CN114123215A

CN114123215A - Sag treatment method based on PIT

Info

Publication number: CN114123215A
Application number: CN202111459830.7A
Authority: CN
Inventors: 康忠健; 刘佳萱; 孙翼森
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2021-12-02
Filing date: 2021-12-02
Publication date: 2022-03-01

Abstract

The invention discloses a voltage sag control method based on PIT. According to the method, the electromagnetic transient model of the chemical device is built, then the stable state of the sensitive loads in the system is analyzed one by one, and the motor start-stop experiment is carried out, so that the verification of the model effectiveness is completed. By changing the voltage sag depth and the voltage sag time and considering the physical indexes of each subprocess device under the process flow influencing the state of the whole process, the process immunity time curve of each sensitive load in the system is obtained, and then the process immunity time of the whole chemical device system is evaluated. And selecting a proper anti-interference electricity strategy, calculating the capacity and current value required by the voltage sag treatment device according to the load side nameplate parameters, selecting the type of the required voltage sag treatment device according to the cutting time, the current and the capacity requirement, and finally verifying the effectiveness of the anti-interference electricity strategy based on the magnetic transient model.

Description

Sag treatment method based on PIT

Technical Field

The invention belongs to the field of electricity, and particularly relates to a voltage sag treatment method based on process immunization time.

Background

Enterprises such as coal, petrochemical, metallurgy, pharmacy and chemical industries are particularly sensitive to electricity interference due to high control precision requirements of production processes, and serious accidents and losses can be caused by interruption of electricity interference in the process. The fundamental reason that system power-fail causes production process interruptions is that the voltage sag tolerance of the production process is not compatible with the supply voltage sag level. With the development of smart grid construction and various industry technologies, users have higher and higher requirements on power quality, especially voltage sag, which has become the most complaint power quality problem and causes great economic loss. In order to improve the adaptability of the sensitive load in the voltage sag process, voltage sag treatment equipment is installed to cooperatively treat the sensitive load at a user side, and the probability of offline and tripping of the sensitive equipment in the voltage sag process is reduced by combining a process immunity time curve of the load, so that the power quality of a power grid is improved.

The voltage sag time of the power supply system is extremely short, generally within 200ms, and the equipment fails after being influenced by the voltage sag, so that the process is interrupted. Following this logical sequence, the general procedure for voltage sag tolerance characteristic evaluation of the process is to determine device failure first and then to determine process interruption. For the determination of device failure, conventional evaluation is based on the voltage sag tolerance curve of the device, which is often sensitive. The ITIC curve is a voltage endurance curve of computer equipment proposed by the information technology industry association based on the requirement of a large computer on the quality of electric energy; the SEMI F47 curve is a voltage sag tolerance curve established by the international society for manufacturing semiconductor devices and materials, and is suitable for use in semiconductor processing, metrology, and automatic test equipment. The two curves are used for comparing the voltage sag characteristic quantity with the voltage tolerance range of the equipment to obtain the influenced state of the equipment. In practice, a single equipment interruption does not immediately result in some process interruption, the nature of which is that the physical parameters (e.g., temperature, velocity, torque, pressure, etc.) reflecting the efficacy of the equipment are outside the process requirements. The CIGRE/circed combined working group C4.110 proposed the concept of the process parameter immune time pit (parameter Immunity time) in 2010 and provided a test method proposal.

The PIT is used for evaluating the anti-interference electricity capability of the power unit of the chemical enterprise, and the process parameters refer to physical indexes which are influenced by each sub-process device under the total process, such as temperature, pressure, valve flow and the like, and are related to element types; PIT is an industry process proposed standard for temporarily reducing immunity.

Based on system modeling, the process immunization time of a single device under different sag depths is obtained. And putting the series of curves into the same coordinate system, further determining comprehensive PIT values of different sag depths, drawing a scatter diagram of the comprehensive PIT values, and taking an envelope line to obtain the comprehensive PIT curve of the chemical plant system. From the logical relationship of the devices and the respective PIT curves, the comprehensive PIT of the whole chemical plant can be obtained by the following formula 1:

PIT_x＝min(PIT₁,PIT₂,...,PIT_m) (1)

in the formula, PIT_xIs the comprehensive PIT of the whole chemical device; PIT (particle image transfer)_k(k ═ 1, 2, …, m) is the course immunization time for each individual device.

The method is characterized in that the process parameter immunity time is firstly combined at home and abroad, a chemical device source-net-charged magnetic transient model is built, the physical indexes of each subprocess device influencing the whole process state under the process flow are considered, the process immunity time of the whole chemical device system is evaluated, a proper anti-electricity-dazzling strategy is selected, the capacity and the current value required by the voltage sag control device are calculated according to the load side nameplate parameters, and the required voltage sag control device is selected according to the requirements of the removal time, the current and the capacity.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art and provides a voltage sag treatment method based on the process immunization time. The method can effectively evaluate the immune time of the whole system in the stable operation process, comprehensively consider the aspects of economic budget, feasibility, effectiveness and the like, determine the voltage sag treatment strategy of the whole chemical device system, select the treatment device, improve the anti-interference capacity of the chemical device system and realize the improvement of the power quality.

The technical solution of the invention is as follows: a voltage sag treatment method based on process immunization time comprises the following steps:

(1) building an electromagnetic transient model of a chemical device system;

(2) carrying out an anti-interference electricity tolerance analysis test by combining the sensitive load process protection value, and evaluating the process immunity time of the device;

(3) based on the process immunization time, comprehensively considering the aspects of economic budget, feasibility, effectiveness and the like, and determining a voltage sag control strategy of the whole chemical engineering device system;

(4) carrying out model selection on a treatment device applied to a sensitive load anti-interference strategy;

(5) and verifying the effectiveness of the voltage sag control strategy in improving the anti-interference capacity of the device based on the model.

The embodiment of the invention has the following advantages:

(1) the method is combined with the process parameter immunity time PIT for the first time at home and abroad, a source-network-charged magnetic transient model is built, and the process immunity time of the chemical device system is estimated based on the model.

(2) Based on the process immunization time of the chemical device system, the capacity and the current value required by the load side are calculated according to the nameplate parameters, and theoretical basis is provided for reasonable model selection of the anti-electricity-dazzling device in the actual production process according to the delay time, the current and the capacity requirement, so that the requirement of the intelligent power distribution network is met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that the present invention can be implemented, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the effects and the achievable by the present invention, should still fall within the range that the technical contents disclosed in the present invention can cover.

FIG. 1 is a flow chart of a voltage sag management method based on process immunization time according to the invention.

FIG. 2 is a schematic diagram of a source-net-load integration model design based on process immunization time according to the present invention. The transient sensitive multiple processes are summarized into a power grid + motor + fan or pump composite model, and a corresponding voltage grade bus and an outlet wire thereof, a relay low-voltage tripping device, a motor and a pump load carried by the motor are built in the model.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 2, the present invention provides a source-grid-charged magnetic transient model based on process immunity time, which includes a corresponding voltage class bus and its outgoing line, a voltage sag control device, a motor and its carried pump load.

According to the above device, as shown in fig. 1 and fig. 2, the present invention provides a voltage sag management method based on PIT, which comprises the following steps:

(1) collecting various electrical parameters of circuits and pumps in the system;

(2) constructing a source-network-charged magnetic transient model;

(3) evaluating the immune time of the system process of the chemical device based on the electromagnetic transient model;

(4) calculating the capacity and the current value required by the load side according to the nameplate parameters, determining a voltage sag treatment strategy and carrying out model selection on the required voltage sag treatment device according to the cutting time, the current and the capacity requirements;

(5) and (4) building a simulation model after the voltage sag treatment device is added, and verifying the effectiveness of the anti-interference strategy by comparing whether the voltage sag time is shortened compared with that before treatment.

The method combines the process immunity time technology for the first time at home and abroad, and provides a method for setting and selecting parameters of the voltage sag treatment device. The critical cutting time of the stable operation of the whole system can be effectively determined, and the corresponding voltage sag treatment device is selected at the load side according to the power of the sensitive equipment for treatment, so that the anti-interference electricity tolerance of the important equipment of the device is improved, the safe operation of petrochemical enterprises is realized, and the quality of electric energy is stably improved.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the present invention without departing from the technical spirit of the present invention.

Claims

1. A sag treatment method based on PIT is characterized in that: according to the electrical parameters of the chemical device system and the technological parameters of the sensitive load, such as rotating speed, lift and flow, a source-network-charged magnetic transient integrated model of the chemical device system is built, the process immunity time of each sensitive device in the system is analyzed and evaluated, and then the process immunity time of the chemical device system is obtained according to the process immunity time of the minimum cut set of each sensitive device. Based on the process immunization time of the chemical device system, the selected treatment device and the parameters thereof are determined, and the effectiveness of the treatment strategy is analyzed and evaluated, so that technical support is provided for improving the anti-interference capacity and the electric energy quality in the process flow of the petrochemical enterprise.

2. The integrated electromagnetic transient model of chemical plant system of claim 1, wherein: aiming at the condition that a motor carries a pump load in the system, a two-mass model is constructed to obtain a process immune time curve of each sensitive load in the system, and then the process immune time of the whole chemical device system is obtained by integrating the upper envelope curve of the process immune time curve of each sensitive load.

3. A source-network-charged magnetic transient integrated model is characterized in that: the system comprises buses of all voltage classes in a chemical device system and an integrated model of outgoing lines, motors and sensitive loads of the buses, the motors and the sensitive loads, and can detect electrical parameters such as voltage, active power, reactive power and the like of the buses, the induction motors and pump loads of all voltage classes and process parameters such as lift and flow.