High Voltage Busbars Research Articles

Mathematical Models of the Phase Voltages of High-, Medium- and Low-Voltage Busbars in a Substation during a Phase-to-Ground Fault on High-Voltage Busbars

The electrical energy supply of industrial equipment is provided by electrical power stations with high- (HT), medium- (MV) and low-voltage (LV) busbars. Consumers are connected to either MV or LV busbars. In this paper, a real power station was considered, through which the gasoline extraction from the well gas installation is powered. Electric consumers (electric motors) supplied by a MV busbar have active power of 13.54 MW, and those fed by a LV busbar have active power of 6.4 MW. Since electrical consumers operate in explosive environments, the design and operating conditions are more severe than in the case of electrical installations operating in non-explosive environments. The case of a single phase-to-ground fault occurring on the HV transmission lines feeding the power station has been analysed. First, the mathematical models for the calculation of the phase voltages, the dissymmetry and asymmetry coefficients, the reduction coefficient of the plus sequence component, and the effective values of the phase voltages were established. The influence of the source impedance (the equivalent impedance of the HV transmission lines) and of the neutral point configuration of the HV/MV medium-voltage transformer on the calculated quantities was analysed. Then, the results obtained using the established mathematical models were compared with those obtained experimentally by provoking a single-phase-to-ground fault near the HV busbars of the real power station. This study has shown that the de-symmetrisation of the phase voltages of the MV and LV busbars is lower when using the Y/Δ connection for the HV/MV transformer. As a result, it is recommended the Y/Δ connection be used for this transformer, instead of the Y0/Δ connection.

Разработка тепловой модели токопровода с полимерно-газовой изоляцией для передачи электроэнергии оффшорных ветроустановок

On the basis of the National Research University "MPEI", within the framework of the project to create a busbar with polymer-gas insulation for the transmission of electricity from offshore wind turbines, a study is being carried out to develop insulating structures for high-voltage busbars. The work is devoted to the development and justification of the design of a special conductor with combined insulation (polymer-gas) for laying in sea water for the transmission of electrical energy from wind turbines, where a polymer coating of current-carrying elements is used to increase the electrical strength and reduce the dimensions of the current conductor, and for to reduce electricity losses, the main gas insulation is used. Technical solutions for the execution of linear and connecting sections of bus ducts with polymer-gas insulation are presented. An analysis of the distribution of the thermal field in the coaxial gap was performed, demonstrating the features of design solutions for linear sections.
 According to the calculations, conclusions were drawn about the possibility of using combined insulation in special conductors.

Performance Analysis of a Relift Luo Converter-Derived Dual-Output DC to DC Converter for Microgrid Applications

A microgrid typically maintains multiple voltage bus bars with AC or DC or both. The various subsystems participating in the microgrid are connected to the appropriate voltage bus bars. Renewable energy sources like the wind energy or the solar photovoltaic energy may also be integrated to the microgrid. A battery-based energy storage system is also usually required. In this work, a dual-output DC to DC converter derived from the double lift or the relift Luo converter is proposed and validated. The proposed system uses a solar photovoltaic source and delivers a high-voltage DC output to deliver power to the high-voltage DC bus bar. A battery of medium voltage is connected across the second output of the dual-output converter. The proposed idea is validated using modeling and simulations in the MATLAB Simulink environment and an experimental prototype.

Interval Type2 Fuzzy Logic Based STATCOM Controller for Stabilizing a Mixed Electrical Network System

Adding renewable energy plants to the electrical grid reduces the performance of energy systems. This results in problems including power fluctuations and poor voltage quality. This paper presents an interval type2 fuzzy logic-based controller, consisting of current and voltage regulators, that is applied to a STATCOM to regulate the DC voltage under various operating conditions. a membership functions not used before in this filed have been used to generate IT2FL sets output. The STATCOM has been connect with the high voltage bus bar in order to use one STATCOM for all the loads According to comparative studies, the proposed method outperforms traditional PI and type1 fuzzy logic-based controllers.The simulation has been implemented using MATLAB/SIMULINK software and the results confirm the feasibility of the proposed system.

On the Dynamic Electro-Mechanical Failure Behavior of Automotive High-Voltage Busbars Using a Split Hopkinson Pressure Bar

High-voltage busbars are important electrical components in today’s electric vehicle battery systems. Mechanical deformations in the event of a vehicle crash could lead to electrical busbar failure and hazardous situations that pose a threat to people and surroundings. In order to ensure a safe application of busbars, this study investigated their mechanical behavior under high strain rate loading using a split Hopkinson pressure bar. Two different types of high-voltage busbars, consisting of a polyamide 12 and a glass-fiber-reinforced (30%) polyamide 6 insulation layer, were tested. Additionally, the test setup included a 1000 V electrical short circuit measurement to link the electrical with the mechanical failure. It was found that the polyamide 12 insulated busbars’ safety regarding insulation failure increases at high loading speed compared to quasi-static measurements. On the contrary, the fiber-reinforced polyamide 6 insulated busbar revealed highly brittle material behavior leading to reduced bearable loads and intrusions. Finally, the split Hopkinson pressure bar tests were simulated. Existing material models for the thermoplastics were complemented with an optimized generalized incremental stress state-dependent model (GISSMO) with strain rate dependency. A good agreement with the experimental behavior was achieved, although the absence of viscoelasticity in the underlying material models was notable.

Development of Insulation Systems for High-Voltage Busbars with Solid Insulation

Development of Insulation Systems for High-Voltage Busbars with Solid Insulation

Experimental and Numerical Investigation of the Behavior of Automotive Battery Busbars under Varying Mechanical Loads

Automotive high-voltage busbars are critical electrical components in electric vehicle battery systems as they connect individual battery modules and form the connection to the vehicle’s powertrain. Therefore, a vehicle crash can pose a significant risk to safety by compromising busbar insulation, leading to electrical short circuits inside the battery. In turn, these can trigger thermal chain reactions in the cell modules of the battery pack. In order to ensure a safe design in future applications of busbars, this study investigated the mechanical behavior of busbars and their insulation. Our results indicated that crashlike compressive and bending loads lead to complex stress states resulting in failure of busbar insulation. To estimate the safety of busbars in the early development process using finite element simulations, suitable material models were evaluated. Failure of the insulation was included in the simulation using an optimized generalized incremental stress state dependent model (GISSMO). It was shown that sophisticated polymer models do not significantly improve the simulation quality. Finally, on the basis of the experimental and numerical results, we outline some putative approaches for increasing the safety of high-voltage busbars in electric vehicles, such as choosing the insulating layer material according to the range of expected mechanical loads.

Investigation of the electro-mechanical behavior of automotive high voltage busbars under combined electrical load with varying indenter geometry and environmental conditions

Abstract As high voltage systems for electrified vehicles and their electronic components exhibit hazardous potential during abuse situations, their development needs special consideration. Battery busbars, representing current-carrying components, pose a special threat in the event of a vehicle crash. While the behavior of Li-Ion cells under different crash loads has already been investigated, there is no detailed knowledge about the electro-mechanical behavior of busbars during crash situations. Therefore, this paper focuses on combining mechanical and electrical loads on thermoplastic-insulated battery busbars. The conducted experimental work includes mechanical penetration of the insulation with various indenter geometries. Simultaneously, a high electrical potential was applied between the indenter and the conducting copper of the busbar. To detect the failure of the busbar, which is considered an electrical short circuit, insulation resistance was measured. Furthermore, the investigation includes the influence of humidity and lower voltage on the electro-mechanical behavior to simulate operating conditions. The results of this paper contribute to current knowledge in meeting the challenges that arise in developing safe vehicle batteries. The critical load limits and failure behavior can be used to improve the prediction accuracy of hazardous situations for the development and design process of high voltage battery systems.

Wireless Sensor Network for Remote Monitoring and Trouble Shooting

The article studies the wireless sensor network technology, using its features and functionality such as low-power, self-organization of networks and short-distance wireless transmission, integrating sensor technology, embedded computing technology, distributed data processing technology and telecommunication technology to transmit sample data into terminals. It solved the cost and the on-site maintenance problems in the wired sensor solution, and the high cost, high energy consumption, low stability and short lifespan problems in the sensor nodes under high-pressure en-vironment. By introducing two project cases including the application in the drug storage in Beijing Double-Crane Pharmaceutical Co., Ltd and the application in temperature control of high-voltage bus bars and high-voltage switches, the article analyses the application of wireless sensor network technology in remote monitoring and trouble shooting and its outlook, but providing the most straightforward and reliable data evidence for corporation steering committee and executives to mi-nimize risks and accidents. It is proved that the research results have significant practical value.

Synchronized Flicker Measurement for Flicker Transfer Evaluation in Power Systems

Voltage fluctuations caused by rapidly changing loads, such as arc furnaces, can propagate to different parts of a power system. Although the flicker level at its origin can be high, levels that are measured at other sites are subject to attenuation, a process that is influenced by fault levels, transformer impedances, line impedances, and composition of the connected loads. This paper presents the methodology, measurement results, and data analysis in relation to synchronized flicker measurements carried out in a high-voltage (HV)/medium-voltage (MV) power system which contains an arc furnace supplied by a dedicated feeder connected to the HV busbar. The flicker transfer coefficients derived from measurement results clearly indicate that flicker transfer from the arc furnace site to the upstream HV busbar is governed by the fault levels at the two locations. However, the transfer of flicker from the upstream HV busbar to other downstream busbars is dependent on the downstream load composition. These flicker transfer coefficients are vital in the application of methodologies described in many reports and standards in relation to establishing planning levels at various voltage levels and in the allocation of flicker emission to customers.

Coupled finite-element-analytic technique for prediction of temperature rise in power apparatus

In order to design the power apparatus such as bus bar or power cable, the current carrying capacity (or ampacity) should be determined exactly since it is limited by maximum operating temperature. The temperature rise in the power apparatus is due to Joule's loss in the current carrying conductor and due to the induced eddy current in the tank. This paper presents a new technique that can be used to estimate the temperature rise in the extra high voltage bus bar. In this paper, the power losses are calculated from the magnetic field analysis for various materials when ac current flows into the single- and three-phase bus bar and are used as the input data to predict temperature rise for the thermal analysis. However, it is not easy to apply the heat transfer coefficient on the boundaries correctly, because the coefficient is not a constant, but depends on temperature as well as model geometry, etc. The heat transfer coefficient is calculated according to the model geometry and varying temperature and is coupled with the finite element method. The temperature distribution in the bus bar by proposed method shows good agreement with the experimental data, compared to that of the analytic method using fixed coefficient.

Optimal exploitation of generator-transformer units

The concept of capability chart, traditionally related to the synchronous machines, has been extended to the whole generator-transformer unit, and has proven to be an effective tool in planning and design activities: different solutions can be compared in terms of active and reactive powers injected by the generating unit into the high-voltage busbar. The operation of the unit in points belonging to the capability chart requires to suitably choose the set-points of the unit controls: a control law is proposed which requires minimum changes to the usual control structures, and does not need new measurements. Numerous tests on a typical generating unit highlight the effectiveness of the capability chart as a planning tool, and the features of the proposed control law.

Calculation of commutation spikes and harmonics on offshore platforms

The AC-supply voltage waveforms on offshore oil platforms can be heavily distorted during drilling operations. The harmonic and commutation distortion is caused by the drilling rectifiers which drive large DC motors. This paper examines a method of analysing these disturbances, especially the commutation spikes which appear on the high-voltage busbars (the point of common coupling)and are spread throughout the platform supplies. The analytical method uses proprietary CAD software and equivalent-circuits to analyse the waveforms using a time-domain approach. The tool thus developed is used to show directly how the drilling and platform parameters will affect the waveshapes. The effects of firing angle, rectifier rating, platform short-circuit levels and cable capacitance amongst others are discussed. It is also shown that variable-speed drives will have a similar effect. The consequence of sharing generation between platforms is illustrated, as is the use of damper circuits to reduce the commutation spikes.

Method for simultaneous measurement of current and voltage on high-voltage lines using optical techniques

A laboratory device for the simultaneous measurement of current and voltage on a high voltage busbar has been constructed. A laser beam may be directed upwards from the ground to interrogate a passive optical transducer attached to a high-voltage busbar. Real and reactive power indications can also be obtained from the output, thus providing complete simultaneous information on the line state. The device uses a combination of magneto-optic and electrogyration effects in crystalline α-quartz. The latter effect has only recently been discovered and should lead to a device with small temperature dependence. The measurement transducer operates in a differential mode and the light beam passes through the quartz at a chosen angle to the optic axis. Quartz is a rugged material, very suitable for use in a transducer. A more highly developed version of the device should provide a convenient, portable, large bandwidth, research tool for diagnostic use. Eventual development could lead to an acceptable instrument for long-term operational use on the power system. Such an instrument would offer the advantages of considerably improved performance over conventional devices, at much lower cost.

Ground relaying of generators in unit connection

A-C GENERATORS in modern power plants usually are operated in unit connection directly on high-voltage bus bars, that is, alternator and transformer form one unit so that the circuit breaker at generator voltage is eliminated. A preferred method of ground protection for such units has been indirect high-resistance neutral grounding by connecting the primary winding of a distribution transformer between generator neutral and ground, and by loading the secondary of this transformer with a resistance of such magnitude that the resulting primary ground current for a solid ground fault at machine terminals becomes 10 to 20 amperes. This grounding method was first suggested <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> in this country by L. F. Hunt as a means of minimizing fault damage within generators. The sensitivity of this scheme of protection depends on the lowest permissible pickup current of a relay activated by the current through the resistance. This pickup current indicates the parts of the machine windings which are protected. The straight line in Figure 1 shows that the assumed relay setting would lead to relay operation for faults anywhere between machine terminal (100) and location a, whereas ground faults between the neutral (0) and a would lie in the unprotected or dead zone.

Sensitive Ground Relaying of A-C Generators [includes discussion

Increased use has been made recently of high resistance neutral grounding of generators which operate in unit connection on high-voltage bus bars. High resistance grounding is achieved by connecting a constant resistance between the secondaries of a distribution transformer, the primaries of which are connected to the generator neutral and to ground. Replacing this resistance by one of nonlinear characteristic improves the protection by reducing the dead zone. Ground protection of the complete winding, including the neutral, may be achieved by introducing permanent neutral displacement by means of a small distribution transformer.

Field measurements of insulation

Failures of insulation in service can be largely avoided by making field tests at regular intervals with suitable testing equipment. The paper deals with the field testing of the insulation of high-voltage switchgear, busbars and transformers, and describes the apparatus and methods employed by the authors on the Central Electricity Board's system. There are three main testing techniques: (a) the measurement of power factor; (b) the measurement of potential distribution; and (c) the measurement of insulation resistance; and practical testing equipments, designed to make such measurements and to satisfy the onerous conditions of field use, are described. Three wattmeter types of power-factor-measuring apparatus are described, two operating at 10 kV for bushing tests, and one operating at 50 kV for tests on busbar systems. Details are given of a modified form of bridge specially developed for field testing. The measurement of the potential distribution on bushings under service conditions is discussed, and reference is made to an electronic testing set for the measurement of insulation resistances up to 10 000 megohms at 5 000 V. More than 2 000 tests have been made on installed apparatus, and the results obtained are summarized. Twenty-four faulty bushings have been located by test and taken out of service before breakdown. Special test methods are described in order to facilitate making power-factor measurements on transformer bushings and orifice insulators. Information is also given on the power factor of oil in service. Methods are suggested of continuously supervising the insulation of important installations in cases where the low-voltage end of the insulators can be isolated from earth. Finally, the merits and demerits of the three main test methods are summarized in order to assist the maintenance engineer in choosing the method or methods which will best fulfil his requirements.