Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions

© 2021 Springer Nature Switzerland AG. This is a post-peer-review, pre-copyedit version of Benasla, M., Denaï, M., Liang, J. et al. Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions. Electr Eng (2021). The final authenticated version is available online https://doi.org/10.1007/s00202-020-01168-3Wide-area damping controllers (WADCs) are effective means of improving the damping of inter-area oscillations and thereby ensuring a secure operation of modern highly stressed interconnected power systems; however, their implementation costs are high. Therefore, the controller must be well configured and designed to ensure its cost-effectiveness. Several techniques have been proposed in the literature to design effective controllers and good results have been achieved. However, some important practical aspects that could potentially impact the performance of the designed controller have not been addressed or studied in sufficient detail in these previous works. One such aspect is assessing the performance of the designed controllers under major system upsets resulting in large deviations in the frequency and fluctuations in the power. These may lead to controller saturation which could negatively impact its damping performance or even cause instability. In this paper, the impact of such large upsets is investigated on several test systems via extensive small- and large-signal analyses and it is shown that, during severe transients, controller saturation may occur and persist over a long period of time, posing a potential threat to the power system stability. This paper presents a very effective solution to alleviate this problem and help design more robust WADCs. The simulation results show that the proposed solution works well and leads to improved power system stabilisers performance during transient upsets.Peer reviewedFinal Accepted Versio

Design and real-time implementation of data-driven adaptive wide-area damping controller for back-to-back VSC-HVDC

This paper proposes a data-driven adaptive wide-area damping controller (D-WADC) for back-to-back VSC-HVDC to suppress the low frequency oscillation in a large-scale interconnected power system. The proposed D-WADC adopts a dual-loop control structure to make full use of the active and reactive power control of VSC-HVDC to improve the damping of the power system. A data-driven algorithm named the goal representation heuristic dynamic programming is employed to design the proposed D-WADC, which means the design procedure only requires the input and output data rather than the mathematic model of the concerned power system. Thus, the D-WADC can adapt to the change of operating condition through online weight modification. Besides, the adaptive delay compensator (ADC) is added to effectively compensate the stochastic delay involved in the wide-area feedback signal. Case studies are conducted based on the simplified model of a practical power system and the 16-machine system with a back-to-back VSC-HVDC. Both the simulation and hardware-in-loop experiment results verify that the proposed D-WADC can effectively suppress the low-frequency oscillation under a wide range of operating conditions, disturbances, and stochastic communication delays

Forced oscillation detection amid communication uncertainties

This article proposes a novel technique for the detection of forced oscillation (FO) in a power system with the uncertainty in the measured signals. The impacts of communication uncertainties on measured signals are theoretically investigated based on the mathematical models developed in this article. A data recovery method is proposed and applied to reconstruct the signal under the effects of communication losses. The proposed FO detection with communication uncertainties is evaluated in the modified 14-machine Southeast Australian power system. A rigorous comparative analysis is made to validate the effectiveness of the proposed data recovery and FO detection methods

A model reference-based adaptive PSS4B stabilizer for the multi-machines power system

Two-inputs adaptive IEEE multi-bands power system stabilizer (PSS4B) was developed for oscillations damping control in power systems. Two supplementary loops based on model reference (MR) adaptive control were added to the typical PSS4B design. The MR has the same loops’ parameters of the typical PSS4B, and hence, avoiding a complex tuning process. The proposed PSS has a self-tuning gain reduction block to avoid any negative impact due to the high gains value during the disturbance time. The proposed PSS was applied on the four-machine benchmark power system. To evaluate the robustness of the proposed PSS, it was tested in comparison with the Delta W PSS, one-input multi-bands PSS4B (1iMB) and two-inputs multi-bands PSS4B (2iMB) stabilizers. The integration of the proposed PSS was demonstrating using different study cases. These cases consider the small-signal stability (SSS), large-signal stability (LSS) and the coordination test for the local and inter-area excited power modes. The proposed PSS demonstrated robust and superior responses in all cases

A Procedure to design fault-tolerant wide-area damping controllers

The idea of a smart grid is based on the increased integration of information technologies throughout the power grid. Technologies, such as phasor measurement units, are being deployed to increase the number of wide-area measurements across the bulk power system providing increased awareness of the system operational state. However, from a critical infrastructure perspective, the advanced metering infrastructure introduces a concern: the loss of communication among devices and the power grid. This communication loss may interfere with the wide-area control system performance and adversely affect the power system dynamics. This paper proposes a method based on genetic algorithms for wide-area robust damping controller design considering multiple operation points and loss of communication links related to the input and to the output of the central controller. The method is applied to enhance the damping of the electromechanical oscillations in an IEEE benchmark system: the simplified 14-generator model of the Southeastern Australian power system. The performance of the designed controller is evaluated using modal analysis and non-linear simulations in the time domain. The obtained results demonstrate the effectiveness of the method to design a single centralized controller that provides satisfactory damping to the electromechanical oscillations over several operating points, even when there is a loss of a communication link, thus being robust with respect to is an important aspect of a critical power grid infrastructure62338323405FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2015/02569-6; 2015/24245-8; 2015/18806-7; 2016/08645-

Study on Wide-Area Controller Design and Effect of Delays in Power Systems

One of the major issues in an interconnected power system is the damping of the inter-area oscillations which significantly reduces the power transfer capability. Though conventional controllers have been used such as power system stabilizer (PSS) to stabilize the local oscillations, these are not efficient to provide adequate damping to the inter-area modes. Advances in Wide-Area Measurement System (WAMS) makes it possible to use the information from geographical distant location to improve power system performances. A speed based Wide-area Damping Controller (WDC) provides supplementary control signal through the exciter of selected machine. The controller takes local and remote speed deviation signal as feedback. Here, geometrical measures for controllability and observability is performed to select the feedback signals and controller location. However, obtaining the remote signal may introduce a time-delay which may degrade the system performances or may even lead to instability. Here, depending upon feedback,two type of configurations are illustrated i.e.synchronous and non-synchronous. The effect of time-delay is studied for both the configurations.To consider the time-delay in the design stage, it is modeled with 2nd order Pade approximation. The controllers are synthesized with an objective of H∞ control with regional pole placement. Performances for both the type of feedback configurations are evaluated. To show the effectiveness of the designed controllers, two case studies have been taken up a 4 machine system and another 10 machine system. It has been found that with WDC the oscillations died out quickly. Also, study illustrated that a non-synchronous feedback performs better compare to synchronous feedback WDC

Control of frequency in future power systems

Future power systems will face a significant challenge due to the reduced stability of frequency. The reduction of inertia drives this challenge due to the increasing level of power electronics connected to renewable energy sources. In this thesis, new control techniques,such as a new secondary frequency control, a control of a population of water heaters(WHs), and a control of a population of battery energy storage systems (BESSs), are studied. A fuzzy logic-based secondary frequency controller was developed to supplement the conventional frequency control in large synchronous generators. This controller is suitable for the provision of mandatory frequency response in the Great Britain (GB) power system, where an additional 10% power output for primary response and 10% for secondary response are required within ten seconds and thirty seconds respectively. The controller was demonstrated using a simplified GB power system and a multi-machine benchmark power system. The results showed that, following a disturbance, the controller improved frequency deviation and error compared to the conventional PI controller. Thus, the controller provides a stable frequency control in future power systems. A hierarchical control of a population of WHs and BESSs was used to provide frequency response services. This was based on two decision layers. The aggregator layer receives the states of WHs/BESSs and sends a command signal to each WH/BESS control layer. The hierarchical control enables the aggregator to choose the number of controllable WHs/BESSs and set the desired amount of responses to offer different frequency response services. As a result, it reduces the uncertainty associated with the response of the population during a frequency event. The WH/BESS controller provides a response based on the last command signal from the aggregator, the value of frequency deviation (ΔF) and the level of the water temperature or BESS state of charge (SoC). The WH/BESS controller provides a response even when a failure occurs in the communication with the aggregator control layer. The WH/BESS controller handles both negative and positive ΔF. Hence, the aggregated loads participate in both low and high frequency responses. The response of the population of BESSs goes from the highest to lowest SoC when the frequency falls and from the lowest to highest SoC when it rises. The response from WHs is from highest to lowest water temperature when the frequency drops. Thus, this reduces the risk of a simultaneous power change in a large number of controllable loads at the same time, which, in turn, reduces the impact. The dynamic behaviour of a population of WHs/BESSs was modelled based on the Markov chain to allow the aggregator to offer different frequency response services. A Markov-based model was also used to evaluate the effective capacity of aggregated WHs/BESSs during the frequency event. The Markov-based model was demonstrated on a simplified GB power system and the South-East Australian power system, considering different aggregation case studies