Nonlinear optimal STATCOM controller based on game theory to improve transient stability

The present article demonstrates the design of a nonlinear optimal FACTS controller based on Hamiltonian function method. Static Synchronous Compensator (STATCOM), a most popular FACTS device has been selected for this purpose. A suitable Hamiltonian function has been formulated to optimize the desired cost functional. The act of the executed controller is correlated with a customary linear model STATCOM controller based upon investigation of the transient stability of a SMIB power system. The designable parameters of the traditional controller are estimated by a stochastic optimization method, Particle Swarm optimization (PSO). The study of investigated results reveals that the proposed optimal nonlinear controller is substantially good and works better than the customary model traditional STATCOM controller even during contingencies like earth fault incidents.

This paper presents a novel nonlinear control scheme for designing static synchronous compensators (STATCOM). A passivity-based approach is proposed for designing robust nonlinear STATCOM controller. The mathematical model of STATCOM will be represented by a Euler-Lagrange (EL) system corresponding to a set of EL parameters. By employing the Park's transformation, the differential geometry approach is used to investigate the power system dynamics with considering STATCOM under the synchronous d-q frame. The STATCOM controller based on passivity is obtained with a feedback control law from linear system models. Digital computer simulation for a large operation point variations have been studied the STATCOM controller design. Simulation results show that the proposed STATCOM controller can effectively enhance transient stability of the power system even in the presence of large operation point variations

This paper aims to design a nonlinear control scheme for a Static Var Compensator (SVC) in order to improve dynamic stability in a Single Machine Infinite Bus (SMIB) power system. The nonlinear model of the SMIB system is exactly linearized applying feedback linearization method, and the optimal control law is estimated by the Linear Quadratic Regulator (LQR) principle. The performance of the proposed nonlinear controller is compared with the performance of a conventional controller whose parameters are optimized through Genetic Algorithm (GA). The results and effectiveness of the proposed control schemes are presented employing time domain simulation and analysis. It has been observed that, in comparison with the conventional controller, significant improvements in dynamic stability of the test power system are achieved by the proposed nonlinear control strategy.

Comparative analysis of controllers for stability enhancement for wind energy system with STATCOM in the grid connected environment

A Static Synchronous Compensator (STATCOM) is one of the Flexible AC Transmission System (FACTS) device which plays an vital role in power system network in alleviation of small and large transient disturbances and better voltage regulation. This paper proposed a self tuning Proportional-Integral (PI) controller for STATCOM which provided a voltage support at point of common coupling (PCC). Self tuning of PI controller was achieved by adapting PI controller gains with system parameters by using Bats Echolocation controller which mimics the Bats Echolocation behavior. In the proposed controller, the system voltage (parameter) at point of common coupling compared with reference voltage and then Bats Echolocation Controller updates the PI controller gains according to the variation obtained between them. This paper also proposed a Cascaded Multilevel Inverter (CMLI) instead of conventional Voltage Source Inverter (VSI) for STATCOM to obtain better voltage regulation at point of common coupling. The voltage imbalance between H-bridge cells in CMLI was rectified by prosing Multicarrier Pulse Width Modulation (PWM) techniques, The proposed controller was validated by comparing the simulation results with fixed gain PI controller and Self tuning PI controller using Neural controller and Particle Swarm Optimization.

The static synchronous compensator (STATCOM) is one of the flexible AC transmission system (FACTS) devices. The STATCOM and wide area measurement system (WAMS) are used in power systems. This paper describes the coordinated design of the wide area controllers and STATCOM controllers using a bacterial foraging algorithm (BFA). BFA is a new type of global optimization algorithm. The parameters of the controllers are optimized simultaneously by using the BFA to minimize the fitness function. The fitness function is the performance of the integral of the time-weighted squared error (ITSE). The fitness function is calculated by solving the differential equations. A 10-machine 39-bus new England system is a complex power system and is used to test the method of the coordinated design. The results show that the coordinated design of these controllers can improve the damping of the interconnected power system.

This paper deals with the simultaneous tuning of proportional integral controller of static synchronous compensator (STATCOM) associated with lead-lag controller (LL) in order to improve the stability performance of combined wind farm (CWF). This type of farms has been developed to summarize the main benefits of Squirrel-Cage Induction Generator (SCIG) and doubly fed induction generators (DFIG). The performance of CWF with the tuned STATCOM is studied during line-to-line and three-phase faults. Multi-objective Lightning Attachment Procedure Optimization Algorithm (LAPO) is used as an intelligent optimization technique to determine the control parameters which can achieve the specified objective functions; minimizing the error signal and maximizing the output signal. The multi-objective LAPO is used to obtain the optimized values of AC voltage regulator, DC voltage regulator, current regulator, gains and time constant of LL. The ability of STATCOM tuned by multi-objective LAPO is examined by studying the performance of three wind farms. The first one is CWF and two other wind farms; one of them is based only on SCIG (SCIG-WF) and the other based only on DFIG (DFIG-WF) when they associated with the tuned STATCOM LAPO during grid fault. The results show that CWF associated with the tuned STATCOM LAPO has the best performance during grid faults compared with the other wind farms.

This paper aims to develop a coordinated controller to enhance the low voltage ride through (LVRT) performance of a permanent magnet synchronous generator (PMSG) based variable speed wind energy conversion system (WECS). This coordinated control comprises of a pitch angle control, a flux weakening control and a static synchronous compensator (STATCOM) control. The pitch angle control is adjusted to smooth the WECS output power fluctuations or to enhance the LVRT performance. The flux weakening controller is used to reduce the overvoltage of DC-link capacitor, and the STATCOM control is used to ensure continuous operation of WECS during symmetrical and asymmetrical grid faults. The proposed coordinated control method is compared with the conventional LVRT strategy based on the braking chopper (BC) via time series simulation results and effectiveness of the proposed control is verified.

A static synchronous series compensator (SSSC) has the ability to emulate a reactance in series with the connected transmission line. A static synchronous compensator (STATCOM) is able to provide the reactive power to an electricity network. When fed with some supplementary signals from the connected power system, both SSSC and STATCOM are able to participate in the power system inter-area oscillation damping by changing the compensated reactance or the provided reactive power. This paper analyses the influence of SSSC and STATCOM on power system small signal stability. The damping controller schemes for SSSC and STATCOM are presented and discussed. The IEEE 39-bus New England system model as the test system is built in DIgSIELNT PowerFactory, in which the damping control strategies for both SSSC and STATCOM are validated by time domain simulations and modal analysis. Furthermore, comparison studies show that the SSSC is a better solution in term of equipment capabilities and costs.

Adaptive control universality of STATCOM for efficient wind energy conversion systems

This paper presents the transient stability analysis of a robust nonlinear co-ordinated generator excitation by thyri-stor controlled series capacitor (TCSC) controller and a control strategy of a static synchronous compensator (STATCOM) is proposed to improve of power system. This study analyses the stability of aperiodically sampled-data control systems with and without communication delays by application using a new augmented Lyapunov functional method, which compared with most of existing methods that commonly require each term of a Lyapunov Krasovskii functional(LKF) to be non-negative, the proposed method waives this requirement by introducing an augmented term. A nonlinear feedback law for the generator is found, which linearises and decouples the power system model. Robust nonlinear control theory is then employed to design the nonlinear co-ordinated controller that consists of two controllers is the generator excitation and the TCSC controllers. The proposed control strategy of the STATCOM was then tested on a single machine infinite busbar system. Simulation results show that the proposed controller can ensure transient stability of the power system in a critical fault clearing time, which may occur at the generator busbar terminal. These criteria are extended to investigate the stability of the systems with polytopic uncertainties and the exponential stability of the system.

Flexible AC Transmission Systems (FACTS) devices have been used in power systems since the 1970s for the improvement of its dynamic performance. Among these devices, Static Synchronous Compensator (STATCOM) is a shunt connected FACTS device, which is capable of providing reactive power compensation to the power system. STATCOM is a multiple input and multiple output system. In this paper, the CSC based STATCOM is controlled by the pole placement. But the best constant values for pole placement controller's parameters are laboriously obtained through trial and error, although time consuming. So the genetic algorithm (GA) is employed to find the best values for pole placement controller's parameters in a very short time. These methods are tested in MATLAB, and their results are obtained. The simulation results show an improvement in input-output response of CSC-STATCOM.

The Flexible AC Transmission Systems (FACTS) control strategies inherits prime importance in power quality improvement with using endless numbers of devices to gain reactive power compensation and maintaining power factor. STATCOM plays a vital role and is highly acceptable and widely used in transmission and distribution networks as a dynamic shunt compensator due to its ultramodern characteristics. It serves several applications in power system, like, reactive power compensation, harmonics reduction, power factor improvement etc. and adds reliability of the system. The wide enhancement in STATCOM controller involves various solid-state converter terminologies, controlling algorithms, self-commuting operations, magnetic configurations etc. has been stated in many research works. This paper deals with a review on state-of-art STATCOM controlling device with meaningful applications in the power system.

This article proposes a model reference adaptive control (MRAC) of static synchronous compensator (STATCOM) for enhancing the integration of driven wind turbine‐based self‐excited induction generator (SEIG) into electrical grids. An MRAC‐based Massachusetts Institute of Technology adaptive mechanism is utilised to control the reactive power flow of grid‐integrated SEIG. The voltage‐source inverter sinusoidal pulse width modulation of the STATCOM is used to overcome the abnormal operating conditions in the wind energy conversion system. This accordingly increases the low‐voltage ride through (LVRT) capability. The abnormal operating conditions are faults occurring at the point of common coupling between the generator and the grid. The proposed MRAC is compared to proportional‐integral (PI) controllers tuned by genetic algorithm (GA). To evaluate the proposed control of STATCOM for enhancing grid‐integrated SEIG, a part of the Egyptian 220 kV network integrated with Zafarana Wind Energy System is used. The results provide evidence of an efficient and robust proposed adaptive control performance rather than static PI controller whose parameters tuned by GA in the voltage, currents, and wind generator speed responses. Moreover, the proposed controller increases the capability of continuous operation of the wind turbines under different abnormal operating conditions and also increases the LVRT capability.

Voltage stability assessment of isolated hybrid dish-stirling solar thermal-diesel microgrid with STATCOM using mine blast algorithm