The increasing penetration of power electronics interfaced renewable generation (e.g. offshore wind) has been leading to a reduction in conventional synchronous-machine based generation. Most converter-interfaced energy sources do not contribute to the overall power system inertia; and therefore cannot support the system during system transients and disturbances. It is therefore desirable that voltage-source-converter...
Due to the manifest electromagnetic coupling effect, parallel cables cause couples of problems to its operation safety and management. The present paper describes the questions brought by parallel cables from the following three aspects: influence on parameter asymmetry, influence on induced voltage in metal shield of cables and influence on distance protection. This paper analyzes the parameter asymmetry...
The access of distributed generator (DG) is inevitable in the construction of smart distribution network, but it will cause original fault-diagnosis methods failure. In this paper, based on deeply analysis of diagnosis information structure in distribution network with DGs, study fruits within the domain at home and abroad are surveyed. Firstly, from the aspects of accuracy and rapidity, the main...
Presently, all of local power enterprises mostly have built video monitoring systems, because there were no standards that can be adopted in initial stages, these systems were running independently and cannot be interconnected, so the need of accessing video information between different areas cannot be met. The first problem of interconnection that need to be solved is to unify call signaling and...
The purpose of research on calculation of low voltage distribution network theoretical line loss is define a calculating method and through the method to calculate the low voltage distribution network theoretical line losses. The calculation of low voltage distribution network theoretical line losses is the foundation of the power system economic operation, the reactive power optimization and the...
Smart distribution grid is an important part of smart grid, which connects the main network and user-oriented supply. As an “immune system”, self-healing is the most important feature of smart grid. Major problem of self-healing control is the ‘uninterrupted power supply problem’, that is, real-time monitoring of network operation, predicting the state power grid, timely detection, rapid diagnosis...
Because there are slow evolutionary process and difficult smooth convergence in evolutionary programming algorithm, a mutation operator for distribution network reconfiguration is proposed. In order to guarantee that new individuals from mutation is close to the optimal individual actively, times of topology restructure should be inversely proportional to evolutionary generations, and both selection...
In order to alleviate the problems, such as the periodic fluctuations of reactive power, the poor quality of ac current and the long steady-state response time, caused by the traditional direct power control(DPC) in three-phase voltage source (Pulse Width Modulation)PWM rectifier, a novel DPC strategy of double hysteresis comparator bands and multiple switching tables (DM-DPC) is put forward in this...
Recent blackouts of major power systems in North America, Europe, Russia and in other parts of the world clearly show the topicality of the blackout problem and the necessity to call attention to this phenomenon once more. Based on thorough analysis, the authors hold that the overloads on transmission lines are the primary cause of cascade-like processes followed by blackout development. The solutions...
Currently, conventional energy generators implement Automatic Generation Control (AGC) to regulate active power disturbance of power system attribute to wind power fluctuation after large capacity wind power integrated into grid. As an auxiliary means, wind farm would follow wind power schedule, adjust output plan in short-term and adopt emergency control in order to reduce the effect of wind power...
This paper proposes a new fault location method in distribution networks using Prony analysis. This method just needs the measured voltage transients without multi-recording nodes. Fault-originated traveling waves propagate along the distribution network and reflect at the discontinuity points, so the recorded transients contain some characteristic frequencies associated with specific paths, which...
Network model data from provincial dispatching center and several district dispatching centers are merged into whole network model in the provincial dispatching center in the construction of smart grid in china. Network Analysis Software of province and district are integrated tightly because of model mergence. Under this circumstances, two schemas of Integrated Network Analysis Software (NAS) of...
In high temperature superconducting windings a slight unbalance of the branch inductances of the windings might result in heavy circulating current because of zero resistance of HTS tapes compared with conventional ones. It is proverbial that the circulating current worsens the distribution of leakage magnetic filed and consequently does harm to the ac loss and critical current in the tapes. In this...
Transmission line de-icing with 18kV, 40kHz high frequency and high voltage excitation based on skin effect of conductor and dielectric loss is presented to overcome the existing technical defect. It is suitable for high voltage power network and need not outages. It increase the frequency of de-icing current to strength the skin effect of transmission lines, thus causing the line unit resistance...