Distribution Network Losses Research Articles

Research on the Optimal Operation Method of DC Microgrid Base on the New DC Power Distribution Management System

The grid-connected operation of the distributed generation (DG) via the direct current (DC) microgrid is the operation mode of the DC power distribution system in the future. Considering the grid-connected operation of multiple DC microgrids, we have proposed a new type of DC power distribution management system aiming at the lowest operating cost of the entire DC power distribution system. Our proposed DC power distribution management system can be used to carry out the optimized dispatching for the connected DC microgrids, thereby achieving the economic, safe, and stable operation of DC power distribution management systems. At the same time, through the different nodes where the modular multilevel converter (MMC) is connected to the alternating current (AC) distribution network, a DC power distribution management system can control the active and reactive power generated by the MMC, achieving the control of the load flow of the upper-stage AC grids in real time. The example simulation shows that the method proposed in this paper has a great role in reducing the transmission losses of the power distribution network, achieving electric power peak-load shifting, and utilizing renewable energy. Thus, it can not only maximize the use of distributed renewable resources, but also enable mutual support and optimal scheduling between a DC power distribution system and multiple microgrids.

Impact of Distributed Generation in Distribution Network Losses and Voltage Profile

Impact of Distributed Generation in Distribution Network Losses and Voltage Profile

Reconfiguration and DG Sizing and Placement Using Improved Shuffled Frog Leaping Algorithm

In this paper is proposed a reconfiguration methodology with the presence of Distributed Generation (DG), aimed at achieving the minimum power loss, minimum number of switching operation and minimum deviation of bus voltage while satisfying all constraints using improved shuffled frog leaping algorithm (ISFLA).The performance of the proposed method is examined on 33 and 69 bus IEEE test distribution systems. The ISFLA performance is evaluated with the well-known algorithm including of harmony search algorithm (HSA), refined genetic algorithm (GRA), particle swarm optimization (PSO), differential evolutionary (DE) and conventional SFLA. Simulation results showed that the total power loss and voltage bus minimum in primary distribution network can be reduced significantly. Also the results in different scenarios are showed that the simultaneous reconfiguration and DG placement method is better in less losses and also in more minimum voltage. Moreover, the ISFLA superiority is proved in comparison with the HAS, GRA, PSO, DE, and SFLA in view of more convergence speed and accuracy and also converges in less number iteration. Also, the performance of the proposed method is favorable compared to previous studies.

Electricity Theft Detection in Power Grids with Deep Learning and Random Forests

As one of the major factors of the nontechnical losses (NTLs) in distribution networks, the electricity theft causes significant harm to power grids, which influences power supply quality and reduces operating profits. In order to help utility companies solve the problems of inefficient electricity inspection and irregular power consumption, a novel hybrid convolutional neural network-random forest (CNN-RF) model for automatic electricity theft detection is presented in this paper. In this model, a convolutional neural network (CNN) firstly is designed to learn the features between different hours of the day and different days from massive and varying smart meter data by the operations of convolution and downsampling. In addition, a dropout layer is added to retard the risk of overfitting, and the backpropagation algorithm is applied to update network parameters in the training phase. And then, the random forest (RF) is trained based on the obtained features to detect whether the consumer steals electricity. To build the RF in the hybrid model, the grid search algorithm is adopted to determine optimal parameters. Finally, experiments are conducted based on real energy consumption data, and the results show that the proposed detection model outperforms other methods in terms of accuracy and efficiency.

Smart Meter Data-Based Three-Stage Algorithm to Calculate Power and Energy Losses in Low Voltage Distribution Networks

In this paper, an improved smart meter data-based three-stage algorithm to calculate the power/energy losses in three-phase networks with the voltage level below 0.4 kV (low voltage—LV) is presented. In the first stage, the input data regarding the hourly active and reactive powers of the consumers and producers are introduced. The powers are loaded from the database of the smart metering system (SMS) for the consumers and producers integrated in this system or files containing the characteristic load profiles established by the Distribution Network Operator for the consumers, which have installed the conventional meters non-integrated in the SMS. In the second stage, a function, which is based on the work with the structure vectors, was implemented to easily identify the configuration of analysed networks. In the third stage, an improved version of a forward/backward sweep-based algorithm was proposed to quickly calculate the power/energy losses to three-phase LV distribution networks in a balanced and unbalanced regime. A real LV rural distribution network from a pilot zone belonging to a Distribution Network Operator from Romania was used to confirm the accuracy of the proposed algorithm. The comparison with the results obtained using the DigSilent PowerFactory Simulation Package certified the performance of the algorithm, with the mean absolute percentage error (MAPE) being 0.94%.

Data clustering‐based approach for optimal capacitor allocation in distribution systems including wind farms

Optimal placement and sizing of shunt capacitors are important issues to improve voltage profile and reduce power losses in distribution networks. In this regard, dealing with stochastic nature of wind farms (WFs), the issue becomes more complex in wind-integrated radial distribution networks. This study aims at optimal siting and sizing of shunt capacitors considering wind uncertainty. Application of probabilistic approach causes to access more real and extensive information about the network. To do so, Monte Carlo simulation (MCS) is employed to assess stochastic variation of wind farm output. As the salient feature of this research, K -means-based data clustering approach is utilised, in which all data-points of the output power of WFs are bunched into desired clusters to ease the solving of simple MCS. The voltage profile and power losses are analysed to do the optimal siting and sizing of capacitors. In order to assess the effectiveness of the proposed method, results are compared with the simple MCS that proves the efficiency of the proposed method from the viewpoint of computation time.

Analysis of the impact of accessing the distributed energy storage system on power distribution network

When distributed energy storage on user side is connected to the distribution network, it will have a significant impact on the distribution network. So the reasonable access for energy storage system has become a key problem. Therefore, this paper analyzes the impact on power distribution network loss and voltage stability by accessing distributed energy storage on user side. Firstly, the relationship between voltage stability of distribution network and distributed energy storage access is studied. It is concluded that the distributed energy storage is beneficial to the voltage stability of distribution network. Then the calculation method of distribution network loss before and after distributed energy storage access is analyzed. Finally, the access location of distributed energy storage is simulated and analyzed. Considering the network loss and voltage stability, it is concluded that small capacity distributed energy storage should be connected at the end of the line, and a certain large capacity distributed energy storage should be connected at the beginning of the line.

Study on the Optimal Planning of Distributed Renewable Power Generation Based on Long-Term Sequence Simulation in Regional Distribution Network

Distributed renewable power generation has obvious volatility and randomness. It has different impacts on voltage, power loss, power quality and so on with different integration schemes in distribution network. It could improve the distribution network voltage level and reduce the power loss with reasonable integration scheme. Conversely, if the integration scheme is not reasonable, it will have bad impacts on power loss and voltage level of the distribution network. TO achieve the optimal planning scheme of Distributed renewable power Generation, a optimal planning method has been proposed in this paper. In the method, the minimum power loss of region distribution network as the optimization objective, long-term sequence simulation with wind energy, solar energy and load actual dates for at least one year in a row has been used to get the annual power loss and voltage qualified rate on different integration schemes. A model is verified by an actual case, which is a large-scale distribution network including multiple feeders. It is shown that the feasibility of the integration scheme. Secondly, the operation requirements of Distributed renewable power generation have been proposed based on the simulation analysis of impacts on voltage distribution of Distributed renewable power generation with PQ and PV operation mode. It is shown that appropriate voltage control strategy could be used to enhance voltage qualified rate.

Co-optimization of energy and reserve in standalone micro-grid considering uncertainties

The electrical energy systems suffer from several problems of operation including production of greenhouse gas emissions and low energy efficiency in fossil fuel-based power plants as well as high energy losses in transmission and distribution networks. Transition from the traditional centralized power generation into distributed power generation, via distributed energy resources, is introduced as a solution to deal with these problems. Micro-grid concept, as a cluster of distributed energy resources and local loads, is introduced to effectively realize distributed power generation. In standalone mode, micro-grid operator faces uncertainties which should be appropriately tackled into the operation problem formulation. For this purpose, a new decision making framework is proposed in this paper which guarantees optimal scheduling of distributed energy resources to simultaneously provide energy and reserve. The proposed modeling framework, which is visualized through a new risk-based stochastic approach, controls the risk of micro-grid operator in decision-making by Conditional Value at Risk method. Numerical results demonstrates the effectiveness of the proposed framework to model the operation problem of a standalone micro-grid under different uncertainties. Moreover, sensitivity analysis reveals that by increasing the percentage of invoked reserve the expected total cost of micro-grid operator increases to manage the uncertainties.

Distribution Network Power Loss Analysis Considering Uncertainties in Distributed Generations

Distribution network loss analysis is crucial for the economic operation in residential distribution networks. The increasing level of distributed generation (DG) has considerably improved the overall sustainability but raised the uncertainty in system losses and exacerbated voltage profiles. This paper presents a nodal distribution loss analysis approach in which the losses induced by loads and DGs are calculated recursively. In order to characterize the uncertainty, the Latin hypercube sampling (LHS)-based approach is presented for obtaining DG output samples. Further, the LHS-based sampling and loss analysis methods are combined into a proposed stochastic framework for loss analysis, which takes into account the DG output uncertainty. Case studies on a 36-bus radial distribution network verified the stochastic loss analysis method. Compared with the simple random sampling method, the proposed LHS-based stochastic loss analysis method can reach the same accuracy level for nodal voltages and losses more efficiently.

A Simulation Scheme for Unordered Power Charging Of Electric Vehicles On Distribution Power Network

With the lack of support for new energy electric vehicles (EV) and the continuous introduction of new policies, EV are entering a period of rapid development. However, the large number of unordered access distribution network of EV users in the period will have a great impact on the power distribution network. EV will further aggravate the load peak valley of the grid during peak periods. It may lead to a series of problems such as overload of distribution network line, voltage drop, increase of distribution network loss and overload of distribution transformer. This paper makes an in-depth analysis of the influence of unordered access charging on power distribution network from theoretical and practical perspectives. For example, Network load, voltage, line loss, etc. Based on the analysis results, a smart charging station based on variable distribution is proposed. It is the best solution to solve the current problem by intelligent orderly control method.

Study on the Influence of Aging and High Impedance Faults on Line Loss of 10kV Distribution Line

With the rapid development of economy in China, the distribution network structure of China tends to be complicated. The overhead line is affected by environmental factors so that aging and high impedance faults occur, which increases the line loss and is not conducive to reliable and economic operation of the power system. In order to analyse the influence of aging and high impedance fault on the line loss of distribution network, this paper firstly establishes the mathematical model of the aging of 10kV distribution line, in which the impedance variation of each type of line with different operating years is obtained based on the actual measurement data. Then, the high-impedance grounding additional loss model under different grounding medium is established by experimental statistics. Finally, taking a distribution network as an example, the equivalent resistance method is utilized to calculate and analyse the influence of aging and ground faults on the distribution network loss. The results of the example show that on the one hand, the line loss of the distribution network increases exponentially with the operating period, and the line loss rate of the line with a long operating period easily exceeds the line loss standard; on the other hand, the high impedance fault will greatly increase the line loss rate for distribution network of smaller scale.

Multi-objective bi-level photovoltaic access planning based on copula theory and included angle cosine method

A multi-objective stochastic bi-level programming method for PV access planning is proposed by cooperating both the Copula theory and included angle cosine method. In order to consider the effect of dependent uncertain irradiance on distribution network operations, the scenarios for correlated uncertain irradiance are obtained by combining the Copula theory and Latin hypercube sampling. Then, to coordinate the distribution network loss and voltage violation, included angle cosine method is applied to determine the weight of different objective functions in the programming model. In addition, the optimal power flow model of the radial distribution network is approximated by second-order cone programming losslessly. The case study verifies the feasibility of the proposed model.

OPTIMASI REKONFIGURASI JARINGAN DISTRIBUSI RADIAL UNTUK MEMINIMALKAN RUGI JARINGAN MENGGUNAKAN METODE SIMPLE BRANCH EXCHANGE

The increasing electric energy consumption must be balanced with good electricity network quality. To overcome this, we need a distribution network reconfiguration. Reconfiguration in power distribution network is done to improve power distribution network quality. Problem that exist in the radial distribution network is power losses. To minimize the power losses can be overcome by compensating capacitor. Done by determining the location of capacitors in distribution networks. With that the capacitor compensates the distribution network is more effective and efficient in distributing power.
 In this research discusses the network reconfiguration using simple branch exchange method to reduce power losses in radial distribution networks . Plant that used in this final project is IEEE 33 bus feeders. Simple branch exchange method is a kind of heuristic method . It works by selecting the order of the loop is done for distribution networks reconfiguration. 
 Simulation results show that the use of a simple branch exchange method for reconfiguring network can reduce energy loss by 63,4677 kW. From the simulation results using the distribution system IEEE 33 bus feeders, showed that the decrease of energy losses from 202,6845 kW become 139,2168 kW.

Influence of distributed photovoltaic power generation on distribution network and the design of optimal access scheme

Distributed photovoltaic (PV) access to distribution network will affect the line loss and voltage of the system, and affect the reliability and economic operation of the distribution system. Therefore, in this study, firstly, node analysis models of distribution network system with four different typical load distribution is established. Secondly, the changes of voltage and network loss caused by distributed PV access to distribution network systems with four typical load distribution are analysed, and the formula of optimal access position and optimal access capacity of distributed PV system under different load distribution system is derived. Thirdly, on the basis of the work data of a distribution line with 43 distributed PV access in Tongchuan city, Shaanxi Province, China, the influence of distributed PV power generation on line loss and voltage of distribution network under different weather conditions are analysed. Finally, an optimal PV access scheme for distribution network based on ant colony algorithm is proposed to ensure the reliable and economical operation of distribution network after distributed PV access. The simulation model of distribution system with distributed PV access is established under Matlab, and the simulation results show the correctness and effectiveness of the proposed formula and the optimisation scheme.

CHARACTERISTIC LAYOUTS OF DISTRIBUTION NETWORKS WITH THE ANALYSIS OF VOLTAGE DEVIATIONS AND EXPEDIENCY OF ITS CONTROL

Urgency of the research. It is well-known that electric energy characteristics are the levels of electromagnetic compatibility of electric grid providing adequate performance of any electrical means connected to the grid if the electric energy characteristics do not exceed permitted values. In the context of general idea of electromagnetic compatibility of consumers within power supply grids, power quality is the topical problem of modern electric-power supply industry. Target setting. The issue of assessing the possibility of ensuring the quality of electricity in terms of voltage deviation by consumers is very important. The problem of voltage fluctuations is relevant, so that voltage deviation have a negative impact on functioning electrical equipment Actual scientific researches and issues analysis. Papers [2-11] are devouted the effective management methods of electrical energy consumption. The articles [6-8] shows that under present conditions only system approach ensures accurate identification and prediction of electric power losses in distribution networks that are characterized by considerable ambiguity. Uninvestigated parts of general matters defining. Generalized diagram of the voltage modes characterizes the state for the entire distribution network connected to the main substation; it consists of the branched 10 kV network, all the distribution transformers, and all the 0.4 kV networks connected to those transformers. Along with the generalized diagram, values of the available voltage losses have been obtained; those values occur within 10 kV and 0.4 kV networks in terms of the favourable conditions of voltage control and the initial values of the admissible voltage deviations of electrical receivers. Moreover, that is the basis to determine operating position of control tappings of distribution transformers. The research objective. Since one of the important characteristics of electrical energy is the deviation of the voltage in the network, it is advisable to carry out its analysis in the urban distribution networks in terms of Levanevska substation, town of Zaporizhzhia. To simplify practical representation of possible voltage modes on the main substation buses and within the whole distribution networks, it is expedient to use graphic representation – so-called generalized diagram of voltage modes. That diagram helps make the analysis of voltage modes more demonstrative than analytical calculation; besides, the diagram gives great possibilities for further study. The statement of basic materials. While analyzing voltage mode in the distribution networks and determining the required law of voltage control in the main substation (MS), one should take into consideration great amount of factors effecting and complicating that study. Those factors include the following: changes in the operating mode of the network, differences in the points of connections of electrical receivers (ER) to the distribution network, differences in possible operating positions of the control tappings in the distribution transformers (DT), differences in the points of DT connections to 10 kV network, available dead zones of automatic voltage controller etc. Owing to that fact, it is required to perform generalized analysis of the voltage mode and conditions of its control within 10 kV and 0.4 kV distribution networks and on main substation buses. To do that, one should apply probabilistic calculation methods. At the same time, it is expedient to use graphic depiction (so-called generalized diagram (GD) of the voltage modes) to simplify representation of possible voltage modes on MS buses and within the whole distribution network. That diagram will help make the analysis of the voltage modes more clearly arranged than analytic calculations; moreover, it gives great opportunities for further study. Conclusions. Voltage deviation in the distribution networks has been performed and expediency of the voltage deviation control for electrically closest and farthest consumers have been analyzed in terms of Levanevska substation, town of Zaporizhzhia. Expediency of practical application of generalized diagrams for that purpose has been demonstrated. It has been defined that in the modes of maximum and minimum loads, voltage exceeds the admissible deviation norms of ± 5 %. Conclusion has been made on the expediency of more careful voltage control. Generalized diagram for 0-1 and 9-10 hours with the maximum voltage deviations has been constructed. Graph of dependences has been developed; formula of voltage deviations in the main substation, due to the voltage passing along that line, has been defined. According to the voltage data before and after the implementation of control, graphs of voltage deviations on the distribution transformer and in terms of the farthest consumer have been constructed.

Impact of Multiple Battery Energy Storage System Strategies on Energy Loss of Active Distribution Network

The implementation of grid energy storage technologies is essential to maximize the absorption of renewable energy. The operation of distribution network with multiple distributed energy resources is complicated. Therefore, this article proposes different optimal operational strategies for battery energy storage system (BESS) in coordination with wind based distributed generation for distribution network. The BESS charging and discharging schedules for all strategies are subjected to the network operational constraints such as node voltage limit, feeder current limit and nodal power balance etc. The improved genetic algorithm is developed to evaluate the impact of different operational strategies on the energy loss of distribution network. The validation of economic benefits in terms of operation and electricity consumption cost is also performed. The suggested strategies are investigated on the standard 33-bus distribution network. The results indicate that optimal operation of BESS can reduce the energy loss and also increase the economic benefits for the distribution system.

A Novel CAP-WDM-PON Employing Multi-Band DFT-Spread DMT Signals Based on Optical Hilbert-Transformed SSB Modulation

We propose and experimentally demonstrate a novel carrier-less amplitude/phase modulation wavelength-division-multiplexing passive optical network (CAP-WDM-PON) with its bandwidth efficiency enhanced by using a multi-band discrete Fourier transform spread (DFT-spread) discrete multi-tone (DMT) signal based on Hilbert-transformed single-sideband (HB-SSB) modulation. The DFT-spread technique is utilized to extend orthogonal subcarriers, which effectively restrain the high-peak signal formation probability, and thereby, it can significantly reduce the high peak-to-average power ratio of the DMT signal. The proposed optical line terminal (OLT) in CAP-WDM-PON suggests five downlink optical subcarriers. For each optical subcarrier, there are as many as $6\times20$ Gb/s SSB digital DMT channels CAP modulated on them, which can be efficiently generated by using only one set of optical transmitter hardware. The experimental results show that the proposed system is capable of accommodating $5\times6$ channels (20 Gb/s per channel) within an optical distribution network (ODN) loss budget of 19.4 dB, and there is a 2.4-dB ODN loss budget improvement by utilizing the DFT-spread scheme. More importantly, the proposed spectral- and bandwidth-efficient CAP-WDM-PON system requires six times less downlink optical transmitters at the OLT, which can be translated into savings in cost, power consumption, and footprint. In addition, key techniques, such as pre-equalization for high-frequency components and digital HB-SSB modulation format for generation of multi-band DMT signals, are also studied.

OPTIMASI TITIK INTERKONEKSI DISTRIBUTED GENER-ATION (PLTM MUARA) GUNA MEMINIMALKAN RUGI – RUGI DAYA MENGGUNAKAN METODE ARTIFICIAL BEE COLONY (ABC) PADA PENYULANG PANJI

Distributed Generation (DG) is a small power plant that can increase realibility, voltage profil, and reduce power losses in distribution network. DG interconnection locations that are less suitable can in/crease power losses. A possibility that can be done to reduce these power losses is by optimizing DG interconnection points. Optimization of the DG interconnection points on the feeder of Panji aims to minimize power losses, where the initial power losses occur at 48.2 kW. Optimization technique is using the Artificial Bee Colony (ABC) method with losses after simulation at 32.263 kW. When compared with the conditions before and after optimization there is a differ-ence in power losses of 16.035 kW, to a decrease in power losses of 33.2% from the previous loss.

Autocorrelation Analysis of Vibro-Acoustic Signals Measured in a Test Field for Water Leak Detection

Reducing losses in water distribution networks is a worldwide challenge and all utilities are developing proper strategies for the active control of leaks. Temporary or permanent grids of units for the continuous monitoring of pipelines through vibro-acoustic measurements are probably the most commonly adopted leak detection systems. Such systems generally rely on the definition of proper thresholds to detect increments in the vibration levels associated with leaks. Since the thresholds are strongly dependent on the local boundary conditions of the monitored network, the initial setup is costly and time consuming, and the risk of undetected leaks or false alarms increases. This work aims to investigate leak detection methods based on the inherent properties of the measured signals instead of their relative amplitude. In particular, the possibility of detecting water leaks in small-diameter plastic pipes by analyzing the autocorrelation function of vibro-acoustic signals is assessed. An experimental campaign is conducted in a full-scale test facility that simulates the actual network. The measurements concerning artificially generated leaks are attained by two accelerometers and one hydrophone. The experimental results confirm the effectiveness of the proposed approach, which is therefore proven as a promising tool for leak detection.