The invention discloses a fault distance detection method for an active power distribution network, and the method comprises the following steps: first, obtaining the data of an active power distribution network; second, determining each power supply section so as to confirm the troubled section; using the forward-backward sweep method to calculate the injection current of the downstream of the troubled point to the troubled point; calculating the voltage phase amount and the current phase amount at the downstream end of the troubled section and calculating the nominal position of the troubled point; and finally calculating the distance from the troubled point to a transformer substation. In the method of the invention, the distribution-type power supply multi-point accessing is considered, and only through the use of the local voltage and current phase amounts and the synchronous current phase amount of the distribution-type power supply, it is possible to realize the fault distance detection for the active power distribution network. In addition, through the comparison of the current at the two sections of an area section, the positioning of a troubled area section can be realized. Through the calculation of the fault current and the contribution of the downstream current of the fault point to the fault current, the positioning and distance detection for the fault can be realized, making the method suitable for the fault distance detection under the condition of a multi-point distribution-type power supply accessing.

Fault distance detection method for active power distribution network

The invention discloses a protection method of a DC distribution network system, DC protection device are arranged on each switch in that DC distribution network system, and all the protection devicesare connected to the communication interaction platform The protection device starts to judge the direction of the fault current after detect the fault current, and sends the judged fault information such as the magnitude and the direction of the current to the communication interaction platform The protection device obtains the fault information from other protection devices through the communication interaction platform, and compares and judges the fault area by combining the fault information of the switch and the adjacent switch protection devices, so as to realize the fault area positioning and marking According to the direction of the fault current flowing through the switch where the protection device is located and its adjacent switches, it is judged whether the fault is an in-area fault or not By comparing the fault information between the protection devices, the invention realizes the quick and accurate judgment of the fault area The accurate location of the fault areaprovides reliable basis for the correct removal and isolation of the fault

A protection method of a DC distribution network system

The invention discloses a transient energy protection method for a fault current of a direct current transmission line, and belongs to the technical field of relay protection of a DC distribution network After the DC line fault current characteristics are fully considered, the positive and negative current instantaneous values and the maximum load current are compared; firstly the fault occurrence and the failure type are determined, and then the difference of line current characteristics of different fault types is used to determine the fault type, and finally the fault current transient energy difference and a delay action on the line are used to determine the fault occurrence position; the fault section can be determined quickly and accurately, a reliable action is achieved without theline communication, andthe sensitivity is high; the transient energy protection method is suitable for the line protection of a DC power distribution system, and helps to improve the line protectionof DC power distribution engineering

Transient energy protection method for fault current of direct current transmission line

The invention belongs to the technical field of fault diagnosis of DC power network, in particular to a single-terminal quantity protection method of ring-shaped flexible power network line. The method comprises the following steps: measuring voltages of two terminals of additional inductors at the installation position of DC power line protection; The equivalent model of post-fault converter is established. The MMC is equivalent to the series circuit of capacitor and inductor, and the VSC and DCT are equivalent to the parallel capacitor on the DC side. The complex modulus network of DC line based on 0-modulus and 1-modulus is established. The initial value of the additional inductance voltage after the fault is obtained by solving the complex modulus network of the DC line. The relationship between the initial value of the additional inductor voltage and the fault types in and out of the region is obtained. The fault location identification criterion based on the initial value of additional inductance voltage is established and the fault location identification threshold is adjusted. Based on the initial value of the additional inductor voltage, the fault pole judgment criterion and the fault pole judgment threshold are established. Single-ended electrical quantity is used to identify faults quickly and accurately, and communication is not needed, and the reliability is high.

single-end quantity protection method of a ring-shaped flexible power network line

Provided in the invention is a full-fault-current-based single-pole fault identification method for a flexible direct-current distribution network so that limiting problems that the single-pole faultroute selection is easy to be under noise interference and the fault identification rate is low in a small current grounding mode can be solved. A ring flexible direct-current distribution network with the complicated topological structure is used as a study object; and a single-pole fault identification method based on full fault information of transient-state and steady-state direct currents isput forward. On the basis of a fault current transient-direction differential protection principle, a fault location under the circumstance of the metallic or low-transition resistor is identified; and a fault location is determined according to a small-resistor-switching-based direct-current steady-state current differential protection principle under the circumstance that the fault can not be identified accurately because of system operation mode changing or large transition resistance. According to the invention, with comprehensive utilization of the full fault current information, the fault is identified quickly in a low-transition-resistance short-circuit state and the fault identification rate is high in a high-transition-resistance state.

Full-fault-current-based single-pole fault identification method for flexible direct-current distribution network

The invention belongs to the technical field of power system relay protection and particularly relates to a DC line relay protection method for a multi-terminal flexible medium-voltage DC power distribution system. The method comprises the steps of main protection and the backup protection. The main protection reflects an inter-electrode short-circuit fault of a DC line and a unipolar grounding fault of a small transition resistor, wherein a fault type and a fault interval are identified based on a current state matrix. The backup protection adopts the duration of the voltage imbalance as a starting criterion, so as to protect a judging fault interval of positive and negative current imbalance state matrixes at an installation part and isolate faults. The method determines the action signal of a DC breaker according to the switching-on/off signals of the main protection and the backup protection. The main protection only depends on the status signal values -1, 0 and 1 of two adjacent protection and transmission current elements, so that the requirement on a communication system is reduced. The backup protection judges the occurrence of a fault only based on the voltage, wherein the unbalanced current calculation is aiming at the positive current and the negative current of the same protection part. Therefore, the generation of errors due to the communication delay or the non-synchronized communication can be avoided.

DC line relay protection method for multi-terminal flexible medium-voltage DC power distribution system

The invention discloses an improved impedance type active distribution network fault location algorithm based on phasor analysis, belonging to the technical field of safe and stable operation of power systems. A one-variable quadratic ranging equation of distance-to-fault applicable to all kinds of fault types is built based on synchronous detection data of FTU devices at power access points before a fault and according to the fact that a transition resistor at a fault point consumes zero reactive power. The synchronous detection data is substituted into a forward-backward sweep power flow program containing distributed generation, load iteration calculation is performed to get the actual load power, fault location of a three-phase unbalanced active distribution network under various fault types is realized without pre-judging the fault type and faulty phase, the distance x(total) from an actual fault point to a main grid is calculated, and the searching and ranging process ends. The algorithm needs no pre-judgment on the fault type and faulty phase, and is of high ranging accuracy. The active distribution network fault location algorithm put forward by the invention has high ranging accuracy and good robustness.

Chen Bingyan

Papers

DC line relay protection method for multi-terminal flexible medium-voltage DC power distribution system

Improved impedance type active distribution network fault location algorithm based on phasor analysis