Robust Control of Hydro-Thermal Power System Considering Energy Capacitor System

This article proposes a robust controller design of hydro-thermal power system considering of the thermal power plant area connected to the hydro power plant area. The automation generation control of an interconnected hydro-thermal power system with a small Energy Capacitor System (ECS) augmented to both area has been investigated. The controller is used in order to control the frequency robustly and to improve the power system stability due to the uncertainties in load change and energy capacitors in the system. The power from the load changes are introduced into the system and treated it as the uncertainty during the design process. The H-infinity loop-shaping design procedure (H-infinity LSDP) is adopted as the control design procedure in this study. The results reveal that H-infinity LSDP can achieve higher performance and more robustness compared with PID controller

Smoothing Output Fluctuations of Wind Turbines and Enhancing Power System Frequency Using Coefficient Diagram Method

Due to recent expansion of renewable energy applications, Wind Energy System (WES) is receiving much interest all over the world. However, output fluctuations of wind generators can cause network frequency variations in power systems, which can consequently decrease the power quality. This problem of output fluctuations needs to be solved for further expanding wind energy conversion into power system. On the other hand, area load change and abnormal conditions can lead to mismatches in frequency and these mismatches have to be corrected by the load frequency system. This paper therefore proposes a new load frequency control (LFC) design using Coefficient Diagram Method (CDM) in the presence of wind turbines (WT), for improving network frequency quality. The CDM technique reduces the effect of uncertainty due to governor and turbine parameters variations and load disturbance. Digital simulation performed on a single-area power system with wind turbines validates the effectiveness of the proposed scheme. Results show that, with the proposed CDM technique, the overall closed loop system performance demonstrated robustness. Performance comparisons between the proposed controller, a classical integral control and Model predictive control is carried out confirming the superiority of the proposed technique in presence of doubly fed induction generator (DFIG) WT

Functional PCS power supply system with EV battery storage for stable PV power delivery

This research proposes a residential Photovoltaic-Power Conditioning Subsystem (PV-PCS) in a functional and stable power supply system with battery storage (Electric Vehicle [EV] storage etc.) to reduce PV output fluctuation. In PV power generation, PV power fluctuations caused by weather changes make it difficult to obtain stable power output. Further, it can then be expected that this adversely affects the power system. In this paper, functional power supply system model is constructed with power fluctuation suppression control system using bidirectional DC/DC converter and existing residential PCS and EV battery storage. Furthermore, simulation results of the electric battery power suppression element of the PV power fluctuation are also shown by using Simple Moving Average (SMA) control method to suppress PV power fluctuation. PV power suppression system using existing residential PCS has an advantage that can not only suppress the energy change during normal operation but can also construct the isolated power supply in an emergency case of power supply loss. In this emergency case, EV battery storage control provides the power to critical loads during utility outage. This feature is not available without storage. Also, effectiveness of PV-PCS interconnection stable power supply system with existing residential PCS in Japan was proposed. Moreover, a basic research of solar power generation amount of solar radiation estimation and the resulting simulation on information acquisition method of solar energy capacity using Geographic Information System (GIS) are presented

Application of Geographic Information System to Power Distribution System Analysis

AbstractThis paper presents a new application of Geographic Information System (GIS) in the field of electric power engineering. GIS can analyze and visualize information related to Geography. Recently photovoltaic (PV) generation is introduced in the power system day by day for the needs of clean energy. If it is installed in large quantities, voltage variation occurs with a risk of worsening electric power quality. In this context the limit of introducing PV in the power system should be correctly grasped. This research focuses on distribution system with large amount of PV. In order to grasp the limit of introducing PV in the distribution system, PV generation should be evaluated correctly and analyze the state of the distribution system. Although PV generation is proportional to solar radiation, the amount of solar radiation is affected by the shadow of the building, the angle, and the direction. Therefore, it is difficult to grasp solar radiation falling on the PV panels accurately and calculate PV generation. GIS can solve the problem. GIS can model actual townscape and analyze the amount of solar radiation. By executing solar radiation analysis to the modeled townscape, the amount of solar radiation on any places in the town can be evaluated. Using the result of the analysis, PV generation installed on any places in the town can be estimated and more proper distribution system analysis can be performed than conventional analysis

Construction of power supply system using electric vehicle for stable power delivery from PV generation

Abstract This research aims to propose a power supply system in which conventional photovoltaic (PV) system attains advanced functions. First, each household can use the power independently from the power system and load in the power system is reduced in the event of power shortage. Second, stable power is obtained from PV in which the output fluctuates due to the change in the amount of solar radiation. Third, PV output suppression is avoided when voltage of the distribution line is increased by the reverse power flow. Fourth, stable power is supplied to each household and refuge in the event of disaster. To achieve these, grid-connected and self-sustaining power supply system is developed by connecting a DC/DC converter between electric vehicle (EV) battery and conventional power conditioning subsystem (PCS) of PV system. In this paper, the power supply system model is presented. Also, the bidirectional DC/DC converter circuit is described in consideration of PV system installed in Kyushu Institute of Technology and of major EV in Japan. Finally, the hardware configuration of the proposed system is shown. It is considered that the effectiveness can be evaluated by constructing the proposed system

PI-MPC Frequency Control of Power System in the Presence of DFIG Wind Turbines

Abstract For the recent expansion of renewable energy applications, Wind Energy System (WES) is receiving much interest all over the world. However, area load change and abnormal conditions lead to mismatches in frequency and scheduled power interchanges between areas. These mismatches have to be corrected by the LFC system. This paper, therefore, proposes a new robust frequency control technique involving the combination of conventional Proportional-Integral (PI) and Model Predictive Control (MPC) controllers in the presence of wind turbines (WT). The PI-MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. A frequency response dynamic model of a single-area power system with an aggregated generator unit is introduced, and physical constraints of the governors and turbines are considered. The proposed technique is tested on the single-area power system, for enhancement of the network frequency quality. The validity of the proposed method is evaluated by computer simulation analyses using Matlab Simulink. The results show that, with the proposed PI-MPC combination technique, the overall closed loop system performance demonstrated robustness regardless of the presence of uncertainties due to variations of the parameters of governors and turbines, and loads disturbances. A performance comparison between the proposed control scheme, the classical PI control scheme and the MPC is carried out confirming the superiority of the proposed technique in presence of doubly fed induction generator (DFIG) WT

Adaptive frequency control in smart microgrid using controlled loads supported by real-time implementation.

The operation of the system's frequency can be strongly impacted by load change, solar irradiation, wind disturbance, and system parametric uncertainty. In this paper, the application of an adaptive controller based on a hybrid Jaya-Balloon optimizer (JBO) for frequency oscillation mitigation in a single area smart μG system is studied. The proposed adaptive control approach is applied to control the flexible loads such as HPs and EVs by using the JBO which efficiently controls the system frequency. The suggested technique uses the power balance equation to provide a dynamic output feedback controller. The main target is to regulate the frequency and power of an islanded single area μG powered by a PV and a diesel generator with integrations of smart bidirectional loads (HPs and EVs) that are controlled by the proposed adaptive controller in presence of electrical random loads. Moreover, the JBO is designed to minimize the effect of the system load disturbance and parameter variations. For a better assessment, the proposed controller using JBO technique is compared with two other methods which are the coefficient diagram method (CDM) and adaptive one using classical the Jaya technique. In the obtained results, the frequency deviation is found as 0.0015 Hz, which is fully acceptable and in the range of the IEEE standards. The MATLAB simulation results reveal that the suggested technique has a substantial advantage over other techniques in terms of frequency stability in the face of concurrent disturbances and parameter uncertainties. The real-time simulation tests are presented using a dSPACE DS1103 connected to another PC via QUARC pid_e data acquisition card and confirmed the MATLAB simulation results