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Based on the problem of accuracy ratio drift with temperature in FOCT engineering application, the conclusion that the main FOCT temperature error is coming from some optic devices as the sensor unit, SLD source, phase modulator, delay fiber is described. Feasible methods to restrain temperature error are discussed from a technical point of view, FOCT engineering prototype is developed and the temperature...
This paper analyses the mechanism of the sympathetic inrush current of the converter transformer of the HVDC transmission system. The impacting factors of the sympathetic inrush current, including the system impedance, the closing angle and the initial remnant flux of the incoming transformer, and the operating condition of the HVDC system and so on, are analysed utilizing on the PSCAD/EMTDC soft...
In this paper, we propose a fault line detection method based on optimized cascaded bistable system (OCBS) for distribution network. Firstly, we use Genetic Algorithm (GA) to optimize the potential function parameters of bistable system (BS), and use OCBS to extract transient zero-sequence current (TZSC) in noise background. Then, as for fault line detection criterion, we define the square distance...
Traditional grounding method is hard to handle increasing capacitive grounding current in single-phase arcing faults due to the development of distribution systems. Therefore, automatic suppression strategy of single-phase arcing fault is proposed and simulation of arcing fault and its automatic suppression is realized in this paper. An improved zero sequence parameters measurement (IZSPM), injecting...
Dissolved gas analysis is worldwide accepted as an effective method for identifying incipient fault of power transformer. In order to enhance its accuracy and reliability, fault diagnosis model has been developed based on improved grey relation method with combined weight in this paper. Experts determined weight of dissolved gases for fault diagnosis with analytic hierarchical process and improved...
A method to Design the DC reactor is proposed for modular multilevel converter based high voltage direct current(MMC-HVDC). Firstly, the maximal current value allowed in an arm was acquired base on the parameters of the valve. Secondly, the maximal value of fault current when a DC pole-to-pole fault was happening was calculated. If the maximal value of fault current was smaller than or equal to the...
This paper introduces a modular multilevel converter (MMC) sub-module topology and analyses several major component failure characteristics of the sub-modules. Sub-modules using a hot reservation redundancy fault-tolerant control strategies for solving sub-module fault. For MMC redundancy policy problems caused by the asymmetric operating state and the DC current disturbances, two ways are presented...
A continuous drive to reduce offshore wind levelized cost of energy (LCoE) is paramount in order to reduce subsidies to offshore wind energy, driving it closer to market prices. The use of Diode Rectifier units for the connection of off-shore wind power plants has been proposed as a technical alternative to reduce both installation and operating costs. Adequate management of the harmonics introduced...
This paper shows the relationship between transmission line current and IGBT rated current in different package and voltage classes for VSC-HVDC application. Different semiconductor solutions for future high power systems are compared on their thermal performances, switching behaviours, power losses, chip-level current sharing and reliability. The latest development in IGBT chip and package technologies...
The first UPFC of China is to be installed in the 220kV power network and is planned to be in full operation at the end of 2015. This UPFC is expected to increase the transmission line capability and reduce transmission loss by regulating line active and reactive power flow, so as to meet the demand of growing load. This paper caries out a comprehensive investigation on the power flow control capability...
Nan'ao multi-terminal VSC-HVDC transmission system is composed of three converter stations, and its submodule monitoring strategy can be divided into four parts, each as valve control system, fault recording system, PCP system and SCADA system. Different manufacturers of the control and protect system make the submodule monitoring strategy complex. This paper studies the problems which occurred during...
With UHVDC continuous accessing, the receiving-end grid that high percent power outside and weak power supply support inside has been impacted. In order to analyse impact of Jinsu ± 800kV DC project on the receiving-end of Jiangsu power grid, electromagnetic transient model of Jinsu DC project was built on the real-time digital simulation system platform detailed, electromechanical transient model...
This paper presents a novel isolated DC-DC converter with high efficiency by utilizing the proposed double full bridge double tapped inductor (DFBDTI) topology. PWM plus phase-shift modulation algorithm and dual-target control strategy are used in the converter to reduce switching loss and reactive power in the transformer when the output voltage fluctuates widely around its rated value. Thus, high...
With the rising need for energy storage facilities in power systems of various jurisdictions, it is imperative to investigate the profitability of operating energy storage facilities. This paper assesses the economic viability of a transmission-connected Vanadium Redox Battery (VRB). The system under consideration has a power rating that is large enough that the impacts of its operation on the pool...
This paper details design, development and control methods of an isolated modular DC/DC converter (IMDCC) system. A 10kW downscaled prototype is constructed to show the working principles, hardware design procedures, and control circuits implementation. In this prototype, there are two MMC stations, namely the inverter end and the rectifier end, each consisting of N half-bridge (HB) sub-modules (SMs)...
In this paper, a comparative study of the impacts of two VSC control strategies which are vector control and power-synchronization control strategy on the dynamic interactions between the AC and DC network is conducted. Firstly, a hybrid AC/DC system model which consists of synchronous generators and a VSC MTDC grid is established in the PSCAD. Moreover, based on the established system model, the...
In this paper, a three-terminal VSC-MTDC system, containing one constant voltage terminal and two constant power terminals which have different parameters, is built in the PSCAD. With the vector and power synchronization control under consideration, there will be eight combined control strategies for this MTDC system. And then these combined control strategies are tested and compared under the AC...
Wind power series generation is an effective method to solve the problem of finite time length of wind power output data in simulation. It can provide the necessary data support for the plan and operation of the power system with wind power. Hence, it is of great significance. Markov Chain Monte Carlo (MCMC) method as its specific technology is widely used. But how to select reasonable number of state...
With the rapid development of distributed generators, the teed lines are widely used due to the lower construction cost. The differential protection is a common scheme for teed lines, but it has a high requirement for the synchronization of data sampling. So this paper mainly focuses on the application of distance protection in the teed system. Considering the length difference between three terminal...
Electromagnetic environment(EME) is one of the key issues during the ultra-high voltage direct current power transmission projects. The analysis methods of electromagnetic environment data and influence of line configuration, voltages applied and climatic parameters should be clearly studied. This paper presents the monitoring and measuring platform of EME parameters in the National Key Laboratory...
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