Main Busbar Research Articles

Preliminary design for the sizing of an emergency thermal power plant (GE) for the continuity of service of a production chain. case of the Kakula concentrator

This work concerns the preliminary project for the sizing of a thermal power station with emergency generators capable of supplying electrical energy to the Kamoa concentrator located in kakula. The Kakula concentrator, beneficiary of this preliminery project is a plant that concentrates the ore coming from the Kakula mine and having a grade of 5%. After treatement, a copper concentrate of about 55% is obtained and transported for sale. For the choice of generators, the most important element was the determination of the power to be supplied. To do this, we based ourselves on some principales of general electricity. The results enabled us to choose thirteen (13) generators of 4500 kVA of the brand SDMO that we coupled in parallel to obtain a power of 58500 kVA. Then, we chose a 50 MVA transformer to raise the 11 kV voltage produced by generators to a voltage of 33 kV which must be available on the main busbar of the plant. In the end, we proposed a general scheme of the plant with an automatic start system for the generators using an inverter.

Electrodynamic Forces in Main Three-Phase Busbar System of Low-Voltage Switchgear—FEA Simulation

This paper concerns the effects of electrodynamic forces that act on current paths that are part of high-grade industrial distribution switchgear. This work is composed of experimental and simulation sections. In the experimental section, the short-circuit tests are presented and the occurrence of electrodynamic forces are shown in a visible way. The formation of electrodynamic forces in the current circuits of electrical energy distribution systems is related to the flow of high currents, but mostly it is related to short-circuit currents. In order to highlight these phenomena, the detailed specification of the parameters during tests is displayed. In the simulation section, the physical phenomenon of electrodynamic forces is being captured by employing a detailed real-scale model of switchgear and current paths. Therefore, the authors proposed employment of the FEM (finite element method) in order to obtain values of electrodynamic forces acting on the current paths by executing the detailed 3D coupled simulation. The analysis of the results and aftermath effects of their interactions provided interesting conclusions that concerned the operation of such power distribution layouts in critical short-circuit conditions.

Development of 3-phase fault detection, protection, and automation application with the present of DG in AC power system using GOOSE protocol

In this research work, a protection and automation solution is developed, encompassing SEL751 and SEL751A protection relays that communicate through the IEC-61850 Generic Object-Oriented Substation Event (GOOSE) protocol to deliver high-speed detection and clearance of a 3-phase (3P) fault. The study case is a standard IEEE 13-bus grid including the main system generator (G1), power lines, loads, distributed generation (DG), bus bars, and feeders, equipped with protection relays for detecting over-current faults based on time and current. Two protection relays, B1 in the main system and B2 on the DG side, are integrated with a GOOSE protocol communication system. These settings are configured in such a way that, in the event of the main system breaker being disconnected, the DG cannot be connected to the network, making it a suitable setting for anti-islanding mode (AIM). The efficiency of the relay settings is tested by subjecting the power grid to a 3P fault, by the selected Time-Overcurrent (TOC) U3 inverse curve. Throughout the paper, the descriptions of the study, the grid, assumptions, settings calculations, and analysis of results are systematically presented. For the verification of relay settings, the performance of relays is practically tested and accurately analyzed in detail. The results obtained indicate that the presented strategy is quite effective for the configuration, setting operation, and coordination of relays for fast detection and communication through the GOOSE protocol.

PREVENTIVE START-UP OF AN EMERGENCY DIESEL GENERATOR OF THE SHIP’S ELECTRIC POWER SYSTEM

The development of the method of preventive protection for the purposes of safe operation of the ship’s electric power system in emergency situations associated with malfunctions of its elements that occur during operation is considered in the paper. It has been shown that the existing devices form a command to start an emergency diesel generator at the moment when the voltage on the main switchboard busbars disappears. This circumstance causes a break in the power supply of responsible consumers of electric energy for a time equal to the start time of the emergency source. At the same time, the vessel loses control, and in most cases, the course. In this regard, it has been paid special attention in the paper to the development of a method for the preventive start of an emergency diesel generator, in which the launch command is formed before the vessel is de-energized, but with a real threat of this event. The conditions under which the preventive start of an emergency diesel generator should be carried out are formulated. Within the framework of the proposed approach, the energy state of the entire ship’s electric power system is predicted in the case of a decrease in its generating capacity, and, if necessary, a command to start an emergency source of electric energy is formed. At the same time, the most dangerous situation develops at a time when, in case of a failure of the generator unit of the main power plant, preventive unloading of the network turns out to be ineffective. It has been shown that there are emergency modes of vessel operation, such as flooding or fire in the room of diesel generators, in which the probability of simultaneous failure of all main electricity sources at once is especially high. The application of the proposed method of preventive start-up of an emergency power source will allow, in case of failure of at least one of the generator units of the main power plant operating in parallel, flooding or fire on the ship, to carry out structural adaptation of the system in advance to the malfunction that has arisen and go into a partially operational state, bypassing the emergency situation. At the same time, the interruption in the power supply of responsible consumers ensuring the safety of the vessel operation will either be significantly reduced or it will not happen at all. A functional diagram of a simple device implementing the proposed approach in practice is presented. A brief description of his work is given.

Novel control approach for integrating water electrolyzers to renewable energy sources

AbstractGreen hydrogen can be produced by integrating water electrolyzers to renewable energy sources. The integration confronts the problem of renewable power volatility that requires advanced control strategies. There are three main electrolyzer control approaches, which are: battery hysteresis cycle, model‐based scheduling, and frequency response. These approaches do not fully solve the problem of electrolyzer operation under power fluctuating conditions. This study introduces a novel integration and control approach for water electrolyzers based on model predictive control algorithm. The algorithm controls electrolyzer load so that steering the system into a breakeven energy balance across the main DC busbar that links generation and demand sides. However, the energy balance is subject to power conditioning losses and capacity constraints of electrolyzer. The novel approach uses simplified prediction models for the generation and demand and introduces a compensator for model uncertainty based on a novel role to the battery as a sensor of energy imbalance. The approach is tested on a 5 kW polymer electrolyte membrane electrolyzer and showed that fully automated energy balancing is achievable for grid connected and stand‐alone systems. Also, the electrolyzer can operate at partial capacity with improved efficiency and hydrogen yield, and it is applicable to any mix of renewables.

A logical reasoning-based method for sensing the operating status of equipment

Grid equipment monitoring is to achieve comprehensive perception, rapid analysis and accurate disposal of grid operation status. As the scale of the grid continues to expand, many problems such as low efficiency in single point-based alarming, complicated and difficult process, irregular work norms, etc., have occurred in the current operating mode, which greatly restricts the improvement of management level of monitoring operation. Based on the correlation between substation monitoring information and monitoring equipment operation, we establish the correspondence between primary equipment such as main transformer, busbar, line and capacitor and the corresponding telemetry such as current, voltage, active power, reactive power and frequency. Then we analyze the occurrence mechanism of power grid equipment operation events, sense the equipment operation status, and realize timely and accurate sense and push of equipment operation defects and faults, thereby improving operational efficiency of monitoring devices.

Investigation of occupational hazard of 750 kV extra high voltage substations

Objective: To understand the current status of major occupational hazards in 750 kV extra high voltage (EHV) substations. Methods: In July 2019, through investigating and detecting the sulfur hexafluoride, power frequency electric field and noise occupational hazards of 750 kV EHV substations in substation 1, substation 2, substation 3, substation 4, substation 5, substation 6 and substation 7, the exposure intensity of the sulfur hexafluoride, power frequency electric field and noise intensity that the operators are exposed to during the inspection process were analyzed. Results: The qualified rate of 358 sulfur hexafluoride test results was 100.0% of the seven 750 kV EHV substations. The qualified rate of 8 h time-weighted average of the power frequency electric field of those 750 kV EHV substations contacted by operators was 100.0%. Among the 847 power frequency electric field detection points, the exceeding standard rate of power frequency electric field was 64.3%, and the differences in the power frequency electric field detection exceeding standard rates of different substations and inspection areas were statistically significant (χ2=87.52, 50.86, P<0.01) . The highest exceeding standard rate of power frequency electric field was the circuit breaker inspection area (94.4%, 34/36) . The noise intensity test results of the seven EHV substations were 41.1-79.7 dB (A) , and the qualified rate was 100.0%. Conclusion: The sulfur hexafluoride, power frequency electric field and noise that the operators contacted in 750 kV EHV substations meet the requirements of occupational exposure limits. The inspection areas of main transformers, capacitors, reactors, bus bars and switches have high power frequency electric field radiation, should be select equipment iand give priority to robot inspection, and reasonably adjust the inspection time to reduce the intensity level of substation operators' exposure to power frequency electric field.

A hybrid intelligent busbar protection strategy using hyperbolic S‐transforms and extreme learning machines

AbstractIn power systems, busbars connect important components such as generators, transmission lines, and loads. A typical fault occurrence on the busbar may result in the isolation of faulty sections from other normally operating parts of the system resulting from differential protection operation. Although the main busbars' protection scheme is differential protection, its operation is significantly affected by magnetic saturation of the current transformer (CT), particularly during external fault occurrence or energizing power transformers. Saturation of the CT may generate a spurious differential current and is the main reason for the differential scheme malfunctioning. Previous research presented different methods to modify and improve busbars' differential protection scheme. However, there has been lack of a comprehensive study to assess the efficiency of the busbar protection scheme regarding all involved, and influencing aspects including various fault types, energizing power transformer, (high) fault resistance, fault angle (changing from 0° to 360°), and the angle of the sources. Thus, in this study, a hybrid intelligent busbar protection scheme is proposed and the effects of all these factors are investigated. The proposed strategy utilizes the hyperbolic S‐transform as a signal processing technique to extract an efficient feature that is able to discriminate internal faults from other abnormal modes, that is, external faults and inrush current under CT saturation. To obtain this goal, a learning‐based classification method known as extreme learning machines is used to classify the system conditions based on the selected features. The proposed protection scheme was found to have low sensitivity to CT saturation and noise and was able to accurately detect internal faults from half a cycle to one cycle of the power system depending on the fault resistance.

Transient angular stability on medium voltage distribution systems with distributed generation

The dynamic behaviour of a 32 MW gas-turbine generating unit, connected to the 23 kV main busbar of a substation, is analysed in this article. The study is focused on the representative faults occurring in an electrical system and allows the determination of the maximum times in with a fault must be delivered to maintain the stability of generator. A three-phase power network is modelled with the Alternative Transients Program (ATP). Simulation results are reported and analysed for typical variables of interest such as machine rotor angle, frequency, and power. According to the study results, machine stability is greatly affected by three-phase faults, as compared to the dynamic behaviour under single-phase faults. The analysis carried out is useful to improve and maintain the security of operation of the electrical grid and in aligned to the current regulations and recent reforms of the Mexican electric sector. The fact that the performed study was usually not mandatory but has been pending since the commissioning of distributed generation plants in the Central Mexican Region is emphasized.

Thermal Analysis of Heat Distribution in Busbars during Rated Current Flow in Low-Voltage Industrial Switchgear

The manuscript presents advanced coupled analysis: Maxwell 3D, Transient Thermal and Fluent CFD, at the time of a rated current occurring on the main busbars in the low-voltage switchgear. The simulations were procured in order to aid the design process of such enclosures. The analysis presented the rated current flow in the switchgear busbars, which allowed determining their temperature values. The main assumption of the simulation was measurements of temperature rise during rated current conditions. Simulating such conditions is a valuable asset in order to design better solutions for energy distribution gear. The simulation model was a precise representation of the actual prototype of the switchgear. Simulations results were validated by experimental research. The heat dissipation in busbars and switchgear housing through air convection was presented. The temperature distribution for the insulators in the rail bridge made of fireproof material was considered: halogen-free polyester. The results obtained during the simulation allowed for a detailed analysis of switchgear design and proper conclusions in practical and theoretical aspects. That helped in introducing structural changes in the prepared prototype of the switchgear at the design and construction stages. Deep analysis of the simulation results allowed for the development concerning the final prototype of the switchgear, which could be subjected to the full type tests. Additionally, short-circuit current simulations were procured and presented.

Fault current limiters: a case study of protection and operational continuity for FPSOs

The Floating Production Storage Offloading offshore (FPSO) has been employed in the oil and gas exploration at the Brazilian pre-salt fields. Due to the increasing production capacity of process plants and consequently its power demands, FPSO power systems are experiencing higher fault current levels, which can present peak values of almost 200 kA in the medium voltage circuit. One solution to keep fault currents within safe values for the new electrical installations is to split the main switchgear busbar in two parts interconnecting them with a pyrotechnic device (PD). However, this typical fault current limiter (FCL) imposes operational restrictions to the FPSO; when the PD is triggered, the production of barrels is severely reduced. This work proposes two alternative FCLs to mitigate this problem: a Pyrotechnic Device (PD) associated with a parallel Air-Core Reactor (ACR) and a resistive Superconducting Fault Current Limiter (r-SFCL). As described in this manuscript, both alternatives allow full operation of the FPSO even after its actuation. The simulation model used to reproduce the transient behavior of two FCLs and the power system of typical FPSO was developed in the software Alternative Transients Program. The results show that the alternatives can limit the fault current below the main switchgear supportability limit, improving the reliability of FPSO’s production.

Analysis of Effect Electric Field Strenght on Safe Distance Below Main Substation Busbar 150 kV

This research is to analyze the effect of electric field strength on the safe distance under the 150kV substation busbar. The research was conducted at 150 kV substation Rancaekek, substation Rancakasumba, substation Cikasungka. The electric field exposure threshold value according to SNI, ICNIRP, IRPA/INIRP and WHO is 10kV / m for the working community. The lowest distance of the busbar conductor to the ground surface is 7.5m. Measurements and calculations of transverse electric field strength from busbar 1 to busbar 2. The height of the test point is 0 m to 2.3 m from the ground surface. From the results of the calculation of the electric field, strength obtained that the shortest minimum safe distance is 7.48 m, while the highest minimum safe distance is 7.88 m. From the results of the measurements of the electric field From the results of measurements of electric field strength obtained that the fastest duration of electric field exposure was 4.42 hours while the longest electric field exposure duration was 5.75 hours. From the calculation of the electric field, strength obtained that: the fastest duration of electric field exposure is 7.56 hours while the longest duration of electric field exposure is 7.91 hours.

Hydraulic characterization of twin-box joints for ITER magnets

The ITER magnet system will be the largest superconducting magnet system ever built. The system, all inside a cryostat, is mainly composed of a Central Solenoid (CS) split in 6 modules, a set of 18 Toroidal Field (TF) d-shaped coils and 6 Poloidal Field (PF) coils. Each of these coils uses variable type of cable-in-conduit-conductors (CICC) actively cooled by a forced supercritical helium flow. Their electrical supply from the current feedthrough of the cryostat is done with Main Busbars (MB) using similar CICC. The electrical MB to coils as well as internal PF and TF coils connections rely on the twin box concept developed by CEA in the early R&D phase. After electrical validation of joint prototypes for the PF and the MB conductors on full size samples, specific hydraulic characterization tasks were done through the Magnet Infrastructure Facilities for ITER (MIFI) contract between ITER Organization (IO) and CEA devoted to develop, improve and qualify manufactured components and assembly processes. These tasks were done on the samples using the CEA OTHELLO dedicated facility able to operate with gaseous N2 in a large Reynolds range at room temperature. The paper explains the way followed to get a full hydraulic characterization of the MB and PF5 joints for the two flow directions. The study of the flow distribution between parallel cooling channels inside the PF5 joint revealed a bypass of the active joint region. The paper reports on this hydraulic behaviour in the relevant magnets operating conditions and outlines the design changes in the joints provoked by the results of this study.

Analysis of Transient Response and Harmonic Disturbances on the Tanker's Electrical System Based on Simulation

Basically a ship has a variety of conditions, namely cargo handling, anchoring, maneuvering, and sailing its requires large electricity consumption. The quality of the voltage is not good will cause damage to electrical equipment on board. Disturbances that occur in electrical system of MT. X may result in a decrease in the performance of existing electrical equipment on the vessel and affect a certain condition as in loading-unloading conditions the time required for loading and unloading becomes longer due to interference with the electrical system. The MT.X tanker system has 5 (five) main busbars: BUS 1, FEEDER PANEL, DSB 2, DSB 3 & 4, and DSB 6. The MT tanker. X has a generator of 3 units with a power of 680 kw each, a frequency of 60 hz and a voltage of 450 V. Transient disturbance analysis under loading-unloading condition occurs transient response due to starting ballast pump where the voltage rises and then drops within 0.5 seconds with the highest value of 100.44% at 4.01 seconds and the lowest value is 99.50% to 4.81 can then reach steady state conditions at 99.9%, which does not exceed the IEEE standard limits. In harmonic disturbances under loading-unloading conditions, in the feeder panel connecting the harmonic source with load at the 5th order, the value of VIHD is 8.77%, which exceeds the IEEE standard of 5%. While the value of VTHD in loading and unloading conditions also exceeded the predefined standard limits. After installation of the filter, it can be seen that the value of VIHD at the 5th order in loading-unloading condition decreased to 3.6% after the installation of filter on feeder panel, or equal to decrease as much as 5.17%. The decline in the value of VIHD has fulfilled the IEEE 519-2014 standard of 5% on each individual order. Meanwhile, VTHD value in loading-unloading condition also decreased, from 11.18% to 7.02%.

Mechanical Properties of ITER CICC Jacket in China

The ITER magnet system is made up of four main subsystems: 18 toroidal field (TF) coils, a six-module central solenoid coil, 6 poloidal field (PF) coils, and 18 correction coils (CCs). The Feeder system with its main busbar and correction coil busbar represents one of the main magnet components as well. All coils and busbars with different dimensions used cable-in-conduit conductors (CICCs). China needs to provide six different types of conductors. The ITER CICCs consist of a cable made of Nb3Sn or Nb-Ti strands inserted in a stainless steel tube (called jacket or conduit). Depending on the coil type, the jacket material is either made of a low carbon AISI 316LN (for TF coil) or AISI 316L grade stainless steels (for PF and CC coils, etc). Mechanical properties of base material need to be tested at room and/or cryogenic temperature under predefined mechanical deformation and heat treatment conditions. This paper concerns mechanical tests on the jacket materials, including static tensile tests, fatigue crack growth rate, and fracture toughness tests.

The Stability Analysis of ITER TF Main Busbar in 15 MA Plasma Current Reference Scenario

The Stability Analysis of ITER TF Main Busbar in 15 MA Plasma Current Reference Scenario

Bus Differential Protection in Industrial Systems With Generators Connected Directly to the Main Distribution Bus

In industrial facilities with on-site generation, there are two major approaches to connect generators to the main distribution busbar. One is to connect generators through step-up delta-wye transformers with low-resistance grounded wye on the busbar side. The second common method is to connect generators directly to the main distribution busbar and use low-resistance grounding or hybrid grounding in the generator neutral. A grounding resistor in the step-up transformer’s wye side neutral or in the generator neutral will limit the ground fault in the main distribution system. When busbar differential protection is used on the main busbar, sensitivity for bus ground faults has to be evaluated to ensure detection of limited low-level ground faults. While step-up transformer grounding resistors can be selected to allow ground faults of higher magnitudes detectable by bus differential protection, the choice of grounding resistor is more complex when generators are connected directly to the main busbar. In such systems, a grounding resistor in the generator neutral limits the generator fault to protect the alternator core from excessive damage. At the same time, busbar differential protection needs to detect a limited low-magnitude ground fault on the bus. This paper discusses considerations to select the main distribution busbar differential protection type, CTs, and relaying scheme to enable detection of busbar ground faults limited by the generator low-resistance grounding resistor.

Status of the ITER Conductors in China

The ITER magnet system is made up of four main subsystems: the 18 toroidal field (TF) coils, the central solenoid, the six poloidal field (PF) coils, and the correction coils (CCs). The feeder system, with its main busbar (MB) and CC busbar (CB), represents one of the main magnet components as well. All coils and busbars with different dimensions used cable-in-conduit conductors. China has signed three conductor packages, which are the so-called procurement arrangements, between ITER and the Chinese Domestic Agency (CN DA): a TF conductor package, a PF conductor package, and a CC and feeder conductor package. They include 7.5% of the TF conductors (11); all the PF2 (12), PF3 (16), PF4 (16), and PF5 (16) conductors; all the CC (18) conductors; and the MB (3) and CB (2) conductors for the feeders. Complex technologies have been developed by ASIPP for the serial production of all ITER conductors, in terms of cabling parameter design, welding, and elaboration of cable insertion, compaction, and winding processes. China has finished all qualification phases and is well into the main series production. All conductor samples required for quality control have successfully passed the SULTAN tests with good performance. The status of the production of ITER conductors in China is described in this paper.

A Predictive Reactive Power Measuring Based on Time Series and DLSL Algorithm for Compensating Applications

Electric reactive power is one of the effective control parameters in the static Var compensators of power systems. These compensators have a time delay due to their natural performance such as thyristor ignition and reactive power measurements. Therefore, in this paper, a new predicted reactive meter based on time series and delta least squares lattice (DLSL) is proposed to avoid the mentioned time delay. At first, the electric arc furnace (EAF) based on the hidden Markov model and actual measured data are modeled. Then, reactive power model coefficients of time series are adequately calculated based on the actual voltage and current data collected from modeling ac EAFs as time-varying and unbalanced load that can generate voltage and current harmonics, voltage flicker, and reactive power destruction in the main busbar. Now, to determine the prediction relationship coefficients online, the DLSL algorithm that has a very good performance for fast sampling is applied. Finally, this method is implemented in the control system of thyristor-controlled reactor/fix capacitor connected on the same busbar. The experimental results based on actual measuring data show the accuracy and validity of the presented method.

AC Loss of ITER Feeder Busbar in 15MA Plasma Current Reference Scenario

Superconducting feeder busbar is a crucial component of the International Thermonuclear Experimental Reactor feeder system. AC losses including hysteresis loss and coupling-current losses (10 cycles and 1000 cycles) of the toroidal field feeder main busbar are described and calculated in detail in 15MA plasma current reference scenario in this paper. The critical current density is taken independent of magnetic field, and then the hystersis loss is evaluated; the calculated values of time constant of strands and sub-cables and the test values are approximate, and then the coupling losses are evaluted, too.