Zarko Janda

Coordinated Reactive Power-Voltage Controller for Multimachine Power Plant

This paper presents a newly developed voltage and reactive power control device, the coordinated Q -V controller (CQVC), for a multimachine steam power plant (SPP). The requirements for the new controller are defined based on identified inadequacies of manual Q-V control. The controller uses a feed-forward correction signal based on the application of the sensitivity matrix at a power plant level. It is designed and its performance initially assessed using the Matlab/Simulink environment. The performed simulations show that all the primary design objectives are met. The Q-V controller maintains the voltage at the SPP busbar with a certain droop characteristic during slow voltage changes in the power system whilst also maintaining equal per unit reactive power sharing among the SPP generators. This ensures that the power system fully benefits from all generating units during system perturbations. The performance of the designed CQVC is validated by comparing simulation results with measured responses obtained from a real CQVC installed at a SPP.

PLC-Based Model of Reactive Power Flow in Steam Power Plant for Pre-Commissioning Validation Testing of Coordinated Q-V Controller

The paper presents the digital realization of a model of reactive power flow (QFM) in a steam power plant using a programmable logic controller (PLC). The steam power plant (SPP) model is developed for pre-commissioning validation testing of the coordinated reactive power-terminal voltage (Q-V) control system. The SPP QFM includes a model for a synchronous generator, an excitation system, a step-up transformer, and the generators droop characteristic modeled through the automatic voltage regulator (AVR). A QFM synthesis is based on a series of experiments performed on site. The parameters of the generator and AVR are estimated from recorded generator voltage and current time responses to a step change in voltage reference of the AVR. To get a complete QFM, transformers and network reactances are also included. In order to calculate reactive power (Q) flows more accurately, the generator Q output is adjusted by taking into account its real power output. Standard PLC hardware, as industrial grade equipment appropriate for on site testing, is used for practical QFM implementation after discretization of the continuous mathematical model. The developed QFM response is verified through a series of experiments performed in the laboratory.

Mathematical model of steam power plant for voltage and reactive power control

The paper presents development of mathematical model of steam power plant for studies of reactive power - voltage (Q-V) control. The model of realistic six generator power plant is developed in Matlab-Simulink environment. All relevant components of the system studied are modeled in sufficient detail including synchronous generators, turbines and governors, exciters and AVRs, transformers, and the network. Several case studies are used to investigate potential problems that could occur if manual control was performed by the plant operator to restore the voltage at a point of common coupling or to produce the required reactive power set by the system operator. Results of simulations are compared with recorded responses at the power plant and confirmed the accuracy of developed mathematical model.

Robustness of Commissioned Coordinated q - V Controller for Multimachine Power Plant

This paper presents commissioning details of a coordinated reactive power-voltage controller (CQVC) installed in a multimachine steam power plant (SPP). The CQVC regulates reactive power and voltage of a 1992MVA multimachine SPP. After briefly introducing basic control principles and relevant details about the CQVCs implementation, CQVC parameterization and tuning are thoroughly discussed. Once commissioned,the CQVC performance under various operating conditions is assessed. It is shown that the CQVC successfully maintains an HV busbar voltage and allocates reactive power to participating generators in accordance to their capability. Numerous CQVC responses recorded at the site are presented to demonstrate controllers performance under normal and extreme plant and network operating conditions.

Quasi-independent voltage-reactive power zone controller

In this paper the zone controller is presented which regulates the reactive power-voltage characteristic (Q-V) of the zone pilot node by altering the reactive power outputs of power plants within the zone. As far as the zone is self-sufficient regarding reactive power needs, the generation is adapted to fit consumption and quasi-independent operation is achieved. As soon as limits are reached the import/export of the zone has to be permitted and voltage is maintained along the defined Q-V characteristics while providing reactive support to surrounding zones. Reactive power is distributed among power plants according to equal reactive reserve margin so maximal voltage stability margin is maintained. The result is minimization of losses due to minimization of reactive power flows among the zones and thus across long distances. Finally simulation results of the proposed controller are given in order to present the controller response in the quasi-independent operation mode.

Intra-plant reactive power-voltage control: Practices, drawbacks and challenges

The paper discusses reactive power-voltage (Q-V) control in a multi-machine steam power plant (SPP). After briefly introducing some of the basic characteristics of synchronous generators voltage control through automatic voltage regulators, the practices of widely applied manual voltage references setting for Q-V control in SPP is illustrated through several examples of SPP response recorded at site. Further the case studies were developed with the emphasis on the drawbacks of manual intra-plant Q-V control by building a mathematical model of realistic SPP in Matlab-Simulink. Relying on noticed drawbacks the paper highlights the requirements for enhancing SPP reactive power response and voltage support to the power system by coordinated Q-V control at power plant level. Finally, the paper illustrates the achieved performances of coordinated Q-V controller in real SPP.

Robustness of commissioned coordinated Q-V controller for multi-machine power plant

Summary form only given. This paper presents commissioning details of a coordinated reactive power-voltage controller (CQVC) installed in a multi-machine steam power plant (SPP). The CQVC regulates reactive power and voltage of a 1992MVA multi-machine SPP. After briefly introducing basic control principles and relevant details about the CQVCs implementation, CQVC parameterization and tuning are thoroughly discussed. Once commissioned the CQVC performance under various operating conditions is assessed. It is shown that the CQVC successfully maintains a HV busbar voltage and allocates reactive power to participating generators in accordance to their capability. Numerous CQVC responses recorded at the site are presented to demonstrate controllers performance under normal and extreme plant and network operating conditions.