Photovoltaic Output Fluctuation Research Articles

Prediction and control of Hopf bifurcation in a large‐scale PV grid‐connected system based on an optimised support vector machine

The unstable Hopf bifurcation (UHB) of a power system generally precedes the saddle-node bifurcation, so the UHB point can be the system critical point of voltage collapse. However, after the large-scale photovoltaic (PV) power station is connected to the system, the fluctuation characteristic of PV output can lead to the change of UHB point position and the evaluation process of system voltage stability is also affected. Therefore, according to the feature that the UHB point has the minimum value of hopf bifurcation index (HBI) index, a method for predicting the equilibrium HBI value is proposed based on an optimised support vector machine (SVM) algorithm (including particle swarm optimisation SVM and genetic algorithm optimisation SVM). Once the HBI prediction value of the current operating point (the equilibrium point) is less than or equal to the preset HBI alert value, it is possible to take an emergency load-shedding measure to remove a small amount of load, and the position of UHB point under maximum PV output is used to set the amount of load-shedding, so the oscillatory collapse of the load bus voltage caused by a sudden increase of PV output or load fluctuation can be avoided. Taking a large-scale PV power station access to the classic three-node system as an example, the prediction and control method is verified. Simulation result shows that the method is simple and practical, as well as suitable for on-line prediction and control of UHB point in a PV grid-connected system, which is able to improve the prevention and emergency control capability of the system voltage stability.

太陽光発電の出力変動を考慮した作業系統決定法の提案

In the near future, more and more photovoltaic (PV) generation systems are expected to be installed into electric power systems. Since the output of PV varies depending on weather, there is a possibility of causing not only power imbalance but also line overloads. The PV output fluctuations make it impossible to obtain feasible system configurations during outage works by conventional methods. In this paper, therefore, we propose an improved method for determining system configurations, and show several simulation results to demonstrate the effectiveness of the proposed method.

Analysis of possible introduction of PV systems considering output power fluctuations and battery technology, employing an optimal power generation mix model

AbstractThis paper presents an evaluation of the impact of extensive introduction of photovoltaic (PV) systems and stationary battery technology into the optimal power generation mix in the Kanto and Kinki regions. The introduction of solar PV systems is expected to be extensively deployed in the Japanese household sector and utility companies in order to address the concerns of energy security and climate change. Considering this expected large‐scale deployment of PV systems in electric power systems, it is necessary to investigate the optimal power generation mix which is technologically capable of controlling and accommodating the intermittent output‐power fluctuations inherent in PV systems. Against this background, we develop both a solar photovoltaic power generation model and an optimal power generation mix model, including stationary battery technology, which can be used to explicitly analyze the impact of PV output fluctuations at a detailed time interval resolution such as 10 minutes for 365 consecutive days. Simulation results reveal that PV introduction does not necessarily increase battery technology due to the cost competitiveness of thermal power plants in the load‐following requirement caused by PV systems. Additionally, on the basis of sensitivity analysis on PV system cost, dramatic cost reduction proves to be indispensable for PV to supply bulk electricity similarly to thermal and nuclear power plants. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(2): 9–19, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22329

Analysis on Possible Introduction of PV System Considering Output Power Fluctuation and Battery Technology Employing Optimal Power Generation Mix Model

This paper presents the evaluation on the impact of an extensive introduction of photovoltaic (PV) system and stationary battery technology into optimal power generation mix in Kanto and Kinki region. The introduction of solar PV system is expected to be extensively deployed in Japanese household sector and utility company in order to address the concerns of energy security and climate change. Considering this expected large-scale deployment of PV system in electric power system, it is necessary to investigate the optimal power generation mix which is technologically capable of controlling and accommodating the intermittent output-power fluctuation inherently derived from PV system. On these backgrounds, we develop both solar photovoltaic power generation model and optimal power generation mix model, including stationary battery technology, which are able to explicitly analyze the impact of PV output fluctuation in detailed resolution of time interval like 10 minutes at consecutive 365 days. Simulation results reveal that PV introduction does not necessarily increase battery technology due to the cost competitiveness of thermal power plants in load following requirement caused by PV system. Additionally, on the basis of sensitivity analysis on PV system cost, dramatic cost reduction proves to be indispensable enough for PV to supply a bulk of electricity similarly as thermal and nuclear power plant.

地域偏在による平滑化効果の低減を考慮した太陽光発電出力変動推定手法

Smoothing effect of photovoltaic (PV) generation is quite important because amount and cost of countermeasure for maintaining soundness of power system highly depends on assessment of the effect. In order to estimate the PV generation accurately, it is important to take into account of PV sites' distribution. In this paper, we propose a method for estimating the total output of PV considering reduction of smoothing effect caused by uneven distribution of PV sites, using some measured data. In the thought experiment, we made some ideal model representing uneven distribution. The model is extended to apply realistic distribution of Hokuriku region. Finally, total PV output fluctuations in Hokuriku region are estimated both even and uneven distribution cases.