CN107117058B - A power quality monitoring system for electric vehicle charging stations - Google Patents

Abstract

The invention relates to the technical field of power quality of electric power systems, and in particular to a power quality monitoring system for electric vehicle charging stations, which is suitable for power quality monitoring, evaluation and management of centralized electric vehicle charging stations. It consists of three connected parts: power supply system, charging system and monitoring system. The power supply system, charging system and monitoring system are respectively connected to the power quality monitoring device of the charging station. DC charging is connected between the charging system and the power quality monitoring device of the charging station. Mechanical and electrical energy quality monitoring terminal and AC charger electrical energy quality monitoring terminal; the monitoring system is also connected to the central server, management client and data server. It has a unified timing function, which can ensure maximum safety, realize power quality monitoring, analysis, evaluation and prediction of charging stations, locate, analyze, compare, evaluate and diagnose power quality problems caused by a single charger branch and the charger itself. Ensure data consistency and comparability at all measurement points.

Description

A power quality monitoring system for electric vehicle charging stations

Technical field

The invention relates to the technical field of power quality of electric power systems, and in particular to a power quality monitoring system for electric vehicle charging stations, which is suitable for power quality monitoring, evaluation and management of centralized charging stations for electric vehicles.

Background technique

Electric vehicles are one of the key directions for the development of new energy vehicles. They are of great significance for energy conservation, environmental protection, and reduction of carbon emission pollution. Electric vehicle charging facilities are an important part of the electric vehicle industry chain, so the development of charging facilities and charging facilities must be fully considered. The impact on the power quality of the power grid is crucial.

At present, a variety of electric vehicle charging modes have been proposed at home and abroad, mainly the most common slow charging mode, that is, charging electric vehicles with a lower charging current, usually using AC charging piles; and using a higher charging current to charge electric vehicles in a short period of time. A fast charging method for charging batteries inside is usually a centralized electric vehicle charging station, and its main equipment is a DC charger. In particular, the large-scale use of centralized electric vehicle charging stations will not only have an impact on grid planning and capacity expansion, but also have a great impact on the power quality of the power system, which is mainly manifested in: load imbalance, that is, When charging stations use high-current fast charging, a large current of 150 to 600A will be formed, which may cause instability in the power grid, and excessively intensive centralized charging may cause excessive instantaneous load on the charging station, affecting the load regulation and load capacity of the power grid. and power supply capacity will cause tests; harmonic pollution, that is, large-capacity chargers using power electronic devices produce harmonics, causing increased additional losses and heat in the lines or transformers, causing local inductors and capacitors in the power grid to resonate, making harmonics further Amplified, higher harmonics can cause malfunctions of control equipment, thereby causing production or operation interruptions; for switches and relay protection equipment, harmonics may cause the solid-state tripping device of electronically protected low-voltage circuit breakers to trip abnormally. It may cause interference to the protection and automatic devices of the starting components composed of sequence component filters; as well as voltage deviation, frequency deviation, voltage flicker, three-term imbalance, etc.

Currently, there is no power quality monitoring system for electric vehicle charging stations, especially centralized electric vehicle charging stations that use large-capacity DC fast chargers. In particular, the current charging stations may be equipped with power quality monitoring systems, or electric energy Quality control methods, such as using grid-side harmonic control methods for electric vehicle charging stations that have been put into operation, and investing in specific equipment for harmonic control to prevent the charging stations from injecting harmonic current into the grid. The above are all for the entire charging station. The power quality is monitored and protected, but a separate branch in a station, such as a DC charger, cannot be monitored, evaluated, and managed online.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, the present invention provides an electric vehicle charging station power quality monitoring system. The purpose is to provide a power quality monitoring and management system suitable for large-scale centralized electric vehicle charging stations. The system can realize power quality monitoring, analysis, evaluation and prediction of the entire charging station, and can locate, analyze, compare, evaluate and predict. Diagnose power quality problems caused by a single charger branch and the charger itself, and the system uses a unified timing function to ensure data consistency and comparability at all measurement points.

In order to achieve the above objects, the technical solution adopted by the present invention is:

A power quality monitoring system for electric vehicle charging stations, which consists of three connected parts: a power supply system, a charging system and a monitoring system; the power supply system, the charging system and the monitoring system are respectively connected to the power quality monitoring device of the charging station; the charging system and the charging The station power quality monitoring device is connected to a DC charger power quality monitoring terminal and an AC charger power quality monitoring terminal; the monitoring system is also connected to the central server, management workstation and data server.

The charging system includes a DC charger and an AC charger. The DC charger is connected to the DC charger power quality monitoring terminal; the AC charger is connected to the AC charger power quality monitoring terminal; the monitoring system includes the power quality of the charging station. Monitoring platform, charging station security monitoring system and charging station charging monitoring system. The charging station power quality monitoring platform is connected to the charging station power quality monitoring device. The charging station power quality monitoring platform is also connected to the central server, management workstation and data server.

The charging station power quality monitoring device, DC charger power quality monitoring terminal and AC charger power quality monitoring terminal communicate through communication links and upload power quality data to the charging station power quality monitoring platform; all data are run on the central server The corresponding functional modules of the charging station power quality monitoring platform are processed and stored in the data server; the management workstation realizes the access, control, management, data presentation and user interface of the system platform.

The charging station power quality monitoring platform runs on the central server and includes power quality analysis, power quality trend prediction, power quality assessment, branch power quality comparison and evaluation, charging station load monitoring and analysis, timing module, and communication module , protection module, data processing module, data storage module, data query module and user access; the charging station power quality monitoring device, DC charger power quality monitoring terminal and AC charger power quality monitoring terminal will obtain the power quality data through communication The link is uploaded to the charging station power quality monitoring platform. Power quality analysis analyzes the various power quality data obtained. Power quality trend prediction realizes power quality trend prediction based on current and historical power quality data. Power quality assessment realizes the power quality status of the charging station. Assessment; comparison and evaluation of branch power quality. The power quality data of the DC charger or AC charger obtained through analysis and comparison and combined with the overall power quality data of the charging station; charging station load monitoring and analysis, real-time calculation and monitoring of charging. The load status of the station and provides data support functions for power quality monitoring; the timing module can be compatible with both GPS and Beidou systems to ensure the time accuracy of the entire power quality monitoring system and the time synchronization function of each subsystem; the communication module provides internal All communication management functions; the protection module provides the protection functions required by the system; after the data processing module uniformly processes the underlying original data, the data storage module stores the processed data in the data server, and the system queries the data stored in the server through the data query module Data; user access provides a unified access interface for management workstations.

The charging station power quality monitoring device includes a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module; the device passes through the current monitoring module, The voltage monitoring module, frequency monitoring module, and power monitoring module cooperate with each other to realize the back-end of the charging station power supply system, that is, the multiple harmonic voltages and harmonic currents, the fundamental voltage RMS and true RMS values within the entire charging station, Collection of power quality data such as current fundamental wave effective value and true effective value, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental wave active power, true power factor, system frequency deviation; the timing module realizes the system Unified timing function; the communication module is responsible for sending and receiving communication instructions and power quality data with the charging station power quality monitoring platform; the protection module issues early warning information and automatically executes when monitoring or predicting extreme situations in the monitored object based on collected data Corresponding protection actions; the UI module provides user settings and operation interaction functions; the storage and wave recording module stores the collected data in the local data space in real time according to the preset period and data type.

The DC charger power quality monitoring terminal includes a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module; the device passes the current monitoring module The cooperation of voltage monitoring module, frequency monitoring module and power monitoring module can monitor multiple harmonic voltages and harmonic currents at the front end of the DC charger, voltage fundamental wave effective value and true effective value, and current fundamental wave effective value. and collection of power quality data such as true effective value, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental active power, true power factor, system frequency deviation; the timing module realizes the unified timing function of the system; communication The module is responsible for sending and receiving communication instructions and power quality data between charging and charging to the power quality monitoring platform; the protection module sends out early warning information and automatically performs corresponding protection actions when monitoring or predicting extreme conditions in the monitored object based on the collected data; The UI module provides user settings and operation interaction functions; the storage and wave recording module stores the collected data in the local data space in real time according to the preset period and data type.

The AC charger power quality monitoring terminal includes a current monitoring module, a voltage monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module; the monitoring terminal uses the current monitoring module, voltage monitoring module The module and the power monitoring module cooperate with each other to collect the RMS and true RMS values of the voltage fundamental wave, the RMS and true RMS values of the current fundamental wave, voltage deviation, three-phase voltage imbalance, voltage fluctuation and flicker, and fundamental wave active power. , true power factor and other power quality data; the timing module realizes the unified timing function of the system; the communication module is responsible for sending and receiving communication instructions and power quality data between charging and charging to the power quality monitoring platform; the protection module is used to monitor or prepare based on the collected data. When an extreme situation occurs to the monitored object, an early warning message is issued and corresponding protective actions are automatically executed; the UI module provides user settings and operation interaction functions; the storage and wave recording module stores the collected data in real time according to the preset period and data type. Local data space.

The power quality monitoring system has a unified timing function, supports Beidou and GPS dual timing, and uses, stores, and analyzes power quality data at each node in the system, including a charging station power quality monitoring platform and a charging station power quality monitoring device. , DC charger power quality monitoring device terminal and AC charger power quality monitoring terminal both have time domain and frequency domain characteristics to ensure data consistency and traceability of power quality, especially harmonics and phases.

The charging station power quality monitoring device, DC charger power quality monitoring device terminal and AC charger power quality monitoring terminal themselves can analyze and manage power quality data. On the other hand, the charging station power quality monitoring platform can analyze and manage power quality data based on the obtained data. The data of each node are used to analyze and evaluate the power quality of the branch. Especially for harmonic pollution, harmonic offset or increase of multiple nodes may occur. The data obtained by the system through the power quality monitoring device of the charging station is compared with the data obtained at the same time. Analyze and compare data from DC charger power quality monitoring device terminals and AC charger power quality monitoring terminals on each branch to locate, analyze, compare, evaluate and diagnose power quality problems caused by a single charger branch and the charger itself. .

A monitoring method of the power quality monitoring system of an electric vehicle charging station is:

Users manage the system through the charging station power quality monitoring platform running on the central server and its supporting management workstation, including system security management, system configuration, and data analysis and query functions;

Further, the user starts or stops the system through the management workstation;

Furthermore, the user controls the charging station power quality monitoring platform through the management workstation to use a unified timing function for the charging station power quality monitoring device, DC charger power quality monitoring terminal and AC charger power quality monitoring terminal to ensure consistent data at all measurement points sex and comparability;

Further, a charging station power quality monitoring device is provided at the back end of the charging station power supply system, a DC charger power quality monitoring terminal is provided at the front end of a single DC charger, and an AC charger power quality monitoring terminal is provided at the front end of a single AC charger. Maintain online operation without interruption, and collect and store power quality data in real time.

Further, the charging station power quality monitoring device, DC charger power quality monitoring terminal and AC charger power quality monitoring terminal perform local preprocessing and local storage of temporary data, and at the same time upload it to the charging station power quality monitoring platform;

Further, the charging station power quality monitoring platform stores or reads data from the data server;

Furthermore, the charging station power quality monitoring platform realizes power quality monitoring, analysis, evaluation and prediction of electric vehicle charging stations based on various data received, and can locate, analyze, compare, evaluate and diagnose individual charger branches and Power quality problems caused by the charger itself;

Furthermore, users can query and access all data through the management workstation, and form various forms and reports.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention has a unified timing function, supports Beidou and GPS dual timing, and can ensure maximum safety.

(2) Power quality data used, stored and analyzed at each node in the system, including charging station power quality monitoring platform, charging station power quality monitoring device, DC charger power quality monitoring device terminal and AC charger power quality monitoring terminal They are all time domain and frequency domain characteristics, so data consistency and traceability of power quality, especially harmonics and phases, can be achieved.

(3) On the one hand, the charging station power quality monitoring device, DC charger power quality monitoring device terminal and AC charger power quality monitoring terminal of the present invention can analyze and manage power quality data themselves. On the other hand, the charging station power quality monitoring platform Analysis and evaluation of branch power quality can be carried out based on the data obtained from multiple nodes. Especially for harmonic pollution, harmonic offset or increase of multiple nodes may occur. The system obtains data through the charging station power quality monitoring device. Analyze and compare with the data of DC charger power quality monitoring device terminals and AC charger power quality monitoring terminals on each branch obtained during the same period, so as to locate, analyze, compare, evaluate and diagnose a single charger branch and the charger itself power quality problems caused.

Description of the drawings

Figure 1 is a system logical structure diagram of the present invention;

Figure 2 is a physical communication topology diagram of the present invention;

Figure 3 is a system functional block diagram of the present invention.

In the figure: power supply system 101; charging system 102; monitoring system 103; charging station power quality monitoring platform 200; charging station power quality monitoring device 201; DC charger power quality monitoring terminal 202; AC charger power quality monitoring terminal 203; DC Charger 204; AC charger 205; management workstation 301; central server 302; data server 303.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, specific implementation modes of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described here are used to explain the present invention and are not intended to limit the present invention.

The present invention is a power quality monitoring system for electric vehicle charging stations. As shown in the system logical structure diagram of Figure 1, the system of the present invention includes three connected parts: a power supply system 101, a charging system 102 and a monitoring system 103. The power supply system 101 and the monitoring system 103 are respectively connected to the charging station power quality monitoring device 201. A DC charger power quality monitoring terminal 202 and an AC charger power quality monitoring terminal are connected between the charging system 102 and the charging station power quality monitoring device 201. 203; The monitoring system 103 is also connected to the central server 302, the management workstation 301 and the data server 303.

The charging system 102 includes a DC charger 204 and an AC charger 205. The DC charger 204 is connected to the DC charger power quality monitoring terminal 202; the AC charger 205 is connected to the AC charger power quality monitoring terminal 203.

The monitoring system 103 includes a charging station power quality monitoring platform 200, a charging station security monitoring system and a charging station charging monitoring system. The charging station power quality monitoring platform 200 is connected to the charging station power quality monitoring device 201. The charging station power quality monitoring platform 200 is also connected to the central server 302, management workstation 301, and data server 303.

The present invention will be described in more detail below:

The present invention includes a charging station power quality monitoring device 201 arranged at the rear end of the charging station power supply system 101, a DC charger power quality monitoring terminal 202 arranged at the front end of a single DC charger 204, and an AC charging electromechanical device arranged at the front end of a single AC charger 205. The energy quality monitoring terminal 203, as well as the charging station power quality monitoring platform 200 running on the central server 302 and its supporting management workstation 301 and data server 303; the charging station power quality monitoring device 201 realizes the power quality monitoring of the entire charging station; Each DC charger power quality monitoring terminal 202 implements power quality monitoring corresponding to the DC charger; the AC charger power quality monitoring terminal 203 implements power quality monitoring corresponding to the AC charger.

As shown in the physical communication topology diagram of Figure 2, the system is connected through communication links. The charging station power quality monitoring device 201, DC charger power quality monitoring terminal 202 and AC charger power quality monitoring terminal 203 communicate and upload through communication links. The power quality data is sent to the charging station power quality monitoring platform 200; all data is processed by the corresponding functional modules of the charging station power quality monitoring platform 200 running on the central server 302 and stored in the data server 303; the management workstation 301 implements the system platform Access, control, management, data presentation and user interface accept the management, scheduling and control of the charging station power quality monitoring platform 200 running on the central server 302, and together with the data server and the central server constitute an electric vehicle charging station power Quality control system. The charging station power quality monitoring platform 200 can realize power quality monitoring, analysis, evaluation and prediction for the entire electric vehicle charging station, and can locate, analyze, compare, evaluate and diagnose power quality problems caused by a single charger branch and the charger itself. . The system uses a unified timing function to ensure data consistency and comparability at all measurement points.

As shown in the system functional block diagram of Figure 3, the charging station power quality monitoring platform 200 runs on the central server 302 and includes power quality analysis, power quality trend prediction, power quality assessment, branch power quality comparison and evaluation, Charging station load monitoring and analysis, timing module, communication module, protection module, data processing module, data storage module, data query module and user access and other modules; charging station power quality monitoring device 201, DC charger power quality monitoring The terminal 202 and the AC charger power quality monitoring terminal 203 upload the acquired power quality data to the charging station power quality monitoring platform 200 through the communication link. The power quality analysis analyzes the various acquired power quality data, and the power quality trend prediction is implemented based on the current situation. Predict power quality trends with historical power quality data; power quality assessment realizes the assessment of the power quality status of charging stations; compare and evaluate branch power quality. The power quality data of DC chargers or AC chargers are obtained through analysis and comparison, and and the overall power quality data of the charging station; charging station load monitoring and analysis calculates and monitors the load status of the charging station in real time, and provides data support functions for power quality monitoring; the timing module can be compatible with both GPS and Beidou systems to ensure the entire power quality monitoring The time accuracy of the system and the time synchronization function of each subsystem; the communication module provides all communication management functions within the system; the protection module provides the protection functions required by the system; the data processing module uniformly processes the underlying original data, and the data storage module The processed data is stored in the data server 303, and the system can query the data stored in the server through the data query module; user access provides a unified access interface for the management client 303.

Further, the charging station power quality monitoring device 201 includes a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module; device Through the cooperation of the current monitoring module, voltage monitoring module, frequency monitoring module and power monitoring module, the back-end of the charging station power supply system can be realized, that is, the multiple harmonic voltages, harmonic currents, and voltage fundamentals within the entire charging station are effectively Collection of power quality data such as value and true RMS value, current fundamental wave RMS and true RMS value, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental wave active power, true power factor, system frequency deviation, etc. ; The timing module realizes the unified timing function of the system; the communication module is responsible for sending and receiving communication instructions and power quality data with the charging station power quality monitoring platform 200; the protection module monitors or predicts extreme situations in the monitoring object based on the collected data. , issues early warning information and automatically executes corresponding protection actions; the UI module provides user setting and operation interaction functions; the storage and wave recording module stores the collected data in the local data space in real time according to the preset period and data type.

Further, the DC charger power quality monitoring terminal 202 includes a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module; Through the cooperation of the current monitoring module, voltage monitoring module, frequency monitoring module and power monitoring module, the device can monitor the multiple harmonic voltages and harmonic currents, fundamental voltage RMS and true RMS at the front end of the DC charger. , current fundamental wave effective value and true effective value, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental wave active power, true power factor, system frequency deviation and other power quality data collection; the timing module implements the system The unified timing function of Automatically execute corresponding protection actions; the UI module provides user settings and operation interaction functions; the storage and wave recording module stores the collected data in the local data space in real time according to the preset period and data type.

Further, the AC charger power quality monitoring terminal 203 includes a current monitoring module, a voltage monitoring module, a power monitoring module, a timing module, a communication module, a UI module, a protection module, a storage and wave recording module. Through the cooperation of current monitoring module, voltage monitoring module and power monitoring module, the monitoring terminal can realize the effective value and true effective value of voltage fundamental wave, the effective value and true effective value of current fundamental wave, voltage deviation, three-phase voltage unbalance, The collection of power quality data such as voltage fluctuation and flicker, fundamental wave active power, true power factor, etc.; the timing module realizes the unified timing function of the system; the communication module is responsible for sending and receiving communication instructions and charging to the power quality monitoring platform 200 and Power quality data; when the protection module monitors or predicts extreme conditions in the monitored object based on the collected data, it issues early warning information and automatically performs corresponding protection actions; the UI module provides user settings and operation interaction functions; the storage and wave recording module is based on preset settings. The collected data will be stored in the local data space in real time at a certain period and data type.

Furthermore, the power quality monitoring system for electric vehicle charging stations has a unified timing function, supports dual timing of Beidou and GPS, and can ensure safety to the greatest extent. The power quality used, stored, and analyzed at each node in the system The data, including the charging station power quality monitoring platform 200, the charging station power quality monitoring device 201, the DC charger power quality monitoring device terminal 202 and the AC charger power quality monitoring terminal 203, all have time domain and frequency domain characteristics, so it can be realized Data consistency and traceability of power quality, especially harmonics and phases.

Furthermore, in the described electric vehicle charging station power quality monitoring system, on the one hand, the charging station power quality monitoring device 201, the DC charger power quality monitoring device terminal 202 and the AC charger power quality monitoring terminal 203 can themselves perform power quality monitoring. Data analysis and management. On the other hand, the charging station power quality monitoring platform 200 can analyze and evaluate the branch power quality based on the acquired data of multiple nodes. Especially for harmonic pollution, harmonic cancellation or harmonic cancellation of multiple nodes may occur. increase phenomenon, the system analyzes and compares the data obtained through the charging station power quality monitoring device 201 with the data obtained during the period from the DC charger power quality monitoring device terminal 202 and the AC charger power quality monitoring terminal 203 on each branch, thereby Locate, analyze, compare, evaluate and diagnose power quality problems caused by individual charger branches and the charger itself.

The working process of the present invention is as follows:

Users manage the system through the charging station power quality monitoring platform 200 and its supporting management workstation 301 running on the central server 302, including system security management, system configuration, and data analysis and query functions.

Further, the user starts or stops the system operation through the management workstation 301.

Further, the user controls the charging station power quality monitoring platform 200 through the management workstation 301 to use a unified timing function for the charging station power quality monitoring device 201, DC charger power quality monitoring terminal 202 and AC charger power quality monitoring terminal 203 to ensure that all Data consistency and comparability at measurement points;

Further, the charging station power quality monitoring device 201 is provided at the rear end of the charging station power supply system 101, the DC charger power quality monitoring terminal 202 is provided at the front end of a single DC charger 204, and the AC charging motor is provided at the front end of a single AC charger 205. The power quality monitoring terminal 203 keeps running online continuously, and collects and stores power quality data in real time.

Further, the charging station power quality monitoring device 201, the DC charger power quality monitoring terminal 202 and the AC charger power quality monitoring terminal 203 perform local preprocessing and local storage of temporary data, and at the same time upload it to the charging station power quality monitoring platform. 200.

Further, the charging station power quality monitoring platform 200 stores or reads data from the data server 303 .

Further, the charging station power quality monitoring platform 200 realizes power quality monitoring, analysis, evaluation and prediction of the electric vehicle charging station based on various data received, and can locate, analyze, compare, evaluate and diagnose a single charger branch. and power quality problems caused by the charger itself.

Further, users can query and access all data through the management workstation 301, and form various forms and reports.

It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive from any angle, and the scope of the present invention is defined by the appended claims rather than the above description, and it is therefore intended that equivalents falling within the claims All changes within the meaning and scope of the requirements are included in the present invention. Any reference signs in the claims shall not be construed as limiting the claim in question.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any minor modifications, equivalent substitutions and improvements made to the above embodiments based on the technical essence of the present invention shall be included in the technical scope of the present invention. within the protection scope of the scheme.

Claims (2)

1. The electric vehicle charging station electric energy quality monitoring system comprises a power supply system (101) and a charging system (102) which are connected; the method is characterized in that: also comprises a monitoring system (103); the power supply system (101), the charging system (102) and the monitoring system (103) are respectively connected with the charging station power quality monitoring device (201); a direct-current charger power quality monitoring terminal (202) and an alternating-current charger power quality monitoring terminal (203) are connected between the charging system (102) and the charging station power quality monitoring device (201); the monitoring system (103) is also connected with the central server (302), the management workstation (301) and the data server (303);

the charging system (102) comprises a direct current charger (204) and an alternating current charger (205), wherein the direct current charger (204) is connected with a direct current charger power quality monitoring terminal (202); the alternating current charger (205) is connected with the alternating current charger power quality monitoring terminal (203); the monitoring system (103) comprises a charging station electric energy quality monitoring platform (200), a charging station security monitoring system and a charging station charging monitoring system, wherein the charging station electric energy quality monitoring platform (200) is connected with a charging station electric energy quality monitoring device (201), and the charging station electric energy quality monitoring platform (200) is also connected with a central server (302), a management workstation (301) and a data server (303);

the charging station electric energy quality monitoring device (201), the direct-current charger electric energy quality monitoring terminal (202) and the alternating-current charger electric energy quality monitoring terminal (203) communicate through a communication link and upload electric energy quality data to the charging station electric energy quality monitoring platform (200); all data are processed through corresponding functional modules of the charging station power quality monitoring platform (200) running on the central server (302) and then stored in the data server (303); the management workstation (301) realizes access, control, management and data presentation and user interface of the system platform;

the charging station power quality monitoring platform (200) is operated on the central server and comprises power quality analysis, power quality trend prediction, power quality assessment, branch power quality comparison and assessment, charging station load monitoring and analysis, time service module, communication module, protection module, data processing module, data storage module, data inquiry module and user access; the charging station power quality monitoring device (201), the direct-current charger power quality monitoring terminal (202) and the alternating-current charger power quality monitoring terminal (203) upload the acquired power quality data to the charging station power quality monitoring platform (200) through a communication link, and the power quality analysis analyzes various power quality data acquired, so that the power quality trend prediction is realized for the current and historical power quality data; the electric energy quality evaluation realizes the evaluation of the electric energy quality state of the charging station; comparing and evaluating the branch electric energy quality, namely analyzing and evaluating the electric energy quality data of the direct-current charger or the alternating-current charger, and integrating the electric energy quality data with the electric energy quality data of the whole charging station; the load monitoring and analysis of the charging station calculates and monitors the load state of the charging station in real time, and provides a data support function of power quality monitoring; the time service module can be compatible with a GPS and a Beidou system at the same time, so that the time precision of the whole electric energy quality monitoring system and the time setting function of each subsystem are ensured; the communication module provides all communication management functions inside the system; the protection module provides protection functions required by the system; after the data processing module performs unified processing on the bottom layer original data, the data storage module stores the processed data into a data server, and the system inquires the data stored in the server through the data inquiry module; user access provides a unified access interface for managing workstations;

the charging station electric energy quality monitoring device (201) comprises a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a time service module, a communication module, a UI module, a protection module and a storage and wave recording module; the device realizes the collection of the power quality data such as the multi-harmonic voltage and harmonic current, the voltage fundamental wave effective value and true effective value, the current fundamental wave effective value and true effective value, the voltage deviation, the three-phase voltage unbalance degree, the voltage fluctuation and flicker, the fundamental wave active power, the true power factor, the system frequency deviation and the like in the rear end of the charging station power supply system through the mutual coordination of the current monitoring module, the voltage monitoring module, the frequency monitoring module and the power monitoring module; the time service module realizes the unified time service function of the system; the communication module is responsible for sending and receiving communication instructions and electric energy quality data between the communication module and the electric energy quality monitoring platform of the charging station; the protection module sends out early warning information and automatically executes corresponding protection actions when the monitoring object is monitored or the monitoring object is estimated to have an extreme condition according to the collected data; the UI module provides user setting and operation interaction functions; the storage and wave recording module stores the collected data into a local data space in real time according to a preset period and a preset data type;

the direct-current charger power quality monitoring terminal (202) comprises a current monitoring module, a voltage monitoring module, a frequency monitoring module, a power monitoring module, a time service module, a communication module, a UI module, a protection module and a storage and wave recording module; the monitoring terminal is used for acquiring power quality data such as multiple harmonic voltages and harmonic currents, voltage fundamental wave effective values and true effective values, current fundamental wave effective values and true effective values, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental wave active power, true power factor, system frequency deviation and the like at the front end position of the direct-current charger through the mutual matching of the current monitoring module, the voltage monitoring module, the frequency monitoring module and the power monitoring module; the time service module realizes the unified time service function of the system; the communication module is responsible for sending and receiving communication instructions and electric energy quality data between the electric energy quality monitoring platform (200) charged to the charging station; the protection module sends out early warning information and automatically executes corresponding protection actions when the monitoring object is monitored or the monitoring object is estimated to have an extreme condition according to the collected data; the UI module provides user setting and operation interaction functions; the storage and wave recording module stores the collected data into a local data space in real time according to a preset period and a preset data type;

the alternating-current charger power quality monitoring terminal (203) comprises a current monitoring module, a voltage monitoring module, a power monitoring module, a time service module, a communication module, a UI module, a protection module and a storage and wave recording module; the monitoring terminal acquires electric energy quality data such as voltage fundamental wave effective values and true effective values, current fundamental wave effective values and true effective values, voltage deviation, three-phase voltage unbalance, voltage fluctuation and flicker, fundamental wave active power, true power factor and the like through mutual matching of the current monitoring module, the voltage monitoring module and the power monitoring module; the time service module realizes the unified time service function of the system; the communication module is responsible for sending and receiving communication instructions and electric energy quality data between the electric energy quality monitoring platform (200) charged to the charging station; the protection module sends out early warning information and automatically executes corresponding protection actions when the monitoring object is monitored or the monitoring object is estimated to have an extreme condition according to the collected data; the UI module provides user setting and operation interaction functions; the storage and wave recording module stores the collected data into a local data space in real time according to a preset period and a preset data type;

the electric energy quality monitoring system has a unified time service function, supports Beidou and GPS double time service, and uses, stores and analyzes electric energy quality data of each node in the system, wherein the electric energy quality data comprises a charging station electric energy quality monitoring platform, a charging station electric energy quality monitoring device, a direct current charger electric energy quality monitoring device terminal and an alternating current charger electric energy quality monitoring terminal which are all of a time domain and a frequency domain characteristic, and data consistency and traceability of electric energy quality harmonic waves, phases and the like are ensured;

the charging station electric energy quality monitoring device (201), the direct current charger electric energy quality monitoring terminal (202) and the alternating current charger electric energy quality monitoring terminal (203) can analyze and manage electric energy quality data, on the other hand, the charging station electric energy quality monitoring platform can analyze and evaluate branch electric energy quality according to acquired data of a plurality of nodes, harmonic cancellation or increase phenomena of the plurality of nodes possibly occur to harmonic pollution, the system analyzes and compares the data obtained by the charging station electric energy quality monitoring device with the data obtained by the direct current charger electric energy quality monitoring device terminal and the alternating current charger electric energy quality monitoring terminal on each branch at the same time, and accordingly electric energy quality problems caused by single charger branch and charger are located, analyzed, compared, evaluated and diagnosed.

2. A monitoring method using an electric vehicle charging station power quality monitoring system as claimed in claim 1, characterized by: the user manages the system through a charging station power quality monitoring platform running on the central server and a matched management workstation thereof, and the system comprises system safety management, system configuration and data analysis and query functions; further, the user starts or stops the system operation through the management workstation; further, a user controls the charging station electric energy quality monitoring platform through the management workstation to use a unified time service function aiming at the charging station electric energy quality monitoring device, the direct-current charger electric energy quality monitoring terminal and the alternating-current charger electric energy quality monitoring terminal, so that the data consistency and comparability of all measuring points are ensured;

further, the charging station power quality monitoring device is arranged at the rear end of the charging station power supply system, the direct current charger power quality monitoring terminal is arranged at the front end of the single direct current charger, and the alternating current charger power quality monitoring terminal is arranged at the front end of the single alternating current charger, continuously keeps on-line operation, and collects and stores power quality data in real time;

further, the charging station electric energy quality monitoring device, the direct-current charger electric energy quality monitoring terminal and the alternating-current charger electric energy quality monitoring terminal perform local preprocessing and local storage on temporary data on one hand, and upload the temporary data to the charging station electric energy quality monitoring platform;

further, the charging station power quality monitoring platform stores or reads data from the data server; further, the charging station electric energy quality monitoring platform is used for monitoring, analyzing, evaluating and predicting the electric energy quality of the electric automobile charging station according to various received data, and can be used for positioning, analyzing, comparing, evaluating and diagnosing the electric energy quality problems caused by a single charger branch and a charger;

further, the user can inquire and access all data through the management workstation, and various reports and reports can be formed.