Ph.D. thesis: 150 p., 33 figures, 3 appendixes, 106 references.
POWER GRIDS, RENEWABLE ENERGY SOURCES, PHOTOVOLTAIC POWER PLANT, INSTABILITY, REDUNDANCY METHODS, LOCAL ELECTRIC POWER SYSTEM, COORDINATION OF SCHEDULES, POWER LOSSES, INTELLIGENT SYSTEMS
The dissertation study is devoted to the research and solution of an urgent scientific task, which is based on substantiation of methods for improving the balance reliability of power grids with renewable energy sources through the use of active electricity consumers.
The paper proposes to consider an electric grid with a significant amount of RES in the balance of power and electricity as a local electric power system (LES) with characteristic problems. In particular, this concerns the instability of generation of wind and photovoltaic power plants (WPPs, PVPs), the creation of a system of ways and means of RES reservation for reliable and high-quality power supply, regulation of electricity parameters in accordance with standards, ensuring self-organization and self-healing as necessary elements of Smart Grid technologies, etc.
For estimation the possibility and effectiveness of methods and means of redundancy of RES electricity generation instability, the criterion method of similarity theory is developed. The analysis of the proportionality and sensitivity of relative costs for possible methods and means of RES backup, it is shown that hydrogen technologies and coordination of power generation and consumption schedules in power plants are preferable. First of all, it is recommended using the possibilities of coordinating the schedules of electricity generation and consumption in local electric power systems (LES). For the value of electricity that remains unbalanced after such coordination, it is appropriate using the hydrogen produced in LES to fully balance it.
It is confirmed that costs per 1 kW of reserve capacity for RES to compensate for their generation instability is differed in sensitive. If measures to compensate for the instability of RES electricity generation are implemented in stages, it is advisable to start with the most effective and low-cost ones. The analysis shows that the coordination of electricity generation and consumption schedules in power plants and hydrogen technologies is one of these methods. Moreover, experience in using “active consumers” at multi-rate tariffs have already existed in power grids.
With increasing the amount of electricity generated by RES in the balance of the power system, the determination the power and electricity losses in power grids caused by electricity flows from RES is important. A method, algorithm, and program for determining the component of power and electricity losses from RES in the total losses of electric power grids have been developed. The method is based on a mathematical model of an electric network for determining losses, which uses the coefficients of current distribution in the branches of the circuit from RES nodes and nodal voltages. As a result, a matrix of power loss distribution coefficients in the branches of the circuit depending on the power in the circuit nodes is formed. The voltages used to form the loss distribution matrix are determined based on the results of calculating the steady-state modes of the power grid or on experimental measurement data. The values of electricity losses in power grids caused by RES can be used in the operational planning of the electricity balance in the EPS and, since they are targeted, their cost can be compensated accordingly.
At present, RES are geographically dispersed in the UPS, which complicates the formation of local power systems, which, while operating in normal modes in parallel with the UPS as balancing groups, can operate in isolation in an autonomous mode in extreme cases. However, the distraction of RES does not allow for the effective formation of local electric power system (LES) in such a way that they ensure the required level of reliability of power supply to electricity consumers. The dissertation proposes to integrate RES into distribution power grids in the form of separate microgrid (MG), which is a key part of the transition to a local electric power system (LES) operating on the principles of SMART Grid. Local MGs, in addition to generation sources and consumers, also have the means to accumulate a certain amount of energy. To ensure the technical and economic efficiency, MGs are combined into an intelligent control system that allows for more rational use of MG resources, effective interaction with the distribution network, and the use of active electricity consumers in the process of balancing the power system mode. The hierarchical structure of the intellectual system of local electric power system (LES) is proposed in the dissertation. Thus, structured LES with smart grids during the limitation of centralized power supply can’t lose renewable energy sources but fully utilize their advantages togeth.
