Gao Kai

Bio: Gao Kai is an academic researcher from Shenyang University of Technology. The author has contributed to research in topics: Renewable energy & Electricity generation. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

Research on Joint Planning of the Source-Grid-Load with New Energy System Energy Balance and Economy

Abstract: With the rapid development of the economy and the depletion of conventional energy sources, it is imperative to vigorously develop new energy sources. The new energy power generation industry, represented by wind power and photovoltaic power generation, has gradually become industrialized and scaled up. Its grid-connected operation effectively relieves the load pressure that the grid is subjected to. However, the output of new energy sources is random and uncontrollable. After grid connection, it will increase the uncertainty of the system and affect the stable operation of the system. Therefore, how to safely and effectively absorb intermittent renewable energy has become a major practical problem facing the new energy power system. Current research results at home and abroad mainly focus on the optimal design of the power supply on the supply side, the optimal dispatch strategy on the grid side, and the demand side. Response mechanism and planning management. Studies involving the stability and economics of power system operation and the joint planning of source and load resources are still in the preliminary stage. Therefore, the establishment of a new energy power system energy balance, economy and the joint planning model of the source and the load provide a theory for the country to promote supply-side structural reforms, formulate phased energy-saving emission reduction targets, renewable energy power supply construction standards and electricity price subsidies and other related policies.

Study on Large-Scale Clean Energy Dissipation Dispatch Method

Abstract: Because of the intermittent, volatile and random nature of most clean energy sources, it is difficult to control and is not easy to use. In the field of new energy power generation, the large-scale network access of energy power will not only increase the impact on the operation of the power grid, but also have a great impact on the existing power grid operation and management modes. With the increase of installed capacity such as wind power and photovoltaic power, the impact of volatility and randomness on the grid has also become apparent. In this paper, a large-scale dispatching solution is proposed to address the reality of large-scale clean energy generation in the power grid, and the impact of renewable energy generation uncertainty on the power grid is addressed.

Dispatching optimization model of gas-electricity virtual power plant considering uncertainty based on robust stochastic optimization theory

Abstract: With the rapid development of renewable energy, virtual power plant technology has gradually become a key technology to solve the large-scale development of renewable energy. This paper focuses on the stochastic dispatching optimization of gas-electric virtual power plant (GVPP). Based on this, wind power plant, photovoltaic power generation and convention gas turbines are used as the power generation side of GVPP. Power-to-gas (P2G) equipment and gas storage tank can realize the conversion and storage of electricity-gas energy. Price based demand response and incentive based demand response are introduced into the terminal load side to regulate the user’s electricity consumption behavior. GVPP bilaterally connects power network and natural gas network, which realizes the bidirectional flow of electricity-gas energy. Firstly, taking the maximization of economic benefits as the objective function, combined with the constraints of power balance, system reserve and so on, a dispatching optimization model of GVPP participating in multi-energy markets is constructed to determine the operation strategy. Secondly, wind, solar and other clean energy have the characteristics of random and fluctuation, which threaten the stable operation of the system. Therefore, a stochastic dispatching optimization model of GVPP considering wind and solar uncertainty is established based on robust stochastic optimization theory. Thirdly, the evaluation indicators of GVPP operation is determined, which can comprehensively evaluate the economic benefits, environmental benefits and system operation of virtual power plant. Finally, in order to verify the validity and feasibility of the model, a virtual power plant is selected for example analysis. The results show that: (1) After the implementation of price based demand response and incentive based demand response, the system load variance changes from 0.03 to 0.013. Through the comparison of load curves, it is found that demand response can play a role of peak-shaving and valley-filling and smooth the power load curve; (2) Stochastic optimization theory can overcome the uncertainty of wind and solar by setting different robust coefficients Γ which reflects the ability of the system to withstand risks; (3) The optimization effect after introducing the P2G subsystem makes the amount of abandoned clean energy close to zero. The operation risk of system is reduced, and the carbon emissions are reduced by 370 m3 too. The market space is expanded from electricity market mainly to natural gas market and carbon trading market.

Modeling and Stability Analysis of Parallel Inverters in Island Microgrid

Abstract: The island microgrid is composed of a large number of inverters and various types of power equipment, and the interaction between inverters with different control methods may cause system instability, which will cause the power equipment to malfunction. Therefore, effective methods for analyzing the stability of the microgrid system have become particularly important. Generally, impedance modeling methods are used to analyze the stability of power electronic converter systems. In this paper, the impedance models of a PQ-controlled inverter and droop-controlled inverter are established in d-q frame. In view of the difference of output characteristics between the two control methods, the island microgrid is equivalent to a double closed-loop system. The impedance model of the parallel system is derived and the open loop transfer function of the system is extracted. Based on the generalized Nyquist criterion (GNC), the stability of parallel system working in island microgrid mode is analyzed using this proposed impedance model. The simulation and experiment results are presented to verify the analysis.

Framework of a Simplified Large-Scale Source-Grid-Load Friendly Interaction System

Abstract: The framework of a simplified large-scale source-grid-load (SGL) friendly interaction system is proposed in this paper. In this simplified system, the control subordinate station (CSS) is merged into the control main station (CMS), eliminating the need to install a large number of CSS. The proposed method can not only save the cost, but also, more importantly, simplifies the control process and reduces the time required to cut off the interruptible load in the event of fault. Meanwhile, the corresponding load selection and shedding methods and processes must be also adjusted. A load shedding process for a precision load shedding system is introduced: on the basis of the classification of the load, different levels of load have been prescribed with different priorities, and the CMS formulates the corresponding load-shedding command according to the planned rules, and sends it to each load control terminal (LCT). The LCT immediately cuts off the corresponding load after receiving the command, in the shortest complete the load shedding task in time and minimizes the impact.

The stability analysis of new power generation based on Ostrowski’s theorem

Abstract: The parameter mismatch between the source side and the grid side of the grid-connected system of new energy generation is one of the factors affecting the stable operation of the grid connected system. In order to ensure the safe and stable operation of the system, the stability region of system parameters is worth studying. In this paper, a fast estimation method of stable region of impedance parameters for grid connected inverters is proposed. Firstly, the impedance model of grid-connected system in dq coordinate system is established based on the impedance analysis method, and the return matrix which is the main element influencing the stability is analyzed and deduced. Secondly, the bands containing eigenvalue loci of the return matrix are obtained based on Ostrowski's theorem, and the stability of the system is judged by Nyquist stability criterion. Finally, the simulation results show that the proposed method can quickly estimate the stable region of the impedance parameters of the grid-connected inverter, which verifies the correctness of the method.