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With the growing number of severe system disturbances and blackouts around the world, controlled system separation is becoming an increasingly important system integrity protection scheme (SIPS) to save the electric power system from a complete or partial disintegration. A successful controlled splitting approach should at least tackle the following two well-known and interrelated problems: "when to split?" and "where to split?". Multiple previous publications consider these problems separately, and even those pursuing a combined approach propose solutions with limited applicability. In this paper, we are proposing a novel PMU-based detector of loss of synchronism that utilizes generator rotor angles and speeds to promptly detect rotor angle instabilities over a wide area. Moreover, we are showing how our loss of synchronism detection principle can be coupled with the known controlled splitting techniques to form an integrated defense scheme against unintentional loss of synchronism. The performance of this wide-area SIPS is demonstrated on the IEEE 39-bus test power system for various types of unstable conditions., Comment: (C) 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

This paper presents a new formulation for intentional controlled islanding (ICI) of power transmission grids based on mixed-integer linear programming (MILP) DC optimal power flow (OPF) model. We highlight several deficiencies of the most well-known formulation for this problem and propose new enhancements for their improvement. In particular, we propose a new alternative optimization objective that may be more suitable for ICI than the minimization of load shedding, a new set of island connectivity constraints, and a new set of constraints for DC OPF with switching, and a new MILP heuristic to find initial feasible solutions for ICI. It is shown that the proposed improvements help to reduce the final optimality gaps as compared to the benchmark model on several test instances., https://doi.org/10.1016/j.epsr.2022.108588

The last decade has seen an immense growth in renewable energy sources such as solar photovoltaic (PV) plants due to environmental concerns. Due to this rapid growth, solar PV plants are starting to have a larger influence on power system stability and thus their dynamic behavior cannot be ignored in stability studies. The lack of well-established models and parameter sets is the primary reason solar PV plants are not modeled with dynamic characteristics. This paper presents a method to define a standard parameter set for representing large-scale and aggregated solar PV plants in stability studies from the perspective of the transmission system operator (TSO). The method takes into account primarily the conditions provided in the grid connection requirements, for illustrative purposes, the connection requirements of the Netherlands are used. Additionally, a relationship defined as short-circuit current (SCC) PV ratio is proposed to estimate the effect of solar PV plants on transient stability. To illustrate the workings of the proposed ratio, the transmission network of the TenneT TSO B.V. in the Netherlands is used. The analysis demonstrated that high values of SCC PV ratio are an indicator that solar PV plants affect the transient stability while low values of SCC PV ratio showed that solar PV plants have minimal effect on the transient stability. Additionally, methods to improve the transient stability are provided which include limiting the operation regions of critical generators, increasing short-circuit ratio by adding a synchronous condenser or static compensator (STATCOM) and decreasing the reactance between the critical synchronous generator and faulted bus.

This paper investigates the transient stability issues that may occur when long underground cables are added to EHV transmission systems. Dynamic behaviour of generators and terminal voltages with respect to various disturbances like cable disconnection/connection and fault currents are studied. Simulations are performed for the 2020 model of the Dutch transmission grid. The effects of partial undergrounding in two case studies with the total transmission length of 280 km are investigated. This work proposes criteria for accurate sizing of cable shunt compensation for dynamic simulation purposes based on grid voltages, generator reactive powers and power exchange with neighbouring grids. Moreover, a comparison between the dynamic behaviour of system variables for three different shunt compensation arrangements including line-end compensation, line-end middle compensation, and cable-end compensation is performed. Finally, a specific switching sequence for line disconnection/connection to improve voltage profiles and generator behaviours is introduced. The simulations are performed in PSS®E environment.

Energization overvoltages are among the severest overvoltages stressing insulations of EHV power system components. Since these overvoltages have a statistical nature, the insulation level should be determined with the use of a statistical approach by which the distribution of overvoltages is calculated. Literature has properly studied the distribution of energization overvoltages in purely overhead line (OHL) or cable systems, but such a study is not available for hybrid systems consisting of both OHLs and cables. It is expected that the overvoltage distributions change substantially when both OHLs and cables are used in a transmission line. This paper tackles this issue by analyzing the overvoltage distributions due to the energization of a 380 kV hybrid OHL-cable circuit, in which the cable length is variable. The study includes various sensitivity analyses to find out the impact of system parameters and topology on overvoltages. By the statistical analysis, it has been discovered that energization overvoltages of a hybrid OHL–cable circuit are higher than those of a fully-cable circuit and very likely lower than those of a fully-OHL circuit with the same transmission lengths.

Zero-missing is a phenomenon in shunt compensated cable systems in which the current through the line breaker does not cross the zero point for several cycles. This paper deals with a thorough investigation on countermeasures of the zero-missing phenomenon in transmission systems and determines the requirements, benefits, and risks of applying each method. The effectiveness of countermeasures is studied on a simulated cable project with different cable lengths in an actual grid model of the Dutch 380 kV transmission system. Results are analyzed based on three criteria related to the IEC standards and the Dutch grid code. In addition, the switching sequence of circuit-breakers is specified to maximize the effectiveness of the countermeasures. A statistical switching analysis is performed for the insulation coordination study since the application of some countermeasures increases the probability of high transient switching overvoltages. Moreover, the closing variation threshold of circuit-breakers is calculated as a function of the circuit impedance and the shunt compensation degree.

Integration of long EHV XLPE underground cables in traditionally OHL-based transmission systems can result in abnormal transients caused by large cable shunt capacitance. Transients associated with switching of long cables may result in severe temporary or transient overvoltages. This paper investigates energization transients related to the installation of long 380 kV cables in transmission systems. Voltages and currents at multiple locations were analyzed in the time-domain after energization of different cable lengths in a 80 km mixed OHL-cable connection in the future Dutch 380 kV grid. Moreover, zero-missing phenomenon, as one of the likely events during energization transients of shunt compensated cables, and its countermeasures are discussed. The study comprises time-domain simulations in PSCAD/EMTDC environment, where an accurate distributed frequency-dependent parameter model of the complete Dutch 380 kV grid is developed.

This paper deals with the shunt compensation design of long 380kV-50Hz XLPE cables by simulating a double-circuit partially cabled connection with the transmission length of 80km in the Dutch transmission system. The proposed procedure for shunt compensation sizing is fully elaborated in this paper. Four sizing criteria are used to find the minimum required size of compensation. All simulations are performed for different cable lengths. Moreover, different compensation arrangements including line-end and distributed arrangements are compared in terms of minimum required compensation size. Finally, the influence of mixed-line configuration, i.e. the number and the location of cable sections, on the minimum required compensation size is investigated by simulating five mixed-line configurations. All simulations are performed for two load-flow scenarios representing two extreme situations in the future planning of the Dutch transmission grid.

Large amounts of offshore wind power plants (WPP) connected through voltage sourced converter high-voltage DC (VSC-HVDC) technology can have significant consequences for the dynamic behavior of the related onshore AC systems. This paper explores the rotor angle stability effects of the integration of 35 GW of wind power in the North Sea, connected to the European mainland, Nordic, and UK power systems. It investigates the influence of the VSC-HVDC topology (e.g. radial versus meshed) and the DC power flow control strategy on the dynamic response of the connected power systems after common disturbances such as the outage of an offshore wind power plant and short-circuits in the AC grid. The results show a significant influence of the power flow control method applied. Radial VSC-HVDC connections for offshore WPPs can be designed such that the stability effects can be minimized, whereas meshed links may propagate disturbances from one synchronous area to another.

This paper quantifies the dynamic interaction between an onshore power system and multi-terminal voltage source converter (VSC)-based HVDC transmission systems which are used for the integration of far and large amounts of offshore wind power. Both point-to-point and multi-terminal direct current (MTDC) connection of offshore wind power plants have been investigated. A 2025-2030 scenario for the power system of the Netherlands and its neighbors has been created as a case study. Special attention is given to the transient stability of critical generators in the Dutch power system for situations with large amounts of onshore and offshore wind power production. Time-domain simulations are performed using the commercial software PSS®E, augmented with user-defined models, for a fourteen-terminal MTDC network which extends from Germany via Netherlands to Belgium. The studies highlight fault propagation in a wider neighborhood when MTDC technology is used for the connection of wind power in the North Sea.