Accounting for flexibility in power system planning with renewables

Due to the increasing deployment of intermittent renewables, the residual load profile, as seen by the dispatchable generation units, becomes lower and more volatile. This paper introduces a new system planning model on a power plant resolution, taking into account technical operational constraints. The objective of this model is to determine the optimal set of generation units, able to serve a given demand. Two initial solutions are obtained; one from a classical screening curve model, and another from a model using mixed integer linear programming (MILP). These initial solutions are perturbed and combined with an operational model to validate and further improve the solution. The developed model complements other models available from the literature, in its level of detail (power plant level and full year – hourly time resolution) combined with a fast computation time (<1 h). The evolution of the optimal amount of generation capacity as a function of the installed wind capacity is examined in a case study. As the share of wind power increases in the portfolio, a shift takes place from base load generation towards mid and peak load. This shift is triggered both by the lower demand and the increasing volatility. This demonstrates that operational constraints of power plants (individual basis) have an important impact on the configuration of the optimal generator set, and need being considered, especially at increasing rates of intermittent renewables.     

Digital control and integration of a 192 MW wind farm with doubly fed induction generator into the Brazilian power system

This paper reports on design of digital control for wind turbines and its relation to the quality of power fed into the Brazilian grid on connecting to it a 192 MW wind farm equipped with doubly fed induction generators. PWM converters are deployed as vector controlled regulated current voltage sources for their rotors, for independent control of both active and reactive power of those generators. Both speed control and active power control strategies are analyzed, in the search for maximum efficiency of conversion of wind kinetic energy into electric power and enhanced quality of delivered power.     

Mathematical modelling of a wind power system with an integrated active filter

A novel technical solution of the power quality and electromagnetic compatibility (EMC) problems has been proposed through computer-aided design of a wind power system. In the considered wind power system, an AC power source generates the power, which is comparable to the consumed power. Consumer equipment is represented by a switch-mode power supply. Instead of the standard solution for the power quality and EMC problems, where a harmonic filter is placed between the load side and the wind-driven power generator, an active power filter has been integrated into the AC/DC/AC converter of the wind power system. A mathematical model of the AC/DC/AC converter built upon the multi-phase bridge-element concept has been introduced. A computer program for analysis of electromagnetic processes in a wind power system has been developed. A practical example of a wind power system has been analysed where the system frequency response is calculated using the developed mathematical model.     

大规模风电对江苏电网规划影响的实证分析

随着我国风电的大力发展,准确合理地认识风力发电的特点及其对电力系统规划的影响对电力系统的发展有着重要意义.基于大量的实际运行数据,依据风电运行模拟方法,研究江苏省千万千瓦级风电场出力的相关性及其对规划的影响;分析了风电出力特征曲线对电力系统规划的价值,通过统计和分析,给出了江苏省风电出力的几类典型特征曲线;在分析大规模风电出力波动性的基础上,研究了2020年千万千瓦风电接入江苏后负荷持续曲线的变化及其对系统规划带来的综合影响.通过实证分析,得出了大规模风电接入后对于电力系统规划工作的有益启示.     

Hybrid wind power balance control strategy using thermal power,hydro power and flow batteries

The increased number of renewable power plants pose threat to power system balance. Their intermittent nature makes it very difficult to predict power output, thus either additional reserve power plants or new storage and control technologies are required. Traditional spinning reserve cannot fully compensate sudden changes in renewable energy power generation. Using new storage technologies such as flow batteries, it is feasible to balance the variations in power and voltage within very short period of time. This paper summarises the controlled use of hybrid flow battery, thermal and hydro power plant system, to support wind power plants to reach near perfect balance, i.e. make the total power output as close as possible to the predicted value. It also investigates the possibility of such technology to take part in the balance of the Lithuanian power system. A dynamic model of flow battery is demonstrated where it evaluates the main parameters such as power, energy, reaction time and efficiency. The required battery size is tested based on range of thermal and hydro power plant reaction times. This work suggests that power and energy of a reasonable size flow battery is sufficient to correct the load and wind power imbalance.     

Renewable energy credit driven wind power growth for system reliability

Environmental concerns over electric power generation from conventional sources has led to widespread public support for renewable energy sources. Governments throughout the world have responded by providing various forms of financial incentives to promote power generation from renewable energy sources. The rapid growth of wind power since the last decade has primarily been driven by governmental subsidies. Long-term growth of wind power should, however, be driven by sustainable market mechanisms. A potential solution is to recognize monetary values to the environmental benefits from renewable energy sources, and to specify targets for their growth. The environmental benefits from wind sources can be leveraged to allow market competition of these sources with the less costly conventional generating sources. A probabilistic method to evaluate the impact of renewable energy credit and wind penetration level on the cost and adequacy of power generating systems is presented in this paper. The technique incorporates reliability and economic analyses and is applied to a published test system to illustrate the results and their influence on key system variables. The paper provides useful information to system planners and policy makers on wind energy application in electric power systems.     

浅论电力市场化改革与电力发展规划

通过对计划经济和市场经济的主要区别、电车工业的特点及我国电力工业特殊性的分析，认为在电力市场化改革过程中及市场化机制较为完善后，电力发展不能仅靠市场调节，仍然需要规划的指导，提出加强市场经济条件下规划工作的建议和措施。     

Reduced-order model of Type-C wind turbine generators

This paper presents a wind turbine generator (WTG) reduced-order model for time domain simulations. Selective modal analysis is used to reduce the model order by focusing on the most relevant modes and variables. In most cases, a single relevant mode is found; thus, a first-order model that captures the relevant mode is derived. Depending on the WTG dynamics, in some cases, reduced-order models of higher order are required. The proposed model is applied to both 4-bus and 39-bus test systems. The results show that the proposed reduced-order model closely resembles the impact of WTGs in a power system, even when large perturbations occur. Line and synchronous generator (SG) outages are taken into account. The proposed model reduces the simulation time and the power system model complexity.     

电网规划与地方规划有机结合的思考

通过分析电网规划与地方规划的现状和面临的问题,提出了具体的改进措施。