Reactive Power-Voltage Integrated Control Method Based on MCR

Dan Chen,Xiaosheng Huang,Guangsheng Li,Yi Wei,Wenjun Zeng,Chuihua Tian,Huan Shi,Hua Ye 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

In power system, the voltage pulsation and deficiency or surplus of reactive power will have a great effect on the quality of electric power supply. Dynamicly local reactive power compensation is one of the best methods to reduce the power network loss and improve the efficiency of transmission and distribution.Through the effective methods of compensation, we can keep the balance of reactive power in the maximum degree by the maintenance of acceptable voltage. This paper firstly describes the principles of synthetic compensation of reactive power and voltage then analyzes the principle of magnetically controlled reactor-MCR in detail and derives the characteristics, secondly analyses the disadvantages of the conventional reactive power compensation devices and the advantages of MCR, thirdly on this basis designs a control strategy of reactive power and voltage which is based on MCR,so as to achieve the goal of dynamic reactive power compensation. At the end of paper, simulator and experimental research are carried out for the model of compensation method; the results accord with the theoretical analyses done before. So the compensation method is proved to be accurate in theory and feasible in practice.

Modeling and Power Quality Analysis of Grid-Connected PV Inverter with Active and Reactive Power Injection Mode

Venkatasamy B.,Kalaivani L. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

A critical search is needed for alternative energy sources to satisfy the present day’s power demand because of the quick utilization of fossil fuel resources. The solar photovoltaic system is one of the primary renewable energy sources widely utilized. Grid-Connected PV Inverter with reactive power capability is one of the recent developments in the fi eld. These types of inverters can produce reactive power in the absence of solar irradiations; also, if necessary, the inverter can operate with reactive power mode even if the P.V. power is available. The reactive power is generally required for the grid voltage regulation and to maintain the power factor, which improves the power handling capability of the system. Also, in a hybrid energy system, the induction type wind generator demands a large amount of reactive power. In this work, the reactive power capability of a grid-connected P.V. inverter has been investigated. The active and reactive power to be injected into the grid is enabled by its reference value and controlled independently. The Power quality study has been carried out for both modes of operation as a simulation. The same conditions also verifi ed in real-time in 75 kW Solar P.V. system

A Study on Efficient Calculation of Effective Reactive Power Reserves Using Sensitivity Analysis

Bae, Moonsung,Lee, Byongjun The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper's simulation was performed on the large scale Korean power system in steady state.

A Study on Efficient Calculation of Effective Reactive Power Reserves Using Sensitivity Analysis

Moonsung Bae,Byongjun Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper"s simulation was performed on the large scale Korean power system in steady state.

AC 계통 무효전력 제어를 위한 HVDC 시스템 설계

최순호(Soon-Ho Choi),최장흠(Jang-Hum Choi),김찬기(Chan-Ki Kim) 대한전기학회 2013 전기학회논문지 Vol.62 No.1

This paper deals with the concept design of HVDC system for controlling AC network reactive power. HVDC system can control active power and reactive power and the control concept of reactive power is similar to SVC(Static Var Compensator). Reactive power is controlled by adjusting firing angle of HVDC system under the condition that AC filters are switched. Reactive power depends on AC voltage condition, considering the steady-state and transient state to maintain the stable operation of AC network in the viewpoint of voltage stability. Therefore, in the design stage of HVDC, the reactive power required in the AC network must be considered. For the calculation of operation angle in HVDC system, the expected reactive power demand and supply status is examined at each AC system bus. The required reactive power affects the determination of the operation angle of HVDC. That is, the range of "control deadband" of operation angle should have the capability supplying the required reactive power. Finally, the reactive power control concepts is applied to 1GW BTB Pyeongtaek-Dangjin HVDC system.

A Study on Efficient Calculation of Effective Reactive Power Reserves Using Sensitivity Analysis

배문성,이병준 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper's simulation was performed on the large scale Korean power system in steady state.

Positive Feedback을 이용한 무효전력 P&O 단독운전 검출기법

이종원,박성열,이재연,최세완 전력전자학회 2022 전력전자학회 논문지 Vol.27 No.5

A grid-connected inverter with critical loads uses mode transfer control to supply stable voltage to the load. An islanding detection method should also be used to quickly detect the grid fault and disconnect the inverter from the grid. However using the existing islanding detection method to detect islanding is difficult due to the small fluctuation of the voltage and frequency of the point of common coupling. This study proposes a reactive power P&O islanding detection method by using the positive feedback technique. The proposed method always injects a small variation of reactive power. When a grid fault occurs, the injected reactive power accelerates the reactive power injection reference. As a result, the reactive power reference value and the sensed reactive power become mismatched, and islanding is detected. Reducing the amount of real-time injected reactive power results in high efficiency and power factor. The simulation and experimental results of a 3 kW single-phase inverter are provided to verify the proposed islanding detection method.

Reactive Power Control Strategy for Inverter-based Distributed Generation System with a Programmable Limit of the Voltage Variation at PCC

Ji-Hoon Im,San Kang,Seung-Ho Song(송승호),Seung-Ki Jung,Ju-Yeop Choi,Ick Choy 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In a grid connected distributed generator, the voltage variation problem at the point of common coupling(PCC) is investigated. This is one of the most frequent power quality issues for the grid connection of large amount of the input power into a weak grid. Through a simplified modeling of the distributed generator and the power network, the magnitude of PCC voltage variation is calculated using the equivalent circuit parameters and the output power of the distributed generator. In addition, the required amount of reactive power which can compensate the voltage variation is presented analytically using a vector diagram method. With the proposed compensation method in a power conditioning system(PCS) for a distributed generation, the PCC voltage variation can be minimized automatically even though the power fluctuation occurs due to the change of input power. The proposed method of the calculation and compensation of the PCC voltage variation is verified by computer simulation and experimental results.

무효전력 경제급전을 고려한 345㎸ 송전계통의 기준 전압 설정 방법

황인규(In-Kyu Hwang),진영규(Young-Gyu Jin),윤용태(Yong-Tae Yoon),추진부(Jin-Boo Choo) 대한전기학회 2018 전기학회논문지 Vol.67 No.5

In the cost based pool market in Korea, there is no compensation of reactive power because the fuel cost for reactive power is relatively low compared to that of active power. However, the change of energy paradigm in the future, such as widespread integration of distributed renewable energy source, will prevent the system operator from mandating the reactive power supply without any compensation. Thus, in this study, we propose the reference voltage of the 345 ㎸ transmission system that minimizes the reactive power supply. This is closely related to the economic dispatch of reactive power aiming at minimizing the compensation cost for the reactive power service. In order to verify the effectiveness of the proposed reference voltage, the simulations are performed using the IEEE 14 bus system and the KEPCO real networks. The simulation results show that a voltage lower than the current reference value is recommended to reduce the reactive power supply and also suggest that the current voltage specification for the 345 kV system needs to be reviewed.

DPLL을 이용한 능동적 단독운전방지를 위한 무효전력변동법

이기옥(Lee Ki-Ok),유병규(Yu Byung-Gu),유권종(Yu Gwon-Jong),최주엽(Choi Ju-Yeop),최익(Choy Ick) 한국태양에너지학회 2008 한국태양에너지학회 논문집 Vol.28 No.2

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. There has been an argument that it may be a non-issue in practice because the probability of islanding is extremely low. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an islanding can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficiently to cause a trip, plus the time required to execute a trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. Third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an islanding. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. Therefore the verification of anti-islanding performance is strongly needed. In this paper, improved RPV method is proposed through considering power quality and anti-islanding capacity of grid-connected single-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"), And the simulation results are verified.