kV Voltage Level Research Articles

Model for 400 kV Transmission Line Power Loss Assessment Using the PMU Measurements

This paper presents an advanced model for monitoring losses on a 400 kV over-head transmission line (OHL) that can be used for measured data verification and loss assessment. Technical losses are unavoidable physical effects of energy transmission and can be reduced to acceptable levels, with a major share of technical losses on transmission lines being Joule losses. However, at 400 kV voltage levels, the influence of the electrical corona discharge effect and current leakage can have significant impact on power loss. This is especially visible in poor weather conditions, such as the appearance of fog, rain and snow. Therefore, loss monitoring is incorporated into exiting business process to provide transmission system operators (TSO) with the measure of losses and the accurate characterization of measured data. This paper presents an advanced model for loss characterization and assessment that uses phasor measurement unit (PMU) measurements and combines them with end-customer measurements. PMU measurements from the algorithm of differential protection are used to detect differential currents and angles, and this paper proposes further usage of these data for determining the corona losses. The collected data are further processed and used to calculate the amount of corona losses and provide accurate loss assessment and estimation. In each step of the model, cross verification of the measured and calculated data is performed in order to finally provide more accurate loss assessment which is incorporated into the current data acquisition and monitoring systems.

Determination of Relay Opening Current Information and Coordination of Distribution Network of Sakarya Province, Yazlık Region

Electricity is delivered to end users through generation, transmission, and distribution phases. The most important issues during energy journey is to provide selective, rapid, and safe protection to ensure energy continuity. In this context, when the operating conditions defined in the protection systems are exceeded, an effective protection system and coordination are required to provide that as few consumers as possible are affected by the energy outage and reliably isolate the fault. If the short circuit is not separate from the network quickly after a short circuit occurs, network equipment and electrical devices may be damaged because of overcurrent that occurs. In this study, the coordination of overcurrent protection relay at 34.5 kV voltage level of the distribution network in Sakarya Province, Serdivan District, Yazlık region is made and MATLAB/Simulink is used in the modeling of the system. All data of inspected distribution network is embedded to MATLAB/Simulink file and then optimum protection is provided on relay coordination settings by performing power flow analysis and short circuit calculations.

On-line data splicing power flow analysis method based on sensitivity

This paper proposes an online data splicing power flow analysis method based on sensitivity analysis. Since the step-down transformer in the whole network data is usually equivalent to the 220 kV side, the equipment below 220 kV is not modeled in detail, and the provincial network data is modeled to 110kV and 35 kV voltage level equipment in detail. Different levels of modeling have a greater impact on the accuracy of stability analysis and calculation. Therefore, the purpose of improving data accuracy is achieved by splicing the entire network data (external network) and provincial network data (internal network). This paper is based on the sensitivity analysis method to stabilize the tie-line power by adjusting the output of the external network units, and form the whole network data that can accurately analyze the stability characteristics of the provincial network. The problem of power flow deviation caused by the voltage and angle deviation of the nodes at both ends of the regional tie line during the data splicing process is solved. Through the actual application of splicing the entire network and Hunan Provincial Network data, the effectiveness and necessity of the proposed method have been verified.

Assessment and Impact of Var Injection Devices on System Parameters

In this research work, analysis and effect of reactive power injection at different voltage level are carried out. The 39-bus test network modeled in mipower software is a part of Rajasthan power system attached with North Regional Grid of Indian Power system synchronized at 765 kV voltage level. The present problem of high load and mismanagement in providing required compensation is addressed in this paper by simulation case study. Reactive power drawl from the components end is judged and analyzed by placing fictious generator at respective voltage level. State power system area is wide, having a hierarchy voltage level varying from 765 to 33 kV, but the utilities are still unaware of obtaining possible sites and voltage level in power system network. As a result, system faces higher loading levels and unnecessary line tripping thus raising losses and reduced reliability. Pertaining to the database collected of financial year 2018–2019. Due to renewable integration the variable load behavior must be accurately known by the system engineers then only load compensation must be provided. Because presently State Load Dispatch Centers provide instructions to the substations to utilize any available compensation device available in the network to use. This paper underlines a way to access the effects on voltage profile, losses, etc. on power system elements with var support at multiple voltage levels. Case studies for real-time network are detailed, to check the observability for a load of 370 MW. The impact of practices followed is observed for the complete network.

Development, Modeling, and Testing of a Unified Controller for Prosumers Connected to 0.4 kV Voltage Level Grids. Part I: Modeling and Test Bench Assembly

Development, Modeling, and Testing of a Unified Controller for Prosumers Connected to 0.4 kV Voltage Level Grids. Part I: Modeling and Test Bench Assembly

Development, Modeling, and Testing of a Unified Controller for Prosumers Connected to 0.4 kV Voltage Level Grids. Part II: Experimental Validation

Development, Modeling, and Testing of a Unified Controller for Prosumers Connected to 0.4 kV Voltage Level Grids. Part II: Experimental Validation

Compensation voltage moduli comparison‐based wide‐area protection algorithm independent of data synchronism and integrity

Secondary direct-current loss within a substation is a severe event. In China, each line protection device is generally powered by one set of secondary direct current (DC) power system within a substation of 110 kV voltage level. In this case, the line protection devices will be immediately taken out of service when the secondary DC is lost, and the lines protected by them will lose their corresponding protections. Once a fault occurs on the line, only the remote back-up protection can be relied on to isolate the fault, which expands the fault influence and increases its clearance time. To handle the above problem, a novel wide-area protection algorithm based on compensation voltage moduli comparison is proposed, which is independent of multi-terminal data synchronism. Then, a comprehensive protection strategy composed of the proposed protection algorithm and the original local distances protection is proposed. The results from a power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC)-based simulation verify that the proposed protection algorithm has higher sensitivity. The comprehensive protection strategy could cope with most line faults effectively, even if only partial data are available, the selectivity and speed of which are better than that of distance protections.

Assessment of voltage changeability with reactive power source allotment for real time network

In this research work investigation of reactive power necessity at standard voltage level is practiced. The 39-bus test network modeled in mipower application is a part of Rajasthan power system, attached with North Regional National Grid synchronized at 765 kV voltage level. State power utilities are unable to obtain the profoundness in providing, static or dynamic compensation at multiple voltage available within the grid. Reactive power drawl from the network end is judged and analysed by placing imaginary generator at available voltage level. In Rajasthan power system voltage level arrays from 765 kV to 33 kV and the utilities are puzzled in managing var penetration due to poor estimation. As a result, higher loading levels and abrupt line tripping raises losses and reduces system reliability. The simulation case studies presented herby from the database of financial year 2018-19 will be envisaged by the utilities after evaluation is over. Presently State Load Dispatch Centers deliver instruction to substations to utilize any compensation device available without prior calculation. But this paper underlines a way to access the effects on voltage profile, losses etc. in power system structure after planned var support at optimum voltage level. Case studies over real time network is detailed, to check the observability for a load of 370 MW. The impact of practices followed is observed for the designed network.

Complementing hydroelectric power with floating solar PV for daytime peak electricity demand

Abstract Renewable energy is the cornerstone of our future energy needs. In particular, solar energy is being utilized at a faster pace than ever. Floating Solar Photovoltaics (FSPV) has recently gained traction as a suitable alternative of land-based large scale PV installation. It is a promising technology to utilize water surfaces for placing solar plants. Not only it utilizes the water as real estate but it has several other advantages as well. For example, FSPV can use the existing transmission and distribution infrastructure that is the part of hydroelectric power plants. In this paper, we evaluate an FSPV plant and its integration with the existing hydroelectric power station of a small reservoir in Pakistan. We have investigated the 500 kV, 132 kV and 11 kV voltage levels for the integration of FSPV plant. Moreover, we have devised a hydro-solar optimization model for the efficient utilization of energy. The combined system consisting of hydroelectric and 200 MWp FSPV produces more than 3.5% additional power overall when compared with production of only hydroelectric power. More importantly the FSPV generation coincides with the daily mid-day peak load thus works as a peaker plant for the national grid.

RAILWAY SYSTEM IMPACT ON VOLTAGE QUALITY AT THE LEVEL OF THE CROATIAN TRANSMISSION NETWORK

Railway systems are single-phase loads, connected to two-phase of the three-phase supply network. Therefore, they negatively affect the voltage quality, primarily the voltage unbalance. In addition to voltage unbalance, railway systems inject current harmonics into the network due to controllable diode or thyristor drives used to operate the train.
 The paper gives a short theoretical description of the harmonic distortion and the voltage unbalance as well as the results of the voltage quality measurement. Moreover, the paper shows the impact of the railway system on the transmission network in the case that the facilities are connected to the 110 kV voltage level.

Study on the Influencing Factors of Insulator on the Back-Flashover Lightning Withstand Performance of ±800 kV UHVDC Transmission Lines

The current research results indicate that the insulator’s insulation performance has a very important influence on the back-flashover lightning withstand performance of UHVDC transmission lines, especially for ±800 kV voltage level. However, it is not clear which factors will influence the insulation performance of the insulator, and the influencing mechanism is also not clear yet. To figure out this problem, the insulator’s insulation performance under different conditions has been deeply analyzed and considered to reveal the influence mechanism in this paper, such as the surface hydrophobicity, pollution degree, and the string type. Firstly, the insulator’s model is established using COMSOL software, and the lightning impulse voltage of insulator is calculated and verified with the corresponding experimental data. Then, the ±800 kV UHVDC transmission lines model is constructed using PSCAD software, and back-flashover lightning withstand level and back-flashover rate are calculated by considering the above lightning impulse voltage as the threshold of flashover. Finally, the back-flashover lightning withstand performance of ±800 kV UHVDC transmission lines is deeply analyzed based on different insulators. The simulation results demonstrate that the back-flashover lightning withstand performance of ±800 kV UHVDC transmission lines is obviously weakened with the increase of the pollution degree and slightly weakened with the decrease of the surface hydrophobicity. Considering the same pollution degree, the V-type string insulator has the least influence, while the II-type string insulator has the greatest influences on the back-flashover lightning withstand performance of ±800 kV UHVDC transmission lines. The research results are beneficial for providing theoretical basis for stable operation and reliable power supply of ±800 kV UHVDC transmission lines.

Method for Localization Aerial Target in AC Electric Field Based on Sensor Circular Array.

The traditional method of using electric field sensors to realize early warning of electric power safety distance cannot measure the distance of dangerous sources. Therefore, aiming at the electric field with a frequency of 50 to 60 Hz (AC electric field), a new method for localization of aerial AC target by the capacitive one-dimensional spherical electric field sensor circular array is studied. This method can directly calculate the distance, elevation, and azimuth of the detector from the dangerous source. By combining the measurement principle of the spherical electric field sensor and the plane circular array theory, a mathematical model for the localization of aerial targets in an AC electric field is established. An error model was established using Gaussian noise and the effects of different layout parameters on the localization error were simulated. Based on mutual interference between sensors, minimum induced charge, and localization error, an optimal model for sensor layout was established, and it was solved by using genetic algorithms. The optimization results show that when the number of sensors is 4, the array radius is 20 cm, and the sensor radius is 1.5 cm, the ranging error is 8.4%. The detector was developed based on the layout parameters obtained from the optimization results, and the localization method was experimentally verified at 10 and 35 kV alarm distances. The experimental results show that when the detector is located at 10 kV alarm distance, the distance error is 0.18 m, the elevation error is 6.8°, and the azimuth error is 4.57°, and when it is located at 35 kV alarm distance, the distance error is 0.2 m, the elevation error is 4.8°, and the azimuth error is 5.14°, which meets the safety distance warning requirements of 10 and 35 kV voltage levels.

Development and type test of ZW-126/D2000-40 vacuum circuit breaker with controlled switching technology

A ZW-126/D2000-40 type single-break vacuum circuit breaker(VCB) with controlled switching technology is designed and produced in this paper. The results of type test based on IEC and GB standards are presented. A 126 kV single-break vacuum interrupter (VI) with 3/4 coil axial magnetic field (AMF) contacts is used in the VCB, which can interrupt short current of 40 kA. The external insulation of the VI is provided by SF6 at 0.1 MPa. In order to match the 126kV single-break VI and controlled switching device, a long-stroke electro-magnetic force actuator (EMFA) with 16kN closing holding force and 3.5 m/s average opening speed is designed. Moreover, a position tracking controlled switching device based on closed-loop control by the technology of fuzzy control algorithm and pules width modulation is applied to the controlled switching device. This device is applied to control the coil current of EMFA and the electromagnetic force, so as to control the EMFA to follow the ideal position curve. The type tests of 126kV VCB are all passed according to the IEC62271-100 and GB1984-2014, including dielectric tests, basic short-circuit tests, short-line fault test, out-of-phase test, etc. The strong capacitive current breaking capacity and mechanical strength of the VCB are proved by the capacitive current switching test of class C2, electrical endurance test of class E2 and mechanical endurance test of class M2. The electromagnetic compatibility (EMC) tests are passed according to the IEC61000-4. The controlled switching test of capacitive current was successful according to IEC62271-302 and GB/T30846-2014, and the controlled switching accuracy is less than ±0.5 ms. The test results showed that the VCB has excellent performance, which has broad application prospects in special occasions at 126 kV voltage level, such as switching capacitor and no-load transformer, etc.

Transmission Line Fault Resistance Values Based on Field Data

Systematic deployment of digital fault recorders has made considerable amounts of field data available and raised the interest to compute fault resistance values from large sets of power system faults and analyze the results statistically. Published results are valuable, however scarce. The present paper gives further contributions by showing results obtained from 89 fault records, for the 400 kV, 220 kV, and 150 kV voltage levels, comparing these with recently published data. Furthermore, the present paper addresses the fundamental question on the existence of a theoretical distribution capable to describe the fault resistance value. For such purpose, an exploratory data analysis is applied to the new results, and a comparison between the exponential and the Weibull distribution is carried out. Results show that both distributions can describe the field data based distributions, the Weibull being more adequate for low resistance values.

PERANCANGAN PENGUKURAN TEGANGAN TINGGI PADA MODUL PEMBANGKIT TEGANGAN TINGGI IMPULS

Measurement of high voltage AC, DC and Impulses on a laboratory scale using expensive measuring instruments. In addition, the measurements taken are at a voltage level of 15 KV. Integrated measurement of high voltage AC, DC and Impulses for 15 KV voltage levels using sign transformers has never been done. Whereas high voltage generation using a sign transformer is only able to generate voltage up to 15 KV voltage only. For that we need a voltage measuring device that is able to measure up to a voltage of 15 KV, and does not require expensive costs. In this Final Project, a high voltage monitoring module for impulse high voltage generator module will be designed using visual studio c #. The results of monitoring the high voltage generator module on the C # visual studio form successfully went well. The voltage test performed produces a value close to the actual value with an average error of 0.01 volts. Unfortunately this test is still not perfect because it is still susceptible to noise so that the measurement process is often interrupted.

Study on clearance optimisation and altitude correction of 750 kV AC side for UHVDC converter transformer

AC system which ±800 kV converter station access to commonly used 500 kV voltage level. With the construction of the Northwest Energy Base, a large number of ultra-high-voltage direct current (UHVDC) project are constructing. The backbone voltage in the northwest region is 750 kV. Phase or phase-to-ground clearance the converter transformer 750 kV AC side required will affect the length of the valve hall and the highest altitude of the project close to 3000 m. In order to optimise the 750 kV AC side and meet the engineering requirements in high altitude areas, this paper carried out the true phase-to-ground and phase–phase discharge characteristics test in the gap of 750 kV AC side in Beijing and Tibet, and the gap discharge voltage was then corrected for altitude. At last, the distance at different altitudes of 3000 m and below between the phase-ground and the phase-to-phase at the AC side of converter transformer is obtained. The results provide the design of UHV converter station in Northwest China with technical support.

The impact of the larger number of non-linear consumers on the quality of electricity

Theoretically this paper will explain the formation of higher harmonic components in the electricity network, their causes, consequences on consumers and the ways of their elimination. Transformer role in the Dyg connection will be explained on the concrete example. For a specific example the waveform of primary (R) phase at 10 kV voltage level, the current of the secondary (r) phase and the neutral conductor at the 0.4 kV voltage level will be determined as shown in the concrete example in the work. Harmonic content will be determined up to 15 harmonics and the effective value of all these currents (phases R and r). THD for current of primary (R) phase and secondary (r) fase will be calculated. In this paper, the dimensional three-phase filter is set to eliminate the maximum harmonic component of current of the primary (R) phase on the 10 kV side of the transformer. The waveform, the corresponding harmonic content for the current and THD of primary (R) phase will be determined. Additional measures have been proposed to reduce the THD. Another parallel filter has been realized to eliminate the second by size harmonic components of primary (R) phase current. It will also compare THD for primary (R) phase as in the previous cases. For the total duration of the simulation, the used time is Tstop = 0.1 sec. All of the above simulations will be realized in the MATLAB/PSB program package and simulation models will be displayed.

Planning of Active Distribution Networks in Croatia

This paper explores the concept of distribution network planning in Croatia from both theoretical and practical point of view. First, the types of distribution system planning are presented. Then the technical criteria for distribution network planning in Croatia is elaborated, according to the Croatian Grid Code and the standard practice of Croatia’s Distribution System Operator. The focus of this paper is to go through the basic differences between planning active and passive distribution networks in Croatia with special attention paid to voltage and power fluctuations caused by distributed generation units. Distribution network configurations that are used in Croatia are also displayed, especially in the context of redundancy and contingency analysis. The availability and type of input data for distribution network planning is thoroughly discussed. In addition, the paper addresses the challenges associated with the elimination of the 35 kV networks and the transition from 10 to 20 kV voltage level in Croatia. Finally, some relatively new but not yet exploited concepts are overviewed, like demand response and electric vehicles along with the future development of smart grids in Croatia.

PyPSA-Eur: An open optimisation model of the European transmission system

PyPSA-Eur, the first open model dataset of the European power system at the transmission network level to cover the full ENTSO-E area, is presented. It contains 6001 lines (alternating current lines at and above 220 kV voltage level and all high voltage direct current lines), 3657 substations, a new open database of conventional power plants, time series for electrical demand and variable renewable generator availability, and geographic potentials for the expansion of wind and solar power. The model is suitable both for operational studies and generation and transmission expansion planning studies. The continental scope and highly resolved spatial scale enables a proper description of the long-range smoothing effects for renewable power generation and their varying resource availability. The restriction to freely available and open data encourages the open exchange of model data developments and eases the comparison of model results. A further novelty of the dataset is the publication of the full, automated software pipeline to assemble the load-flow-ready model from the original datasets, which enables easy replacement and improvement of the individual parts. This paper focuses on the description of the network topology, the compilation of a European power plant database and a top-down load time-series regionalisation. It summarises the derivation of renewable wind and solar availability time-series from re-analysis weather datasets and the estimation of renewable capacity potentials restricted by land-use. Finally, validations of the dataset are presented, including a new methodology to compare geo-referenced network datasets to one another.

Voltage Stability of Low-Voltage Distribution Grid with High Penetration of Photovoltaic Power Units

Voltage stability analysis of power distribution systems with high photovoltaic (PV) penetration is a challenging problem due to the stochastic generation of a solar power system. Voltage stability is an important benchmark for defining PV’s penetration level in active distribution networks considering loading capacity. The massive integration of PV power units, the effect of distribution system characteristics, like high ratio of R/X, and the reported collapses in power networks come up in serious studies that investigate their impact and upcoming problems on distribution networks. Therefore, this paper proposes analytical voltage stability and it is implemented on IEEE 34 nodes radial distribution systems with 24.9 kV and 4.16 kV voltage levels. In this regard, in addition to given properties in stability and power loss analysis, a penetration coefficient for PVs is considered. Simulation results prove that the applied method can illustrate the positive and negative effects of PV in distribution networks.