a voltage control method in distribution systems by reactive power control of inverters interfaced with DGs. The proposed method has been developed in order to reduce distribution loss and voltage regulation into statutory range without any telecommunication. In the proposed method, each interfaced inverter controls reactive power based on voltage control reference, which is calculated from self-information. The calculation rule of control reference has been developed using optimal data which consist of relations between randomly given inputs and corresponding optimal outputs, which are calculated by an optimisation technique. Simulations are conducted to show the effectiveness of the proposed method.

An Efficient Genetic Algorithm for Loss Minimum Distribution System Reconfiguration

This article describes a chromosome coding method of genetic algorithm (GA) for minimizing losses of a radial distribution system when it is subjected to network reconfiguration. By simulating the survival of the fittest among the strings, the optimum string is searched by randomized information exchange between strings by performing crossover and mutation. A vector-based load flow method for distribution systems using sparsity technique, which requires less memory and less number of iterations to converge is used, as this problem requires faster solution. Reciprocal of active power losses is taken as fitness function. The proposed algorithm improves the performance of GA and reduces the number of bits and iterations for distribution system reconfiguration. Results have shown that proposed algorithm has more advantages over previous algorithms when large power distribution systems are considered.