General and Simple Decision Method for DG Penetration  Level in View of Voltage Regulation at Distribution  Substation Transformers

Song, In Kyu; Jung, Won-Wook; Chu, Chul-Min; Cho, Seongsoo; Kang, Hyun-Koo; Choi, Joon-Ho

doi:10.3390/en6094786

Cited by 10 publications

(10 citation statements)

References 13 publications

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“…All TC can be divided into two main groups: mechanically operated [20][21][22][23][24][25][26] and based on pure electronic devices [27][28][29][30][31][32][33]. Mechanically operated TC, which are the most applicable today for control in feeder transformers, have a relatively slow time response extending to 5-10 s. As a result, during fast load variations TC cannot keep always voltage deviations inside the permissible level (±10%) of a nominal value.…”

Section: Introductionmentioning

confidence: 99%

Selecting Ultracapacitors for Smoothing Voltage Deviations in Local Grids Fed by Transformer with Tap-Changer and Distributed PV Facilities

2019

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Widespread use of photovoltaic (PV) small and middle-power plants close or inside existing townships and villages may cause significant deviations of the grid voltage. Owing to the oscillation of solar irradiation and corresponding power flows these voltage instabilities can damage equipment and must be prevented. Designated for the voltage regulation tap-changers in distribution transformers located in a significant distance of such settlements have a sluggish response time. As a possible answer for their delay is the smoothing energy of flows in PV power installation by intermittent capacitor low-pass filtering (LPF) located near those PV facilities. The application of ultracapacitors (UC) for LPF is remarkable due to their sustainability and relatively low costs of energy storage. The parameters selection of such appliances is a well-designed procedure for linear circuits. However, DC–AC inverters in PV facilities are represented by a power (instead of a voltage) source. As a result, the total circuit including such LPF becomes a non-linear and its transient process and consequently, its efficiency is difficult to assess requiring each time of development the UC storage an application complex numerical procedure. Engineers are usual to work with linear circuits that are describing fine by a time constant is designated as a multiplication of a capacitance times load equivalent resistance. In the case of PV DC–AC inverters, such an approach can be applied as well but a value of a time constant should be corrected. Considering a significant cost of UC storage, the non-optimal selection of a correcting coefficient may cause considerable loses. Submitted in the presented article is an original approximation procedure giving an efficiently approachable technique to select correcting coefficient for describing non-linear dynamic process by its linear analog. This way the development low-pass UC filtering in electrical systems with PV plants becomes more efficient and simpler task.

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Section: Introductionmentioning

confidence: 99%

Selecting Ultracapacitors for Smoothing Voltage Deviations in Local Grids Fed by Transformer with Tap-Changer and Distributed PV Facilities

2019

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“…Several relatively simple diagnostic methods have been devised. Some of those presently in use include the power changing rate detection [5,6], the voltage harmonic detection [5,6], and the phase jump detection methods [5,6]. These are all simple and easy to implement.…”

Section: Introductionmentioning

confidence: 99%

Fractional Order Chaos Synchronization for Real-Time Intelligent Diagnosis of Islanding in Solar Power Grid Systems

Tian

et al. 2018

Energies

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Many different methods have been proposed for determining islanding and most of them have drawbacks. The main issue is the difficulty of detecting islanding when the current and voltage values are of the same phase or the frequency remains within the normal range of the grid when islanding occurs. In this study, a non-autonomous Chua's circuit was used to preprocess the grid signal after which a method based on the fractional Lorenz chaotic system and extension theory was used to analyze the preprocessed voltage signal. The capability of a chaotic system to amplify an extremely small signal was effectively utilized for the diagnosis of grid islanding. Simulation results showed that the diagnostic accuracy of the proposed method could be 100% and no other diagnostic method has offered such accuracy. Furthermore, the method proposed in this study is simple, easy to implement, and could be used as a portable system for the real-time monitoring and diagnosis of islanding in a conventional home grid system. detection based on new active disturbance [7] and one for active movement frequency anti-islanding detection [8]. Even though these methods can reduce the time taken to detect islanding, they can also affect the stability of the system or even lead to overall harmonic distortion. Furthermore, if the operating area (for islanding detection) includes other relatively stable power sources connected in parallel such as cogeneration systems. These methods will fail. New algorithms such as the Neural Network Algorithm (NNA) [9] have also been used in detecting islanding. Even though the neural network learns fast, it has a free mode and error tolerance and allows the use of reverse transmission direction to modify the weight and make corrections after repetition. It has a complicated training process that takes a long time. Accurate determinations cannot be made with other algorithms such as Fuzzy Theory [10] or the Genetic Algorithm (GA) [11] when the voltage, frequency, and phase differences are small. The Goertzel Algorithm [12], which is a Discrete Fourier Transformation (DFT) [13], has been recommended in some studies, but the conversion time is long and the width of the Fourier conversion window is fixed. This means that, when the time domain requires high resolution, the harmonic resolution will drop and the method is less than optimal. In 2015, a new, very accurate method has been proposed by Wang et al., which uses the Lorenz integer order [14] to detect islanding. However, many nonlinear systems exhibit fractional-order behavior. Therefore, if the fractional-order concept is considered in the diagnosis system, more accuracy can be obtained with a real physical system. In this study, the use of a non-autonomous Chua's circuit [14] for preliminary processing of the grid signal is described. This is followed by fractional Lorenz chaotic synchronization [15] and the product element model characteristics of the self-synchronization dynamic error are then analyzed. Afterward, the extension method is used to detect th...

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“…If the total capacity of the DG in the distribution system exceeds more than 15% of the main transformer (Mtr) capacity, the system automatically evaluates the substation voltage fluctuation. In a practical system, the on load tap changer (OLTC) and line drop compensation (LDC) methods are used for substation voltage control [29,30]. For LDC, the voltage of the regulating point in the distribution system V reg can be calculated using [29,31,32]:…”

mentioning

confidence: 99%

“…In a practical system, the on load tap changer (OLTC) and line drop compensation (LDC) methods are used for substation voltage control [29,30]. For LDC, the voltage of the regulating point in the distribution system V reg can be calculated using [29,31,32]:…”

mentioning

confidence: 99%

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Development of a Transmission and Distribution Integrated Monitoring and Analysis System for High Distributed Generation Penetration

2017

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Abstract:To date, power system analysis has been performed separately for transmission and distribution systems. Due to the small influence of distribution systems on transmission systems, separate analyses have had no accuracy problems in existing power systems. However, as the amount of distributed generation (DG) in distribution systems increases, neighboring distribution systems and even transmission systems can be affected by the distributed generation. Therefore, a power system operator needs a new system to analyze the power system, one that considers the mutual interactions between the transmission and distribution systems. This paper presents with applications and case studies a transmission and distribution integrated monitoring and analysis system for high DG penetration. The integrated system analyzes the mutual interaction between the transmission and distribution systems due to DG. The preliminary evaluation of the DG connections is automated in this system, using real time online data. Case studies with practical data show the need and effectiveness of transmission and distribution integrated monitoring and analysis for real power systems with high DG penetration.

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General and Simple Decision Method for DG Penetration Level in View of Voltage Regulation at Distribution Substation Transformers

Cited by 10 publications

References 13 publications

Selecting Ultracapacitors for Smoothing Voltage Deviations in Local Grids Fed by Transformer with Tap-Changer and Distributed PV Facilities

Selecting Ultracapacitors for Smoothing Voltage Deviations in Local Grids Fed by Transformer with Tap-Changer and Distributed PV Facilities

Fractional Order Chaos Synchronization for Real-Time Intelligent Diagnosis of Islanding in Solar Power Grid Systems

Development of a Transmission and Distribution Integrated Monitoring and Analysis System for High Distributed Generation Penetration

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