Maximum Allowable Penetration Level Research Articles

Hosting capacity enhancement of renewable-based distributed generation in harmonically polluted distribution systems using passive harmonic filtering

In spite of being economically viable for numerous applications, renewable energy cannot realise its true penetration potential until some of the barriers are not tackled with excellence. Such barriers are harmonic distortion, distribution cable’s ampacity and voltage rise limits, those put bound on the maximum allowable penetration level of renewable energy. This paper formulates the enhancement of power quality-constrained hosting capacity (HC) as a multi-objective optimization (MOO) problem under several constraints of system’s performance indices (PIs). The considered performance indices are individual order and total harmonic distortion in the line current and point of common coupling (PCC)’s voltage, load power factor (PF), distribution line’s ampacity and steady-state voltage profile. In the formulated multi-objective optimization model, an optimal design of a third-order damped filter and size of the distributed generation (DG) unit is simultaneously determined for achieving maximum hosting capacity and power factor at the PCC while keeping system’s other indices such as total voltage harmonic distortion (TVHD) and total filter cost (FC) incurred at a minimum by obtaining a best-compromised solution using the newly proposed Pareto-based multi-objective firefly algorithm (MOFA). The extension of the multi-objective firefly algorithm is considered for producing the Pareto optimal front and various conclusions are drawn by analysing the trade-offs among the objectives by plotting the same on different 2-axis planes. The optimization efficiency and superiority of the proposed multi-objective firefly algorithm based hosting capacity enhancement approach is validated by comparing the results with those obtained by popular multi-objective PSO (MOPSO) and non-dominated sorting genetic algorithm (NSGA-II) under similar objectives. Also, the results of the proposed methodology are compared with those achieved from one of the most recently introduced hosting capacity enhancement approaches in literature. Eventually, the impacts of different background voltage distortion (BVD) levels and load-side’s nonlinearity levels (NLLs) on filter performance, particularly filter cost as well as enhanced hosting capacity, are analysed and various conclusions are drawn.

재생에너지 확대에 따른 국내 계통관성 별 적정 예비력 평가

As the penetration level of renewable energy sources (RESs) increases, the decrease in the system inertia and spinning reserves will be one of the major challenges for the secure operation of power systems. Recently, in order to secure power system frequency within the limit defined in the grid code, accurate analysis on the frequency responsive reserves is getting important. In this study, method of evaluating the minimum level of inertia along with the required reserves to secure system frequency is developed. Furthermore, maximum allowable penetration level of RESs is analyzed in order to secure frequency after a sudden loss of a single generator unit. And with the evaluated minimum inertia for the secure frequency, this study shows the amount of the increased generation and the system frequency response in the time frame after a single generator or two generator units are tripped off. In the developed method, increase in RES penetration is illustrated as a negative load while considering the merit order of conventional generators. A case study is conducted on the future Korean power system of 2024.

Maximum Penetration Level of Micro-Grids in Large-Scale Power Systems: Frequency Stability Viewpoint

Reduction of overall system inertia in response to increasing penetration level of Micro-Grids (MGs) makes frequency control more challenging. In this paper, a new analytical approach to mathematically investigate the impact of Micro-Grids penetration level on power system frequency stability is proposed. The method interprets the frequency dynamic behavior of the penetrated system based on the conventional system in terms of minimum instantaneous frequency, steady state deviation and a 15-second rolling window. Then, new indices are proposed to determine the maximum allowable MGs penetration level. These indices are derived by adapting the developed analytical approach to the required standards regarding the aforementioned criteria. Each index determines an upper bound on reduction of system inertia, which, in turn specifies the associated maximum penetration level. The maximum value of the inertia constant related to the developed indices (whichever is the larger) determines the system maximum allowable penetration level. The effectiveness of the proposed analytical approach and indices is demonstrated on a 16-machine 68-bus system and the IEEE 50-machine systems. Simulation results for large-scale power systems with high stiffness reveal that based on the operating condition, one of the minimum instantaneous frequency or 15-second rolling window impose an upper bound on penetration level.

Power Control of High Penetration PV in Distribution Network

Photovoltaic energy is one of the fastest growing renewable energy sources in the worldand as the issue of energy security is becoming more and more important it could be a promising option. But as photovoltaic energy is becoming widespread and penetration level of photovoltaic power plants increase, issues rise in distribution networks.In this paper a power control scheme for a high penetration photovoltaic power plant in a radial distribution network will be presented. This control scheme includes an efficient Maximum Power Point Tracking (MPPT), DC link voltage control by managing power balance between the hysteresis controlled inverter and a boost converter. Another aspect of High Penetration PV (HPPV) which is overvoltage in Point of Common Coupling (PCC) is also investigated and maximum allowable Penetration Level (PL) will be determined. Simulations have been done in Matlab/Simulink environment.

Power Control of High Penetration PV in Distribution Network

<p>Photovoltaic energy is one of the fastest growing renewable energy sources in the worldand as the issue of energy security is becoming more and more important it could be a promising option. But as photovoltaic energy is becoming widespread and penetration level of photovoltaic power plants increase, issues rise in distribution networks.In this paper a power control scheme for a high penetration photovoltaic power plant in a radial distribution network will be presented. This control scheme includes an efficient Maximum Power Point Tracking (MPPT), DC link voltage control by managing power balance between the hysteresis controlled inverter and a boost converter. Another aspect of High Penetration PV (HPPV) which is overvoltage in Point of Common Coupling (PCC) is also investigated and maximum allowable Penetration Level (PL) will be determined. Simulations have been done in Matlab/Simulink environment.</p>

The Impact of Capacitor Coupled Sub-Station in Rural Electrification of Sub-Saharan Africa

The overall electricity access rate is still very low in most sub-Saharan African (SSA) countries. The rate is even lower in rural areas where most of the population in these countries lives. One of the main obstacles to rural electrification (RE) is the high cost of laying the distribution infrastructure owing to the dispersed nature of loads and low demand. Thus, electrifying the rural areas needs to be considered holistically and not just on the financial viability. To reduce cost, it is important that un-conventional rural electrification (URE) technologies, which are cheaper than the conventional ones be explored. This paper investigates the adoptability and maximum penetration level of sub-station based URE i.e. Capacitor Coupled Sub-station (CCS) technologies in power transmission networks with regard to voltage quality, stability, and capacity constraints without steady and transient state voltage violation. Quantitative data collected from practical power transmission lines in Kenya were used for empirical and analytical approaches developed in this research. The paper developed a method of determining maximum allowable penetration level of CCS without steady state voltage violation derived from a modified distributed generation analogy. The method was based on determination of voltage sensitivities from linearized power system model. Consequently, this method was used to validate repetitive power flow simulations carried out in the case studies.

Method for determining the maximum allowable penetration level of distributed generation without steady-state voltage violations

One of the main factors that may limit the penetration level of distributed generation (DG) in typical distribution systems is the steady-state voltage rise. The maximum amount of active power supplied by distributed generators into each system bus without causing voltage violations can be determined by using repetitive power flow studies. However, this task is laborious and usually time-consuming, since different loading level and generation operation modes have to be evaluated. Therefore this article presents a method that, based on only one power flow solution and one matrix operation, can directly determine the maximum power that can be injected by distributed generators into each system bus without leading to steady-state voltage violations. This method is based on the determination of voltage sensitivities from a linearised power system model. In addition, this article proposes a numerical index to quantify the responsibility of each generator for the voltage level rise in a multi-DG system. Based on this index, utility managers can decide which generators, and in which degree, should be penalised by the voltage rise or rewarded by not depreciating the voltage profile. The method is applied to a 70-bus distribution network. The results are compared with those obtained by repetitive power flow solutions in order to validate the proposed method.