Model Of Multi-machine Power System Research Articles

Power system harmonic analysis with real geomagnetically induced current from the 2003 halloween storm

It is well understood that geomagnetically induced currents (GICs) flow through the grounded neutrals of wye-connected transformers, generating harmonic currents that flow along frequency-dependent transmission lines. Harmonic currents affect protection systems and cause harmonic voltage drops that disturb power system voltage stability. In the literature, GICs are modelled as dc-currents for harmonic analysis. However, GICs are multi-frequency currents having both positive and negative polarities. Therefore, a representative harmonic analysis of power systems is only possible when GICs are modelled as multi-frequency AC currents. In this paper, the authors subjected a multi-machine power system model to real GICs from the 2003 halloween storm. Representative time intervals within the storm were selected, and a harmonic analysis of transmission line and generator stator currents was carried out. The results showed that the harmonic spectrum of currents fluctuated with a real GIC instead of reaching a steady state with a DC model for GIC. Moreover, harmonics induced on generator windings increase the risk of dynamic voltage and power system instability. The results confirm the susceptibility of power system generators to GICs and validate the use of synthetic GIC for modelling the effect of power system stability.

Photovoltaic System Control for Power System Frequency Support in Case of Cascading Events

In a power system with a high-share of photovoltaic systems, the frequency response can be improved by the participation of photovoltaics in frequency control. If the photovoltaic system operates at reduced power, in a so-called de-loaded mode, and maintains a specific amount of power reserve, then participation in system frequency control is usually realized by a droop control method. The implementation of this method is very simple, but it does not provide the recovery of PV power reserve before the secondary frequency control reacts. This means the PV system cannot provide additional support to the grid if a new disturbance occurs in a short time following the first one. This paper presents a novel approach for PV system control in providing support to system frequency. The novel control algorithm aims to enable rapid recovery of PV power reserve which makes the PV system capable of providing support to the cascading disturbance events. The development of such PV system control model is based on a detailed mathematical analysis of the dynamic frequency response. The effectiveness of the proposed method was tested on a two-area multi-machine power system model and through 4 different study cases.

Solar, Wind and Their Hybridization Integration for Multi-Machine Power System Oscillation Controllers Optimization: A Review

Massive growth in global electrical energy demand has necessitated a genuine exploration and integration of solar and wind energy into the electrical power mix. This incorporation goes a long way in improving the cumulative generated power capacity of the power system. However, wind and solar photovoltaic (PV) are intermittent in nature, making the provisioning of a good maximum power tracking (MPPT) scheme necessary. Furthermore, the integration is characterized by synchronization challenges and introduces various modes of power system oscillations as it is converter-driven. This greatly affects the overall stability of the integrated power mix. Consequently, various technological models have been designed to address these challenges ranging from MPPT schemes, phase-lock loop (PLL), virtual synchronous generator (VSG), power system stabilizers (PSS), flexible AC transmission system (FACTS), coordinated control and artificial intelligence (AI). In this work, a multi-machine power system model is reviewed for integration stability studies. Various technical solutions associated with the integration are also reviewed. MPPT, PLL, VSG, PSS, FACTS, coordinated control, and various optimization technique schemes used for damping controller design are discussed.

Output fluctuations minimization of wind integrated hybrid power system using electronic coordinated control of governor and blade

Using electronic coordinated control of governor and blade in the wind integrated hybrid power system, this study evaluated four proposed techniques for minimizing output fluctuations owing to high wind power penetration. Four cases were investigated for simulation analysis in this study. The power system frequency and energy generation were used as indexes to evaluate the best-proposed techniques. The control of all wind turbine blade angles was demonstrated using a constant and variable reference power generating technique. In terms of wind farm output power characteristics, grid frequency fluctuations, and wind farm energy levels, case 2 performed better than other suggested systems (cases 1, 3, and 4). Frequency deviations were kept to a minimum of ±0.2 Hz. The performance of the power system with higher wind power penetration was investigated using a numerical analysis employing a multi-machine power system model. The real wind speed data were recorded on Hokkaido Island, Japan.

Dynamically adaptive method for under frequency load shedding protection scheme reconfiguration

The increased integration of the new generation technologies into the electric power system (EPS) which are mainly inverter-based changes its characteristics. The main issue that arises is the appearance of faster frequency dynamics that are caused by production connected through inverters. This leads to the need for changing conventional under-frequency load shedding (UFLS) schemes because, in cases of high dynamics of frequency change, conventional UFLS algorithms are not able to stop initial frequency drop and prevent power system collapse. This paper proposes reconfiguration method for conventional strategies transforming their response from static and inflexible to a dynamic and adaptive one. The focus of the paper is the proposed method for dynamical change of UFLS stage thresholds to minimize the number of activated UFLS stages during a particular disturbance event and therefore enable more efficient response of the system to further disturbances. The method effectiveness was demonstrated on a multi-machine power system model consisting of various generation technologies.

Robust Design of Power System Stabilizers Using Improved Harris Hawk Optimizer for Interconnected Power System

In this present work, a new metaheuristic method called a Harris hawk optimizer (HHO) is applied to achieve the optimal design of a power system stabilizer (PSS) in a multimachine power system. Several well-known chaos maps are incorporated into the HHO to form a chaotic HHO (CHHO) with the aim of improving static operators and enhancing global searching. To assess the CHHO performance, exhaustive comparison studies are made between anticipated chaotic maps in handling unconstrained mathematical problems. At this moment, The PSS design problem over a wide permutation of loading conditions is formulated as a non-linear optimization problem. The adopted objective function defines the damping ratio of lightly damped electromechanical modes subject to a set of constraints. The best PSS parameters are generated by the proposed CHHO. The applicability of the proposed CHHO based on PSS is examined and demonstrated on a 10-generator and 39-bus multimachine power system model. The performance assessments of the CHHO results are realized by a comparative study with HHO through extensive simulations along with further eigenvalue analysis to prove its efficacy. The simulation results convincingly demonstrate the high performance of the proposed CHHO-PSS under various operating scenarios.

Adaptive Fuzzy Dynamic Surface Control for Multi-Machine Power System Based on Composite Learning Method and Disturbance Observer

A composite learning dynamic surface control is proposed for a class of multi-machine power systems with uncertainties and external disturbances by using fuzzy logic systems (FLSs) and disturbance observer (DOB). The main characteristics of the proposed strategy are as follows: (1) The approximation ability of FLSs for nonlinear model of multi-machine power systems is enhanced considerably by using the composite learning method and providing additional correction information for the FLSs. These findings differ considerably from previous designs that focus directly on the system's tracking performance. (2) The filtering errors caused by the utilizations of the first-order low-pass filters in dynamic surface control (DSC) are compensated effectively by designing the compensating signals in the control law design process. (3) The compound disturbances including the FLSs' approximation error and external disturbances are estimated and mitigated by constructing DOB. Finally, the proposed control algorithm is verified on the StarSim Hardware-in-loop experimental platform, and the experimental results validate the effectiveness of the proposed control strategy in suppressing disturbances and enhancing the robustness of the controller.

Modified vector controlled DFIG wind energy system based on barrier function adaptive sliding mode control

Increased penetration of wind energy systems has serious concerns on power system stability. In spite of several advantages, doubly fed induction generator (DFIG) based wind energy systems are very sensitive to grid disturbances. DFIG system with conventional vector control is not robust to disturbances as it is based on PI controllers. The objective of this paper is to design a new vector control that is robust to external disturbances. To achieve this, inner current loop of the conventional vector control is replaced with sliding mode control. In order to avoid chattering effect and achieve finite time convergence, the control gains are selected based on positive semi-definite barrier function. The proposed barrier function adaptive sliding mode (BFASMC) is evaluated by testing it on a benchmark multi-machine power system model under various operating conditions. The simulated results show that the proposed method is robust to various disturbances.

Dynamic stability enhancement of TCSC‐based tidal power generation using quasi‐oppositional harmony search algorithm

This study presents the dynamic and steady state stability improvement of a tidal power generation system (TPGS) assisted power system model (i.e. single machine infinite bus (SMIB) system) using a thyristor controlled series capacitor (TCSC). To achieve this objective, the TCSC used in the studied model is optimally designed using quasi-oppositional harmony search algorithm (QOHSA). The complete dynamic equation of the studied power system is realised based on d–q-axis decomposition. Eigenvalue analysis is performed using the frequency-domain approach to study the steady-state stability while the time-domain-based simulation is carried out to determine the dynamic stability of the studied system. To corroborate the effectiveness of QOHSA, results yielded by this algorithm are compared with those obtained using particle swarm optimisation technique. It may be inferred from the results obtained in this study that the QOHSA tuned TCSC outperforms the other in improving the overall stability of the TPGS-based SMIB system following disturbance. Furthermore, a similar analysis is extended to the TPGS-based multi-machine power system model to validate the efficiency of QOHSA in optimal designing of TCSC for dynamic stability improvement.

Anfis Coordination of Changes In Power Oscillation Damper Parameters with Variation In Power System Operating Point

Abstract In this paper an Adaptive Neuro-Fuzzy Controller was designed to adaptively adjust the parameters of a power Oscillation Damper as the power system operating point changes due to change in operating point in a large interconnected Network fitted with FACTS device and Power Oscillation Damper. As a foundational work the generalized mathematic model of multi-machine power system with embedded FACTS was developes. The results obtained clearly reveals the effectiveness of this approach.

Frequency Control of Power System with Solar and Wind Power Stations by Using Frequency Band Control and Deadband Control of HVDC Interconnection Line

In recent years, environmental problems are becoming serious and renewable energy has attracted attention as their solutions. However, the electricity generation using the renewable energy has a demerit that the output becomes unstable because of intermittent characteristics, such as variations of wind speed or solar radiation intensity. Frequency fluctuations due to the installation of large scale wind farm (WF) and photovoltaics (PV) into the power system is a major concern. In order to solve the problem, this paper proposes two control methods using High Voltage Direct Current (HVDC) interconnection line to suppress the frequency fluctuations due to large scale of WF and PV. Comparative analysis between these two control methods is presented in this paper. One proposed method is a frequency control using a notch filter, and the other is using a deadband. Validity of the proposed methods is verified through simulation analyses, which is performed on a multi-machine power system model.

Robust Partial Feedback Linearizing Excitation Controller Design for Multimachine Power Systems

This paper presents a new robust nonlinear excitation controller design for synchronous generators in multimachine power systems to enhance the transient stability. The mismatches between the original power system model and formulated mathematical model are considered as uncertainties, which are modeled through the satisfaction of matching conditions. The exogenous noises appearing from measurements are incorporated with the power system model including the two-axis model of synchronous generators. The partial feedback linearization technique is used to design the controller which transforms the original nonlinear multimachine power system model into several reduced-order linear and autonomous subsystems. The desired control law is obtained for each subsystem and implemented in a decentralized manner provided that the dynamics of the autonomous subsystems have no effects on the overall stability of the system. The analysis related to the dynamics of noisy autonomous subsystems is also included and the proposed controller has the excellent capability to decouple these noises. Finally, the performance of the proposed control scheme is evaluated on an IEEE 39-bus benchmark power system following different types of large disturbances. The performance of the proposed controller is compared to that of a partial feedback linearizing controller, which is designed without robustness properties, to verify the effectiveness of the proposed control scheme.

A real-time nonlinear decentralized control of multimachine power systems

This paper proposes the application of a new nonlinear decentralized control to the multi-input multi-output model of multimachine power systems. The goal is to control the terminal voltage as well as the rotor angle to obtain high-performance transient stability and good post-fault voltage regulation. The proposed stabilizing feedback laws for the power system are shown to be globally asymptotically stable in the context of Lyapunov theory. The effectiveness of the proposed control action is demonstrated through some computer simulations on a two-area benchmark power system under a large sudden fault and a wide range of operating conditions. The results are compared with those of the traditional automatic voltage regulator (IEEE type I AVR) plus the power system stabilizer control structure and speed governor.

Optimal Feedback Excitation Decentralized Coordinated Control Model of Multi-Machine Power System

A new model based on optimal feedback gain has been proposed for the power system decentralized control. In this model, the block gain coefficient has been optimized to achieve excitation decentralized coordinated control of the multi-machine power system. The simulation of the Henan Yudong grid verified the effectiveness of the control strategy.

A Robust H-Infinity Controller Based STATCOM for Damping Power System Oscillations

The main objective of this paper is to present the performance of the H-infinity controller application to the multi-input multi-output (MIMO) nonlinear model of a static synchronous compensator (STATCOM). In large scale power system, quick damping of system oscillations are necessary as it may lead to complete breakdown of the system. A detailed mathematical model of single machine and multi-machine power system with STATCOM is carried out and the H-infinity control technique is applied to damp quickly these oscillations under various faulted operating conditions. The simulation results show the effectiveness and robustness of the proposed control schemes compared to conventional PI controller tuned by Genetic Algorithm (GA)

Reduction of frequency fluctuation for wind farm connected power systems by an adaptive artificial neural network controlled energy capacitor system

Frequency fluctuations are a major concern for transmission system operators and power grid companies from the beginning of power system operation due to their adverse effects on modern computer-controlled industrial systems. Because of the huge integration of wind power into the power grid, frequency fluctuations are becoming a serious problem, where randomly varying wind power causes the grid frequency fluctuations of the power system. Therefore, in this paper, the minimisation of the frequency fluctuation of a power system, including a wind farm, is proposed using an energy capacitor system (ECS). A scaled-down, multi-machine power system model from Hokkaido prefecture, Japan, is considered for the analysis. A novel adaptive artificial neural network (ANN) controller is considered for controlling the DC-bus connected ECS. The control objective is to standardise the line power of the wind farm, taking into consideration the frequency deviation. The effects of wind power penetration levels, as well as load variations, are also analysed. The proposed control method is verified by simulation analysis, which is performed with PSCAD/EMTDC using real wind speed data. The adaptive ANN-controlled ECS was found to be an effective means of diminishing the frequency fluctuation of multi-machine power systems with connected wind farms.

Dynamic Modeling and Damping Function of GUPFC in Multi-Machine Power System

This paper presents a new dynamic model of multi-machine power system equipped with GUPFC for power system study, and using PSS and GUPFC POD controller some effective control schemes are proposed to improve power system stability. Based on UPFC configuration, an additional series boosting transformer is considered to define a GUPFC configuration and its mathematical model; Phillips-Heffron scheme is used to formulate machine model, and modification of network dealing with GUPFC parameter is carried out to develop a MIMO as well as comprehensive power system with GUPFC model. Genetics Algorithm method was proposed to lead-lag compensation design, this technique provides the parameter controller. The controller produced supplementary signals, the PSS for machine and POD for GUPFC. By applying a small disturbance, the dynamic stability power system was investigated. Simulation results show that the proposed power system with GUPFC model is valid and suitable for stability analysis. The installation of GUPFC without POD decreased the damping oscillation. But, the results show that the presence of GUPFC in power system network provided by PSS and POD controller is very potential to improve system stability. A 66% overshoot reduction could be reached, it is obtained 12 s in settling time (shorter), although the rise time become 700 ms longer. Simulation results revealed that the role of POD controller is more dominant than the PSS, however both PSS and GUPFC POD controller simultaneously present a positive interaction. Phase angle of converter C, δC is the most significant control signal POD in oscillation damping.

Decentralized nonlinear H ∞ controller for large scale power systems

The aim of this paper is to design nonlinear decentralized controllers for multi-machine power systems. The design procedure is based on H ∞ control theory and consists of two parts. First, the feedback linearization technique is used. Then, a robust controller is designed using the linear matrix inequalities (LMI) approach. The controller has two blocks. One, is a nonlinear function of some local measurable signals such as the generator active and reactive powers, the rotor speed and the armature current. The other block is a PID controller. The linear H ∞ theory is used to tune the PID parameters. The method results in a controller which is easy for implementing in practice. The performance of the controller is tested on a sample multi-machine power system model. Simulation results show the effectiveness, robustness and good performance of the proposed controller.

A Novel System-Centric Intelligent Adaptive Control Architecture for Damping Interarea Mode Oscillations in Power System

In this paper, theoretical formulation and implementation results of an intelligent approach to develop a power system stabilizer are proposed. In this approach, a novel methodology that designs a hybrid controller with two algorithms, namely, a neural-network (NN)-based controller with explicit neuroidentifier and an adaptive controller that evolved from a model reference adaptive controller, is designed. This design performs as a novel system-centric controller (where the controller adapts based on system changes). The NN is trained offline with extensive data and is also adjusted online. The main advantage and uniqueness of the proposed scheme is the controllers' ability to complement each other in the case of parametric and functional uncertainties. Moreover, the online NN identifier, models and predicts the plant states/output in the event of functional change during abnormal operating conditions. The theoretical results are validated by conducting simulation studies on a fully nonlinear multimachine power system model consisting of five two-area equivalent generators and eight equivalent buses with varying generator schedules. The results confirm the theory, indicating that the proposed architecture damps interarea low-frequency oscillations faster than other conventional controllers, thus increasing generator stability margin as well as power transfer capability.

Robust decentralised output feedback sliding mode control technique-based power system stabiliser (PSS) for multimachine power system

In this paper, we propose a power system stabiliser (PSS) design scheme based on robust decentralised output feedback sliding mode control technique. We demonstrate the proposed technique on a 10-machine, 39-bus power system and compare it with classical PSS design. Although the proposed technique is based on linearised model of the nonlinear multimachine power system, the efficacy of the controller has been demonstrated by the simulation using nonlinear model.