The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without t...
详细信息
ISBN:
(纸本)9781849192125
The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without the need of communication, uses current traveling waves to identify faulted feeder, and the bus bar voltages to determine a event caused by fault or switch operation. In the protection scheme, current traveling waves are measured by current transducers in N line and phase lines, and wavelet multi-resolution analysis is used to decompose traveling wave signals. The initial traveling waves are compared in magnitude and polarity with each other to determine the faulted feeder. The protection is independent of microgrid operation connected with the main power grid or in island.
Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission *** with the increase of operation voltage to 1000 kV and tower height to more than ...
详细信息
Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission *** with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many *** Progression Model (LPM) was proposed to solve these *** some fundamental works, such as when the upward leader initiates and how it propagates, is still *** experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader *** upward leader from the test transmission line was clearly *** inception voltage and characteristics was *** streamer and leader initiated from the ground wire and conductor bundle were *** experiment results show that the leader initiating from the ground wire is more active in the inception *** velocity of the upward leader acquired is about 1.2-3.0 cm/μs.
A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded is presented. The feasibility of tripping single-phase circuit when a phase-tophase or two-phase-to-ground fault occu...
详细信息
ISBN:
(纸本)9781849198349
A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded is presented. The feasibility of tripping single-phase circuit when a phase-tophase or two-phase-to-ground fault occurs is studied with induction motor loads as the focus. The paper at first analyses the effect of a induction motor runs with one phase cut off theoretically. And then a real power distribution system model with 110kV, 35kV and 6kV voltage levels is built in PSCAD/EMTDC. Three feasibility criteria are proposed for motors in continuous operation with single-phase opened. At last, the novel protection scheme is testified in simulation with protection time and reclosing time as variables respectively. The results verify that the scheme is feasible and power supply reliability is improved.
Virtual synchronous generator(VSG)is grid-friendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control ...
详细信息
Virtual synchronous generator(VSG)is grid-friendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.
Arc fault occurs easily when circuit breakers (CB) cut the AC filters circuits in HVDC substation frequently. A transient arc model and online detection method are proposed in this paper. The proposed arc model is bas...
详细信息
Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequ...
详细信息
Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequently or refuse to trip. To solve these problems, through mass of starting signal simulation and analysis under different fault conditions, this paper focuses on the travelling-wave starting element and figures out the travelling-wave identification method. This paper summarizes the frequency and voltage characteristics of travelling-wave head, puts forward a new method in real-time travelling-wave fault identification. In addition, the analysis course included in this paper is a useful attempt that can be used in similar fault travelling-wave analysis.
A two-level distributed state estimation method for substation-dispatch center is proposed. After zero impedance three-phase state estimation based on KCL has been applied in substation, up load ripe data are treated ...
详细信息
In the deregulated retail market, consumers should have more right of choice for paying for their energy demand. This paper focuses on the design of electricity price package mechanism in retail market considering the...
详细信息
Performance of a power system security early warning and control system depends on accuracy of power grid parameter to a great extent. It is important to develop a practical branch parameter estimation method. From th...
详细信息
Performance of a power system security early warning and control system depends on accuracy of power grid parameter to a great extent. It is important to develop a practical branch parameter estimation method. From the results of expanded state estimation application, which is a representative parameter estimation method proposed before, it often happened that the parameters could not be estimated or estimated imprecisely. Focusing on IEEE 9 and a real-life area power grid in China, deep research on expanded state estimation method is carried out. As a result, these numerical instability and local optimization problems existing in the method were found here. A novel parameter estimation method based on Tabu search strategy is proposed to overcome these problems existing in the expanded state estimation method. Its good behavior in numerical stability and global optimization is verified by numerical tests on IEEE 9 and the real-life area power grid in China.
Because the fault characteristics is not obvious, the high resistance grounding fault feeder selection in a resonant grounding system has always been a hot and difficult problem in the field of power system protection...
详细信息
暂无评论