Small Signal Stability Analysis Based on Multi-Band Parallel Technology in Henan Power Grid

Modern Power systems are designed for the fine tuning of frequency and less tolerance for system frequency deviation from nominal value. The Power System is dynamically subjected to the small perturbations of load leading to non-oscillatory Instability due to insufficient damping. The article entente the single area and two area load frequency control and small signal stability analysis. It dispenses the simulation of single area and two area systems with small perturbations of load, with three cases for both kinds of power systems. Case1 without any controller, case2 with PI controller and case3 with Fuzzy Controllers. The simulation is carried out for both single area and two area power systems with all three cases. In the first part of the case study, the simulation results of single area power system for all three cases have been presented. In the second part, the simulation results of two area power system for all three cases have been presented. The simulation results demonstrate the effectiveness of Fuzzy Control perpetuates the frequency with in the endurable range of frequency and subsequently it ensures the small signal stability of both the Power systems against load disturbances.

The power system small signal stability analysis considering wind generation intermittence is studied comprehensively in this paper. The modelling of doubly‐fed induction generator (DFIG) involving the converters with application of stator flux‐oriented vector control strategy is addressed briefly. In order to reveal how the intermittent nature of wind power affects the operating behaviour of an existing power system, a probabilistic small signal stability analysis method based on Monte Carlo simulation technique is proposed to explore and exploit the impact of intermittent grid‐connected wind power on small signal stability. The IEEE New England test system is applied as benchmark to verify the proposed model and approach. Total 3 scenarios are elaborately designed to figure out the potential relationship between the small signal stability indices and the wind generation intermittence. Finally, some preliminary conclusions and comments were drawn based on the numerical simulation results. Copyright © 2010 John Wiley & Sons, Ltd.

With the integration of large-scale wind farm of direct-driven permanent magnet synchronous generator (PMSG) type into power systems, the impacts on the existing power system have to be evaluated elaborately and systematically. This paper will discuss the impact of grid-connected wind farm of PMSG type on power system small signal stability. First, a simplified practical model of wind farm of PMSG type is derived for analyzing small signal stability in this paper. The rotor-flux-oriented control strategy is applied in the modelling of PMSG. Second, the simulation scenario involving replacing synchronous generator with wind farm of PMSG type based on the IEEE 3-generator-9-bus test system as benchmark is carried out to conduct the eigenvalue analysis and to assess the effect of wind farm of PMSG type on power system small signal stability. Finally, some preliminary conclusions and comments are drawn according to the simulation results.

Small signal stability analysis and control of the wind turbine with the direct-drive permanent magnet generator integrated to the grid

This paper reports a new technique for achieving optimized design for power system stabilizers. In any large scale interconnected systems, disturbances of small magnitudes are very common and low frequency oscillations pose a major problem. Hence small signal stability analysis is very important for analyzing system stability and performance. Power System Stabilizers (PSS) are used in these large interconnected systems for damping out low-frequency oscillations by providing auxiliary control signals to the generator excitation input. In this paper, collective decision optimization (CDO) algorithm, a meta-heuristic approach based on the decision making approach of human beings, has been applied for the optimal design of PSS. PSS parameters are tuned for the objective function, involving eigenvalues and damping ratios of the lightly damped electromechanical modes over a wide range of operating conditions. Also, optimal locations for PSS placement have been derived. Comparative study of the results obtained using CDO with those of grey wolf optimizer (GWO), differential Evolution (DE), Whale Optimization Algorithm (WOA) and crow search algorithm (CSA) methods, established the robustness of the algorithm in designing PSS under different operating conditions.

The increasing installation of aggregated renewable generation based Full Rated Converters (FRC) in current power systems is modifying their dynamic characteristics. This paper analyses the influence of large scale inclusion of non-synchronous generation through back-to-back Voltage Source Converters' (VSC) connection on power systems, by presenting the dynamic changes on inter-area oscillations in different penetration level cases. The aggregated model of VSC units is assumed. The Small Signal Stability Analysis (SSSA) is used to show the dynamic behaviour and presents the performance of the power systems related to the domain frequency modes in a test grid system. From the analysis, it is shown that the mode shapes and participation factors are displaced according to the penetration levels. Eigenvalue sensitivity analysis according to the inertia is also applied, showing the impact of the large penetration of non-synchronous generation.

On small signal stability of an AC/DC power system with a hybrid MTDC network

Summary form only given. Small signal stability analysis in a power system is typically concerned with electromechanical oscillations. For this purpose, it is adequate to model the transmission system using a constant admittance matrix. For torsional oscillations and HVDC interactions, the frequency of interest is much higher and the constant admittance representation is not sufficient. This paper proposes a hybrid model, which allows the parts of the transmission network in the vicinity of HVDC converters or any other dynamic devices to be modeled with their dynamics and the remaining parts to be modeled as constant admittances. The proposed hybrid methodology for small signal stability assessment is the main contribution of this paper. The proposed methodology is validated against an electromagnetic transient simulation program (PSCAD/EMTDC) using time responses. The proposed model and two other small signal models are compared against each other in the frequency domain using modal analysis.

Small signal stability analysis is very much essential to find stability conditions of a power system due to lack of damping torque when small disturbances are applied. This work is intended to find the effect of wind energy conversion system (WECS) on small signal stability conditions of conventional power system with PMSG based WECS for a SMIB system. The direct drive permanent magnet synchronous generator is considered in the analysis, and the small signal model is derived to assess the small disturbance stability. The eigenvalue analysis investigates the dynamic behaviour of power system under different modes. Therefore, by using eigenvalue analysis, the relation between the modes and the state variables are obtained. By varying the controller parameters, their influence on the eigenvalues are studied. The results show that the system stability can taband grid side converter controller parameters.

The integration of a large number of voltage source converters (VSCs) into the power grid decreases the small-signal stability of the power system. When several VSCs with different control parameters are simultaneously connected to the power grid to form a multi-converter grid-tied system, the potential destabilizing factors increase. Thus, parameter optimization for stability-weakest parameters that have the greatest impact on the system stability becomes more significant in addressing small-signal stability issues. This paper first proposes a stability evaluation function based on the Gerschgorin disc theorem, which can assess the stability of the multi-converter grid-tied system. Then a parameter sensitivity method is proposed to identify the stability-weakest parameters. Finally, an iterative calculation-based parameter optimization method is developed to regulate the identified stability-weakest parameters. Hence, the parameter optimization technique in this research can improve the system stability without requiring eigenvalue solutions and has the merit of low computational complexity. Simulation results based on both the MATLAB/Simulink (2023a) and the RT-LAB (OPAL-RT 5700) platform of a multi-converter grid-tied system validate the correctness of the theoretical analysis and the effectiveness of the parameter optimization method.

As an effective solution for managing the access of distributed generations, medium-voltage AC/DC distribution networks are emerging as prospective forms of future distribution systems under the circumstances of increasing energy crisis and environmental pollution. Compared with the transmission systems, the medium-voltage distribution network has a lower voltage level, and the two-level voltage source converter (VSC) has become the preferred topologies for the interconnected converter. This paper proposes a comprehensive small-signal model for two-level-VSC-based medium-voltage AC/DC distribution systems, considering AC and DC distribution networks, AC filters, and all the controllers in the VSCs. The complex transformation between two dq coordinate systems in current studies is avoided based on the characteristics of dq transformation and discipline of the linearization. The impact of various control parameters on the small signal stability of the AC/DC distribution system is analyzed, and the feasible region of each parameter is obtained based on the small signal model proposed. Numerical calculations by MATLAB programming and electromagnetic transient simulations on PSCAD are compared. The results indicate that the small-signal mathematical model proposed in this paper can accurately represent the dynamic process of corresponding AC/DC distribution system, and the analysis of impact of parameters on small-signal stability can also be proved.

Modelling Analysis in Power System Small Signal Stability with Grid-Connected Wind Farms of DFIG Type

Using Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) technologies, in a Multi-terminal de (MTDC) system, has been envisaged as an attractive solution for connecting the large offshore wind farms that have been planned to meet the EU renewable energy targets. The control and operation of VSC-HVDC technologies comprise a number of challenging tasks, aiming to assure an effective integration of MTDC systems in ac transmission systems. Stability studies play a key role within this framework Among them, small signal stability analysis is required. Therefore, in this paper, modal analysis is performed for assessing small signal stability, in terms of the electromechanical modes of oscillation, considering the combined AC-MTDC system. Also, this paper evaluates the interest of installing classical Power Systems Stabilizer (PSS) in the onshore VSC stations for providing additional damping to the electromechanical modes of oscillation. Simultaneous tuning is performed for adjusting the parameters of these PSS based controllers. For this purpose, an optimization based approach exploiting Evolutionary Particle Swarm Optimization (EPSO) is proposed. Modal analysis and time domain simulations are performed to evaluate the effectiveness of the proposed solutions. © 2014 Power Systems Computation Conference.

In this paper, an approximate aggregated impedance model (AAIM) of a grid-connected wind farm with multiple wind turbine generators (WTGs) for the small-signal stability study is derived. The derivation is conducted under the condition that the WTGs inside the wind farm are of the same type and from the same manufacturer. The AAIM derived can be seen as the impedance model (IM) of a grid-connected aggregated WTG. The IM of the aggregated WTG is the weighted average of the IMs of the individual WTGs in the wind farm and hence is simple to be built. The reactance of the line connecting the aggregated WTG to the external AC grid is the maximum eigenvalue of the network reactance matrix of the grid-connected wind farm. In addition, the derivation justifies the representation of a wind farm by an aggregated WTG in the IM-based small-signal stability analysis. Finally, two example grid-connected wind farms are used to evaluate and demonstrate the effectiveness of the AAIM proposed in the small-signal stability analysis. It is also shown that the computational burden of the stability analysis of a large-scale wind farm could be effectively reduced when the AAIM is used.

This chapter describes the impacts that time delays in feedback have on small signal as well as transient stability of power systems. We present a power system model comprising of delay differential-algebraic equations (DDAEs) and describe general techniques to compute the spectrum of DDAE and to integrate such equations in time domain. The focus is on delays arising in measured signals, e.g., remote frequency measurements for power system stabilizers (PSS) of synchronous machines. Several examples based on a benchmark system, the IEEE 14-bus test system, as well as a real-world system are discussed and analysed.