Fast Identification Algorithm Of Fault Direction In Distribution Network Of DGs And RTDs Simulation Experiment Research

The research content of this paper is from the large scale of new energy accessed to the operation risk assessment in ShanXi power grid and the research project of hybrid energy storage solution.With the large number of distributed generations(DGs)such as solar energy and wind energy accessing the distribution network,the traditional radial structure distribution network is transformed into a multi-power supply system.Traditional three-phase current protection schemes based on current amplitude is difficult to meet operation requirements.Therefore,it is imperative to study a protection method of distribution network with distributedgenerations.This paper proposes and improves a fast direction recognition algorithm for distribution network with distributed generations.The algorithm only needs the post-fault current phase information to determine the direction of the fault,and then realize the fault area positioning.The fault identification algorithm only uses the post-fault current phase information to avoid the need to use a large number of power directional elements in the distribution network due to DGs access,which greatly improves the economical reliability of the distribution network.This identification algorithm can cooperate with the communication channel to form a new type of differential protection scheme;This identification algorithm can also replace the power direction relay,and be combined with current protection to constitute a new direction of current protection.This paper proposes and improves a fast fault direction recognition algorithm.This algorithm separates the fundamental frequency current information from the post-fault current.The algorithm calculates the phase of the post-fault current and its positive and negative derivative vectors through the discrete fourier transform.Through a series of calculation,the fault direction identification vector is drawn and the fault direction is identified.This article builds two distribution network system models on RTDS,and analyzes and validates the fault fast direction identification algorithm applied in various types of single-phase,two-phase and three-phase in different experimental environments.The feasibility of this algorithm is confirmed under disturbances of other factors.It is conclude that this fault identification algorithm is not affected by power flow,grounding resistance,types of fault,penetration level of DGs,fault location and harmonics,etc.And this algorithm can reliably identify the direction of the fault occurred in the entire length of the line.It can identify faults comprehensively,accurately and quickly.The fault fast direction identification algorithm in this paper takes into the interference of the transient factors.This paper concludes a method to avoid the interference of the transient process;And in the specific post-fault current phase range,the method increase the phase detection circuit.In the actual line,it can be programmed into the microprocessor relay protection.This phase detection circuit can get post-fault current phase accurately,and increase the possibility of practicability.In this paper,The influence of system frequency offset on the algorithm is analyzed.And the phase of the fault current is corrected and can be more accurate.So,it can get the fault current phase accurately and improve the accuracy of fault direction identification algorithm.