STUDY OF MICRO PROCESSOR BASED DISTRIBUTED BUS PROTECTION

A new distribution principle of bus protection is presented.The protection system description,its design features,hardware structure,construction of data communication network are given.Dynamic simulation experiments show its distinguishing advantages over traditional centralized principle.

Study on the Effect of Multi-Type Current Transformers Hybrid Operation on Differential Protection of the Bus Based on Dynamic Simulation

This paper analyzes characteristics of multi type current transformers hybrid operation for each branch of the bus and their effects on differential protection of the bus. By theoretically analyzing transmission characteristics of multi type current transformers and their influence factors, we study the dynamic model testing method of multi type current transformers for the bus, and design 3 kinds of testing schemes by making the equivalent model based on the field of P-level current transformer, TPY-level current transformer and electronic current transformer, and build the hybrid operation testing platform of multi type current transformers. Finally, we compare and analyze the transmission characteristics difference of multi type current transformers on the same branch and the characteristics difference of hybrid operation in two successive external faults, analyze the cause behind the differences, and put forward the corresponding improvement measures.

High-Impedance Bus Differential Protection Modeling in ATP/MODELS

This paper presents a modeling of a high-impedance bus differential protection logic using the ATP (Alternative Transients Program) MODELS language. The model is validated using ATP simulations on an electrical system consisting of a sectionalized bus arrangement with four transmission lines (TLs) and two autotransformers. The obtained results validate the model and present some of the advantages of using this type of bus protection, such as fast and safe operation, even when under adverse conditions such as current transformers (CTs) magnetic core saturation upon the occurrence of external faults.

论商业秘密及其保护

侵犯商业秘密是不正当竞争行为;商业秘密应具备秘密性、保密性、价值性、实践性、合法性和风险性的条件;应在立法中对商业秘密的法律属性、构成要件及侵权者的法律责任予以界定和明确。

Towards a standardisation for digital inputs and outputs of protection functions in IEC 60255 series

Fully digitalized substations using IEC 61850 process bus are being introduced all over the world.Numerous utilities have featured pilot projects,demonstrators or even industrial scale deployment of these Fully Digital Protection,Auto-mation and Control Systems(FD-PACS).Product standards such as profiles for Instrument Transformers have been developed and published(IEC 61869-6 and IEC 61869-9 by TC 38-Instrument Transformers).This raises the question about the standards for digitally interfaced protection functions.In 2016,IEC TC 95(Measuring relays and protection equipment)charged a working group to investigate this subject and to elaborate recommendations concerning requirements and testing of protection IED with digital inputs and outputs for protection standards(IEC 60255-1xx series).For protection functions,publisher/subscriber based data streams are supposed to comply with IEC 61850 and IEC 61869 standards.This holds in particular for Sampled Values(SV)representing energising inputs of the protection function,and is also applicable to Generic Object Oriented Substation Event(GOOSE)which can be used for input or output of protection functions.Quality attributes of published data depend on the operational and connection status of the function and the hosting IED.In addition,protection functions have to take into account the information regarding the time synchronisation of the received SV and other parameters.This paper gives an overview of these features and the proposed way to take them into account in the IEC 60255 standard series.It describes the progress of WG 2 and relates it to existing standardization documents.

An adaptive limited wide area differential protection for power grid with microsources

The operation mode of power grids with intermittent distributed generations(DGs)changes frequently due to the bidirectional power flow.In comparison with the conventional grids,the protection relays in power grids with micro-sources are more difficult to set.To tackle this problem,this paper proposes an extended bus differential protection(EBDP)strategy based on the limited wide area(LWA).In this method,the micro-grids are divided into several protection areas at the core of the bus.The whole protection areas are protected by the wide area current differential relays,which are also configured to protect each component in this protection area.Moreover,the protection areas can be changed adaptively according to the power flow direction.Finally,a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform.The simulation results indicate that the proposed adaptive limited wide area differential protection(LWADP)has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault,and can be widely utilized in larger micro-grids.

Complex Percentage Differential Relay

This paper introduces a new complex percentage differential relay for bus protection. It allows greater CT errors during the external fault and is still sensitive to the intemal fault with high fault resistance or out-flowing current.The CTs of the differential circuit of the new relay may have different transformation ratio, so the new relay can share CTs with other relays and don’t need special CTs only for differential protection. It may be applied in transformer differential protection as well.

IEC 61850 as Backbone for Smart PAC Systems

This paper discusses a working definition of smartness in protection,automation and control systems(PACS)in substations.A summary is given about the standard IEC 61850 features that support smartness,i.e.,the data model,the multiple communication services,and the system configuration description language(SCL).With help of known examples of application functions for control,supervision,and protection,the building of smart systems out of the modules of IEC 61850 is demonstrated.From the possible architectures,the standardized redundancy is explained.The process bus is exploited in detail since it is seen by users as the core of a smart substation.In this context,attention is given also to the time synchronization in theµs range over the communication network,a rather new part of the standard.In the last part,all features are summarized and it is concluded that IEC 61850 may really be named the backbone for smart PAC systems.