Advanced Materials Research Vols. 1092-1093

Abstract: In order to make on-line monitoring on the temperature of high voltage switch circuit breakerand find outthermal fault in time. This paper puts forward a new method with radio frequency and magnetic saturation power supply technology to make on-line monitoring on the temperature of high voltage switch circuit breaker, it designs the high voltage switch circuit breaker contact temperature online monitoring device. The device mainly includes monolithic temperature collector and data receiver, they transmit data wirelessly, and this makes high temperature monitoring terminal and the data receiving terminal completely electrical isolated. Integrated temperature collector doesn’t need external power supply, it uses small CT saturation technology for continuous power. The experiment shows that the temperature error is ±2°C, it can meet online temperature monitoring requirements of high voltage switch circuit breaker contact.

Abstract: For the shortcomings of large overshoot and poor anti-disturbance ability when using the traditional PID control, ADRC control algorithm that is a nonlinear state error feedback control algorithm has been proposed in the sophisticated control system of static reactive power generator. The simulation results show that the algorithm can make the system reactive power compensation more quickly and more effectively, therefore the control strategy is feasible.

Abstract: A simulation model of 230kV substation primary system and TSC+TCR typed dynamic reactive power compensation control system was constituted with RTDS, and the feasibility of control system with a case was validated. The control system was to monitor the variation of power system equivalent susceptance with sampling the power system voltage, established the relationships between power system susceptance and the firing angle of TCR, adjusted TSC switch and TCR firing angle to dynamically compensate the reactive power of power system. The simulation results demonstrate that the control system can guarantee power system voltage stability and real-time adjust power factor.

Abstract: The abrupt dip of grid voltage would provoke a series of electromagnetic transient processes in stator and rotor of DFIG, which would threat the security of wind turbines fault ride through (LVRT) and stable operation of power system. Analyzing the fault current characteristics of DFIG is very useful to improve the LVRT strategy and adjust the relay protection setting of power system. In this paper, electromagnetic transient processes of DFIG are given a detail analysis after protection circuit of DFIG works due to the dip of three phase voltage in system. Then, the general expression of stator and rotor fault current is derived, and the validity of this method is verified. At last, the influences of the system short-circuit capacity and wind turbines accessing capacity on the fault current and system protections are analyzed when the wind turbines are accessed to the distribution network.

Abstract: Development of intelligent grid have increasing demands for time synchronization, high precision, large scale, high performance time synchronization system has become necessary guarantee for the normal operation of the power grid. This article introduced the composition of the time synchronization system, discusses the IEEE1588 implementation of high precision clock synchronization principle and SDH data transmission principle, analysis of the PTP protocol for transmission through the principle of the SDH E1 line, gives the networking scheme of PTP over the E1 way, which meet the precision requirement of 1 us.

Abstract: Because the undersea cables have the large charging power, the wind power systems will inject too much reactive power to the grid which will lead the bus voltage out of range. This paper established the distributed parameter model of the output lines and analyzed the reactive voltage distribution in different operation modes. By controlling the reactive power of the wind turbines, with the effect of the reactive power compensation device, the paper did the research on the configuration and controlling of the reactive power for the purpose that the exchanging reactive power between the offshore wind farm and the grid is zero. Through simulation this paper analyzed and verified the validity of the controlling strategy.

Abstract: In this paper, a novel energy-efficient single-phase induction motor with three parallel-connected stator windings and two external capacitors has been proposed. By selecting the appropriate capacitors, the currents in the three windings will be approximately symmetric at rated load, thus high rated efficiency can be obtained. Based on the symmetrical component method, the condition for balanced operation is analyzed and the method for determining the requested capacitances is also obtained. The approach for calculating the steady-state performance is proposed.

Abstract: The simulation of fault treatment performance for distribution automation systems and the key technologies of training systems are discussed in this paper, which include key technologies for basic platform, auxiliary decision-making analysis for grid faults, load-transfer analysis for power system operating mode, loop closing analysis for power system operating mode and distribution network training simulation and so on. The results of simulation of fault treatment performance for distribution automation systems and training systems operation show a good accuracy and effectiveness of the method.

Abstract: With the developing of technology, such as application of new energy, new material, large scale energy storage technology, ultra-long distance large scale transmission technology, intelligent control, estimation, message communication, internet, we establish a new industrial era. Well, sustainable development became an important issue. We need to supply much more cleanable and efficiency energy to meet the environment protecting and unstopping load of power gird increasing. So, smart grid came to our sight.In this paper, first we discuss that electricity is the foundation of modern industry. Second, we put forward the new problems that modern industry brings about, and discuss the necessity of developing smart grid. And then we particularly discuss the rewards that developing intelligent grid, such as solving the energy crisis, changing the running mode of grid, advancing the intelligent life, promoting the electricity client involved in the power market adjusting process and so on, as well as provided the relevant examples. All of these do well to future sustainable development. At last, we sum up the whole paper.

Abstract: With the application and development of Power Electronics, HVDC is applied more widely China. However, HVDC system has the possibilities to cause subsynchronous torsional vibration interaction with turbine generator shaft mechanical system. This paper simply introduces the mechanism, analytical methods and suppression measures of subsynchronous oscillation. Then it establishes a power plant model in islanding model using PSCAD, and analyzes the effects of the number and output of generators to SSO, and verifies the effect of SEDC and SSDC using time-domain simulation method. Simulation results show that the more number and output of generators is detrimental to the stable convergence of subsynchronous oscillation, and SEDC、SSDC can restrain unstable SSO, avoid divergence of SSO, ensure the generators and system operate safely and stably