Reactive Power Consumption Research Articles

Statistical Investigation of the Disturbances Affecting the Power Distribution Networks (HTB/HTA) of a Few Source Substations in South-Benin

Power quality is a significant issue that has become increasingly important to both electric power utilities and their customers because of financial losses caused by insufficient. In this work, the Fourier transform (FT) has been exploited for the statistical investigation of the disturbances affecting the electrical distribution networks (HTA) in South-Benin. The data coming from the overhead line disturbances and underground cables, especially from the source substations of MARIA-GLETA, VEDOKO, AKPAKPA, GBEGAMEY and SEME have been treated. These data have been collected and made in our disposal by the Beninese Electricity Energy Company (SBEE) over the period from 2010 to 2017. Harmonic Distortion Rate (TDH) and the Disturbance Rate (D<SUB>R</SUB>) have been used to evaluate the variation coefficient of the different disturbances registered at the each source substation, in order to characterize the harmonic pollution and the reactive power consumption. According to the EN 50160 N standard, the results obtained show that VEDOKO registered 500 to 2000 interruptions of duration between 0.4x10⁵ and 1.8x10⁵ minutes, between 2013 and 2016 especially due to a very critical load shedding. The dominance of the disturbances observed has been due exclusively to the incidents setting off and the load shedding incidents in 2017. 2013 and 2015 have been characterized by the frequent blackouts of long living, and occasion considerable damages, and consequently slow down the economic activities, social and cultural life of consumers.

Management of Peak Loads in an Emerging Electricity Market

An electricity market is a trading platform provided by the actors in the electricity sector to sell and buy electricity while maintaining the stability of the transmission network and minimizing energy losses. The management of electrical energy for rational use consists of all the operations that the consumers can carry out in order to minimize their electricity bill, while the producers optimize their benefits and the transmission infrastructure. The reduction of active and reactive power consumption and the smoothing of daily and yearly load profiles are the main objectives in this work. Many developed countries already have properly functioning electricity markets, but developing countries are still in their infancy of deregulated electricity markets. The major tools used in smoothing the load profiles include decentralized generation, energy storage and demand response. A load power smoothing control strategy is proposed to smooth the load power fluctuations of the distribution network. The required power change is determined by evaluating the power fluctuation rate of the load, and then the required power change is allocated to some generators or to some stored reserves. Otherwise, the consumers are made to curtail their power consumption. The ideas proposed in this work provide important opportunities for energy policy makers and regulators. These ideas would only be feasible if there exists real-time communication among the actors in the electricity market. The results indicate that as much as 1100 Megawatt-hours of energy can be stored for smoothing the load profile, when applied to the Southern Interconnected Grid of the Cameroon power system; and that Time of Use (TOU) pricing could be used instead of rotating blackouts in case of energy shortage.

Detailed Primary and Secondary Distribution System Model Enhancement Using AMI Data

Reliable and accurate distribution system modeling, including the secondary network, is essential in examining distribution system performance with high penetration of distributed energy resources (DERs). This paper presents a highly automated, novel method to enhance the accuracy of utility distribution feeder models to capture their performance by matching simulation results with corresponding field measurements. The method is demonstrated using an actual feeder from an electrical utility with high penetration of DERs. The method proposed uses advanced metering infrastructure (AMI) voltage and derived active power measurements at the customer level, and data acquisition systems (DAS) measurements at the feeder-head, in conjunction with an AC optimal power flow (ACOPF) to estimate customer active and reactive power consumption over a time horizon, while accounting for unmetered loads. The ACOPF uses the measured voltage magnitudes, derived active power measurements, and the feeder head measurements to obtain a complete active power and reactive power capture of the feeder loads. Additionally, the method proposed estimates both voltage magnitude and angle for each phase at the unbalanced distribution substation. The accuracy of the method developed is verified in two stages: by comparing the time-series power flow results obtained from the enhancement algorithm with OpenDSS results and with the field measurements available. The proposed approach seamlessly manages the data available from the optimization procedure through the final model verification automatically.

Варианты систем электродвижения ледоколов мощностью 60 и 120 МВт

Variants of electric propulsion systems for powerful icebreakers with the use of transistor frequency converters or thyristor frequency converters with direct coupling (DFC) are considered. Rowing motors synchronous or asynchronous. With transistor converters, the semiconductor element base is mainly imported, with thyristor FCs, it is mainly domestic. But DFCs work with reactive power consumption, and its generation requires the use of additional devices, such as passive filters or STATCOMs. When the propellers of icebreakers are reversed, the energy of the propellers is recuperated. In electric propulsion system with transistorized FСs, resistors and choppers are used to absorb the regenerated energy. In electric propulsion system with DFC, it is possible to recuperate energy into the mains, and this allows you to reduce the power of the resistors. Resistors are included in STATCOMs, expanding their functions (reactive power generation, voltage filtering, energy absorption).

Generic Analysis Framework for Modular Multilevel Converter HVDC with Multi-Infeed Line-Commutated Converter HVDC System

This paper proposes a generic analysis framework for a grid supporting modular multilevel converter (MMC)-high voltage DC (HVDC) in a multi-infeed of line commutated converter (LCC) and MMC (MILM) system. MMC-HVDC can support the grid by compensating for the exact reactive power consumptions within the MMC-HVDC system and the varying power system conditions in the MILM system. Maximum active/reactive power capability (MPQC) curve and PQ loading curve comparison process is introduced to properly design a grid supporting MMC-HVDC. While the MPQC curve presents the maximum PQ range of the MMC-HVDC system based on the submodule capacitance value and the modulation index, the PQ loading curve presents the reactive power requirement from the power system that MMC-HVDC needs to compensate. Finally, the comparison of these two curves yields the proper value of submodule capacitance and the modulation index for sufficiently supporting the MILM system. The proposed framework is validated with detailed PSCAD/EMTDC simulation; it demonstrated that it could be applied to various power system conditions.

Reactive power control

The article investigates the methods of control of reactive power modes. It is shown that ensuring the efficiency of electricity transmission and distribution is inseparable from setting and solving problems related to reducing electricity losses in networks. Moreover, one of the most effective ways to reduce electricity losses, as well as improve its quality at the terminals of electrical receivers is to compensate for reactive power, which is carried out using various compensating devices. It is shown that the control of the reactive power mode is carried out in accordance with the Methodology for calculating the fee for the flow of reactive energy between the power transmission organization and its consumers. It is shown that the indicator of economically advantageous value of the level of reactive energy consumption can be cos φз, the value of which is predetermined. The procedure for controlling the reactive power mode contains two main stages: the stage of determining the magnitude of the possible reduction of the current cos φ above the set and the stage of determining and implementing control effects aimed at eliminating possible deviations. Preferably, it is preferable to focus on those methods that are based on the study of forecast estimates, which constitute the source information for management decisions. It is expedient to use adaptive methods of exponential smoothing as a basis for operative forecasting of electric loading. Reactive power mode is controlled by compensating units. It is shown that the control of voltage modes in the power supply system significantly affects the modes of reactive power consumption. In this regard, it is advisable to comprehensively solve the problem of reactive power control both by controlling the compensating units and the impact on the voltage regimes of the power supply system. In the calculation model, the reactive load of the distribution network is given by its static characteristics, which can be the basis for regulating the reactive load. To implement regulation in the power supply centers of electrical networks, technical means are provided on the basis of changing the transformation coefficient or generating reactive power by counter-voltage regulation.

Estimation of distribution transformer kVA load using residential smart meter data

A major challenge observed for smart meters installed at North American residential premises involves the absence of reactive power consumption measurement of residential customers, which limits the accurate assessment of kVA loading for a distribution transformer (DT), necessary to assess the loss of life and failure of a DT. This paper presents a hardware-free novel strategy for DT kVA load estimation that operates at the utility server level without requiring a fixed power factor assumption or reactive power load information across all residential customers. The proposed strategy provides a simple and effective fixed-point iteration-based formulation for a balanced secondary distribution network, that is extended for an unbalanced three-phase underground secondary distribution network. The efficacy and a detailed statistical analysis of the proposed scheme are studied on a balanced and an unbalanced secondary distribution systems against 1,000 random load profiles through Monte-Carlo simulations which represent uncertainty in smart meter data, with theoretical analysis on convergence and stability also provided. The results indicate that the proposed scheme provides better results in comparison to fixed power assumptions, with respect to the voltage magnitude estimation, and the results from this work may contribute to further smart-grid applications in DTs.

Optimisation of the FE Model Based on the No-Load Test Measurement for Estimating Electromagnetic Parameters of an Induction Motor Equivalent Circuit Including the Rotor Deep-Bar Effect

The various measurement procedures for determination of electromagnetic parameters for the induction motor (IM) equivalent circuits including the rotor deep-bar effect were proposed in the literature. One of them is the procedure based on the load curve test (LCT). Since the execution of the LCT can pose some difficulties, especially in industrial conditions, as an alternative, the finite element method (FEM) can be employed to simulate the IM operation under the LCT. In this work we developed the optimisation technique for the finite element (FE) model. This technique is performed with the use of the stator current space-vector components which determine the IM input active and reactive power consumption during no-load operation. Relying on the LCT simulation carried out with the optimised FE model the inductance frequency characteristic can be determined and then used as the reference characteristic in the electromagnetic parameter estimation for the IM equivalent circuit including the rotor deep-bar effect. The presented research results demonstrate proper conformity between the inductance frequency characteristics obtained from the LCT performed experimentally and determined by means of the optimised FE model. Satisfactory conformity is also achieved in the case of the torque-versus-slip frequency curves acquired from the measurement and calculated by the IM space-vector model with estimated electromagnetic parameters. All of this validates the effectiveness of the proposed technique for the FE-model optimisation and the usefulness of the presented approach using the FEM in the electromagnetic parameter estimation for the IM equivalent circuit including the rotor deep-bar effect.

Impact of the Integration of a STATCOM Controlled by LQG/H2 Regulator in an Energy System

Nowadays, the reactive power consumption is becoming a serious problem for electricity network management. To overcome this problem, several solutions are proposed in the literature. In the present study, the static reactive power compensator (STATCOM) solution is used to keep the network voltage within its rated range. The STATCOM is modeled in the axes of Park reference frame and is driven controlled by a SVPWM strategy. Its control scheme is based on a multivariable Linear Quadratic Gaussian (LQG/H2) controller, which has the advantage of being applied to systems whose condition is not measured. Simulations are performed using the MATLAB/SIMULINK software. Results are presented, compared and discussed.

ONE ASPECT OF REACTIVE POWER COMPENSATION IN 0.4 kV RURAL NETWORKS

A sign of today is the development of powerful agro-industrial enterprises and sources of dispersed generation in rural areas. The issues of uninterrupted power supply and improvement of electricity quality indicators in such distribution networks are relevant. In rural electrical networks of alternating current, the total transmitted power S contains active P and reactive Q power of inductive nature, which is due to active – inductive load and therefore, respectively, the current in the power supply system has active and inductive components. The load consumption of active and reactive power characterizes the coefficient of active power cosφ, which is defined as the ratio of active power to total. Quite often in energy the reactive power factor tgφ is used as the ratio of reactive power to active power. In our opinion, this more clearly reflects the ratio of the amount of energy consumed. The article considers the conditions for providing the necessary values ​​of the power factor in the mode of compensation of reactive power of the power supply system of low-power processing enterprises of agricultural products. The analytical dependence of the power of the compensation device required to ensure the desired value of the power factor is determined. An algorithm for calculating the harmonic components of the capacitor bank current in the network with sources of higher harmonics has been developed. The calculations take into account the dependences of current harmonics on the load of 0.4 kV network consumers. Conducted analysis of the occurrence of possible resonant phenomena in the 10 (6) kV network. The value of the capacitor bank current is determined in the case when the source of the higher harmonics is the power supply system itself or the consumers of electricity in the 0.4 kV network.

Advanced approach to compensation of reactive power in isolated arctics electrical supply systems

Compensation of consumed reactive power is an important task for the electric power industry. In real conditions, reactive power is constantly changing. In order to achieve good compensation, it is necessary in a timely maner to adjust the reactive power of the compensating devices. We suggest advanced compensation system for isolated electrical grids in the Arctic. In this system power adjustment of the compensating device is made with expected consumption of reactive power. Consumption is forecast by the measured values of reactive power using a Taylor series.

ПАРАМЕТРИЧНА ОПТИМІЗАЦІЯ РЕЖИМІВ РОБОТИ МАГІСТРАЛЬНИХ ЕЛЕКТРИЧНИХ МЕРЕЖ ЗА КРИТЕРІЄМ ВТРАТ АКТИВНОЇ ПОТУЖНОСТІ

It is shown that the use of controlled shunt reactors enables, based on ultra-high voltage transmission lines, to create a controlled generation of new generation FACTS types that meet the requirements of modern power systems and combinations. Typical modes of operation of the high-voltage power line with installed controlled shunt reactors are analyzed. The efficiency of the use of controlled shunt reactors as measures of transverse compensation in ultrahigh voltage transmission lines is shown. The article shows that due to a smooth change in the consumption of excess reactive power of the transmission line, the normalization of the voltage values is achieved, and, accordingly, the total power losses are reduced. Ref. 9, fig. 3, tables 3.

Thermographic Measurement of the Temperature of Reactive Power Compensation Capacitors

An excessive increase in reactive power consumption is unfavorable from the point of view of a power system. For this reason, devices compensating reactive power consumption are used. The capacitor is one such device. Capacitors must be tested regularly during their exploitation. One of the activities that should be performed is testing the degree of heating of the cells of a capacitor bank. Thermography can be used to perform such tests. This non-contact method has its limitations. Due to the angular emissivity and the change in the distance between the lens and the object under observation, the temperature measured with a thermographic camera may differ from the actual temperature. This phenomenon is visible on cylindrical capacitor cases. Consequently, depending on the location of the observation point on the capacitor case, the result of the thermographic temperature measurement may be different. To investigate this phenomenon, experimental work has been undertaken.

Development of Intelligent Smart Metering System through Remote Monitoring and Control under Robust Conditions

Abstract This paper discusses the development of intelligent smart metering infrastructure for smart buildings based on information and communication technologies. The system collects electrical parameters, like real power, reactive power, voltage, current, power factor, and energy consumption, and physical parameters, such as temperature, humidity, and occupancy of the building. The electrical data are collected using Raspberry Pi 3B along with Smart Pi module. The physical parameters are collected by using a wide range of sensors communicating with the data acquisition module wirelessly by Wi-Fi technology. The monitoring platform is developed both in the customer end for the energy user and remote end for monitoring and control by the system operator. The developed system also has a parallel mode of communication based on LoRa technology, which will come into the picture if the primary mode of communication fails, ensuring there is always a continuous transfer of data under natural disaster situations. In addition, the system has an occupancy detection–based Internet of Things control module through which the system operator can remotely control selected appliances in the customer side based on the occupancy of the building as well as during disaster situations. The developed system also paves the way for secured smart buildings by continuous tracking of the building physical parameters, like temperature, humidity, and occupancy of the building during emergency situations like floods, earthquakes, and terrorist attacks, by which relief operations can be provided.

Дослідження залежності ккд від завантаження свердлильного верстата

The question of research of dependence of efficiency on loading of the drilling machine is considered. To achieve this goal in the work were set and solved the following tasks: - to analyze the design and technological features of the drilling machine part; - to develop a new design of a drilling machine with a network analyzer; - to investigate the new design of a drilling machine with a network analyzer. About 80 % of drilling machines at Ukrainian enterprises are operated in excess of the established shelf life, which leads to their low quality of operation, high accident rate and failure of electromechanical equipment. The average shelf life of the electric drive in the industry does not exceed 6 years. Up to 10–18 % of electric motors and up to 30 % of auxiliary equipment fail and are repaired annually. The vast majority of engines can be repaired 4-5 times and after repair often do not work even for one year. The operation of drilling machines with an induction motor (short-circuited rotor), which are in poor technical condition, leads to an increase in financial costs due to increased power consumption. The cost of electricity consumed by the electric drive of drilling machines during the service life is significantly higher than the cost of equipment and maintenance costs and more than 4 times higher than its own. The electricity bill includes a system of surcharges for additional reactive power consumption. Reactive power charges at enterprises account for up to 10% of total electricity costs, and these costs tend to increase. Today, there is a need to apply the latest technical solutions and scientific approaches to solving the problem of improving the quality of operation of asynchronous electric drives of drilling machines. A research stand has been developed to determine the asynchronous motor of a drilling machine, which allows to identify the dependence of efficiency on the magnitude of the load, calculate the parameters of the substitution scheme and energy characteristics for the nominal mode of operation of the electric drive. Key words: drilling machine, network analyzer, research stand

Investigation of dynamic pressure fluctuations in closed hydraulic circuits as a function of centrifugal pump speed gradients

Electrical consumers, such as pumps, contribute towards the stable operation of the electrical power grid due to active and reactive power consumption. If the consumers are indirectly connected to the grid via power electronic converters, the positive contribution is reduced or non-existent. Consequently, the ability to compensate imbalances within the power grid is greatly reduced. A research project founded by the European Union is focusing on investigations to utilize power converter technology of pump drives for grid stabilization. But in order to stabilize the fluctuating power grid frequency rapid adjustments of the pump speed are required, which can cause major troubles in the hydraulic system. For instance, rapid changes in pump speed are causing the emission of hydro acoustic pressure waves into the pipe system, which are exciting the structure of the hydraulic system and lead to undesirable vibrations and noise emissions. Most critical is the direct excitation of natural frequencies in the entire piping system based on the inherent pressure fluctuations caused by transient fluid flow and pump speed changes. Converter control for grid-adaptive speed adjustment is only possible as long as there is no significant increase in dynamic pressure fluctuations in the whole hydraulic system. For this purpose, a research pump is operated with different rotational speed gradients in a closed hydraulic circuit. Dynamic pressure sensors were used to record the resulting pressure fluctuations at various locations of the hydraulic system. Additionally, an outlook towards an active reduction of the dynamic pressure fluctuations by means of a specially developed hydrodynamic actuator is given. These results are an initial step but of particular interest towards the knowledge of permissible grid adaptive speed control regimes, which can be applied to a pump in a hydraulic piping system.

Two-stage ADMM-based distributed optimal reactive power control method for wind farms considering wake effects

Since the connection of small-scale wind farms to distribution networks, power grid voltage stability has been reduced with increasing wind penetration in recent years, owing to the variable reactive power consumption of wind generators. In this study, a two-stage reactive power optimization method based on the alternating direction method of multipliers (ADMM) algorithm is proposed for achieving optimal reactive power dispatch in wind farm-integrated distribution systems. Unlike existing optimal reactive power control methods, the proposed method enables distributed reactive power flow optimization with a two-stage optimization structure. Furthermore, under the partition concept, the consensus protocol is not needed to solve the optimization problems. In this method, the influence of the wake effect of each wind turbine is also considered in the control design. Simulation results for a mid-voltage distribution system based on MATLAB verified the effectiveness of the proposed method.

Effect of Symmetrically Switched Rectifier Topologies on the Frequency Regulation of Standalone Micro-Hydro Power Plants

Micro-hydro power plants (μHPPs) are a major energy source in grid-isolated zones because they do not require reservoirs and dams to be built. μHPPs operate in a standalone mode, but a continuously varying load generates voltage unbalances and frequency fluctuations which can cause long-term damage to plant components. One method of frequency regulation is the use of alternating current-alternating current (AC-AC) converters as an electronic load controller (ELC). The disadvantage of AC-AC converters is reactive power consumption with the associated decrease in both the power factor and the capacity of the alternator to deliver current. To avoid this disadvantage, we proposed two rectifier topologies combined with symmetrical switching. However, the performance of the frequency regulation loop with each topology remains unknown. Therefore, the objective of this work was to evaluate the performance of the frequency regulation loop when each topology, with a symmetrical switching form, was inserted. A MATLAB® model was implemented to simulate the frequency loop. The results from a μHPP case study in a small Cuban rural community called ‘Los Gallegos’ showed that the performance of the frequency regulation loop using the proposed topologies satisfied the standard frequency regulation and increased both the power factor and current delivery capabilities of the alternator.

Improving Transient Stability of Dual Stator-Winding Induction Generator-Based Wind Farms by Slip Frequency Control

This article studies improving rotor-speed stability of dual stator-windings induction generators (DWIG)-based wind turbines during a severe fault in the power system. A novel instantaneous slip frequency control (ISFC) with a supplementary control loop containing braking resistors (BRs) is introduced. The ISFC drive technique is selected primarily for its fast-dynamic performance. An active power feed-forward loop in this drive technique can adequately regulate the generator’s slip restricting reactive power consumption. The supplementary control loop includes a mechanism that can bring sufficient braking resistance into the circuit to keep the slip’s optimal value according to the wind speed. At first, the proposed DWIG-based wind turbine equipped with the ISFC drive technique is described. Then the factors affecting the rotor speed stability are analyzed, and the improved ISFC is proposed. The topology and the proposed drive technique are simulated in MATLAB/Simulink platform and experimented with a scaled 1.2-kW prototype. Both simulation and experimental results demonstrate the significant impact of the proposed method.

Comparative study between the melting process of an aluminum batch and a steel batch in a high frequency induction furnace

In this work we analyzed a laboratory induction furnace, having a small capacity, fed by a high-frequency static converter. The measurements were carried out in the case of an aluminum batch, and a steel batch, using the power quality analyzer CA8334B. We studied the influence of the type, temperature and amount of processed material, on the electrical parameters of induction furnace during the melting process. Large electromagnetic disturbances (harmonic currents, current unbalances, reactive power consumption) were recorded, especially during the preheating period of crucible and the first stage of heating, when the furnace worked at low power, for the both batches. The experiments allowed the elaboration of some measures for optimization of melting process in the analyzed induction furnace, in terms of efficiency and mitigation of electromagnetic disturbances.