Chao Zhang

Bio: Chao Zhang is an academic researcher from Guangxi University. The author has contributed to research in topics: IEC 61850 & Electric power system. The author has an hindex of 3, co-authored 5 publications receiving 28 citations.

The importance of IEC 61850 interoperability testing

Abstract: This paper discusses the factors affecting interoperability between multi-vendor devices, the necessity for interoperability testing, and the types of interoperability should be conducted. It is recommended that proof-of-concept interoperability should be preformed before full scope integration, and it is crucial to adopt interoperability testing as part of site commissioning test. Interoperability testing is the next step forward after conformance test to ensure an IEC 61850 based substation automation system will interoperate as it is designed in the field. Conformance test can reduce the number of costly issues and problems during integration, site commissioning and operation. Devices passed conformance test may still subject to issues during integration, commissioning and operation. Conformance test does not mean interoperability test. Conformance testing cannot replace interoperability testing.

An integrated PMU and protection scheme for power systems

Abstract: This paper presents an integrated PMU and protection scheme for power systems The scheme integrates local and wide area control and protection systems by implementing the WAMS function and substation protections into one system to identify the overload caused by flow transfer from isolation of main trunk line This integrated system mainly consists of three major components: local interface unit for local measurement with IEC 61850 9-2 format, optical communication network interfaces for data exchange compatible with IEEE C37118 and IEC 61850, PMU integrated protection completes protective functions with flow transfer identification

A new scheme of control and protection based on utilizing phasor measurement technique

Abstract: This paper presents an integrated PMU and protection scheme for power systems. The scheme integrates local and wide area control and protection systems by implementing the WAMS function and substation protections into one system to identify the overload caused by flow transfer from isolation of main trunk line. This integrated system mainly consists of three major components: local interface unit for local measurement with IEC 61850 9-2 format, optical communication network interfaces for data exchange compatible with IEEE C37.118 and IEC 61850, PMU integrated protection completes protective functions with flow transfer identification.

A derivative based instantaneous frequency tracking algorithm

Abstract: Frequency is an important parameter for power system operation and protection. A frequency-tracking algorithm is presented for its fast and accurate measurement, which combines second derivative with linear approximation based on the sinusoidal characteristics of an AC signal and supplements a posteriori error processing. A Lagrange Polynomial-Fitting technique is used to calculate the second derivative, whilst an error compensation rate and a modifying factor are introduced to increase algorithm accuracy. The remainder of the fitting polynomial is analyzed, with the samples acquired in a half cycle data window filtered by equal ratios theorem to enhance the robustness, as well as the real time performance. Matlab simulation results show that the algorithm is suitable for instantaneous power system frequency tracking with high accuracy and a certain suppression of second harmonic interference.

An integratedpmu and protection schemefor power systems

Abstract: synchronised with a GPS-clock and compute the corresponding phasor component from widely dispersed locations. Phasor technology provides time synchronized sub­ second data, which is applicable for wide area monitoring; real time dynamics and stability monitoring; and improvements in state estimation, wide area protection and controls. The implementation in WAMS technology thus far, however, is designed as an independent measurement unit, the PMU (Phasor Measurement Unit). The PMU device, although it may be implemented as a substation lED and even merged into an individual protective relay, usually its functions are separated from local protective systems. By this arrangement, it is difficult to coordinate the system monitoring, control and backup protection with the local protection systems, which could result in a conflict of interests between the system control and local protection and prevents correct actions being taken in case of system emergency. At the same time, with more and more substation IEDs (Intelligent Electronic Devices) being put into operation, increased complexity results from a number of issues, such as commissioning, maintenance and EMC (Electro Magnetic Compatibility). This paper presents the design and development of a novel scheme for the integrated control and protection of power transmission systems. The scheme integrates local and wide area control and protection systems by implementing the WAMS function and substation protections into one system. This integrated system coordinates stability and emergency control, system oscillation detection and protection.

IEC 61850 based substation automation system architecture design

Abstract: This paper investigates various Ethernet LAN architectures for substation automation system applications with protection, control, monitoring data flows and their performance requirement. The paper discusses conceptual architecture designs and related redundancy technologies such as RSTP, PRP and HSR protocols. The suitability of these architectures and the redundancy technologies for mission-critical, time stringent realtime tasks such as SMV and GOOSE tripping over the Ethernet LAN applications are examined.

Real-time power system analysis and security monitoring by WAMPAC systems

Abstract: The outline of this paper is to implement real-time analysis and security monitoring in the smart power system. Security is the ability of the power system to withstand contingencies. The principal role of Wide Area Monitoring, Protection and Control (WAMPAC) system is to maintain a secure system state, i.e. the system that can withstand each specified contingency. The advanced WAM system uses real-time measurements to monitor system status and hence determines whether or not it is secure. The WAMPAC system is used to deploy proper control actions on load, transmission and generation in a wide time frame from fast protection systems to slower control of generators. This paper also explores the challenges and opportunities to implement online system analysis capability in order to monitor system security and stability indices. Therefore, the implemented hardware/software setup for monitoring and analyzing system in real-time format will be presented by the online results available with real-time software. Online load flow and contingency results aim to proper security monitoring of power system in wide area which is useful for most application such as system remedial actions.

Interoperability and interchangeability considerations in microgrids employing IEC61850 standard

Abstract: Due to the recent changes in electrical networks, microgrid operation schemes have evolved dramatically. Coupled with smartgrid concepts, microgrids are required to be more intelligent and establish communication with its components. In order to sustain reliable and sustainable power delivery under heavy deployments of Distributed Generators (DGs), passive power network operation schemes have to be replaced with new generation dynamic methods. Utilization of communication in microgrids brings about new challenges such as communication reliability, time delays, plug-and-play and standardization considerations. Having a standard communication procedure has utmost importance in a network where there are different equipments manufactured by different vendors and having different features. IEC61850 substation communication standard has been introduced by International Electrotechnical Commission (IEC) to address this challenge. It has received much attention in power engineering circles and several pilot projects have been implemented. As a result, it has been found out that several concepts such as interoperability and interchangeability have to be considered in networks designed with IEC communication standards. This paper summarizes the latest developments in this field and discusses the required steps that shall be taken to unleash capabilities of microgrids in current smart network era.