Wind Power Penetration In System Research Articles

Hybrid model-data-driven dynamic VAR planning for wind-penetrated power system using spectral surrogate techniques

The increasing wind power penetration and proliferation of induction motor loads, of which dynamic impact cannot be revealed through steady-state analysis, bring challenges to the short-term voltage stability of modern power systems. This study proposes a hybrid model-data-driven approach for dynamic VAR source planning to enhance the short-term voltage stability of wind-penetrated power systems to reduce the computation burden of electro-mechanical transient models. Firstly, the theoretical background of Stochastic Spectral Embedding (SSE) is introduced. Then, a surrogate model for the electromechanical transient model is established using SSE following efficient expansion coefficient calculation and a designed partition strategy for the studied problem. Furthermore, a hybrid model-data-driven VAR deployment optimization model is established with 3 objectives, which is solved by a dual-population-based evolutionary algorithm (DPEA). The accuracy and effectiveness of the model are verified on a modified New England 39-bus system. Simulation results prove that the computational cost is reduced significantly in comparison with conventional model-based method without a compromise in accuracy and the proposed method is also more accurate than methods based on other surrogate models. The proposed SSE-based model can be applied to other power system analysis with electro-mechanical transient models to alleviate the computational cost.

Optimal Sizing and Siting of BESS in High Wind Penetrated Power Systems: A Strategy Considering Frequency and Voltage Control

Optimal Sizing and Siting of BESS in High Wind Penetrated Power Systems: A Strategy Considering Frequency and Voltage Control

Enhancing transient stability and dynamic response of wind-penetrated power systems through PSS and STATCOM cooperation

The large-scale integration of doubly-fed induction generator (DFIG) based wind power plants poses stability challenges for power system operation. This study investigates the transient stability and dynamic performance of a modified 3-machine, 9-bus Western System Coordinating Council (WSCC) system. The investigation was conducted by connecting the DFIG wind farm to the sixth bus via a low-impedance transmission line and installing power system stabilizers (PSSs) on all automatic voltage regulators (AVRs). A three-phase fault simulation was carried out to test the system, with and without power system stabilizers and a static synchronous compensator (STATCOM) device. Time-domain simulations demonstrate improved transient response with PSS-STATCOM control. A 50% reduction in settling time and 70% decrease in power angle undershoots at the slack bus are achieved following disturbances, even at minimum wind penetration levels. Load flow analysis shows the coordinated controllers maintain voltages within 0.5% of nominal at 60% wind penetration, while voltages at load buses can deviate up to 15% without control. Eigenvalue analysis indicates the PSS-STATCOM boosts damping ratios of critical oscillatory modes from nearly 0% to over 30% under high wind injection. Together, the present findings provide significant evidence that PSS and STATCOM cooperation enhances dynamic voltage regulation, angle stability, and damping across operating ranges, thereby maintaining secure operation in systems with high renewable integration.

Revamped Sine Cosine Algorithm Centered Optimization of System Stabilizers and Oscillation Dampers for Wind Penetrated Power System

The mapping of damping ratios and damping factors by Sine-Cosine Algorithm (SCA) is significant in the analysis of low frequency oscillations generated in an integrated network having multiple conventional and renewable energy sources. Multiple random models with unknown search spaces and uncertain conditions and constraints, which incorporate the fluctuation of solutions towards or outwards at the initial stage for solving real-time problems can be analyzed by a revamped sine-cosine algorithm (RSCA) model. In this paper, the SCA has been revamped to explore the stability threshold for a stable system under dynamic nonlinear operating conditions. It is achieved with the infusion of suitable mathematical functions for optimizing the parameters of Power System Stabilizers (PSSs) and Doubly Fed Induction Generator (DFIG) system-based oscillation dampers to enhance the Small Signal Stability of power systems through effective damping of low-frequency oscillations (LFOs). These LFOs weaken the effective power generation and demand management cycle in conventional power systems when the system faces conditions like intermittent renewable energy sources, overloading conditions, impulsive faults etc. The small-signal and transient stability studies for various disturbances and different operating conditions are investigated, and the performance of the proposed RSCA for optimized parameter tuning of system stabilizers and oscillation dampers are analyzed on the modified benchmarking systems with wind generators using MATLAB Ⓡ simulations. The efficiency and robustness of the proposed algorithm has been verified under selective critical operating conditions, line outages, and load uncertainties to prove that the low frequency modes are damped with an elevated positive damping ratio and rapid settling time with reduced oscillations. The application of system stabilizers and oscillation dampers optimized through the proposed RSCA shows a reduced settling time in the LFOs created and improved damping ratio of 0.22 for an increase in 20% loading and 50% of wind power generation in the case study of Two Area Four Machine System.

Fuzzy based virtual inertia emulation in a multi-area wind penetrated power system using adaptive predictive control based flywheel storage

The concept of virtual synchronous generator (VSG), which imitates the behaviour of a real synchronous generator, is considered as a solution for lack of inertia caused due to integration of renewable sources. Unlike most of the existing VSG techniques, which are based on the idea of infinite energy, this paper takes into consideration the energy level of energy storage. This paper proposes a fuzzy based VSG topology to adjust VSG parameters according to the magnitude of perturbation while addressing the constraints on key operational parameters of energy storage. The proposed fuzzy logic controller (FLC) provides set point to an adaptive predictive controller, which in turn provides reference power command to energy storage. Particle swarm optimization (PSO) is employed so that flywheel energy storage system (FESS) tracks any random reference signal. To facilitate VSG operation while addressing operational limits, adaptive predictive controller for FESS is implemented. The FESS speed and converter power rating constraints are directly stated in the supervisory controller development, which are mostly included in an ad hoc way. For various disturbances, the efficacy of the controller is validated in MATLAB/Simulink as well as in real-time by means of the OPAL-RT (OP4510) device. The real-time simulations validate the superior performance of the proposed VSG technique.

Adaptive predictive control of flywheel storage for transient stability enhancement of a wind penetrated power system

Flywheel energy storage system (FESS) needs to be operated within its allowable speed range because it will be shut down outside this range. Furthermore, the power supplied/absorbed by FESS is constrained by the associated power electronic interface. This article proposes supervisory adaptive predictive control (APC) scheme for flywheel energy storage system to enhance power system transient stability while addressing the constraints mentioned earlier. The supervisory adaptive predictive controller gives a reference power command signal to the inner control loop of FESS while ensuring the operation of FESS within its regime of operation. The gains of the inner control loop are optimized by employing Genetic Algorithm (GA). The constraints on the state of charge of FESS and power rating of the associated converter are explicitly included in the adaptive predictive controller formulation, which is usually done in an ad hoc manner. The performance of the proposed control strategy is evaluated under four scenarios: a step wind disturbance, realistic wind profile, doubly fed induction generator (DFIG) outage, and a severe symmetrical fault condition on modified New York/New England 16 machine 68-bus power system. The validity of the adaptive predictive control based flywheel energy storage system (APC based FESS) in improving transient stability of power system is verified by the simulation studies carried out in MATLAB/Simulink environment.

Equilibrium strategy based policy shifts towards the integration of wind power in spot electricity markets: A perspective from China

As part of China's power industry reforms, developing appropriate market designs for the inclusion of renewable energy in the electricity spot market has been an ongoing challenge. This paper examined the effects of different market rules on wind power producer behavior to identify the policy implications for a renewable-friendly spot market, for which a market equilibrium model was developed to assess power transactions in the day-ahead and balancing markets, with the upper level being wind power producers seeking the best profits, and the lower level being the market clearing process to minimize generation costs. A case study is given, in which different scenarios are explored to assess the effects of bidding regulations and imbalance pricing mechanisms and to simulate the rising wind penetration in power systems. It was found that in the region modeled: more relaxed bidding regulations could provide wind producers incentives by allowing more profitable strategies; the imbalance pricing settings influence market results and producer revenues; and lower spot prices and power generation costs occur if a larger wind share was fed into the power system and could result in a unit revenue decline. Therefore, new policy directions are needed for the development of China's renewable-friendly electricity markets.

Ultra battery application for adaptive model predictive control in wind penetrated power systems

This work pertains to utilization of small sized Ultrabattery (UB) in wind penetrated power system for LFC. Matlab level 2 S function coding is used to develop a custom made block for adaptive model predictive control for intelligent applications. Inner loop of UB is genetically tuned to mimic the first order reference system; the tuned storage system is connected with wind penetrated power system; with its voltage loop coupled to a function NACE (new area control error) for. A Staircase disturbance is introduced in wind penetrated power system. Investigation studies carried in MATLAB SIMULINK Environment reflect significant improvement in frequency response and tie power deviation of the system. The small rated UB combined with inertial response from wind farms marks for profitable operation. UB voltage and power response is also detailed and power constraints on power electronic converter are maintained within limits.

Intelligent monitoring of small sized supercapacitor in wind-penetrated power system

This work pertains to integration of supercapacitor energy storage system with wind-penetrated two-area power system. A small-sized SCES device is incorporated in automatic generation control of each area. For robust and optimum usage of SCES, a customized neuro-adaptive predictive control model is developed using level 1 S-function coding. This model feeds reference power command to the converter of storage system with its voltage used as feedback loop. A step load disturbance reflecting load outage is introduced back to back in the power system. It is seen through simulation studies carried out in MATLAB Simulink Environment that there is significant improvement in frequency response and tie power deviations. SCES converter power limits are fully maintained; besides, SCES voltage and power response is also depicted.

Multi‐objective robust tuning of STATCOM controller parameters for stability enhancement of stochastic wind‐penetrated power systems

This study proposes a robust optimisation method for controller parameter tuning of Static Synchronous Compensators (STATCOMs) to enhance the stability of a wind-penetrated power system. The uncertainties of the wind power output and the pre-contingency state of STATCOMs, which both have a significant impact on the solutions, are addressed. Firstly, a novel index is proposed to quantify the robust optimality of the solutions, which is the sensitivity of solution results to the variations of the potential uncertainties. Then, a multi-objective robust optimisation model is proposed to simultaneously optimise three objectives: (i) short-term voltage stability index, (ii) transient (rotor angle) stability index, and (iii) robustness of the solutions. Finally, an improved non-dominated sorting genetic algorithm-II is developed with (1) Latin hypercube sampling-based initial generation, and (2) adaptive mutation rate. The proposed method is tested on a modified New England 39-bus system with industry-standard models and recommended model parameters. Simulation results verify that the much higher computational efficiency and the stronger robustness of the proposed method over conventional methods.

Operating point optimization of wind turbine generators for provision of inertial response and frequency control

Inertial and frequency control approaches for wind turbine generators have proven to be effective in mitigating the frequency control and stability problems inherent to power systems and microgrids with high penetration levels of wind generation. This paper proposes an optimization formulation to determine the operating point of de-loaded wind turbines in order to improve the mechanical dynamics of the wind turbine-generator set. Such operating point optimization reduces the speed deviation magnitude and settling time of the wind turbine caused by the action of inertial and frequency control. The optimization approach is integrated into a combined inertial and frequency control approach for type-4 wind turbine generators. The optimized control approach, based on the concept of virtual synchronous generator, may extend the inertial response and frequency control capabilities of type-4 wind turbine generators, thus improving the transient and steady-state frequency performance of high wind penetrated power systems.

Assessment and Damping of Low Frequency Oscillations in Hybrid Power System Due to Random Renewable Penetrations by Optimal FACTS Controllers

This paper presents a detail investigation on low frequency oscillations of a variable solar and wind penetrated power system. An optimized UPFC controller is proposed for damping low frequency oscillations to enhance small signal stability of such a power system. The modulation index of series converter and phase angle of shunt converters are controlled simultaneously in proposed UPFC controller there by incorporating the advantage of SSSC and STATCOM. The squirrel search algorithm (SSA) is proposed for tuning controller gains. The proposed UPFC controller has been compared with SSSC and STATCOM controllers to damp oscillations. Random variation of SPV, wind energy and their integration with varying synchronous generations has been considered in this work. It has been observed that increasing solar, variable wind and their interaction with variable synchronous power generation put more detrimental effect on low frequency power system oscillations. The detail time domain simulation and system eigen values predicted that proposed controller is able to damp these oscillations much efficiently for enhancing stability of such a critical power system.

Non-Network Solution Coordinated Voltage Stability Enhancement With STATCOM and UVLS for Wind-Penetrated Power System

This paper proposes an effect orientated approach to enhance the short-term voltage stability for wind-penetrated power systems. The low system stability with high uncertain renewable energy is addressed by coordination of network and non-network solutions, i.e., STATCOM placement and UVLS respectively in this paper. The proposed model considers the uncertainties of power systems, including operating points load dynamics and multiple contingencies. Unlike other methods that try to minimize the cost, the proposed method aims to maximize the voltage stability enhancement with a fixed cost. The high computing burden is alleviated by a net flow-based scenario reduction algorithm. Compared with the conventional approaches, this paper has three major contributions: 1) Device placement is coordinated with demand response. 2) Operating points and type 4 wind turbines are considered. 3) An effect maximizing DP algorithm with a robust scenario reduction method is applied. The effectiveness and efficiency of the proposed method is demonstrated on the New England 39-bus test system.

A scenario-based planning framework for energy storage systems with the main goal of mitigating wind curtailment issue

This paper provides a new multi-objective (MO) framework for expansion studies of energy storage systems (ESSs) in high wind penetrated power system. The proposed approach well considers the issues originated from the wind power curtailment via introducing expected of wind curtailment cost as an objective function of the studies. All other imposed costs of installing storage units are modeled as expected of total social cost. Also, the effect of uncertainties is modeled through an internal scenario analysis. In this regard, two criteria including maximum regrets of wind curtailment cost and total social cost are considered as the other objectives of the proposed MO optimization procedure. These all the crucial and maybe contradictory aspects of the ESSs expansion problem are treated via a Posteriori MO optimization algorithm, i.e. the Non-dominated Sorting Genetic Algorithm II (NSGA II). The proposed methodology is implemented on the modified IEEE 24-bus test system and its anticipated applicability is well verified.

An optimal Fuzzy-logic based frequency control strategy in a high wind penetrated power system

This paper introduces a new load frequency control (LFC) model in the presence of high wind power penetration level. The main issue in a wind-penetrated power system is to maintain the system frequency in a normal operating band which is specified by the given system grid codes. Essentially, the power system equilibrium point changes following a contingency, and in this case, the high penetration of wind farms makes it harder to regain an acceptable system equilibrium points through conventional control applications. In order to overcome the aforesaid problem, a new Fuzzy-logic controller is designed optimally in this paper using the artificial bee colony (ABC) algorithm. In this approach, the ABC algorithm tunes the membership function parameters of the Fuzzy controller to acquire a good-enough performace of the proposed strategy. More importantly, the proposed Fuzzy-logic controller is blessed with robustness, simplicity, and reliability in order to ameliorate the frequency deviation. It is worth saying that the stability analysis is presented in this paper as well as the noise analysis of the proposed method. The research results indicates how effectively wind farm could participate in the system frequency control through inertial control, primary frequency control, and supplementary frequency control.

A Frequency Control Strategy Considering Large Scale Wind Power Cluster Integration Based on Distributed Model Predictive Control

With large scale wind integration and increasing wind penetration in power systems, relying solely on conventional generators for frequency control is not enough to satisfy system frequency stability requirements. It is imperative that wind power have certain capabilities to participate in frequency control by cooperating with conventional power sources. Firstly, a multi-area interconnected power system frequency response model containing wind power clusters and conventional generators is established with consideration of several nonlinear constraints. Moreover, a distributed model predictive control (DMPC) strategy considering Laguerre functions is proposed, which implements online rolling optimization by using ultra-short-term wind power forecasting data in order to realize advanced frequency control. Finally, a decomposition-coordination control algorithm considering Nash equilibrium is presented, which realizes online fast optimization of multivariable systems with constraints. Simulation results demonstrate the feasibility and effectiveness of the proposed control strategy and algorithm.

Developing a multi-objective framework for expansion planning studies of distributed energy storage systems (DESSs)

This paper presents a framework for expansion planning studies of distributed energy storage systems (DESSs) in high wind penetrated power systems. The main objective is to find optimal location and capacity of DESSs in the viewpoint of independent system operator (ISO) while ensuring the maximum usage of wind farms output generation. Three different criteria are introduced for expansion planning studies. Minimizing wind curtailment cost together with transmission congestion cost are considered to properly deal with the issues associated with the curtailment of wind energy and constraints of transmission network. Furthermore, the minimum normalized profit for all DESSs' owners needs to be maximized to model the requirements of DESSs' owners in the studies. These all the crucial aspects of the DESSs expansion problem are treated via a well-organized posteriori multi-objective (MO) optimization algorithm, i.e. the Non-dominated Sorting Genetic Algorithm II (NSGA-II). The proposed method is applied to the modified IEEE 24-bus test system, and the results are presented to verify the applicability and efficiency of the proposed DESSs planning in a renewable-based power system.

Coordinated voltage control of wind-penetrated power systems via state feedback control

This paper presents an optimal coordinated voltage control scheme for preserving long-term voltage stability of power systems. Linear quadratic integral (LQI) controller is employed to construct this scheme. Also, this paper considers the detailed dynamic model of doubly-fed induction generator (DFIG) wind turbine, synchronous generators, over excitation limiter (OEL) and under-load tap changer (ULTC) system, which are important elements influencing voltage stability of power systems. The proposed approach at each time instance involves following two major steps: First, the power system nonlinear equations are linearized and optimal controllers are obtained by LQI technique. Then, in the second step the system dynamic behavior is investigated via time-domain simulations by applying the attained optimal control signals at the first step. The impact of the proposed coordinated voltage control scheme is evaluated by time domain simulations on a well-known test system, under variable wind speed and fault conditions.

Optimal Location of Thyristor-Controlled Series Compensation and Static VAR Compensator to Enhance Steady-state Performance of Power System with Wind Penetration

Wind generation connection to power system affects steady-state and transient stability. Furthermore, this effect increases with the increase of wind penetration in generation capacity. In this article, optimal location of flexible AC transmission system devices is carried out to solve the steady-state problems of wind penetration using a genetic algorithm. Case study is carried out on modified IEEE 39-bus system with wind penetration increases by 50%; the system suffers from outage of one generator with load decrease in one of system buses by 15%. The system suffers from minimum voltage reduction, total loss increase, and violation of power and power angle limits. Series and shunt flexible AC transmission system devices are used in this article. Results showed that series flexible AC transmission system devices in certain range are able to solve these problems associated with wind penetration in power systems with acceptable cost saving.

Dynamic Reactive Power Compensation of Large-Scale Wind Integrated Power System

Due to progressive displacement of conventional power plants by wind turbines, dynamic security of large-scale wind integrated power systems is significantly compromised. In this paper we first highlight the importance of dynamic reactive power support/voltage security in large-scale wind integrated power systems with least presence of conventional power plants. Then we propose a mixed integer dynamic optimization based method for optimal dynamic reactive power allocation in large-scale wind integrated power systems. One of the important aspect of the proposed methodology is that unlike static optimal power flow based approaches, the proposed method considers detailed system dynamics and wind turbine grid code compliance while optimizing the allocation of dynamic reactive power sources. We also advocate that in large-scale wind integrated power systems, 1) better utilization of existing wind turbines especially wind farms with additional grid support functionalities like dynamic support (e.g., dynamic reactive power support, etc.) and 2) refurbishment of existing conventional central power plants to synchronous condensers could be one of the efficient, reliable and cost-effective option to address not only the issue of dynamic voltage security but also to strengthen other dynamic capabilities of the system including system inertia, etc. that are also significant challenges in large-scale wind penetrated power system. The proposed methodology is applied to the detailed model of the western Danish power system which is characterized by large-scale wind integration and least presence of central power plants.