The appeal for more reliable, efficient and resilient power grids has become indispensable with the recent technological development and ever-increasing demand for electrical energy. These goals might be achieved by introducing sensors and actuators in the power grid, with the purpose of enabling a smart control of the power network. All power devices must be connected using a reliable communication network, which should be able to operate even when the power grid fails. Currently, several communication technologies have been applied for supporting this new application scenario. This article aims for reviewing both academic and market use cases for technologies applied to the mission-critical, control networks and Smart Grid applications, such as teleprotection, self-healing, communication with control centers and field devices, among others. More specifically, the key aspects, potential technologies, main protocols and use cases of operating data networks in energy transmission, power distribution and smart grid environments, including circuit and packet switching technologies, are discussed into details. Furthermore, resilience and the main telecommunications technologies used in power grids, as well, the correlation among them, are exploited in practical point of view. The article provides a broad discussion on the best telecommunication options to build the emerging intelligent energy distribution systems, covering control networks, teleprotection, and smart grid applications.

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Control Networks and Smart Grid Teleprotection: Key Aspects, Technologies, Protocols, and Case-Studies

Distribution systems continue to grow and becoming more complex with increasing operational challenges such as protection miscoordination. Initially, conventional methods were favoured to solve overcurrent relay coordination problems; however, the implementation of these methods is time-consuming. Therefore, recent studies have adopted the utilisation of particle swarm optimization and genetic algorithms to solve overcurrent relay coordination problems and maximise system selectivity and operational speed. Particle swarm optimization and genetic algorithms are evolutionary algorithms that at times suffer from premature convergence due to poor selection of control parameters. Consequently, this paper presents a comprehensive sensitivity analysis to evaluate the effect of the discrete control parameters on particle swarm optimizer and genetic algorithms performance, alternatively on the behaviour of overcurrent relays. Optimization algorithms aim to minimise overcurrent relay time multiplier settings and accomplish optimal protection coordination. The findings indicate that particle swarm optimization is more sensitive to inertia weight and swarm size while the number of iterations has minimal effect. The results also depict that 30&#x0025; crossover, 2&#x0025; mutation, and smaller population size yield faster convergence rate and optimise fitness function, which improves genetic algorithms performance. Sensitivity analysis results are verified by comparing the performance of particle swarm optimization with the genetic algorithms which show the former parameter setting outperforms the latter. The relay operational speed is reduced by 15&#x0025; for particle swarm optimization and system selectivity is maximised. The optimal protection coordination achieved using particle swarm optimization showed superiority of the algorithm, its ability to circumvent premature convergence, consistency, and efficiency. 

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Effects of Particle Swarm Optimization and Genetic Algorithm Control Parameters on Overcurrent Relay Selectivity and Speed

Distribution systems continue to grow and becoming more complex with increasing operational challenges such as protection miscoordination. Initially, conventional methods were favoured to solve overcurrent relay coordination problems; however, the implementation of these methods is time-consuming. Therefore, recent studies have adopted the utilisation of particle swarm optimization and genetic algorithms to solve overcurrent relay coordination problems and maximise system selectivity and operational speed. Particle swarm optimization and genetic algorithms are evolutionary algorithms that at times suffer from premature convergence due to poor selection of control parameters. Consequently, this paper presents a comprehensive sensitivity analysis to evaluate the effect of the discrete control parameters on particle swarm optimizer and genetic algorithms performance, alternatively on the behaviour of overcurrent relays. Optimization algorithms aim to minimise overcurrent relay time multiplier settings and accomplish optimal protection coordination. The findings indicate that particle swarm optimization is more sensitive to inertia weight and swarm size while the number of iterations has minimal effect. The results also depict that 30% crossover, 2% mutation, and smaller population size yield faster convergence rate and optimise fitness function, which improves genetic algorithms performance. Sensitivity analysis results are verified by comparing the performance of particle swarm optimization with the genetic algorithms which show the former parameter setting outperforms the latter. The relay operational speed is reduced by 15% for particle swarm optimization and system selectivity is maximised. The optimal protection coordination achieved using particle swarm optimization showed superiority of the algorithm, its ability to circumvent premature convergence, consistency, and efficiency.

https://ieeexplore.ieee.org/ielx7/6287639/9668973/09672123.pdf

A significant component in electrical power systems are substations, in which the substation communication network is essential. Due to the evolving nature of communication protocols, and the introduction of the IEC 61 850 standard, substation communication networks can provide fast and reliable information transmission. Such improvements in transmission allow for improved protection and control of the power system network. A well-designed substation communication network can be achieved with the use of appropriate modeling, and as a result, this paper aims the review the methods in which parts of, or the entire substation communication network can be modeled. Modeling methods aim to determine various parameters of a substation communication network design, which include the traffic load distribution, and various message delays under different network conditions that may be experienced. In order for modeling to be carried out, a general structure of a substation communication network must be defined, which is laid out by the IEC 61 850 standard. The findings of the review in this paper show that there are various methods in which a substation communication network can be modeled, which include analytical modeling, software-based modeling, hardware/experimental modeling, and time-series based modeling. However, each method enables for different parameters to be found, with some of the methods having drawbacks including a limited network model size, and inability to find certain necessary parameters. The methods reviewed in this paper can be used and expanded on to create useful and accurate models of a substation communication network.

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A Review of the Methods Used to Model Traffic Flow in a Substation Communication Network

The reliability evaluation of IEC-61850 based Substation Communication Network (SCN) is often achieved by using combinatorial methods such as Reliability Block Diagram (RBD) because it is considered to be conceptually simple and easy to apply. These methods, however, assume that all system faults can be identified and fully repaired; which is not practically achievable. As a result, the methods overstate the performance of the system during its useful life. System diagnostic coverage is one of the critical factors that necessitate consideration during the evaluation of system reliability when SCN interface with IEC-61508 based Safety Related System (SRS) in power distribution centres. In this article, the impact and significance of quality of repairs comprising repair efficiency and diagnostic coverage on the reliability of the system are investigated using Markov and symbolic dynamics based on linear dynamical systems. The originality of the research is in the utilisation of transition probability matrix and its eigenvalues to analyse the effectiveness of repair efficiency and the dynamical behaviour of the system under varying levels of repair efficiency and system diagnostic coverage. The results indicate that the magnitudes of the eigenvalues can be used to optimally select the individual factors in order to attain the desired reliability and availability of IEC-61850 based SCN, this aspect is characterised the spectral gap on the complex plane. The results also indicate that the effectiveness of the repair efficiency factors is dependent on the level of system diagnostic coverage, wherein high impact is noticeable at low system diagnostic factors.

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Impact of Imperfect Repairs and Diagnostic Coverage on the Reliability of Multi-Channel IEC-61850 Substation Communication Network

The Port of Durban (PoD) is currently upgrading its existing power supply to a supply voltage of 132 kV. The design of this electrical substation system will take into consideration the modernization of the substation system that will improve flexibility and improved efficiency. Modern power systems substation are equipped with Intelligent Electronic Devices (IEDs). The IEDs are designed to comply with IEC 61850 standard communications protocols with interoperability features for substation protection, control and coordination. Substation Automation Systems (SAS) provides facilities for monitoring and controlling all the equipment in the substation locally and remotely. The Supervisory Control And Data Acquisition (SCADA) system will be developed to provide users/operators with Human Machine Interface (HMI) or graphical representation of the electrical substation that will be used for controlling, monitoring and protection of devices in real time and this will help maximize availability, efficiency, reliability, safety and data integration.

SCADA and Substation Automation Systems for the Port of Durban Power Supply Upgrade

The Port of Durban (PoD) is currently upgrading its existing power supply to a supply voltage of 132 kV. This is due to the ageing of the existing 33 kV infrastructure and increasing aggregate demands of electrical power for new developments and upgrades to existing facilities. This infrastructure upgrade will also include the implementation of Supervisory Control and Data Acquisition (SCADA) and Substation Automation Systems (SAS) to monitor and control the electrical power systems network. This paper evaluates in detail SCADA and SAS design requirements that will be considered for this upgrade. Automated substation control and monitoring systems protect high voltage equipment from faults, disturbances and overloading on the power grid and optimizes the distribution and transmission of power from the utility to its customers.

Implementation of Substation SCADA and Automation Systems in the Port of Durban

The Port of Durban (PoD) is currently upgrading its existing power supply to a supply voltage of 132 kV. The existing 33 kV supply cables are old and have exceeded their designed life resulting in unplanned power outages. The existing 33 kV switchgear is old and obsolete as a result it is difficult to maintain. The existing maximum demand capacity will not be able to cater for the additional loads required for the planned expansion developments.The electrical load flow is a very important and fundamental tool for the analysis of any power systems and in the operations as well as planning stages. The electrical load flow study was conducted using PowaMaster software to analyse the behaviour of PoD’s electrical network post implementation of the new substation onto the currently existing network. In performing the electrical load flow study, load diversification is one of the critical input parameters that was considered because it is a true representation of the network behavior. The load forecasting was based on the planned developments commissioned between 2017 and 2027. The electrical load flow study was also to validate if all the new selected reticulation cables and transformers as part of the design have been correctly sized and will be able to operate reliably without compromising security of firm supply with the implementation of all the planned future loads. This report entails the results of the electrical load flow study that was conducted to analyse the voltage stability and system reliability of the PoD’s electrical network in conjunction with new 132/33 kV Langeberg Substation.

Siphokazi Mnukwa

Papers

SCADA and Substation Automation Systems for the Port of Durban Power Supply Upgrade

Implementation of Substation SCADA and Automation Systems in the Port of Durban

Electrical Load Flow Analysis of 132/33/11 kV Port of Durban’s Substation