The urgent problem of the relaying protection in modern AC/DC hybrid connected grid and development wide area communication, information process intelligent technology powerfully promotes (WARP), which has become a research hotspot that attracts extensive attention. Originated from basic concept protection, this paper analyses advantages, effects functions protection. two main approaches to realize are on-line adaptive setting (OAS) principle fault element identification (FEI), introduced...

In the transient process of power grid faults, transferring distortion current transformer (CT) can seriously affect relay protection performance. Under these conditions, it is difficult to analyze ferromagnetic characteristic magnetizing branch in equivalent circuit CT. The Jiles-Atherton hysteresis model (J-A model), which widely used digital simulations, accurately describe and saturation core characteristics; however, acquire parameters J-A transformers practical use still a challenging...

When faults or disturbance occurs in AC/DC hybrid complex power grid, there have happened many generator, transformer and transmission line differential protection maloperation accidents caused by current (CT) saturation, which seriously threaten the safe stable operation of grid. As analytical analysis CT transient characteristics is very complex, it urgent to develop model can accurately simulate practical use. In this paper, different class (P, PR TPY) CTs use are taken do physical test....

In recent years, the zero-mode inrush current of high-impedance transformer with built-in high-voltage winding (T-Hin), which has large amplitude and decays slowly, causes misoperation zero-sequence overcurrent protection. Compared magnetizing current, waveform is inconsistent irregular, few researches have proposed mathematical analysis as well improved protection using characteristics. this paper, expression derived. Further considering parameter differences, T-Hin larger, tends to cause...

This paper proposes a hybrid UHVDC system dedicated for long-distance power transmission and back-to-back interconnection of the receiving region grids. The terminal is formed by LCC MMC in cascaded connection. combines merits hierarchical connection asynchronous interconnection, which optimizes network structure makes distribution grids more flexible. topology introduced detail. control strategy DC fault clearing are proposed. Finally, built PSCAD / EMTDC. simulation verifies effectiveness...

When a switching-on transformer is energized, complex sympathetic inrush will flow through adjacent operating transformers, which may cause the protection misoperation in power system. At present, mathematical analysis of usually based on model that without load, engineering error. In this paper, analytical expressions flux linkages, source current and load for integration with possible power-source are presented. The models simulation established PSCAD. influencing factors key...

Large-scale electricity has fed into Central and Southern China through DC transmission lines. Any one of the lines suddenly outage will result in a large proportion power-shortage. Recently, there are many harmonic protection misoperations caused by AC disturbance, resulting line exit operation. Therefore, it is necessary to analyse effect disturbance on harmonics study methods for protections. In this study, based theory switching function, interaction AC–DC systems studied. The cause...

Converter protection, including bridge differential protection and valve short‐circuit frequently malfunctions during the disturbance from an AC system, such as fault inrush current, which severely threatens safe stable operation of AC/DC hybrid power system. This paper analyzes cause maloperation based on mechanism analysis simulation tests. It is found that saturation current transformer in delta winding YD converter system main reason for this sort maloperation. To solve problem, proposes...

During the inrush period, multiple misoperation accidents of differential protection transformers happened, which seriously threatened safe and stable operation power grid. In traditional malfunction analysis, only current process is considered, electromagnetic transient interaction between transformer other non-linear ferromagnetic components such as CT hardly considered. Here, variation rule waveform characteristic analysed, influence secondary load type on second harmonic proportion dead...

High short-circuit impedance transformer is widely used because of its advantage in limiting current. Among the two types high transformers commonly used, high-voltage winding built-in type frequently occurs zero-sequence over-current protection maloperation during no-load closing, while another low-voltage series reactance rarely reported. The main difference between them lies structure. However, existing simulation models can hardly reflect difference. Through research, equivalent circuit...

In view of the misoperation inter-turn protection high voltage shunt reactor(HVSR) connected with submarine cable in offshore wind power project during conventional opening and closing operation, a comparative analysis principles different manufacturers analytical process operation sceneis are carried out. Based on analysis, two scenarios summarized, namely, zero-sequence source generated by saturation iron core is judged to be mistaken as an internal fault, measurement impedance decreases...

The excessive short-circuit current restricts the development of power grid. By using fast switch to dynamically change system topology structure during faults, flowing through conventional circuit breaker can be limit under switchable range, but application will affect relay protection. In this paper, flexible short-current suppression technology is introduced firstly. Then, influence on line protection, differential distance protection and zero-sequence discussed, optimized strategies are...

For the construction of smart grid, protection needs to be accurately measured, and current transformer correctly transfer transient process. The process nonlinear ferromagnetic elements mainly includes inrush CT saturation. Differential misoperation is rarely caused by a single factor. It involves coupling effect between In this paper, magnetizing sympathetic saturation are studied from aspects principle analysis digital simulation. Based on an accident, its impacts differential analyzed....

This paper analyses the mechanism of sympathetic inrush current converter transformer HVDC transmission system. The impacting factors current, including system impedance, closing angle and initial remnant flux incoming transformer, operating condition so on, are analysed utilizing on PSCAD/EMTDC soft. Based this, this proposed two identification methods for simulation proofs validity these methods.

The analysis of maloperation cases indicates that mal-operations the transformer differential protection caused by sympathetic inrush usually occur under combined action and current (CT) saturation. process characteristics mal-operation are analyzed. According to wave firstly increases maximum gradually then decays slowly, a new identification method is proposed, based on calculation fundamental component increment current. can identify quickly reliably adopt effective measures accordingly...

In differential protection, the methods to correct amplitude and phase deviation of currents in primary secondary winding Y/Delta-connected transformer will weaken harmonic characteristics. Researchers have proposed inrush restraint criterion current directly. However, helping effect circulating delta may cause symmetrical or waveform distortion, reliability based on typical magnetizing characteristics be affected. This paper reveals generating mechanism, influencing factors current.

The circulating current in the D-winding may cause primary waveform distortion, and reliability of restraint criterion based on typical magnetizing inrush characteristics will be affected. with is sum current. Using to compensate can improve differential protection. When phase not saturated, about zero. Therefore, unsaturated replaced by opposite Based this, an engineering practical calculation method for proposed. In method, segmented currents are used replace Phasor analysis demonstrate...

For the Y/D-connected transformer, if circulating current in D-winding can be obtained to compensate primary current, accuracy of inrush identification method will improved. At present, constructing algorithm is still insufficient. The mapping relationship between and unbalanced quantity (zero-mode zero-mode voltage, neutral point voltage) by deriving transformer differential equation this paper. A for based on proposed. In algorithm, only winding needs measured, there no requirement...

This paper proposes an intelligent and digital improvement scheme for the GIS circuit breaker. Based on concept of integration primary secondary system, control system breaker is reconstructed by device. The conditional loop based cable relay integrated circuit. protection function, including three-phase inconsistency, anti-jump, over-current storage motor, carried out software. condition monitor, remote operation, interlock are realized device substation network.

For the Inverter-Interfaced Distributed Generator (IIDG) access system, a ground fault occurred on 110 kV contact line, and zero-sequence current distribution both sides of line was analyzed by combining characteristics controlled source IIDG after fault, relationship between sequence quantities, neutral grounding method transformer capacity IIDG. Factors. The analysis points out that side mode determines zero sequences line; when system circuit breaker is disconnected, mainly affects...

High voltage shunt reactor((referred to as HSR, the same below)) is an important equipment used absorb reactive power and limit overvoltage level in system. Its frequent fault inter-turn short circuit of winding. The traditional protection based on principle zero sequence component has been maloperation for many times site. Based analysis structure electrical characteristics this paper defines root cause protection, puts forward a new type scheme which composed core saturation criterion,...