Phasor Data Concentrator Research Articles

Interpreting and implementing IEC 61850-90-5 Routed-Sampled Value and Routed-GOOSE protocols for IEEE C37.118.2 compliant wide-area synchrophasor data transfer

Flexibility and adaptability requirements of future electric power grids for integrating distributed energy resources (DERs) call for the development of wide-area monitoring, protection and control (WAMPAC) applications, utilizing synchrophasor measurements provided by the phasor measurement units (PMUs).IEEE C37.118 is the most utilized protocol for real-time exchange of synchronized phasor measurement data. In order to fulfill some gaps not addressed in IEEE C37.118, and also to harmonize with the IEC 61850 power utility automation standard, the IEC 61850-90-5 technical report has been developed. IEC TR 61850-90-5 introduces a mechanism for transfer of digital states and time synchronized phasor measurement data over wide-area networks between PMUs, phasor data concentrators (PDCs) and WAMPAC applications in the context of IEC 61850.This work interprets the IEEE C37.118.2 and IEC 61850-90-5 Routed-Sampled Value and Routed-GOOSE protocols and describes the design and implementation of a library named Khorjin with the functionality of (1) an IEEE C37.118.2 to IEC 61850-90-5 gateway and protocol converter and (2) an IEC 61850-90-5 subscriber and traffic parser.The main contribution of this work is the development of Khorjin library using only standard C libraries (i.e. independent from any operating system). This is allowing the use of the library in different platforms.The design requirements and functionality of the Khorjin library has been tested in the KTH SmarTS Lab real-time hardware-in-the-loop (HIL) simulation environment to assess its conformance to the functional requirements of IEEE C37.118.2 and IEC 61850-90-5 standards.

Communication latency reduction in wide area measurement control and protection system

Latency in communication network is critical in wide area measurement control and protection (WAMCP) of large power networks, as it deteriorates the system performance. In this paper, the WAMCP communication network is analysed in the context of data latency for dedicated as well as shared topologies. In an attempt to increase the overall reliability of the WAMCP, new communication architecture is proposed. Also, different methods are discussed to reduce the latency values of WAMCP. In case of shared networks, two routing protocols have been compared—distance vector and link state routing protocols—for different scenarios in terms of link failures. The role of the phasor data concentrator (PDC) timeout settings in reducing the communication delay is also presented.

A Bounded Model of the Communication Delay for System Integrity Protection Schemes

This paper investigates the latency of system integrity protection schemes (SIPSs) and proposes a bounded model of the communication delay. To be specific, SIPSs can be divided into wide-area protection and substation-area protection. For the former, the data buffering of phasor data concentrators and the automatic protection switching of synchronous optical network/synchronous digital hierarchy are utilized to limit the latency of regional and backbone networks, respectively; then, the communication delay is modeled as bounded, instead of average or stochastic in the literature. For the latter, the network calculus theory is used to restrict the latency in switched Ethernet networks, and the communication delay is modeled as bounded. In practice, SIPSs need to preprogram the time delay of protective relays and expect the communication delay as predictable or predetermined. Hence, the proposed bounded model is more realistic than the average or stochastic model. Further, the bounded model suggests the network dynamics and worst-case performances. It can be a useful tool in the relay setting as well as in the planning, design, and assessment of SIPS networks.

ADMM Optimization Strategies for Wide-Area Oscillation Monitoring in Power Systems Under Asynchronous Communication Delays

In this paper, we present a suite of asynchronous distributed optimization algorithms for wide-area oscillation estimation in power systems using alternating direction method of multipliers (ADMMs). We first pose the estimation problem as a real-time, iterative, and distributed consensus problem. Thereafter, we consider a probabilistic traffic model for modeling delays in any typical wide-area communication network, and study how the delays enter the process of information exchange between distributed phasor data concentrators that are employed to execute this consensus algorithm in a coordinated fashion. Finally, we propose four different strategies by which the convergence rate and accuracy of this consensus algorithm can be made immune to the asynchrony resulting from the network traffic. We carry out extensive simulations to show possible numerical instabilities and sensitivities of the ADMM convergence on our proposed strategies. Our results exhibit a broad view of how the convergence of any distributed estimation algorithm in a generic cyber-physical system depends strongly on the uncertainties of the underlying communication models.

Synchrophasors data analytics framework for power grid control and dynamic stability monitoring

This article develops a framework for phasor analytics necessary to enable advanced wide-area control and monitoring applications. The key component in this building is the smart phasor measurement unit for control (PMU/C) which from the substation can feed accurate fundamental and low order harmonics phasors to the phasor data concentrator at a higher than the standard rate of one point per cycle. The second piece of the building is the dynamic generator state estimation, which is mandatory to enhance the observability of dynamic phenomena and thus, improves control performance and protection dependability. Following dynamic state estimation, a combined time and frequency domain processing of voltage, angle and frequency measurements based on S-transform is proposed as a good mean for extracting critical features which enable crisper information that are more easily interpretable than the raw phasor time-series. Gluing all the proposed pieces at both substation and supervisory levels, it is possible to build a smart wide-area situational awareness system, able to close the loop through educated and well informed operators for handling geomagnetic disturbance (GMD) impacts on the grid and/or through fast control and automation devices for dealing with stability issues.

Data Compression for Next Generation Phasor Data Concentrators (PDCs) in a Smart Grid

The storage space and cost for Smart Grid datasets has been growing exponentially due to its high data-rate of various sensor readings from Automated Metering Infrastructure (AMI), and Phasor Measurement Units (PMUs). The paper focuses on Phasor Data Concentrators (PDCs) that aggregate data from PMUs. PMUs measure real-time voltage, current and frequency parameters across the electrical grid. A typical PDC can process data from anywhere ten to forty PMUs. The paper exploits the need for appropriate security and data compression challenges simultaneously. As a result, an optimal compression method ER1c is investigated for efficient storage of IREG and C37.118 timestamped PDC data sets. We expect that our approach can greatly reduce the storage cost requirements of commercial available PDCs (SEL 3373, GE Multilin P30) by 80%. For example, 2 years of PDC data storage space can be easily replaced with only 10 days of storage space. In addition, our approach in combination with AES 256 encryption can protect PDC data to larger degree as per National Institute of Standards and Technology (NIST) standards.

Life Cycle Management Tools for Synchrophasor Systems: Why We Need Them and What They Should Entail

Abstract: A synchrophasor system solution generally incorporates precise timing sources, Phasor Measurement Units (PMUs), Phasor Data Concentrators (PDCs), communication network and phasor based applications. Even though all components may pass the laboratory tests, there is no guaranty that everything will work properly together after installation and deployment in the field. To preserve an acceptable level of service quality, the system components need to be tested keeping in mind different stages of the deployment. This paper discusses various aspects of a comprehensive life-cycle management model for Synchrophasor technology, ranging from the component to the overall end-to-end system level, and rigorous procedures for testing and evaluating such mission critical systems. In this effort, a unique PMU calibration lab is constructed to execute standardized PMU acceptance tests according to IEEE and IEC standards, such as the IEEE C37.118.1a among others. Field end-to-end calibrator is introduced using an accurate reference PMU called “Gold PMU” to perform field acceptance and periodic maintenance tests utilizing the nested testing concept. To illustrate the value of synchrophasor life-cycle management tools, use cases for state estimation and fault location application end-to-end tests are implemented to evaluate impact of accuracy deterioration and component failure on the performance of the synchrophasor system.

A New Approach for Optimal Placement of PMUs and Their Required Communication Infrastructure in Order to Minimize the Cost of the WAMS

In recent years, power utilities have been designing and implementing wide area measurement system (WAMS) to provide more intelligent monitoring, control, and protection for the power grid. In this paper, a new method is presented for the optimization of the cost of different parts of the WAMS. In this method, the cost of optimal placement of phasor measurement units (PMUs) and a phasor data concentrator (PDC), as well as their associated communication infrastructure (CI) are simultaneously considered and minimized. For this purpose, the binary imperialistic competition algorithm is used for the optimal placement of PMUs. Dijkstra’s single-source shortest-path algorithm is used to obtain the minimum CI cost. It is also used for optimal placement of PDC. Because of the good adaptability of the proposed methodology to understudy problem, the proposed method is implemented in different conditions of the power network such as $\boldsymbol {N-1}$ contingency condition (e.g., a single-line outage or a single-PMU outage), and some important and practical considerations are provided. Practical considerations are the availability of preinstalled PMUs in some buses and the availability of the communication links in some parts of the power network. The effectiveness of the proposed method is verified on different IEEE standard test systems.

Monitoring of Wide Area Power System Network with Phasor Data Concentrator (PDC)

This paper presents the fault detection technique in wide area power system network using Phasor Data Concentrator (PDC). Single line to ground (SLG) fault data of transmission line is processed using the WAMS technology. Phasor Data Concentrator (PDC) is primarily data collecting centres located at the control centre processing unit and is responsible for collecting all the PMUs data that is transmitted over the communication link, which will detect fault in transmission line. This will help the operators in control centre to monitor the health of wide area power system network, and can initiate corrective actions when time is the critical issue. In this paper, the voltage and current phasor information, and other transmission line parameters from 14 IEEE bus system is processed and detects the fault in transmission lines. The proposed fault detection technique in transmission line of wide area power system network is very useful for improving power system reliability and power quality.

Design phasor data concentrator as adaptive delay buffer for wide-area damping control

Phasor Data Concentrators (PDCs) are employed to aggregate data frames from multiple Phasor Measurement Units (PMUs) with the same time-stamp into data packets. This function is an essential step in the utilization of PMU data in Wide-Area Monitoring and Control (WAMC) system. This is facilitated by assigning a fixed and heuristically decided wait time to the PDC buffer. The processed PMU data packets are sent to WAMC applications or similarly PDCs at higher hierarchies in the WAMC system when either a PDC buffer is full or its wait time has passed. In this paper, two methods to configure adaptive PDC wait time based on recent PMU traffic delay patterns are proposed. The purpose is to reduce the frequency of performing delay compensations in wide-area damping control system. With the adaptive PDC delay buffer in place, the wide-area damping controller only switches its gain once every five seconds, given the studied PMU traffic delay scenarios, instead of the current practice which requires the control gain to be adapted on a per PMU data frame basis, e.g., 50 or 60 times every second. The proposed methods offer a perspective to efficiently utilize the supporting Information and Communication Technology infrastructure with the purpose to simplify the design and implementation of wide-area damping control system.

Intruder Detection and Prevention in a Smart Grid Communication System

Smart Grid is an electrical network that uses digital and other advanced technology to monitor and manage the transport of electricity from all generating sources to meet the varying demand of the end-users. The important nodes of the Smart Grid are the phasor measurement unit(PMU),Smart meter(SM) and phasor data concentrator(PDC). All PMU's within substation will form a communication network with a gate-way node called phasor data concentrator which updates data from PMU's within the cluster range. Proper management of data exchange between PMU's and PDC's are an essential thing to meet in the concept of Smart Grid. In this paper we are considering PMU as a sensor node and PDC as a central node and the data is exchanged between this nodes. Proposed intrusion detection algorithm, Packet loss avoidance using Time Division Multiple Access (TDMA) protocol and security algorithm improves system security in response to malicious attacks. Network simulator NS2 is used to create simulation scenario for detecting attacks. Hardware is tested using LPC2148 microcontrollers and Zigbee.

Robust algorithm to estimate fault synchrophasor from fault‐transient synchrophasor in phasor data concentrator

A fault-transient synchrophasor is computed over a window of pre-fault and fault samples. A fault synchrophasor is computed over a window of fault samples only. Fault-transient synchrophasors are discarded and are generally not used in the synchrophasor applications. Recently, an algorithm has been proposed to compute fault synchrophasor from fault-transient synchrophasor in phasor data concentrator (PDC). The accuracy of the existing algorithm deteriorates due to fault-induced transients and inaccurate fault starting time. A robust algorithm has been proposed to compute fault synchrophasor from fault-transient synchrophasor in PDC. The proposed algorithm does not use fault starting time in the calculations. It also performs better than the existing algorithm when fault-induced transients are present in the signal. The proposed algorithm is simple, non-iterative and performs satisfactorily in various investigated scenarios. The advantage of the proposed algorithm has been demonstrated in the context of fault location application.

Development and Application of a Real-Time Test Bed for Cyber–Physical System

Enhanced integration of information and communication technologies in the smart grid has led to an increase in the number of cyber assets and has also opened up the possibility of a cyberattack. It is necessary to understand the complex relationship between the cyber and physical domains, and its potential impact on the power grid because of a successful cyber–physical attack. A cyber–physical test bed that can model and simulate the smart grid is necessary to test and validate algorithms and devices. This paper presents the development of an end-to-end, real-time cyber–physical test bed using Real-Time Digital Simulator and Network Simulator 3 (ns-3). A methodology for integrating the hardware phasor measurement unit and the phasor data concentrator in the test bed is presented along with the detailed modeling of the communication network for the power system. The developed test bed is validated and used to demonstrate the impact of different cyberattacks on the power system and tested algorithms.

Security Implications of Transport Layer Protocols in Power Grid Synchrophasor Data Communication

Wide-area monitoring and control (WAMC) systems based on synchrophasor data streams are becoming more and more significant to the operation of the smart power grid. Reliable and secure communication, and higher quality of service (very low latency, high availability, etc.) of data are crucial to the success of WAMC systems. However, the IEEE standard for synchrophasor data communication (IEEE Standard C37.118.2-2011) does not place any restrictions on the choice of transport layer protocols. In light of this, we examine the communication between synchrophasors [phasor measurement units (PMUs)] and phasor data concentrators to analyze potential security vulnerabilities present at the transport layer, and investigate the advantages and disadvantages of both the TCP and UDP protocols, respectively, with an emphasis on security issues. Demonstrations of attacks related to these security vulnerabilities are shown in lab environment and underlying mechanisms are analyzed to determine the capabilities attackers to succeed with them.

Tool for testing of phasor measurement units: PMU performance analyser

Phasor measurement units (PMUs) are one of the key sensor technologies for real-time wide area monitoring to realise the smart power grid vision. Before deploying the PMUs, it is important to test and validate performance of this sensor to ensure high reliability and accuracy under different operating scenarios of the power system. However, PMU testing needs to be made simpler, easier, automated and cost-effective to encourage the PMU vendors and utilities to get their PMUs tested. This has been the driving motivation for the development of a new procedure and tool for testing PMUs in this study. The results and findings of PMU testing and analysis using a newly developed software application named ‘PMU Performance Analyzer' (PPA) have been discussed in this study. PPA can work with a real-time digital simulator and a phasor data concentrator to make the PMU testing simple, easy, mostly automated, less time-consuming, highly accurate and cost-effective.

A flexible platform for synchronized measurements, data aggregation and information retrieval

Synchronized measurements enable a number of applications, which shape most of the features of the smart grid paradigm. Phasor measurements units (PMUs) have an increasing role in power system state estimation, detection of inter-area and other low frequency oscillations, parameter identification, power system control and protection. Although standardization is in place for both information retrieval and data communication, there is a need to further optimize the way measurements obtained from sources with different reporting rates are exploited, by designing a platform flexible enough to simultaneously run in real time most of these PMU-based applications. In this paper such a platform is presented. It encompasses multiple PMUs from different vendors, manages detailed information about the measurement chain and its associated uncertainties and exploits a unique communication infrastructure with OpenPDC as the underlying layer for data fusion. It is based on a powerful Java EE7 application that extends OpenPDC and represents the environment for extracting, managing and processing the information. The Java EE7 application has been developed aiming for security, scalability, portability, concurrent access and big data processing. Such goals could have not been achieved without making some of the latest enterprise technologies work together. The end result can be exploited as a highly capable and interactive processing node within the grid and it also hints at important features that can be included in the upcoming IEEE C37.247 Standard for Phasor Data Concentrators for Power Systems.

A Secure Wireless Spectrum Control, Error Correction Scheme in Synchrophasors

There is an immediate need to find solution on spectrum crunch for communication framework and how to defend against cyber-attacks while sustaining energy delivery function specifically carried by Phasor Measurement Units (PMUs) and Phasor Data concentrators (PDC) [Phadke, 2008]. The paper uses the concept of exploiting antenna directivity by assigning the same frequency to all three directions, and thus co-channel isolation will be increased, and eventually reducing the interference and increasing the channel capacity. The paper also discuss the error correction control, and security challenges that are required in existing TCP/IP networks for PMU and PDC devices.

Investigation of Signal on Transmission Lines in Power System

Single of phasor measurement unit (PMU) in smart grid is analyzed. On the power transmission links, single of voltage and current are measured by kinds of PMUs, messages of PMUs are concentrated to PDC (Phasor data concentrator) and super PDC in power systems. Signal quality is important to power transmission, power utilization and power control for stability a power system. Harmonics, inter-harmonics, decaying DC (direct current) offset, and additive white Gaussian noise are analyzed. Odd-number harmonics and inter-harmonics affect the quality of power signals. Decaying DC offsert components influence current signal of power transmission line whose model is modeled by EMTP (Electromagnetic transient program) worldwide. Noise is generally a negligible factor on power transmission lines, since signal-to-noise (SNR) is always below 40 dB.

Exposing vulnerabilities in electric power grids: An experimental approach

During the past few years, coordinated and targeted cyber attacks of unprecedented levels of sophistication have been conducted against critical infrastructures. Simple experiments and probes are now turning into concerted cyber operations, carried out for profit or political reasons. Examples of critical infrastructures include airports, railway networks, hospitals, energy plants and networks and dams. Among these, electric power grids are possibly the most critical assets, since virtually all the critical infrastructures strongly depend on power distribution networks for their operation. To improve the accuracy and coherence of supervisory control and data acquisition/energy management systems (SCADA/EMSs), utility operators are increasingly integrating emerging technologies for power data collection. This paper presents the results of a thorough security analysis of two key enabling technologies used for data collection in power grids: (i) phasor measurement units (PMUs) also known as synchrophasors and (ii) phasor data concentrators (PDCs). Evidence is provided to demonstrate that these technologies are vulnerable to traditional cyber attacks (due to weaknesses such as the lack of encrypted communications channels and weak password policies), as well as to emerging cyber attacks (due to the lack of input validation and sanitization).

Simultaneous Optimal Design of Measurement and Communication Infrastructures in Hierarchical Structured WAMS

The ability of data recovery during communicational failures is one of the significant advantages of the wide area measurement system (WAMS) with hierarchical structure. For this purpose, in addition to the proper partitioning of the WAMS, the relative location of phasor measurement units (PMUs) and phasor data concentrators (PDCs) should be selected so as to maximize the reliability of the communication network. The aim of this paper is to develop an organized method for partitioning the WAMS as well as proposing a new algorithm for the simultaneous optimal placement of PMUs and PDCs. In the proposed method, first it is assumed that PMUs are installed at all of the system buses. Then, redundant PMUs will be omitted sequentially to provide the system observability with the maximum communication reliability. The IEEE 30-, and 118-bus systems are used to demonstrate the proposed algorithm. Contingencies such as PMU loss and line outage are considered in power system observability achievement. Finally, to show the applicability of proposed methods to real dimensional power systems, the IEEE 300-bus power system is also analyzed in the normal operating condition.