Real-time Transient Stability Analysis Research Articles

Virtual testbed for development and evaluation of power system digital twins and their applications

Digital twins (DTs) show considerable promise for development of applications and solutions across a diverse range of power system services. Ensuring these applications function as intended without causing disruptions or unexpected issues requires comprehensive testing prior to practical deployment. However, current approaches to power system digital twin (PSDT) application development and testing experience significant obstacles, including limitations and risks associated with accessing real-world power systems, models and data. This article introduces a virtual testbed based on the concept of a virtual physical twin (VPT), that replaces the need for access to a physical twin (PT), as a platform designed to remove the heavy reliance on online data flows and provide a close to real-world environment. A testbed enables simultaneous development and testing of DTs and their related applications in a realistic, interactive, and safe setting without impact on the operation of the actual power system. A complete workflow for PSDT testbed implementations is proposed, with all necessary steps from concept to the eventual connection to the physical system. To validate the practical implementation steps, utility, and value of the testbed, a real-time transient stability analysis with two artificial intelligence algorithms is provided. The proposed testbed is expandable and adaptable, promoting the development of advanced and intelligent PSDTs. The key benefit of the testbed is that it enables the development of DT and its application closely in a realistic environment without affecting the operation of PT.

Novel pair‐wise relative energy function for transient stability analysis and real‐time emergency control

In recent years, situation awareness and risk mitigation have become the challenging issues in large-scale power grids. This study presents a novel pair-wise relative energy function for real-time transient stability analysis and emergency control. The proposed energy function is able to accurately identify the clusters of critical and non-critical generators significantly faster when compared with previous methods. Additionally, a new emergency control criterion is proposed in order to stabilise the identified critical generators within a comparatively short interval after fault clearance. The emergency control scheme computes the capacity of the requisite generation curtailment using the pre-calculated relative energy of the equivalent post-fault system. Finally, the relative energy oscillation trajectories that occur in the critical cluster are utilised in order to locate the most appropriate generator to launch the emergency control. When compared with the existing methods, it is evident that the novel approach can be applied practically for power systems transient stability analysis and emergency control. The effectiveness of the proposed method is demonstrated and evaluated using the New England 10 machines 39-bus and 16 machines 68-bus systems.

A Visualization Tool for Real-Time Dynamic Contingency Screening and Remedial Actions

This paper proposes a real-time visual interactive transient stability screening and remedial action tool that uses an approach based on Lyapunov functions to enable the selection of appropriate remedial actions that stabilize power systems due to large disturbances and cascading failures. At present, there is no effective tool that enables making a well-informed choice from amongst a profusion of remedial action alternatives. Conventionally, transient stability analysis of power system is performed offline to assess the capability of the power system to withstand specific disturbances and to investigate the dynamic response of the power system as the network is restored to normal operation. In this paper, postfault stable and controlling unstable equilibrium points are determined using a homotopy-based approach. Subsequently, stability assessment of the system and the corresponding potential remedial actions are determined from the equilibrium points of the system dynamical model. The real-time transient stability analysis and remedial action algorithm are incorporated with the visualization tool to facilitate interactive decision making in real time. The transient stability analysis and remedial action algorithm, and the visualization tool are demonstrated on several test systems including the equivalent Western Electricity Coordinating Council system and the simplified New England 39 bus test system.

A tracking time domain simulator for real-time transient stability analysis

Real-time transient stability analysis requires analysis of hundreds of contingencies in tens of minutes using on-line data from the state estimation. The final objective is to present timely information about transfer limits and stability margins and eventually implement corrective actions. In this paper, we assume that the dynamic contingency analysis (DCA) has to be repeated every 15 minutes. During this period of time the loading and configuration conditions of the system change significantly but not drastically. We verify that the set of the relevant contingencies remains almost the same in the time interval comprised between two cycles of the functions associated to DSA. Parallel-in-time formulated algorithms can be used in tracking the load conditions in real time adopting as initial guess for the simulation of each contingency, the trajectories obtained for the same contingency at the previous cycle of DSA functions (that is the ones calculated in the previous 15 minutes). In this way, the information obtained In a previous cycle of DCA is not lost completely as in step-by step algorithms. The feasibility of the approach has been tested on the Italian 380-220 kV transmission system operated by ENEL SPA. A parallel implementation of the approach on an nCUBE multiprocessor is reported.

A distributed computing approach for real-time transient stability analysis

Power system online dynamic security assessment (DSA) is a challenging computing problem. A key problem in DSA is the analysis of a large number of dynamic stability contingencies every 10-20 minutes using online data. In order to speed up the transient stability analysis, parallel processing has been applied and several results can be found in the literature. In this paper, the authors present a distributed approach for real-time transient stability analysis. Distributed computing is economically attractive providing the processing power of supercomputing at a lower cost. Several distributed software environments like the parallel virtual machine (PVM) allow an effective use of heterogeneous clusters of workstations. Both functional and domain decomposition of the transient stability problem were tested under PVM on a homogeneous cluster of eight DEC ALPHA and on an IBM SP2 machine. Functional decomposition has been obtained by the Shifted-Picard algorithm, whereas domain decomposition has been obtained concurrently running different contingencies on different nodes of the cluster, using the very dishonest Newton algorithm. In order to assess the performance of these approaches, time domain simulations, adopting detailed modeling for synchronous machines, have been carried out on a realistic-sized power network comprising 2583 buses and 511 generators.

Feasibility study of transient stability analysis for operator training simulators

The existing operator training simulators (OTSs) simulate the slow dynamics of power systems in real time but this limits the capability of simulating accurate dynamic behaviour after a disturbance. A feasibility study for the modelling of real time transient stability behaviour in the OTS is described. The goal was to analyse not only the CPU timing for the OTS simulation cycle with real time transient stability analysis but to also investigate the resulting improvements in the quality of the OTS. The results confirm that the transient stability can be simulated in real time for systems of realistic size on readily available workstations. More importantly, the results show significant differences in the dynamic behaviour when transient stability is simulated, strongly suggesting that the present OTSs do not provide enough accuracy for training under certain conditions.

Operator Training Simulator with real-time transient stability analysis

The operator training simulator (OTS) system, which is integrated with a real-time transient stability analysts program, has been in operation at the training center of Hokuriku Electric Power Company since July, 1990. The developed OTS system achieves real-time transient stability analysis with approximately 100 generator and 400 node power systems by parallel processing performed on a computer system with multiprocessor architecture. This paper outlines the developed OTS system and describes the requirements, design concepts, modeling and parallel calculation method of transient stability analysis and the verification result of the developed transient stability analysis program. >