The smart substation, revolutionarily changing every aspect of the modern substation, is developing fast in the world and being massively deployed in China quickly. A smart substation is typically implemented with a sophisticated combination of smart primary high-voltage equipment and hierarchically networked secondary devices. Based on the IEC61850 communication protocol, the functionalities, such as the information sharing and interoperability among smart electric equipment, are realized in smart substations. It is regarded as the basis for the development of smart grid and represents the future development trend of substation technologies. This paper reviews the fundamental vision of the smart substation. The state of the art and the challenges encountered in the practice of engineering implementation are presented. Future developments to solve the present challenges and promote the development of smart substations are also described.

Smart Substation: State of the Art and Future Development

IEC 61850 based substation automation system: A survey

This paper presents the characterization of network delays in an IEC61850 process bus substation area network, both through theoretical analysis and simulations. Several design targets were defined considering the recommendations of standards and good design practices: number of network hops, total network delay, probability of the delay being exceeded, link load, network topology and availability. An analytical delay estimation methodology is proposed, considering both the steady-state traffic and traffic resulting from a breaker failure event. A complete substation is taken as an example for characterizing the network delays, considering a star network topology. Simulations allow to obtain the cumulative distribution functions and percentile values of network delays. Results show a good agreement between the simulation and the analytical analysis. While the delay is best characterized statistically through simulation, finding the maximum network delay through simulations can be very time consuming, making the analytical analysis more suitable.

Characterization of Substation Process Bus Network Delays

To ensure reliability and availability of IEC 61850 based substation automation systems (SAS), High-availability Seamless Redundancy (HSR) or Parallel Redundancy Protocol (PRP) or both are used. This paper presents the analysis and comparison of the device connection capability and data recovery time performance for HSR and PRP networks. An IEC 61850 based substation with both HSR and PRP bays is designed and modelled using the OPNET. The device connection capabilities, e.g. the maximum number of devices that can be connected to a fixed bandwidth network, under various operating conditions are evaluated and studied. A comparison study between an HSR network and PRP network has also been carried out. The results show that the device connection capability of an HSR network can be reduced by as much as half as each packet is duplicated in the HSR network. The results also show that the Ethernet bandwidth utilization is decreased as the number of devices increases. The work may help utilities to determine the number of devices that can be connected into an HSR/PRP process bus network in order to ensure the network performance.

Modeling and Performance Analysis of Data Flow for HSR and PRP under Fault Conditions

To achieve a highly reliable data communication network, Future Intelligent Transmission Network Substation (FITNESS) project has considered three different substation data communication redundancy networks. These include two independent parallel star networks, High-availability Seamless Redundancy (HSR) network, and Parallel Redundancy Protocol (PRP) network. This paper presents the assessment and comparison analysis of the data flow performance for these three networks. A typical 275 kV substation with the consideration of three redundancy networks is modelled and simulated using OPNET a communication network simulation tool. The data flow capability performance with respect of the network time delay for the typical protection and control equipment requirements (e.g. IEDs and MUs) in one bay are simulated and analysed. Results show that two independent parallel star networks have the highest data flow capacity. The capacity of PRP network is reduced by a half, while the capacity of HSR network is reduced to a quarter. The results also reveal that Ethernet Switch can consume a part of network bandwidth as well. The work would help power utilities to determine an optimal number of devices to be installed and to ensure highly reliable data communication network for protection and control functions in an IEC 61850 based digital substation.
 
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Assessment and analysis of different process bus redundancy networks performance for IEC61850-based digital substation

Substations are increasingly reliant on devices compatible with IEC61850 standards. However, the conformity of a device with the standards does not necessarily guarantee interoperability with devices from different manufacturers. The use of devices compatible with IEC61850 standards presents a challenge to many system integrators, especially due to a lack of familiarity with features, such as generic object-oriented substation event, reporting, sample values, and the need for system redundancy. To facilitate a smooth implementation, all of the features and the data exchanges between devices need to be tested to ensure the system operates correctly. It is important to determine the compatibility of the devices made by different manufacturers. This paper presents a technique to assess the performance of merging units from different manufacturers, when operating with intelligent electronic devices, performing a distance protection function. The performance of the process bus with a parallel redundancy protocol is evaluated using a closed-loop approach involving a real-time digital simulator.

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Interoperability Performance Assessment of Multivendor IEC61850 Process Bus

An IEC61850 based Standardised Substation Protection and Control (P&C) System demonstrates significant construction and operational advantages over conventional P&C normally used in transmission substations. Utilities face big challenges in updating their transmission network, such as lifecycle coordination between primary plant and secondary systems and the complex wiring associated with connecting them together. These problems can be solved by strictly adhering to the IEC61850 standards and realizing options such as interoperability and “plug & play” swapping of devices. This project set up a flexible protection and control proof of concept laboratory that represents the protection schemes used in a UK 400kV substation to assess the performance of IEC 61850 on the P&C scheme before being applied to a real transmission substation. The paper will discuss the compatibility between conventional hardwired relay and IEC61850 Intelligent Electronic Devices (IEDs), the communication between Merging Unit and IEDs through Fibre Optic Communications, the relay test set and testing software. Utilities seek to gain confidence in the system so that when it is rolled out to a real substation it will perform as expected, and the engineers involved in the roll-out are confident in the use of IEC61850 technology.

http://ieeexplore.ieee.org/iel7/6819621/6809516/06822845.pdf

Design, construction and validation of a next generation protection and control system based on IEC61850 standards

Traditional protection and control systems in many UK National Grid Substations are reaching the end of their asset design life This provides an opportunity to investigate whether new architecture that deploys Intelligent Electronic Device (IED) technology can deliver a reliable solution that is economically appropriate and delivers long life The application of IEDs that utilize the IEC61850 based process bus reduces the life-time cost of the secondary systems and improves flexibility and functionality by accommodating high-speed peer-to-peer communications The interconnectivity of devices on a single network offers significant benefits including a plug and play approach to future system changes However, it requires interoperability among multi-vendor protection relays and control devices over an operating life of many decades The realisation of this requires significant and detailed testing to help National Grid gain confidence in the use of these technologies In this paper the substation architecture and the associated Power Networks are modelled in RTDS with faults applied at different locations on the transmission lines The paper presents the results of interoperability tests involving multi-vendor Merging Unit (MU) and IED devices, which are then used to evaluate the functional performance of distance protection schemes

Performance testing of IEC 61850 based architecture for UK National Grid standardised Substation automation solutions

The growing consciousness for increased environment protection has made Electric Vehicles (EV) a more attractive and practical alternative to the internal combustion engine car. The increasing number of EVs connected to power systems for charging will have a significant impact on the operating performance of power systems. This paper proposes a methodology to determine the maximum number of EVs that can be charged by estimating the loading capacity of a transformer. The EVs are charged according to users driving requirements while respecting the constraints of the local distribution network. Analysis of transformer dynamic thermal performance is used to determine the maximum allowable load on a transformer. Results show that more EVs can be charged when using the dynamic thermal rating rather than the static thermal rating. The estimated capacity indicates the maximum number of EVs that can be charged, if the normal operation of the power system must be maintained.

Xi Chen

Papers

Interoperability Performance Assessment of Multivendor IEC61850 Process Bus

Design, construction and validation of a next generation protection and control system based on IEC61850 standards

Performance testing of IEC 61850 based architecture for UK National Grid standardised Substation automation solutions

Estimation of capacity for charging electric vehicles