Fanrong Wei

The protection cooperation of distribution network based on protection intelligent center and the validation of its reliability

With the development of communication technology and artificial intelligence, the study of protection intelligent center is becoming the research focus. To make full use of the technology advance, the concept of protection intelligent center is proposed. The protection intelligent center is a remote center which can gather the electrical information of the whole network and give out tripping signals on the basis of analysis. In distribution network, the protection intelligent center could provide multiple protection with its local layer and center layer. This paper focuses on the cooperation method of different types of protection which protection intelligent center can participate in, and proposes a practical scheme which combines the protection deployed in local layer and central layer to reach an optimal protection performance. The protection method of the system proposed in this paper is complicated to achieve multi-space and multi-layer protection, so the verification of the protection cooperation is also provided in this paper.

Similarity Comparison Based High-Speed Pilot Protection for Transmission Line

To solve the following problem: the action speed of protection based on a phasor is restricted by the length of the filtering algorithm time window and the vulnerability to false data, a new pilot protection principle for transmission lines based on waveform similarity is proposed in this paper. By comparing the discrete point sets of current sampling values, a waveform similarity-based algorithm called the Hausdorff distance distinguishes the difference between both side currents of a protected transmission line, realizing fast identification, and removal of the fault. Based on the characteristics of the algorithm, setting methods and protection criterion are discussed. Finally, an improved Hausdorff distance algorithm is proposed to cope with false data. The effectiveness and advantages of the proposed algorithm are validated with theoretical analysis and extensive simulation test results.

Remedial Pilot Main Protection Scheme for Transmission Line Independent of Data Synchronism

For those protective relays highly dependent on common centralized timing synchronization, the threat of loss of data synchronism, e.g., due to cyber-attack, cannot be ignored. In this case, measurements could be falsely timestamped, leading to undesired mal-operation of protection or evident performance deterioration if countermeasures are lacking. In this paper, several different timing attack scenarios and impacts to protective relays on the transmission line are analyzed. To cope with the timing attack scene, a remedial pilot main protection scheme-based only on modulus information of measurements for a transmission line is proposed, independent of timing information. The proposed remedial scheme includes a modulus summation impedance relay, a mid-part relay, and an instantaneous over-current relay. The effectiveness of the proposed scheme has been validated by theoretical analysis and simulation tests.

Hierarchy of distribution centralized substation area protection system based on All-in-One devices

With the rapid development of communication technology and the widely constructing of smart substations, wide-area protection and substation area protection have become hot research topics. As an important part of network protection, substation protection at present only realized the centralization of the information transmission, but the comprehensive utilization of information has not been an in-depth digging, on the other hand, protect devices still been placed centralized in the master control room, the regulation that primary equipment and secondary equipment must be set aside a safe distance results in the Large occupation of land, seldom play out the advantages of information protection which can make the devices highly integrated and miniaturized. In response to those questions, a novel distribution centralized substation area protection system based on All-in-One device is proposed in this paper, and the configuration and function of All-in-One device are also described in detail. Then introduces the VPN scheme of the proposed system. On this basis, considering the features of proposed system structure and networking schemes, this paper brings out a time-sharing cooperation work strategy. The example proves that the strategy is reasonable and effective, while shows the superiority of the distribution centralized substation area protection system compared to the traditional protection system.

The mechanism of fault searching for new energy distribution network based on variation of cutting current

With the increase of demand in power supply demand, increased strength of connection complexity and access of renewable energy, traditional current protection has been unable to meet the needs of the safe and reliable operation of distribution system. To prevent this, the cutting-current-based fault location searching algorithm is put forward in this paper using the single-end current vector. Firstly, the feeders are divided into several stages to determine the searching section. Secondly, search the whole line lengthways for the faulted stage, and the accurate fault location is carried out by the breadthwise search, and the fault can be cleared with the help of the existing method and the proposed method. For larger distribution network, dichotomy algorithm is utilized in lengthways search to minimize the time cost. PSCAD/EMTDC simulation results indicate that such a method can play a complementary role for existing protection equipped for the double end new energy distribution network.

The study of area protection principle optimization based on protection intelligent center indistribution network

With the development of communication technology, a large number of intelligent substation has been constructed, substation area protection and wide area protection technology has been widely used. Then Protection Intelligent Center (PIC) taking over the main functions of multiple substations protection in the distribution network comes into being, making large-scale information centralized processed becomes possible. Against to the problem that traditional local information-based protection is difficult to set and coordinate brought by increasingly complex distribution network, this paper redefines the partition to protection are and its search strategy, gives a fault criterion based on multi-terminal current differential protection. Finally we propose the scheme of current differential protection based on partition principle.

Dealing with the information-missing of the entire station by wide area protection online adaptive technology

There are more and more studies on centralized protection, but the effective protection scheme dealing with the information-missing of entire substation is scarce. To solve this problem, this paper proposes a wide area protection online adaptive algorithm. When the information of entire substation is missing and inter-station line fails, the algorithm will automatically collect current information of all adjacent substation inter-station lines at other side. By comparing one current phase with the phase of all other current phasor sum respectively and sorting the difference value, the fault can be located according to the rank. The algorithm uses the current phase comparison principle, which can locate the fault quickly and accurately, the principle is simple and less information is needed. Finally PSCAD simulation is used to verify the feasibility of the algorithm.

Description of protection intelligent center using IEC61850 defined SCL

Introduce the Protection Intelligent Center that suit the evolution tendency of the substation form, but the new form of substation is lack of corresponding description of information model, Based on IEC61850 defined SCL language, according to the characteristics of the Protection Intelligent Center, the paper put forward the structure of Protection Intelligent Center information model description. Then, based on the description of Protection Intelligent Center, a software application is brought out that can acquire the real-time topology of the grid within the range of Protection Intelligent Center, and the flow chart of software is given. Description of Protection Intelligent Center using IEC61850 defined SCL.