Chandrashekhar Narayan Bhende

Frequency Sensitivity Analysis of Load Damping Coefficient in Wind Farm-Integrated Power System

The presence of frequency sensitive loads such as motors has sustainable impact on power system frequency response (SFR). With increasing wind power penetration into the power system, guidelines for frequency regulation need to be revised to ensure system stability and reliability. Frequency regulation becomes more critical with the presence of frequency sensitive loads in wind integrated power system. This paper presents the impact of frequency sensitive loads on system frequency when wind farm is integrated with the conventional power system. A small-signal linearized model of variable speed wind turbine generator is derived. The typical SFR model is developed for wind farm integrated power (WFIP) system. Sensitivity and stability analysis is carried out for linearized model of WFIP system. The observations drawn from the analysis can be useful for the system operators for decision making of appropriate schemes for primary frequency control, demand response, and setting of relays, etc. for secure and stable power system operation. The proposed analysis is validated in IEEE 9-bus system using MATLAB simulation studies.

PSO based online tuning of PI controller for estimation of rotor resistance of indirect vector controlled induction motor drive

In industries where the operating condition are stringent and which requires excellent dynamic and steady state performance, the most preferred drive is the three phase induction motor with indirect field oriented control. However, its performance is prone to variation in rotor resistance, which needs to be estimated online. Conventionally, the model reference adaptive system with proportional integral controllers is used as adaptation mechanism for estimation of rotor resistance. This mechanism works satisfactorily for one particular operating condition and invariably fails under variable operating condition. Therefore the need arises for an adaptive controller for robust response of a drive with parameter variation. In this paper, the particle swarm optimization based proportional integral controller was applied to estimate the variation in rotor resistance. The proposed system under study is implemented in MATLAB/Simulink environment. The results shows that the estimation of rotor resistance by the proposed controller under all motor operating condition is better than the conventional fixed gain proportional integral controller.

Two-degree-of-freedom multi-input multi-output proportional–integral–derivative control design: Application to quadruple-tank system

This article is concerned with designing a 2-degree-of-freedom multi-input multi-output proportional–integral–derivative controller to ensure linear quadratic regulator performance and H∞ performance using a non-iterative linear matrix inequality–based method. To design the controller, first, a relation between the state feedback gain and proportional–integral–derivative gain is obtained. As the gains of proportional–integral–derivative controller cannot, in general, be found out from this relation for arbitrary stabilizing state feedback gain, a suitable form of the matrices involved in linear matrix inequality–based state feedback design is then chosen to obtain the proportional–integral–derivative gains directly. The special structure of the above matrices allows one to design proportional–integral–derivative controller in non-iterative manner. As a result, multi-objective performances, such as linear quadratic regulator and H∞, can be achieved simultaneously without increasing the computational burden much. To enhance the reference-input-to-output characteristics, a feedforward gain is also introduced and designed to minimize certain closed-loop H∞ performance. The proposed control design method is applied for multi-input multi-output proportional–integral compensation of a laboratory-based quadruple-tank process. The performance of the compensation is studied through extensive simulations and experiments.

Modelling a droop controlled multi PV inverter system to study effects of system parameters on oscillatory modes

This paper presents the small signal model of a multi Photovoltaic (PV) inverter system to study the effect of controller and system parameters on the frequency modes of a microgrid. The paper describes the state space model of a system having two PV inverters connected by a line and working under droop control mode for active power sharing. The PV sources are working under load following mode and P-f, Q-V droops are used for power sharing between the inverters. The complete linear model of the system is developed by linearising the differential equations around an operating point. Eigen value and sensitivity analysis is then done to observe the effect of various controller gains and system parameters on the oscillatory modes. The study concludes that these quantities impacts the damping of few oscillatory modes which even gets unstable for specific values of parameters.

Techno-economical analysis for PV based water pumping system under partial shading/mismatching phenomena

Partial shading and/or mismatching phenomena in Photovoltaic (PV) based system cause reduced extraction of PV power and thus adversely impact the performance of PV based system; especially in case of stand-alone PV systems. In this paper four different configurations namely single stage PV system, centralized DC-DC converter based PV system, PV panel level Distributed maximum power point tracking (DMPPT) based PV system and PV module level DMPPT based PV system are considered for water pumping application. Impact of partial shading and mismatching for the considered four configurations is simulated using MATLAB/SIMLINK. Techno-economical analysis is performed in terms of PV power being extracted, saving in power and investment. From the analysis it is found that PV module level DMPPT based configuration is better in various types of random partial shading/mismatching conditions and increase in extracted PV power as compared to single stage and other configurations; justify the cost of additional investment required for additional DC-DC converters. Cost benefit analysis shows that even after considering the cost of additional DC-DC converters required to implement DMPPT PV module level, this method is more economical as it increases the utilization of installed PV capacity.

Modified MISO DC-DC converter based PV water pumping system

In this paper an modified MISO DC-DC converter based Photovoltaic (PV) water pumping system is designed for population living in remote areas to fulfill their water pumping requirement for various applications like drinking water, water for irrigation and daily needs etc. With the objective of improvement in performance and efficiency of PV based water pumping system and thus to justify its installation cost, a modified Multi-input single-output (MISO) converter is proposed. Contribution of this paper is the implementation of proposed MISO converter to the conventional PV based water pumping system to enhance extraction of power from PV units under partial shading/mismatching phenomena without any energy storage device. Various irradiation patterns are considered to create the mismatching conditions and observe the performance of designed system. To verify the performance of proposed MISO converter, designed system is simulated in MATLAB/SIMULINK environment. Simulation results show that the implementation of proposed MISO converter instead of conventional DC-DC converter based PV water pumping system increases the extracted power from PV units under mismatching phenomena.

Improving the performance of PV based water pumping system for fluctuations in irradiance

In real time field conditions, situation arises when sudden and a large change in insolation level occurs. Such frequent fluctuations in irradiation level, affects adversely the performance of Photovoltaic (PV) based water pumping system. Sudden large fall in insolation leads to generation of PV power which is insufficient for operation of motor-pump system and such frequent variations in insolation level results in unstable operation of PV based water pumping system. In this paper a standalone PV based water pumping system with super-capacitor (SC) as energy storage device is proposed. SC supports the operation of PV water pumping system in case of insolation fluctuations thus ensures stable operation of system. Proposed system is simulated in MATLAB/SIMULINK environment to verify its performance. Results show that in the designed system induction motor-pump system is able to work at constant speed, frequency despite of sudden large change in insolation.