Decentralized proportional-integral controller based on dynamic decoupling technique using Beckhoff TwinCAT-3.1

An improved technique for the design of decentralized dynamic decoupled proportional-integral (PI) controllers to control many variables of column flotation was developed and implemented in this paper. This work was motivated by challenges when working with multiple inputs and multiple outputs (MIMO) systems that are not controllable by conventional linear feedback controllers. Conventional feedback control design consists of various drawbacks when it comes to complex industrial processes. The introduction of decentralization, decoupling, and many advanced controls design methods overcomes these drawbacks. Hence, the design and implementation of control systems that mitigate stability for MIMO systems are important. The developed closed-loop model of the flotation process is implemented in a real-time platform using TwinCAT 3.1 automation software and CX5020 Beckhoff programmable logic controllers (PLC) through the model transformation technique. The reasons for using the CX5020 as an implementation environment were motivated by the reliability, and is built according to new industry standards, allowing transformation, which makes it more advantageous to be used more than any other PLCs. This is done to validate the effectiveness of the recommended technique and prove its usability for any multivariable system. Comparable numerical results are presented, and they imply that industrial usage of this method is highly recommended

An approach for a multi-stage under-frequency based load shedding scheme for a power system network

The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers

Investigation of the application of IEC61850 standard in distribution busbar protection schemes

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology Supervisor: Prof. R. Tzoneva Co-supervisor: Prof. P. Petev 2013Busbars are the most important components in the distribution networks. Faults on the busbar are uncommon, however an occurrence of a busbar fault can lead to a major loss of power. Busbars are the areas in a substation where the levels of current are high and therefore the protective relay application is very critical. In order for the protection scheme to be successful it is important to carry out the following specifications: Selectivity, Stability, Sensitivity, and Speed. To meet all of the above requirements protection must be reliable, meaning that the protection scheme must trip when called up to do so (dependability) and it must not trip when it’s not supposed to (security). The thesis focuses on the reverse blocking busbar protection scheme with aim to improve the speed of its operation and at the same time to increase operational reliability, flexibility and stability of the protection during external and internal faults by implementation of the extended functionality provided by the IEC61850 standard-based protective IEDs. The practical implementation of the scheme by the use of IEC 61850 standard communication protocol is investigated. The research analyzes in detail the reverse blocking busbar protection scheme that is used at the moment in the power systems and it develops an improved IEC 61850 based reverse blocking busbar protection scheme for a distribution network. The proposed scheme is designed for a radial type of a distribution network and is modeled and simulated in the DigSILENT software environment for various faults on the busbar and its outgoing feeders. The results from the simulations are used further for implementation of the designed protection scheme. A laboratory test bench is build using three compliant with the IEC 61850 standard ABB IEDs 670 series, CMC 356 Omicron test injection device, PC, MOXA switch, and a DC power supplier. Two ways of the reverse blocking signals between the IEDs implementation are considered: hard wired and Ethernet communication by using IEC 61850 standard GOOSE messages. Comparative experimental study of the operational trip response speed of the two implementation shows that the performance of the protection scheme for the case of Ethernet communication is better The thesis findings and deliverables will be used for postgraduate studies of other students, research, short courses, and solution of industrial problems. Keywords: Busbar, Power system, reverse busbar blocking scheme; IEC61850; Distribution, Protection relays, IEDs, GOOSE message, laboratory test benc

Innovations in Multi-Vendor Based Transformer Protection Schemes for Transmission Networks Using IEC 61850 Standard

No ethical clearance was required for the study, HDC approved the study to proceed.The Datasets are the configuration of the nine-bus system network in RSCAD, the design of different control logic. Power system data used in the study of the design and development of the Multi-Vendor Based Transformer Protection Scheme for Transmission Network. In order to test this protection, a lab-scale test bench is set up at the CPUT CSAEMS laboratory utilizing a transformer protection relay and CMS omicron injection device.This research aims to develop a transformer current differential protection scheme, investigate the IEC61850 standard-based interoperability challenges between the Intelligent Electronic Devices produced by different vendors (Multi-Vendor), and propose solutions for improving communication between these devices. Using system simulation software tools, researchers employ IEEE systems to implement and test creative ideas and concepts. The transmission system of IEEE 9-Bus is selected as a case study, and IEEE 9 has been modified at bus 6 with sub-transmission and distribution with two parallel transformers. The study utilized the parallel transformers that have a 110/22kV with a 56MVA protected by two IEDs (SEL-487E and ALSTOM MiCOM-P645 relays) differential protection, with a speed of fewer than 20 msec responding to the faults and has communication capabilities of the IEC 61850 standard.The test plan aims to evaluate the performance of parallel transformer differential protection schemes through hardware-in-the-loop (HIL) testing. The methodology involves implementing HIL testing with the RTDS simulator, utilizing MiCOM-P645 and SEL-487E relays for protection scheme testing, and subjecting the system to various fault scenarios and abnormal operating conditions for in-depth analysis. The rationale behind this plan is based on several key factors.</p