Formulation Of Operation Strategy And Development Of Grid-connected Monitoring System For Sodium-sulfur Battery

Nowadays,our country is vigorously developing clean energy represented by new energy sources such as wind power and photovoltaic power generation.However,with the increasing installed capacity of new energy and the influence of natural conditions,the grid-connected new energy greatly reduces the frequency stability of power grid.Energy storage battery has a strong ability to suppress frequency changes,and the energy storage power station composed of it can achieve frequency "peak-shaving and valley-filling" when combined with new energy.Sodium-sulfur batteries,as a kind of secondary batteries with broad application prospects,are developing slowly,and there are few related research institutions in China.Therefore,it is urgent to develop a battery monitoring system matching the parameters and operating conditions of sodium-sulfur batteries for its test and operation,and the effect of stabilizing frequency changes after grid connection should be evaluated effectively.Relying on the platform of sodium sulfur battery,this paper mainly does the following work:According to the parameters of batteries and the actual situation of field connection,the overall structure of the monitoring system is designed on the basis of determining the monitoring requirements and accuracy requirements.The sodium sulfur battery monitoring system is composed of two parts: the host computer and the slave computer.The slave computer mainly realizes the collection and transmission of information of single battery,the acquisition of main circuit information and the relay protection function.In order to ensure the safe operation of the system,a feedback circuit is designed in the main circuit to ensure the reliable operation of the relay protection circuit.The data errors of single cell battery information and main circuit information are analyzed by field measured battery data.The calculation results show that the measurement accuracy meets the expected requirements.The host computer mainly realizes the development of human-computer interaction interface.The main functions of the interface are battery information display,information display and control of auxiliary equipment(Furnace Temperature Controller and bi-directional inverter)for grid-connected battery operation,data storage and viewing.In addition,in order to make the battery charge and discharge smoothly,SOC estimation and battery data simple summary function are added.At the same time,in order to facilitate the field staff,the relevant interface also designed some buttons that are easy to control and display module that is easy to observe the status of the monitoring system.After formulating the operation strategy of the monitoring system,the reactive power compensation scheme of the inverters is also analyzed.In order to evaluate the effect of frequency adjustment of sodium sulfur batteries after grid connection,established a correlation model for primary and secondary frequency modulation of the power grid.Specially,the corresponding simulation model was established according to the parameters and operation data of sodium sulfur batteries.Using the established model,the combined operation units of energy storage-thermal power and energy storage-wind power under different modes are built respectively.The simulation results show that when the sodium sulfur battery runs in combination with other generators,the effect of the sodium sulfur battery on the frequency stabilization is excellent.Finally,based on accurate data statistics and analysis,the application prospect of frequency modulation for sodium sulfur batteries is analyzed.The sodium sulfur battery monitoring system has realized the battery test and trial operation,and the simulation results also show that it has good frequency regulation function.