Valve Hall Research Articles

Parameter Calibration on Replacement Manipulator for UHV Valve-Side Bushing Based on Spinor Theory

In this paper, a structure design scheme of intelligent replacement device for the ultrahigh voltage (UHV) converter transformer valve-side bushing is put forward, and its size is determined according to the actual size of domestic converter station valve hall and UHV converter transformer valve-side bushing. Moreover, the weak links in its working state are analyzed by finite element method to ensure the safety and reliability of the structure. Based on the spinor theory, the forward kinematics and Jacobian matrix model of the manipulator are established, and the analytical solution of inverse kinematics is derived. In order to analyze the accuracy of the intelligent replacement manipulator for the UHV converter transformer valve-side bushing, considering that the end actuator of the robot arm is under heavy load, the absolute positioning accuracy and repeated positioning accuracy are analyzed. In addition, the corresponding error model is established, the least square method is proposed to identify the error model, and the influence of the error caused by the load on the repetition accuracy is analyzed. Finally, the whole process simulation in ROS provides data support for the calculation of repetitive precision and verifies the feasibility of the intelligent replacement device for the UHV converter valve-side bushing.

A three-dimensional intelligent engineering management and control system for the construction of a long-span valve hall project based on a microservice architecture.

Three-dimensional intelligent engineering management and control systems (EMCS) based on the browser/server (B/S) model are an important part of intelligent engineering development. These systems are used for solving the difficulties encountered in engineering management with frequent cross-specialties and are vital tools for data exchange and service sharing among multiple departments. Currently, most engineering management and control systems are based on service-oriented architectures (SOAs). The integration mechanism and high coupling of SOAs leads to the reduction in system expansibility, service quality and service safety of the engineering system, making it difficult for these architectures to serve the construction of long-span valve hall engineering. To address these concerns, the management and application technology of the multidisciplinary data of valve hall engineering based on a microservice architecture (MSA) is proposed to improve the management efficiency of engineering data. A 3D integration modeling method for valve hall engineering structures and geological environments is proposed to establish the topological association between engineering structures and geological environments, without increasing the amount of model data required. A 3D intelligent engineering management and control technology for the entire process of the construction of long-span valve hall engineering is proposed, which realizes the entire process simulation and control of engineering construction based on WebGL technology. Accordingly, a three-dimensional intelligent engineering management and control system for the entire construction process of a long-span valve hall project in Southeast China is established, which can effectively manage and apply the data, display and analyze the three-dimensional model, and control and make decisions regarding the construction schedule. This study provides support for the construction of "smart engineering", promotes information communication and transmission between different project units, and speeds up the transformation from traditional construction management relying on drawings to three-dimensional intelligent construction management based on cloud services.

Research on Digital Twin Virtual Model of UHV Core Power Equipment

In this paper, voltage equalization, corona prevention and noise reduction are studied by using finite element calculation method and multi-objective optimization algorithm for UHV substation, series compensation circuit, transmission line, DC valve hall and outdoor field. The calculation model of multi parameter and multi-objective optimization design is established, the optimal configuration parameters of voltage equalizing structure are obtained, the electric field distribution uniformity and structure rationalization are realized, the corona discharge is effectively restrained, the key technology of voltage equalizing and anti corona is solved, the cost is reduced, the efficiency is improved, and a simulation calculation and optimization design platform with independent intellectual property rights is formed. The research results have been successfully applied to UHV projects in China.

Research on differentiated quality control strategy of UHV converter transformer based on economic sensitivity analysis

±800kV converter transformer is the most difficult and valuable equipment in UHVDC converter station. The total price of converter transformer in a single project is up to RMB 4.9 billion. The converter transformer connects the AC power grid and the converter valve hall, which is the hub of DC transmission. It realizes the electrical isolation, power exchange, voltage matching and on load regulation of AC / DC system through electromagnetic induction. The cost and quality performance of UHV converter transformer also determine the economy and reliability of power system operation. The purpose of this paper is to ± Taking 800 kV converter transformer as the research object, through a large number of investigation and field investigation, the establishment of the ± Procurement cost estimation model of 800 kV converter transformer. In this study, through exploring the cost characteristics and quality characteristics of the main materials and components of the transformer, the concepts of cost sensitivity and quality sensitivity are proposed, and the four quadrant matrix analysis method is used to analyse the cost and quality control of the transformer, and then the differentiated quality control strategy is formulated. It can guide the quality grading control of converter transformer in engineering, and realize the collaborative improvement of power equipment economy and reliability.

Numerical Simulation of Converter Station Fire: A Study focus on the Fire Hazard of Valve Tower

The fire hazard of a valve tower in converter station fires were investigated by using the Fire Dynamics Simulator (FDS). The 2 m2, 5 m2 and 10 m2 transformer oil pool fires with the calculated heat release rate (HRR) of 2.02, 6.23 and 13.78 MW were considered in the simulations, and the smoke propagation process, smoke temperature and visibility were mainly concerned. The results showed that the whole valve tower was immersed in the fire smoke at about 600 s in 2 m2 fire condition, and the maximum temperature rise inside the valve hall was about 20ºC. In the 5 m2 fire condition, the smoke layer height descended to the bottom of the valve tower at about 300 s, and the visibility around the valve modules was lower than 5 m at about 450 s. The maximum smoke temperature inside the valve hall was over 60ºC, and the temperature of smoke around the valve modules ranged from 43 to 52ºC. In the 10 m2 fire condition, the valve tower was immersed in the fire smoke at about 210 s, and the visibility around the valve modules was lower than 5 m at about 300 s. The smoke temperature beneath the ceiling of the valve hall was over 100ºC, and the temperature at the height of valve towers ranged from 65 to 80ºC. It was observed that the larger the fire size was, the higher the fire hazard of the valve tower would be found. In the 5 m2 and 10 m2 pool fire conditions, the thermal damage to the valve tower was non-negligible. The normal operation of the electrical components in the valve tower might be affected, and the failure of electrical components might be occurred.

The Operation of UAV Propulsion Motors in the Presence of High External Magnetic Fields

The operation and maintenance of converter stations (also known as valve halls) in high voltage DC (HVDC) grids is a key element in long-term, reliable and stable operation, especially in inherently adverse offshore environments. However, the nature of the electromagnetic field environment inside HVDC valve halls presents a challenge for the operation of traditional off-shelf inspection robots. In this paper, the impact of the external magnetic field on the operation of an inspection UAV’s propulsion motors is assessed. An experimental method is proposed to simulate the maximum magnetic field interference to off-shelf UAV motors, which can be used to identify their suitability for use in HVDC valve halls inspection robots. The paper’s experimental results compare the performance of direct torque control and field-oriented control algorithms for propulsion motors under the influence of external magnetic flux. Under the influence of a 177 mT external magnetic field, it was found that using direct torque control, the motor rotational velocity steady-state error was up to 55%. With field-oriented control, the steady-state error was 0%, however the peak-to-peak current draw increased by up to 567%.

Research on operation characteristics of UHV converter valve hall based on intelligent image processing and 3D modeling technology

There are many power equipments in the UHV valve hall, including the converter transformer, converter valve tower, all kinds of bushing, tubular bus. The operation condition monitoring of the above main equipment mainly includes electrical performance parameter measurement, oil and gas insulation medium performance parameter measurement and other means. This paper mainly introduces a monitoring method for the operation status of converter valve hall from the perspective of image processing technology. The technology mainly includes: 1) the application of intelligent image processing technology to identify and classify the database of infrared thermal imager and ultraviolet imager; 2) the real-time on-line measurement for the insulation distance of typical fittings through Kalman filter technology, including the measurement of the hottest temperature The insulation distance between partial discharge point and zero potential grounding point; 3) the electric field simulation model of typical main equipment in valve hall is established based on three-dimensional modeling technology of finite element method, and the surface electric field distribution of key main equipment fittings is obtained. Combined with the image database information, insulation distance information and typical main equipment electric field distribution information, the operation state parameters are effectively obtained, and the intelligent algorithm is applied to automatically evaluate its operation state, discover the latent fault and locate the positive fault, so as to provide effective data support and the protection strategy for the main equipment operation and maintenance.

Anomalous Noise Measurement and Analysis of the Valve Hall in ±800kV UHV Converter Station

In order to control the anomalous noise of the pole-I valve hall in a ±800kV UHV converter station, the background noise of the valve hall and the noise of each valve group in the valve tower are measured, respectively. The sound pressure level differences of the valve groups are compared. The anomalous noise locates in the short-circuit pipe of cooling water in the valve tower. Frequency spectrum analysis shows that the abnormal noise is related with the flow of cooling water. The two-dimensional finite element model is established to analyze the influence of chamfer angle and pipe length on the flow velocity of cooling water. The result shows that the abnormal noise is only related with the chamfer angle of the short-circuit pipe with constant flow velocity. The abnormal noise is successfully controlled by structure improvement of the short-circuit pipe and the potential risk to the valve group is avoided, which will give technique support to the operation and maintenance of the valve hall in UHV converter stations.

Research on DC Corona Test of Typical Electrodes and Corona Limited Electric Field Magnitude for Valve Hall Fittings

In order to prevent the surface corona of valve hall fittings and obtain the corona limited electric field magnitude, the research designed dc corona test of spherical electrode and ring electrode with the different radius of curvature. The electrodes were used to imitate valve tower shield plate, grading ring, grading ball and grading shield for bushing. By the reason that the uneven electric field of irregular conductor can’t be calculated theoretically or measured accurately, the three-dimensional finite element model is used for simulating calculation. The variation of typical electrode corona inception electric field is analyzed and threshold value of corona inception electric field of valve hall fittings is acquired. With adequate modification, limited electric field magnitude for the project is proposed. The corona inception electric field magnitude of electrical equipment under the equivalent diameter of 200mm is 2000Vmm−1, and that of electrical equipment with an equivalent diameter of more than 200 mm is 1200 V • mm−1.

Thermal Performance and Insulation Structure Design of ± 400kV Valve Side Bushing of Converter

The design features of inner and outer insulation structure of valve side bushing of ± 400kV converter transformer are representative. Its main insulation structure type and design method are basically consistent with those of ± 800kV converter transformer valve side bushing in China, but its design margin is lower than that of UHV converter transformer bushing, and the valve side bushing of ± 400kV converter transformer is used more in converter valve hall, so its insulation structure design and engineering should be It is necessary to analyze and discuss the insulation structure design of valve side bushing of ± 400kV converter transformer. In this paper, ± 400kV converter transformer valve side bushing insulation accident is analyzed in detail, from which the specific causes of insulation failure are summarized, providing reference for the design of internal and external insulation structure of converter transformer bushing. Based on this, this paper first analyzes the heating mechanism of the double guide rod structure of the converter bushing, gives the design size of the double guide rod structure from the theoretical analysis point of view, further optimizes the core insulation structure of the converter bushing, and gives the external insulation design scheme of the converter bushing from the perspective of internal and external insulation coordination, and checks and calculates the overall electric field distribution The radial electric field strength is controlled at 3.11kV/mm under working voltage and 0.51kV/mm under power frequency withstand voltage, which meet the requirements of electric field strength control in the design of ± 400kV converter bushing. Furthermore, the valve side bushing of the developed ± 400kV converter transformer is tested, and typical type tests such as power frequency dry withstand voltage test and partial discharge measurement, lightning impulse dry withstand voltage test and partial discharge measurement and temperature rise test are passed. The research results of this paper theoretically give the control requirements for the field strength design of the valve side bushing of converter transformer, and optimize the design size of its double guide rod structure, and develop a prototype to prove the effectiveness and reliability of the theoretical analysis. The above research results have good theoretical guidance value and practical significance for the insulation structure design and operation state maintenance of valve side bushing of ± 400 kV converter transformer.

Theory and Experimental Study of Corona Initial E-Field Strength of HVDC Large Fittings

The electrode were used to imitate the valve tower shield plate, grading ring, grading ball and grading shield for UHVDC valve hall. Uneven electric field of the irregular conductor can not be calculated theoretically or measured accurately. The variation of typical electrode corona inception electric field strength is analyzed and threshold value of the corona inception electric field of the valve hall fittings is acquired. With the adequate modification, limited electric field magnitude for the valve hall is proposed. With the gray system MGM (1, M) model fitting and predicting technology, the E-field strength single-point high-precision measurement and the the wide-area time interval corona initial E-field fitting and predicting operation can be realized. The experimental results show that the maximum error is 3.25% within the measured concentration range, which increases with applied voltage. The maximum RSD% is less than 2.7%, showing the good stability. This system can provide the novel method for the study of corona detection of large fittings in UHVDC valve hall.

Automated replacement scheme of DC transformer bushing based on laser scanning profile: Design and experiment

The valve-side bushing is an important part of the ultra-high voltage (UHV) converter transformer. The bushing needs to be replaced at the converter station if the bushing is damaged. The bushing replacement of the existing project needs to be carried out by crane and manual operation. However, the replacement process takes a long time and the lifting accuracy is poor, which may cause damage to the bushing. A scheme based on a 2D laser profile scanner for automatic bushing replacement applied to direct-current (DC) converter transformer is proposed in this paper, which can replace any damaged bushing in the valve hall without removing other equipment. An initial value of the cylinder fitting algorithm based on the 2D laser profile is proposed in order to solve the position of the bushing, which fully considers the characteristics of the laser profile scanner, and uses the circle and straight-line fitting algorithm to solve the initial value. It is proved that the algorithm can improve the efficiency of cylinder fitting by comparing with the results of the mean value method. Industrial robots are used to implement the replacement scheme by using this algorithm, and the feasibility of the replacement scheme is verified.

An Early Warning Method of TCU Failure in Electromagnetic Environment Based on Pattern Matching and Support Vector Regression

With the continuous improvement of the voltage level of the power system, the electromagnetic interference problem of the converter station has become more and more serious. The thyristor control unit (TCU) is the core equipment of the converter valve, and its normal operation is related to the safe and stable operation of the entire converter valve. This paper starts with the actual electromagnetic environment in the converter valve hall, analyzes the failure principle of the TCU under electromagnetic disturbance, and observes the electromagnetic field distribution and sensitive components on the circuit board. Then, a TCU failure early warning method based on pattern matching and support vector regression (SVR) is proposed. The failure trend is deduced by constructing an abnormal information vector, and then the failure predictor is constructed using support vector regression optimized by grid search (GS), genetic algorithm (GA), and particle swarm optimization (PSO). Considering the failure type and warning time comprehensively, an early warning is issued when the failure mode probability increases to the threshold. When new failure modes appear, the failure mode library will continue to expand. The calculation example shows that this method can effectively warn the TCU failure in the electromagnetic environment, and its prediction accuracy can reach 89.2%, which is better than the traditional failure prediction method.

Impact of Temperature on the Transient DC Field Distribution of ±1100 kV UHVDC Wall Bushing

UHV DC wall bushing is the only channel connecting the valve hall and the DC electric field in the converter station. For the epoxy - SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas composite insulation wall bushing, the main insulation material is the epoxy/crepe paper core and SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. The transient process of establishing the DC electric field for the wall bushing is impacted by the temperature gradient. In this paper the 3-D temperature field of the wall bushing has been simulated considering the effect of heat conduction, convection and radiation. The simulation results have been confirmed using a temperature rise experiment. The transient process of the wall bushing under the actual operation condition has been simulated using the gas saturation current density method. The temperature impact on space charge density in the core, the surface charge on the interface, and the electric field distribution on the bushing is investigated. In this way a theoretical basis is developed for the optimal design of the bushing that is conductive to the safe operation of the bushing.

Predictive Analysis for Radiated Electromagnetic Disturbance in MMC-HVDC Valve Hall

The radiated electromagnetic interference (EMI) in the valve hall of the modular multilevel converter (MMC) station must be limited below a certain value to ensure the normal operation of the equipment and the safety of the engineers. In this paper, a method for predicting the radiated EMI is proposed, which takes all the necessary factors, such as the physics-based characteristics for IGBT module, sub-module topology, and converter space structure into consideration. This method involves the improved physical model of semiconductor devices, which discards the non-physical feedback parameter introduced by some previous research. At the same time, through the decoupling of the submodule and the bridge arm circuit, the order of the large-scale system is reduced so that the sub-modules can be calculated in parallel, greatly reducing the overall calculation burden of the model and accelerating the nonlinear small time-step simulation. The wideband characteristics of the converter valve tower are fully considered, with each of the bridge arms regarded as a two-port network with independent sources. The parameter integration and distribution process can also achieve complete parallel calculation. The converter valve tower is modeled as a complex antenna structure with the output voltage of each sub-module as the excitation, the calculation of near-field radiation intensity for the converter valve tower is performed in Alteir FEKO. The measurement conducted inside an actual 49-level converter station verifies the accuracy of the model.

Influence of protrusions on the positive switching impulse breakdown voltage of sphere‐plane air gaps in high‐altitude areas

The construction of ultra-high-voltage direct-current power transmission projects in high-altitude areas calls for the research into the discharge characteristics of the air gaps in the valve hall of a power converter station in such areas. Tests on the switching impulse discharge characteristics of the sphere-plane air gap were conducted at Yangbajing test base (Tibet, China) at an altitude of 4300 m on conditions that there were burrs on the 1.3 m diameter shield balls. The discharge characteristics, under the influences of burrs with different lengths and locations, were obtained and compared with test data from low-altitude areas. The results indicate that the arrangements of burrs with different lengths and locations can significantly reduce the switching impulse discharge voltage of sphere-plane air gaps, while the voltage sag gradually decreased down with increasing burr length. Moreover, the larger the sphere-plane air gap is, the smaller the influence of such burrs have. High altitude also substantially decreased the switching impulse discharge voltage of the air gap. When the surface of shield balls was smooth, the U50 saturation of the air gap was more significant than at low altitude; however, if there were burrs on the shield balls, the saturation effect was less significant.

Strengthening technique on firestop system of valve hall for existing UHVDC converter stations

The ultra-high voltage direct current (UHVDC) converter station is the core of the UHVDC project to realize the mutual conversion of alternating current (AC) and direct current (DC). Its operational reliability directly affects the safety of personnel and equipment and the stable operation of the grid. The firestop system is key part of the protective system in converter station, and it faces the threat of fire and explosion of converter transformer. In this paper, in order to improve the safety performance of the firestop system of the valve hall of the existing converter station, the blast resistant design target of the firestop structure and a fireproof and blast resistant strengthening scheme are proposed; For a typical UHV converter station, the dynamic response process under different explosion conditions is further analyzed by numerical model. The results show that the strengthening scheme proposed in this paper can effectively meet the requirements of blast resistant design targets, and greatly improve the safety performance of the firestop system of the valve hall of the converter station under fire and explosion.

Fire and blast resistance analysis of the firestop system of valve hall in UHVDC converter station

The ultra-high voltage direct current (UHVDC) converter station is the core of the UHVDC project to realize the mutual conversion of alternating current (AC) and direct current (DC). Its operational reliability directly affects the safety of personnel and equipment and the stable operation of the grid. The firestop system is key part of the protective system in converter station, and it faces the threat of fire and explosion of converter transformer. In this paper, in order to analyze the shortcomings of the existing firestop system of valve halls, numerical models for fire and blast resistance analysis of typical firestop system are established. For a typical UHVDC converter station, the temperature distribution under hydrocarbon heating curve and dynamic response under different blast loads are analyzed by using the established numerical model. And the results show that the existing firestop system has good heat insulation performance, while the blast resistance cannot meet the demand.

Research on new blast and fire stopping system of valve hall for UHVDC converter stations

In this paper, a new blast and fire stopping system of valve hall for UHVDC converter station is proposed. With the hydrocarbon temperature rise curve, the fire resistance test of a 1.4m×1.8m sample was carried out, a numerical model for blast resistant analysis of the firestop structure was established, and the blast resistant performances of the original firestop structure and the new structure were calculated. The results show that the new fire and blast stopping system proposed in this paper has a fire endurance time limit of more than 4 hours with the hydrocarbon heating curve. At the same time, compared with the original system, the blast resistant capability of the new firestop structure is greatly improved.

Analysis and Disposal of Typical Breakdown Failure for Resin Impregnated Paper Bushing in the Valve Side of HVDC Converter Transformer

This paper presents analysis, diagnosis and disposal with a typical internal breakdown failure of the resin impregnated paper (RIP) valve side bushing in high voltage direct current (HVDC) converter transformer. Based on the analysis of fault current characteristics at the time of the RIP valve side bushing failure, and field test results of insulation parameters, a method of diagnosing typical breakdown failures of valve side bushings is proposed. Through disassembly inspection of the internal overheating and arcing traces on the failure bushing, the root cause of this typical breakdown failure is found, which is upper axial flashover along the RIP condenser/SF6 interface caused by the abnormal contact of two current-carrying conductive tubes. Temperature distribution inside the bushing with an abnormal contact resistance between the copper conductive tube and aluminum conductive tube under different load current is simulated by using the finite element method. An special device is also developed for repairing defective bushing on-site, and 75 bushings with conductive contact defects have been repaired on the premise of not pushing converter transformers away from the valve hall and even without pulling out defective bushings.