Real-time voltage stability monitoring model of wind power plant penetration in electrical power system networks

AbstractThis paper proposes a methodology to improve the transient stability (TS) of a system with wind energy generators. Induction machines are used widely as generators in the wind power plants. As these induction machines also have the stability problem like other synchronous machines, it is very important to analyze the TS of a system including the wind power plants. In this paper, the simulations and analysis of TS of power system including the induction generators during the short circuit fault conditions are carried out. The effect of pitch angle control on the stability of power system is analyzed. From the simulation results, it can be observed that the pitch control system which prevents the excess wind speed has the significant effect on the TS enhancement of the system. It can also be observed that the controller gain and time constant values have considerable effect on the pitch control system.

Increasing large-scale integration of renewables in conventional power system has led to an increase in reserve power requirement owing to the forecasting error. Innovative operating strategies are required for maintaining balance between load and generation in real time, while keeping the reserve power requirement at its minimum. This research work proposes a control strategy for active power balance control without compromising power system security, emphasizing the integration of wind power and flexible load in automatic generation control. Simulations were performed in DIgSILENT for forecasting the modern Danish power system with bulk wind power integration. A high wind day of year 2020 was selected for analysis when wind power plants were contributing 76.7% of the total electricity production. Conventional power plants and power exchange with interconnected power systems utilize an hour-ahead power regulation schedule, while real-time series are used for wind power plants and load demand. Analysis showed that flexible load units along with wind power plants can actively help in reducing real-time power imbalances introduced due to large-scale integration of wind power, thus increasing power system reliability without enhancing the reserve power requirement from conventional power plants.

A sound power system must have voltage values at all buses that do not exceed the tolerance limit of ± 5% with small power losses. Voltage instability can be caused by interference or sudden power generation outage from the system. Indonesia's Southern Sulawesi power system has been interconnected with wind power plants located in Sidrap Regency and Jeneponto Regency. Wind speed energy used by wind power plants to generate electricity vary and not always constant. Hence, this can cause fluctuations and produce varied outputs that will affect the voltage profile and stability of the Southern Sulawesi interconnection system. Therefore, it is essential to assess the voltage stability of the Southern Sulawesi power system after the integration of Sidrap and Jeneponto WPPs. First, this study analyzes the voltage profile of the Southern Sulawesi interconnection system voltage after integrating the Sidrap wind power plants and Jeneponto Wind Power Plant during the peak day load and peak night load. Second, the study assesses the voltage stability with a varied output power of both Sidrap and Jeneponto Wind Power Plant. After integrating Sidrap and Jeneponto Wind Power Plants, the results showed that the voltage values at all system buses are stable and within the IEEE standard (between 0.95 p.u. and 1.05 p.u.). In addition, the voltages of the Southern Sulawesi power system with various outputs of both WPPs are still stable and within the IEEE standard.

The general purpose of the article is to present in a comparative perspective how the principles of the taxation of wind power plants have evolved. In the Polish tax law, over the past several years, the legislature has undertaken considerable efforts to modify those principles. The lack of the stability of tax legislation may prove to be one of the main reasons for discouraging economic operators from pursuing such investments. Most evidently, the lawmakers do not have a clear vision of a coherent and permanent legal framework in this aspect. The purpose of this article is to present how the principles of the taxation of wind power plants in Poland have evolved. Perhaps the wider experience of other European countries in this regard will help to develop a model of the taxation of wind power plants not only in Poland but also in other East and Central European Union Countries.

The interconnection of wind power plants (WPPs) with distribution networks has posed many challenges concerned with voltage stability at the point of common coupling (PCC). In a distribution network connected WPP, the short-circuit ratio (SCR) and impedance angle ratio seen at PCC (X/RPCC) are the most important parameters, which affect the PCC voltage (VPCC) stability. Hence, design engineers need to conduct the WPP siting and sizing assessment considering the SCR and X/RPCC seen at each potential PCC site to ensure that the voltage stability requirements defined by grid codes are provided. In various literature works, optimal siting and sizing of distributed generation in distribution networks (DG) has been carried out using analytical, numerical, and heuristics approaches. The majority of these methods require performing computational tasks or simulate the whole distribution network, which is complex and time-consuming. In addition, other works proposed to simplify the WPP siting and sizing have limited accuracy. To address the aforementioned issues, in this paper, a decision tree algorithm-based model was developed for WPP siting and sizing in distribution networks. The proposed model eliminates the need to simulate the whole system and provides a higher accuracy compared to the similar previous works. For this purpose, the model accurately predicts key voltage stability criteria at a given interconnection point, including VPCC profile and maximum permissible wind power generation, using the SCR and X/RPCC values seen at that point. The results confirmed the proposed model provides a noticeable high accuracy in predicting the voltage stability criteria under various validation scenarios considered.