Convertible Static Compensator Research Articles

Reinforcement Learning Controllers for Enhancement of Low Voltage Ride Through Capability in Hybrid Power Systems

The present study applies reinforcement learning strategy for controller design to improve the low voltage ride through (LVRT) capability of a hybrid power system through convertible static compensator (CSC). This article considers different configurations of CSC such as static synchronous series compensator (SSSC), one static synchronous compensator (STATCOM), two STATCOMs, and unified power flow controller (UPFC). Both Q-learning and dynamic fuzzy Q-learning (DFQL)-based controllers are designed and their performances were compared with classical proportional-integral derivative (PID) controller considering a 3-machine system consisting of 2-synchronous and 1-wind energy systems. The results of simulation show that the performance of DFQL-based controller is better compared to other 2-controllers in improving the LVRT capability. Further, it is shown that the UPFC and two STATCOMs configurations of CSC provide higher voltage support compared to other configurations.

Optimal design of convertible static compensator supplementary damping controller to avoid wide area uncontrolled islanding

This study presents a new design of a wide area damping controller for the convertible static compensator (CSC) to limit some major blackouts due to asynchronous oscillations. The adaptive neuro-fuzzy inference system (ANFIS) approach is adopted in the dual heuristic programming method to have an optimal response at different disturbances. The proposed ANFIS parameters are optimised by using the multi-swarm particle swarm optimisation method. The CSC dynamic performance in both of unified power flow controller and interline power flow controller configurations is investigated to increase the damping of inter-area oscillations and to prevent the uncontrolled network islanding. The Iranian power grid and New England power system are selected to install CSC and to apply the designed damping controller. It is shown that the considerable number of wide area blackouts could be avoided by CSC application equipped with the proposed damping controller. In other scenarios, which the controlled islanding is an unavoidable task, the boundaries of islands are determined adaptively considering the changes of generators coherency and the loadings of lines. Simulation results verify that the load shedding amounts are decreased and the stability margins of islands are increased. The uncontrolled islanding condition is also delayed significantly.

Investigation of Modified Generalized Interline Power Flow Controller (GIPFC) and Performance Analysis

Nowadays in the restructured scenario, the main challenging objective of the modern power system is to avoid blackouts and provide uninterrupted quality power supply with dynamic response during emergency to improve power system security and stability. In this sense the convertible static compensator (CSC) that is the Generalized Inter line power flow controller (GIPFC), can control and optimize power flow in multi-line transmission system instead of controlling single line like its forerunner FACTS (Flexible AC Transmission System) controller. By adding a STATCOM (Static synchronous Shunt Converter) at the front end of the test power system and connecting to the common DC link of the IPFC, it is possible to bring the power factor to higher level and harmonics to the lower level and this arrangement is popularly known as Generalized Inter line power flow controller (GIPFC). In this paper a new concept of GIPFC based on incorporating a voltage source converter with zero sequence injection SPWM technique is presented for reinforcement of system stability margin. A detailed circuit model of modified GIPFC is developed and its performance is validated for a standard test system. Simulation is done using MATLAB Simulink.Index Terms—Convertible static controller, Flexible AC Transmission System (FACTS), Generalized Interline Power Flow Controller (GIPFC),STATCOM, SSSC, Reactive power compensation.

Design of a new adaptive optimal wide area IPFC damping controller in Iran transmission network

In this paper a new optimal neuro-based wide area damping controller for the allocated multi functional convertible static compensator (CSC) is designed. The ANFIS method is applied to the dual heuristic programming (DHP) method form the adaptive critic design (ACD) family to design the multi mode oscillations damping controller. The most effective wide area damping input signals to the ACD model neural network is selected based on the geometry analysis. The bacterial swarm optimization (BSO) algorithm is applied to the ACD model neural network to have optimal system identification. The proposed method is applied to the allocated CSC in large multi machine interconnected IRAN power system to solve stability problems. Different contingencies at different loading conditions have been simulated and dynamic performance of the proposed method is compared with other methods such as energy based and ANFIS controllers. Also, effectiveness of both possible IPFC and UPFC configuration of the CSC in stability enhancement are compared together. It is shown that like steady state condition, IPFC is more effective than UPFC in inter area mode oscillation damping in the studied network.

A Novel Approach for Modeling Voltage-Sourced Converter-Based FACTS Controllers

Due to their ability to provide reactive power support and control active power flow, voltage-sourced-converter (VSC)-based flexible ac transmission system controllers can be used to improve the power transfer capability of congested transmission lines. A converter-based controller structure has the inherent feature to be used to provide shunt or series compensations. This inherent feature is utilized in the convertible static compensator installed at the New York Power Authority's Marcy substation, which can operate in 11 configurations of shunt and series compensations. Moreover, each configuration can be operated in different control modes. The paper presents a novel approach to model converter-based transmission controllers for load-flow calculations. The paper focuses on modeling converter-based controllers when two or more VSCs are coupled to a dc link (e.g., unified power-flow controller (UPFC), interline power-flow controller, and a generalized unified power-flow controller). This approach also allows efficient implementation of various VSC operating limits, where one or more VSCs are loaded to their rated capacity. A computer program incorporating this approach is developed to illustrate the maximum dispatchability of UPFC and IPFC in a large power system.

ADVANCED MODELING OF FACTS IN NEWTON POWER FLOW

The latest generation FACTS controller named the convertible static compensator (CSC) was recently installed at the New York Power Authority (NYPA) Marcy substation as part of a project that will increase power transfer capability and maximize the use of the existing transmission network. Within the general framework of the CSC, two innovative FACTS controllers are used. The static synchronous series compensator (SSSC) coupled with a transformer is connected in series with a transmission line. The interline power flow controller (IPFC) combining at least two converters, can be configured. Mathematical models of the SSSC and the IPFC and their implementation in Newton power flow are reported. Numerical results based on the IEEE 30-bus are presented to demonstrate the performance of the Newton power flow algorithm with incorporation of the SSSC and IPFC.

Robust modeling of the interline power flow controller and the generalized unified power flow controller with small impedances in power flow analysis

The interline power flow controller (IPFC) and the generalized unified power flow controller (GUPFC) are two innovative configurations of the convertible static compensator (CSC) of FACTS. In this paper, direct modeling of the practical series or/and shunt operating inequality constraints of the IPFC and the GUPFC in power flow calculations are presented. Special initialization of a solution with the IPFC and GUPFC is also derived. Furthermore, an impedance compensation technique is proposed to deal with the numerical instability or the numerical difficulty of the IPFC and GUPFC models when either their coupling transformer impedances are too small or they are transformer-less controllers. Condition number analysis of the Newton power flow equations is given to get insights of the numerical instability of the voltage sourced models of the IPFC and GUPFC with small impedances. Numerical examples are given based on the IEEE 118-bus system, IEEE 300-bus system and a large scale system with 1000-buses.

Modelling of the interline power flow controller and the generalised unified power flow controller in Newton power flow

The latest generation FACTS controller named the convertible static compensator (CSC) was recently installed at the New York Power Authority (NYPA) Marcy substation as part of a project that will increase power transfer capability and maximise the use of the existing transmission network. Within the general framework of the CSC, two innovative FACTS controllers, the interline power flow controller (IPFC) combining at least two converters and the generalised unified power flow controller (GUPFC) combining at least three converters, can be configured. Mathematical models of the IPFC and GUPFC and their implementation in Newton power flow are reported. Numerical results based on the IEEE 30-bus 118-bus and 300-bus systems are presented to demonstrate the performance of the Newton power flow algorithm with incorporation of the IPFC and GUPFC.

Convertible static compensator performance studies on the NY state transmission system

New York Power Authority is installing a new flexible AC transmission system (FACTS) controller, known as the convertible static compensator (CSC), at Marcy 345 kV substation. Two 100 MVA converters are installed. Through one 200 MVA shunt and two 100 MVA series transformers, the converters may be connected to each other and to the system in 11 different configurations. This arrangement of the converters allows STATCOM, SSSC, UPFC, or IPFC deployment at the bus and two of the lines exiting the substation, namely, Marcy-Coopers Corners and Marcy-New Scotland 345 kV lines. Voltage, small signal, and transient stability simulations are conducted using the developed models of these configurations within the user-defined capability of the EPRI's power system analysis package. The focus of the studies is on finding out which configuration of the CSC provides the highest performance improvement from all stability points of view. Modulation controls are designed to improve inter-area oscillation damping. In general, all CSC configurations improve voltage, small signal, and transient stability margins of the system. The performance of the individual devices resulting from CSC configurations and their capabilities in the studied cases is presented. It is shown that the CSC in conjunction with three fixed capacitor banks at three other substations can increase the system power transfer limit by up to 310 MW.

Convertible Static Compensator Performance Studies on the NY State Transmission System

The New York Power Authority is installing a new flexible ac transmission system (FACTS) controller, known as the convertible static compensator (CSC), at the Marcy 345 kV substation. Two 100 MVA converters are installed. Through one 200 MVA shunt and two 100 MVA series transformers the converters may be connected to each other and to the system in 11 different configurations. This arrangement of the converters allows STATCOM, SSSC, UPFC, or IPFC deployment at the bus and two of the lines exiting the substation, namely, Marcy-Coopers Comers and Marcy-New Scotland 345 kV lines. Voltage, small signal, and transient stability simulations are conducted using the developed models of these configurations within the user-defined capability of EPRI's power system analysis package. The focus of the studies is on finding out which configuration of the CSC provides the highest performance improvement from all stability points of view. Modulation controls are designed to improve inter-area oscillation damping. In general, all CSC configurations improve voltage, small signal, and transient stability margins of the system. The performance of the individual devices resulting from CSC configurations and their capabilities in the studied cases is presented. It is shown that the CSC in conjunction with three fixed capacitor banks at three other substations can increase the system power transfer limit by up to 31OMW.

Modeling of the Generalized Unified Power Flow Controller (GUPFC) in a Nonlinear Interior Point OPF

With the progress of installing the latest generation of FACTS devices, namely, the convertible static compensator (CSC) [1], several innovative operating concepts have been introduced to the historic development and application of FACTS. One of the novel concepts is the generalized unified power flow controller (GUPFC), or multiline UPFC, which can control bus voltage and power flows of more than one line or even a subnetwork. The GUPFC should have stronger control capability than the UPFC. A mathematical model for the GUPFC consisting of one shunt converter and two or more series converters is developed and implemented in a nonlinear interior point OPF algorithm. Numerical results with various GUPFC devices based on the IEEE 30 bus system and IEEE 118 bus system demonstrate the feasibility as well as the effectiveness of the GUPFC model established and the OPF method proposed.

FACTS technology development: an update

This overview of the FACTS program sponsored by EPRI identifies the significant challenges and the adopted technology-based solutions that have been developed. FACTS technology has been successfully demonstrated and continues to be implemented at transmission locations in the United States. A STATCOM, UPFC, and convertible static compensator are discussed. The installed FACTS controllers have provided new possibilities and unprecedented flexibility aiming at maximizing the utilization of transmission assets efficiently and reliably. As the development and implementation of FACTS controllers evolve, there will be a need for an overall controller hierarchical logic to optimize transmission system operations.