Wide Area Control Research Articles

Synchronous and non synchronous delay-dependent robust wide-area controllers for power system

Wide-area control is highly efficacious for maintaining sufficient damping of the low-frequency oscillations in the power system. The Wide-Area Measurement System (WAMS) provides wide-area signals to the control site through a communication channel. Even though the wide-area signal improved the dynamic behavior of the power system, a time delay usually exists during the transmission, which is unavoidable. The damping performance of the power system is degraded due to the time delay. In this paper, synchronized and non-synchronized feedback configurations are considered, and the time delay margin is calculated. The Lyapunov theory is adopted for investigating the synchronous and non-synchronous delay-dependent stability criteria for the power system. A lead–lag and a robust H∞ wide-area damping controller (WADC) are proposed to measure the delay margin for synchronized and non-synchronized delay feedback. The relationship between the damping performance and the delay margin is established. It is observed that a non-synchronous feedback-based controller can endure a larger time delay variation than a synchronous feedback-based controller. The nonlinear simulation is carried out to verify the effectiveness of the proposed controllers in Kundur’s two-area system and the IEEE-39 bus test system.

Coordination of Controllers to Development of Wide-Area Control System for Damping Low-Frequency Oscillations Incorporating Large Renewable and Communication Delay

The modern power systems incorporate high penetration of renewable is a large, composite, interconnected network with dynamic behavior. The small disturbances occurring in the system may induce low-frequency oscillations (LFOs) in the system. If the (LFOs) are not suppressed within a stipulated time, it may cause system islanding or even blackouts. Hence, it is essential to investigate the behavior of the system under various levels of disturbances and control action must be taken to damp these oscillations. The established approach to damping the LFOs is by installing power system stabilizers (PSS). PSS uses the local signals from generators to control the oscillations. The dominant source of inter-area oscillations in power systems is due to overloaded weak interconnected lines, converter-interfaced generation, and the action of the high gain exciter present in the system. Consequently, wide area control is needed to control the inter-area oscillations existent in the system. This paper developed a coordinated design of conventional PSS, static compensator, renewable converters, and wide area controller for damping the local and inter-area oscillations in renewable incorporated power systems. The performance of the developed controller is evaluated through the time domain analysis and eigenvalue analysis. A comparison of the introduced controller has been done with other standard conventional methods. The choice of input signals for the wide area controller from the wide-area measurement system is done based on the controllability index. Additionally, the location of the controller must be identified to dampen the inter-area oscillations in the system. In this paper, the controllability index is calculated to find out the highly affected wide area signals for considering it as the feedback signal to a developed controller. The location of the controller is recognized by computing the participation factor. The developed controller has experimented on renewable incorporated large study power systems when time delay and noise are present in wide area signals.

Measurement Platform for Latency Characterization of Wide Area Monitoring, Protection and Control Systems

Measurement Platform for Latency Characterization of Wide Area Monitoring, Protection and Control Systems

Wide Area Control of Inverter based Power Grids

Wide Area Control of Inverter based Power Grids

A fully distributed algorithm for dynamic economic dispatch of cross regional power systems based on alternating direction multiplier method

n this study, a novel approach to dynamic economic dispatch for multi-region power systems is introduced, leveraging the alternating direction multiplier method (ADMM) for computational efficiency. The method begins by dividing an interconnected power system into coherent groups, assigning local processors to each area to estimate black-box transfer function models using Lagrange multipliers. These processors then collaborate to form a global transfer function model through a consensus algorithm, leading to the derivation of a transfer function residue for the optimal wide-area control loop. A wide-area damping controller is designed from this residue, and its effectiveness is validated on two area and IEEE-39 bus test systems using RTDS/RSCAD and MATLAB co-simulation platforms. Simultaneously, the study proposes an economic scheduling model that aims to minimize operational costs while meeting various operational constraints. By severing inter-regional connections, the ADMM enables distributed resolution of the optimization problem, breaking it down into regional sub-problems that are iteratively solved to reach the global optimum. This process eliminates the need for a centralized data repository for multiplier updates, supporting a fully distributed scheduling approach. Additionally, a multi-period optimization technique is integrated to address the power system’s temporal dependencies. The approach's validity is demonstrated through empirical analysis of a tri-regional interconnected system based on the IEEE standard test system, confirming the strategy's effectiveness in economic dispatch.

A STUDY ON OPTIMIZING TRAFFIC SIGNAL CONTROL FOR IMPROVED TRAFFIC FLOW

Addressing traffic congestion holds paramount importance due to its severe economic and environmental repercussions. This study introduces an approach to address this pervasive issue by employing a wide-area control strategy for diverse road networks. The strategy leverages a dynamic offset control method and a multi-agent model to create a unique solution. In this framework, individual intersections function as distinct agents, engaging in negotiations, establishing connections, and forming a dynamic offset control zone resembling a tree structure. Within this structure, agents collaboratively manage green wave synchronization based on real-time traffic conditions at the network boundaries. To evaluate the effectiveness of this approach, comprehensive tests utilize both a simulated road network (Experiment 1) and an actual grid-like road network (Experiment 2). In Experiment 1, the proposed method consistently reduces lost time, resulting in an average reduction of 15% across all scenarios. Experiment 2 demonstrates a reduction in lost time across various intervals, with an impressive average reduction of 34% in lost time across all scenarios. These results demonstrate the strategy's ability to dynamically and adaptively establish green waves that significantly enhance traffic flow. In conclusion, this study demonstrates that the proposed method autonomously conducts offset control, effectively contributing to the smooth flow of vehicles.

Risk of Phase Incoherence in Wide Area Control of Synchronous Power Networks With Time-Delayed and Corrupted Measurements

Risk of Phase Incoherence in Wide Area Control of Synchronous Power Networks With Time-Delayed and Corrupted Measurements

Design of a decentralized wide-area control system to tolerate the loss of communication paths based on coherency analysis

The objective of this article is to design a wide-area control (WAC) system based on coherent groups of generators to overcome the loss of data and communication failures. In the conventional approach, the wide-area controller is designed by employing the state feedback control. It requires all the states on the controller input side and sending signals to all generators’ excitation systems on the output side. Therefore, good communication paths are necessary to get quality data every time. In addition, there should not be any data loss or false data due to phasor measurement units (PMUs) installed at every generator. However, it is not possible to get quality data without losing anything. Hence, it leads to the unstable condition of the entire power system. To address this problem, the area-wise coherency-based WAC system is proposed in this article to overcome the above-mentioned problems. The entire power system is divided into different areas based on coherency. Therefore, the centralized WAC system is divided into decentralized WAC systems based upon coherent groups of generators. This can be achieved by employing structurally constrained H2-norm optimization. Moreover, to validate the strength of the proposed controller, it is compared with different existing controllers reported in the literature by considering different case studies on IEEE-39 and IEEE-68 bus systems.

Grid communications: The wide-area control and situational awareness [Editors’ Voice

Grid communications: The wide-area control and situational awareness [Editors’ Voice

STATCOM-Based Intelligent Wide-Area Controller for Damping Interarea Oscillation

This article presents an online scheme of static synchronous compensator (STATCOM)-based wide-area damping controller for interarea oscillation based on the oscillatory signals from a wide-area measuring system. For this purpose, by evaluating the rotor angles and speed deviations between coherent groups and providing them into the center-of-inertia frame, interarea signals are provided. For estimating controlling gains, using two classification and regression techniques (CART <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and CART <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) as intelligent gain estimators, controlling gains <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are estimated. In this case, each wide-area damping controller (WADC) consists of an intelligent STATCOM with global control signals for adjusting the line susceptance. The proposed classification and regression trees (CARTs) are trained offline in which by using interarea signal (IASs) through real-time evaluations, global controlling signals (GCGs) are estimated. It is an online nonmodel-based controller that estimates the STACOM susceptance based on the interarea oscillations. The effectiveness of the proposed STATCOM-based wide-area controller (SWADC) is evaluated on the New England 39-bus test system and practical Iran nation power grid with the potential of different interarea oscillation patterns. Results present the promising effects for damping the interarea oscillations.

Cooperative control of time-delay wind power grid-connected unit under actuator saturation based on Hamiltonian method

In large-scale wind power generation, wide area control is often employed to overcome power oscillation, but this can result in the appearance of time-delayed voltage, which is transmitted to the wind power grid-connected system as an input signal. Additionally, ensuring the security of multi-grid parallel connection requires limiting the amplitude of the input signal. To address these challenges, this paper investigates the cooperative control problem for time-delayed wind power grid-connected unit under actuator saturation constraints. A novel control strategy that combines passive control with synchronous control is proposed. The system is transformed into a Hamiltonian structure, and a passive controller is designed using the principle of interconnection and damping assignment passivity-based (IDA-PB) to ensure stability. Based on this, an output feedback synchronous controller is proposed to account for saturation when multiple grids are connected in parallel. Stability criteria are provided to ensure the asymptotic stability of each closed-loop system and synchronous stabilization of all systems. Finally, simulation results verify the effectiveness of the proposed control strategy.

A Robust Stackelberg Game for Cyber-Security Investment in Networked Control Systems

We present a resource-planning game for cyber-security of networked control systems (NCSs). The NCS is assumed to be operating in closed loop using a linear state feedback <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {H}_{2}$ </tex-math></inline-formula> -controller. A zero-sum, two-player Stackelberg game (SG) is developed between an attacker and a defender for this NCS. The attacker aims to disable communication of selected nodes and thereby render the feedback gain matrix to be sparse, leading to degradation of closed-loop performance, while the defender aims to prevent this loss by investing in the protection of targeted nodes. Both the players trade their <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {H}_{2}$ </tex-math></inline-formula> -performance objectives for the costs of their actions. The standard backward induction (BI) method is modified to determine a cost-based Stackelberg equilibrium (CBSE) that saves the players’ costs without degrading the control performance. We analyze the dependence of a CBSE on the relative budgets of the players and on the node “importance” order. Moreover, a robust defense (RD) method is developed for the realistic case when the defender is not informed about the attacker’s resources. The proposed algorithms are validated using examples from wide-area control of electric power systems. It is demonstrated that reliable and RD is feasible unless the defender’s resources are severely limited relative to the attacker’s resources. We also show that the proposed methods are robust to time-varying model uncertainties and thus are suitable for long-term security investment in realistic NCSs. Finally, we use computationally efficient genetic algorithms (GAs) to compute the optimal strategies of the attacker and the defender in realistic large power systems.

Online damping control of power system with LME function of wind farm

The wide-area damping controller (WADC) is suggested by this paper in an online for power systems based on the line modal energy (LME) function of the wind farm. The presence of a wind farm always increases inter-area oscillations, but the proposed method has been made doubly-fed induction generators (DFIG) as a strong point to improve inter-area oscillations. For this purpose, an approach was presented based on energy function, a simple Brunovsky system, and an extended state observer (ESO) to control DFIG. The modal energy function supply traits in a network are evaluated in dissimilar methods, and the system overriding mode is recognized with the Tufts-Kumaresan method (TK). Finally, the wide-area control signals in the DFIG grid side converter (GSC) are selected and it is implemented with the voltage-oriented control (VOC). It is effected in diverse conditions on the standard two-area standard network to authenticate the suggested technique by MATLAB.

Review of Wide-Area Controllers for Supporting Power System Stability

Countries around the world are transitioning from conventional power systems dominated by synchronous generators towards low-carbon resources, characterized by high levels of converter-interfaced generators (CIGs). With this transformation, hundreds or even thousands of fast power electronic devices will be added to the grid as CIG penetration increases, thus making the system dynamic response progressively faster and more complex. This future scenario poses significant challenges in power system stability and control. To sustain power system stability in future power systems and achieve a seamless transition, we need to depart from current control practices based on decentralized and stand-alone local control actions and begin to explore new methods. A promising technology to overcome control complexities and underlying stability issues in future low-inertia power systems are wide area control (WAC). Within this technology, the control is no longer based on a purely localized tasks but rather a set of coordinated actions across wide areas in which interplant communication plays a key role. This paper presents the state of the art of existing research efforts in the field of WAC strategies for maintaining stability in large-scale low-inertia power systems of the future. We present different WAC solutions that have been put forward hitherto, we put these control strategies into context, classify them, and finally relate them to each other. We also raise open questions and challenges that need to be addressed in order to ensure a secure transition towards power systems dominated by CIGs.

Sensor/actuator colocation feasibility for distributed damping control using active power modulation

Multi-use distributed active power modulation devices, including energy storage, have the potential to transform the dynamic performance and resilience of modern power systems. Rapid response characteristics relative to traditional power delivery equipment paired with traditional uses (arbitrage, reserve, etc.) make storage an obvious choice for multi-use operation, adding value for asset owners while augmenting stability for reliable operation. Limitations to distributed power control are investigated to provide guidance for those interested in separated sensors and actuators. Substantive distance between the sensor/actuator pair results in non-minimum phase (NMP) which complicates the control design, reducing feedback system effectiveness. It is shown that wide-area control (WAC) is limited by the presence of NMP induced by closed right-half plane (CRHP) zeros - a consequence of sensors placed at locations separated from modulation bus(es). Such geographic separation may be driven by economics, asset owner jurisdiction, technology and/or policy, and is therefore unavoidable. This work suggests that system designers must perform a collocation study before control design and testing. A well-known WAC architecture using synchrophasors as sensors and energy storage devices for active power injection is presented as a detailed case study. • Collocated sensor–actuators pose difficulties which may force modest separation. • Closed right-half plane (CRHP) zeros may result due to such separation. • Noncollocated sensor–actuator pairs may reduce performance and threaten stability. • Bandwidth and performance limitations regarding collocation are determined.

Wide area monitoring, protection, automation, and control systems for medium voltage networks

Distribution medium voltage networks have a branched structure, many power centers, longcable and overhead lines. This complicates the process of their automation, since significant capital costs for new equipment are required. New solutions based on modern technologies can help speed up this process and make it more efficient. The authors propose the use of synchronized phasor measurement technology for automating medium voltage networks. This paper considers approaches that describe the possibilities of implementing the WAMPAC principles in such networks, provides several examples where these principles apply.

Enhancement of inter‐area oscillation damping by wide‐area controlled hydropower plants

This paper examines how the combined use of hydro governors and a wide-area damping controller (WADC) can improve the damping of inter-area oscillations in power systems. Such oscillations can endanger the stability of power grids, thus damping them is a high priority for transmission system operators (TSO). To ensure that low-frequency oscillations decay as fast as possible, a modal linear quadratic Gaussian (LQG) is proposed as a wide-area controller approach. Using the 10-machine New England Test System, the combined application of the WADC in hydropower plants via generator excitation as well as via the hydro governor is examined for their effectiveness in terms of damping capability. In order to minimize the number of essential PMUs in power systems for the model-based WADC, the residue-based input/output signal selection method is applied. To increase the robustness against large disturbance faults, the generator voltage as additional signal is utilized for the WADC. For controller performance and robustness, the verification has been done under various operating points, tie-line failures as well as different PMU delays. The successful damping of the inter-area oscillation by means of wide-area controlled hydropower plants has been also demonstrated through a nonlinear time domain simulation.

Time Synchronization for Smart Grids Applications: Requirements and Uncertainty Issues

Smart grid implementation requires that multiple distributed systems are synchronized within and between substations. This is needed to coordinate the Intelligent Electronic Devices (IEDs) as well as to align in time the measurement data associated with the same event, but collected in different points of a broad geographical area. The time synchronization accuracy requirements in power systems are application-specific and are classified in the IEC Standard 61850-5:2013. Depending on such requirements, alternative solutions can be used. For instance, sub-microsecond time synchronization is essential for the implementation of Wide Area Monitoring, Protection, and Control (WAMPAC) systems. In fact, time synchronization directly and indirectly affects Phasor Measurement Units (PMUs) accuracy. The PMUs can measure the magnitude, the phase, the fundamental frequency and the Rate of Change of Frequency (ROCOF) of ac voltage and current waveforms at times synchronized to the Universal Coordinated Time (UTC). Among such quantities, the phase data are those most strongly affected by time synchronization. If time synchronization accuracy is within ±1 µs, its impact on synchrophasor phase measurement is in the order of a fraction of mrad, i.e., low enough to have a negligible impact on the state estimation uncertainty of most of transmission and distribution systems. However, the need to interpolate the missing phasor values when data from PMUs with a different reporting rate are collected and aligned in time may unexpectedly boost synchrophasor phase estimation uncertainty.

Overview, comparison, and extension of emergency controls against voltage instability using Inverter-Based Generators

This paper provides a general overview of some previously reported schemes for the on-line detection and corrective emergency control of long-term voltage instability in a power system with a significant share of Inverter-Based Generators (IBGs) connected at the distribution level. Next, it proceeds to introduce new wide-area emergency controls to avoid an imminent voltage instability. Reactive support from IBGs is utilized as part of voltage stability emergency control, while in normal operation IBGs are operating at unity power factor. Results are shown for the IEEE Nordic Test System with increased IBG penetration, through feeders adapted from Hellenic Interconnected System wind farms. The newly proposed wide-area controls are compared with existing local emergency control schemes and are shown to have superior performance.

Self-Powered Wide Area Infrastructure Based on WiMAX for Real Time Applications of Smart Grid

This work presents a wireless communication network (WCN) infrastructure for the smart grid based on the technology of Worldwide Interoperability for Microwave Access (WiMAX) to address the main real-time applications of the smart grid such as Wide Area Monitoring and Control (WAMC), video surveillance, and distributed energy resources (DER) to provide low cost, flexibility, and expansion. Such wireless networks suffer from two significant impairments. On one hand, the data of real-time applications should deliver to the control center under robust conditions in terms of reliability and latency where the packet loss is increased with the increment of the number of industrial clients and transmission frequency rate under the limited capacity of WiMAX base station (BS). This research suggests wireless edge computing using WiMAX servers to address reliability and availability. On the other hand, BSs and servers consume affected energy from the power grid. Therefore, the suggested WCN is enhanced by green self-powered based on solar energy to compensate for the expected consumption of energy. The model of the system is built using an analytical approach and OPNET modeler. The results indicated that the suggested WCN based on green WiMAX BS and green edge computing can handle the latency and data reliability of the smart grid applications successfully and with a self-powered supply. For instance, WCN offered latency below 20 msec and received data reliability up to 99.99% in the case of the heaviest application in terms of data.