In order to implement an IEC 61850 communication system, there needs to be a complete understanding of the methods, tools and technologies associated with the communication network, protocol and messaging underpinning the services. The IEC 61850 standard allows for communication between devices within a substation where a peer-to-peer model for Generic Substation Events (GSE) services is used for fast and reliable communication between Intelligent Electronic Devices (IEDs). One of the messages associated with the GSE services is the Generic Object Oriented Substation Event (GOOSE) message. A detailed analysis of the structure for the GOOSE message is required for fault diagnosis, or when developing hardware that is compliant with the IEC 61850 standard. This is one of the stated objectives of the Centre for Substation Automation and Energy Management Systems (CSAEMS) in the training of prospective specialists and engineers. A case study is presented where the structure of the GOOSE message as described in IEC 61850-8-1 is confirmed using firstly simulation, then experimentation with actual IEDs. In the first instance the message structure is confirmed by simulation of the GOOSE message and capturing it using network protocol analyzer software, after which analysis of the packet frame is performed. Data encoding of the GOOSE Protocol Data Unit (PDU) is analyzed with emphasis on the Abstract Syntax Notation (ASN. 1) Basic Encoding Rules (BER). The second part of the case study is conducted through experimentation with IEDs which are used to generate a GOOSE message and network protocol analyzer software is used to analyze the structure. Both the simulation and practical experimentation with actual devices confirm the GOOSE message structure as specified in part 8-1 of the IEC 61850 standard.

Reactive power optimization and voltage control is one of the most critical components of power system operation, impacting both the economy and security of system operation. It is also one of the most complex optimization problems, being highly nonlinear, and comprising both continuous and discrete decision variables. This paper presents the problem formulation, and a thorough literature review and detailed discussion of the various solution methods that have been applied to the Volt/VAR optimization problem. Each optimization method is described in detail, and its strengths and shortcomings are outlined.The review provides detailed information on classical and heuristic methods that have been applied to the Volt/VAR optimization problem. The classical methods reviewed include (i) first-and second-order gradient-based methods, (ii) Quadratic Programming, (iii) Linear Programming, (iv) Interior-Point Methods, (iv) and mixed-integer programming and decomposition methods. The heuristic methods covered include (i) Genetic Algorithm, (ii) Evolutionary Programming, (iii) Particle Swarm Optimization, (iv) Fuzzy Set Theory, and (v) Expert Systems. A comparative analysis of the key characteristics of the classical and heuristic optimization methods is also presented along with the review.

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This paper examines the effects of networked induced time delays on the dissolved oxygen (DO) concentration in the activated sludge process (ASP) of a networked wastewater treatment plant (WWTP). This is a situation in which the controller and the wastewater plant are separated by wide geographical distance. This is a new type of WWTP control that allows two or more WWTPs to be controlled by a single controller placed in a remote location. The objective is to achieve flexibility of control and to reduce its cost. The communication medium between the controller and the WWTPs introduces communication drawbacks into the control system. The influences of network-induced time delays [controller to actuator delay (τ ca ) and the sensor to controller delay (τ sc )] over the behavior of the DO process controlled by both nonlinear linearizing and proportional-integral controllers are investigated for constant and random delays. Investigation of the DO process under random delays was also performed with varying linear controller parameters [proportional gain (K p ) and integral time (T I )]. Simulation results reveal that large network-induced time delays in the closed-loop DO process leads to depletion of the amount of oxygen available for microorganism metabolism, leading to inefficiency of the ASP. The critical delay during which the DO process becomes unstable due to communication drawbacks was also determined for constant and random delays. These values are found to vary depending on the delay type (constant/random), delay magnitude, and the linear controller parameters K p and T I . The results of this study would provide useful information for process performance and form the basis for the design of a robust networked control for the DO process capable of mitigating communication drawbacks in a networked wastewater distributed systems.

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The continued adoption of renewable energy and distributed generators has resulted in a rising number of supply points within the traditional electric power grid, necessitating the need for enhanced monitoring capabilities. The IEC 61850 standard can become an enabling technology for enhanced monitoring, but prohibitively high costs and complexity of compliant devices could become an impediment. Open-source IEC 61850 libraries, coupled with single-board computers and digital signal processors, provide a possible low-cost solution. This work presents the process of modelling and implementing such a device using an IEC 61850 open-source library, a Raspberry Pi embedded platform and an ADE9000 analogue front-end. Measurement accuracy and interoperability compliance tests are conducted to determine the suitability of the device for use in an industrial setting. A key contribution of the findings in this paper is the modelling and implementation of a viable, interoperable and low-cost IEC 61850-based power quality monitoring device using off-the-shelf components and an open-source software library. The implementation of this device provides a platform that is easily modifiable for use in a range of applications. Another contribution is the method of modelling IEC 61850 logical nodes and functions to analogue front-end measurement registers. The knowledge demonstrated shows how device modelling techniques can be used to extract additional information for mapping to existing logical nodes or to develop new ones. The paper's findings result in a low-cost IEC 61850-based power quality monitoring device. The device has applications as a general utility-scale monitor for DER plants, check metering, IEC 61850-based power quality mitigation algorithms and short-term power quality studies. It may also function as a low-cost entry point to IEC 61850-based communications in smaller municipalities, and additionally as a lab test and prototyping tool for technicians, engineers and university students.

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Security and reliability of electrical power supply has become indispensable to modern society, and the system operator is challenged to manage the increasingly complex modern power system in a manner that ensures the expected reliability and security of system operation. In this context, Volt/VAR optimization (VVO) plays a key role in the efficient delivery of power through the transmission system, contributing significantly to the security, reliability, quality and economy of system operation. This article presents the design and implementation of an efficient primal-dual interior-point algorithm for the solution of the VVO problem. The primal-dual interior-point method combines efficient constraint handling by means of logarithmic barrier functions, Lagrangian theory of optimization, and the Newton method to constitute one of the most efficient deterministic algorithms for large-scale nonlinear optimization. The developed algorithm also incorporates the efficient Newton-Raphson load flow computation, which ensures that the solution is feasible with respect to the power flow balance equations at each iteration of the VVO algorithm. Both the VVO and Newton-Raphson load flow problems are formulated in the rectangular coordinates of system voltages. This is a departure from most researchers, who make use of the polar formulation, and adds considerably to the efficiency of the developed algorithm. The efficiency and effectiveness of the developed algorithm has been demonstrated by means of case studies performed on the 6-bus and IEEE 14-bus, 30-bus and 118-bus test systems, which have been selected to analyse the computational efficiency and scalability of the algorithm as it is applied to systems of various sizes. The extensive analyses that have been conducted reveal the developed primal-dual interior-point algorithm's effectiveness and efficiency, particularly in being able to successfully solve the VVO problem for systems of widely varying sizes without disproportionate increase in computational cost or deterioration in the quality of the results. The developed algorithm exhibits characteristics of fast convergence, high efficiency, and scalability to large-scale problems.INDEX TERMS Volt/VAR optimization, reactive power/voltage control, primal-dual interior-point method, optimal power flow, Newton's method, Newton-Raphson load flow, Lagrange multiplier method, rectangular voltage coordinates