CN105490274B - Electric power supply system for subway utility power quality control system and method - Google Patents

Abstract

The present invention provides a power quality control system and method for a subway power supply system, comprising: a collection device for collecting voltage and current at the high-voltage side and low-voltage side; an active filter for calculating and obtaining Harmonic current compensation value and reactive current compensation value, the harmonic current compensation value is equal to the inverse number of the sum of the harmonic current component on the high voltage side and the harmonic current component on the low voltage side, and the reactive current compensation value is equal to the high voltage The inverse number of the sum of the reactive current component on the side and the reactive current component on the low-voltage side; the monitoring device is used to base on the harmonic current compensation value, the reactive current compensation value and the rated active filter Capacity, to determine the working mode of the active filter; it is also used to generate a current compensation instruction according to the working mode of the active filter, the harmonic current compensation value and the reactive current value and send it to the active filter.

Description

Power quality control system and method for subway power supply system

technical field

The invention relates to the field of electric energy quality control and management of electric power systems, in particular to a power quality control system and method for a subway power supply system.

Background technique

With the continuous expansion of my country's cities, people travel frequently, the traffic demand has increased sharply, and the contradiction between urban traffic supply and demand has become increasingly tense, and ground traffic has been unable to meet the current traffic demand. As one of the most economical and efficient urban transportation tools in the world, the subway has developed rapidly in our large and medium-sized cities.

my country's subway power supply system is mainly composed of main substation, traction substation, rectification system and power lighting system. Due to the large fluctuation of the traction load in the subway power supply system and the cable connection of the subway power supply system, a series of unfavorable factors such as harmonics and reactive power transfer are brought to the urban power grid. Subways are generally located in densely populated cities. Once an accident occurs in the urban power grid, it will have a great impact on the power supply of the entire city. For the subway power supply system, when the system load is heavy, the power factor of the system is relatively high but the harmonic content is also relatively high; when the system is lightly loaded or stopped, the system harmonic content is low but the power factor is relatively low, which may It is also accompanied by a large amount of capacitive reactive power transfer. At present, the methods of suppressing harmonics in the subway power supply system and compensating reactive power in the subway power supply system are mainly: installing active filters and power capacitor reactive power compensation devices in the low-voltage power distribution system to suppress harmonics and compensate reactive power respectively. Since the harmonic suppression and reactive power compensation in the subway power supply system are carried out separately, and there is no comprehensive treatment according to a unified physical model, there is often a situation of taking care of one thing and losing the other, resulting in increased economic costs, heavy installation and maintenance workload, and It poses a security risk to the urban power grid.

Contents of the invention

Therefore, the present invention proposes a power quality control system and method for a subway power supply system, which can solve the technical problem in the prior art that the harmonics and reactive power in the subway power supply system cannot be comprehensively managed.

Technical scheme of the present invention is as follows:

A power quality control system for a subway power supply system, comprising:

A collection device, used to collect the voltage and current of the high-voltage side and the low-voltage side;

The active filter is used to calculate the harmonic current compensation value and the reactive current compensation value according to the collected voltage and current, and the harmonic current compensation value is equal to the harmonic current component of the high-voltage side and the harmonic of the low-voltage side The opposite number of the sum of the current components, the reactive current compensation value is equal to the opposite number of the sum of the reactive current components of the high-voltage side and the reactive current components of the low-voltage side;

A monitoring device, used to determine the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter; The working mode of the source filter, the harmonic current compensation value and the reactive current value generate a current compensation command and send it to the active filter.

Preferably, the collection device includes:

a high-voltage collection unit, used to collect three-phase voltages u _a1 , u _b1 , u _c1 and three-phase currents i _a1 , i _b1 , i _c1 on the high-voltage side; and

A low-voltage collection unit, used to collect three-phase voltages u _a2 , u _b2 , u _c2 and three-phase currents i _a2 , i _b2 , i _c2 of the low-voltage side load;

Among them, the voltage signal and current signal are collected synchronously.

Preferably, the active filter includes:

The unit for calculating harmonic components and reactive components is used to calculate the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side and the high-voltage side The reactive components i _aq1 , i _bq1 and i _cq1 of the three-phase current are also used to calculate the harmonic components i _ah2 and i _bh2 of the three-phase current on the low-voltage side based on the collected three-phase voltage and three-phase current on the low-voltage side and i _ch2 , and the reactive components i _aq2 , i _bq2 and i _cq2 of the low-voltage side three-phase current;

The unit for calculating harmonic current compensation value and reactive current compensation value is used to obtain the harmonic current compensation value according to the harmonic components of the three-phase current at the high-voltage side and the low-voltage side: i ^* _cah =-i _ah1- i _ah2 , i ^* _cbh =-i _bh1- i _bh2 and i ^* _cch =-i _ch1 -i _ch2 ; according to the reactive components of the high-voltage side and low-voltage side three-phase currents, the reactive current compensation value is obtained: i ^* _caq =- i _aq1 -i _aq2 , i ^* _cbq = -i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 .

Preferably, the monitoring device includes:

A generating current compensation command unit, configured to generate a current compensation command according to the working mode of the active filter, the harmonic current compensation value and the reactive current compensation value and send it to the active filter, the current compensation The instruction is: i ^* _ca ＝A×i ^* _cah +B×i ^* _caq ; i ^* _cb ＝A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc ＝A×i ^* _cch +B×i ^* _ccq , wherein, 0≤A≤1, 0≤B≤1, the specific values of A and B are determined by the active filter working mode determination unit;

The active filter working mode determination unit is used to calculate and determine the harmonic ratio Kh and reactive power ratio Kq according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter The working mode of the active filter, wherein,

When the harmonic ratio Kh≥100%, the active filter works in the harmonic-complement-only mode, and the values of A and B are: A=1, B=0;

When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1;

When the first threshold value of the harmonic ratio≥Kh≥the second threshold value and the reactive power ratio Kq>the third threshold value, or when the harmonic ratio Kh<second threshold value and the reactive power ratio Kq<100% , the active filters are all working in the reactive power priority mode, and the values of A and B are: 0<A<B<1;

When the first threshold of the harmonic ratio≥Kh≥the second threshold and the reactive power ratio Kq≤the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A= 1,B=1;

When the harmonic ratio Kh<second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power-only mode, and the values of A and B are: A=0, B = 1;

Preferably, the unit for calculating harmonic components and reactive components calculates harmonic components and reactive components based on instantaneous reactive power theory.

A method for controlling power quality of a subway power supply system, comprising the steps of:

Obtain the voltage and current of the high-voltage side and the low-voltage side;

According to the obtained voltage and current, the harmonic current compensation value and the reactive current compensation value are calculated, and the harmonic current compensation value is equal to the inverse number of the sum of the harmonic current component on the high voltage side and the harmonic current component on the low voltage side , the reactive current compensation value is equal to the opposite number of the sum of the reactive current component on the high voltage side and the reactive current component on the low voltage side;

Obtain the rated capacity of the active filter;

determining the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter;

A current compensation command is generated according to the working mode of the active filter, the harmonic current compensation value and the reactive current value and sent to the active filter.

Preferably, the step of obtaining the voltage and current of the high-voltage side and the low-voltage side includes:

Obtain the three-phase voltages u _a1 , u _b1 , u _c1 and the three-phase currents i _a1 , i _b1 , i _c1 of the high-voltage side; and

Obtain the three-phase voltage u _a2 , u _b2 , u _c2 and three-phase current i _a2 , i _b2 , i _c2 of the low-voltage side load;

Among them, the voltage signal and current signal are collected synchronously.

Preferably, the step of calculating the harmonic current compensation value and the reactive current compensation value includes:

According to the obtained three-phase voltage and three-phase current on the high-voltage side, calculate the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side, and the reactive components i _aq1 and i _bq1 of the three-phase current on the high-voltage side and i _cq1 ; and according to the obtained three-phase voltage and three-phase current at the low-voltage side, calculate the harmonic components i _ah2 , i _bh2 and i _ch2 of the three-phase current at the low-voltage side, and the reactive components of the three-phase current at the low-voltage side i _aq2 , i _bq2 and i _cq2 ;

According to the harmonic components of the three-phase currents at the high-voltage side and the low-voltage side, the harmonic current compensation value is obtained: i ^* _cah = _{-iah1 -iah2} , i ^* _cbh = _{-ibh1-ibh2 and} i ^* _cch =- i _ch1 -i _ch2 ; According to the reactive components of the three-phase current at the high-voltage side and the low-voltage side, the reactive current compensation value is obtained: i ^* _caq = -i _aq1 -i _aq2 , i ^* _cbq = -i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 .

Preferably, the step of generating the current compensation command according to the working mode of the active filter, the harmonic current compensation value and the reactive current compensation value includes:

The current compensation command is: i ^* _ca =A×i ^* _cah +B×i ^* _caq ; i ^* _cb =A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc =A×i ^* _cch +B ×i ^* _ccq , where, 0≤A≤1, 0≤B≤1, the specific values of A and B are determined by the working mode of the active filter;

The step of determining the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter includes:

Calculate the harmonic ratio Kh and reactive power ratio Kq;

When the harmonic ratio Kh≥100%, the active filter works in the harmonic-complement-only mode, and the values of A and B are: A=1, B=0;

When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1;

When the first threshold value of the harmonic ratio≥Kh≥the second threshold value and the reactive power ratio Kq>the third threshold value, or when the harmonic ratio Kh<second threshold value and the reactive power ratio Kq<100% , the active filters are all working in the reactive power priority mode, and the values of A and B are: 0<A<B<1;

When the first threshold of the harmonic ratio ≥ Kh ≥ the second threshold and the reactive power ratio Kq ≤ the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A =1,B=1;

When the harmonic ratio Kh<second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power-only mode, and the values of A and B are: A=0, B = 1;

Preferably, the harmonic components and reactive components are calculated based on instantaneous reactive power theory.

The above technical solution of the present invention has the following advantages compared with the prior art:

The invention provides a power quality control system and method for a subway power supply system, which collects the voltage and current of the high-voltage side and the low-voltage side at the same time, so that the finally obtained current compensation command is more accurate; at the same time, the load signal of the high-voltage side and the low-voltage side The fundamental reactive and harmonic signals are extracted separately, and the working mode (compensation mode) of the active filter is determined according to the load working state (harmonic current compensation value and reactive current compensation value) and the rated capacity of the active filter , and generate current compensation commands according to the working mode, harmonic current compensation value and reactive current value. The system and method comprehensively consider the reactive power and harmonic signals existing in the power grid, and comprehensively manage them according to a unified physical model, with high reliability; at the same time, the system and method can automatically adjust the working mode according to the load working state, The power distribution system has a high power quality throughout the operation stage, and the safety and reliability of power consumption are improved.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

Fig. 1 is the schematic diagram of a kind of subway power supply system power quality control system in the embodiment 1 of the present invention;

Fig. 2 is the flow chart of calculating harmonic current compensation value in the embodiment 1 of the present invention;

Fig. 3 is the flow chart of calculating reactive current compensation value in embodiment 1 of the present invention;

Fig. 4 is a flow chart of generating a current compensation command in Embodiment 1 of the present invention;

Fig. 5 is a flowchart of a power quality control method for a subway power supply system in Embodiment 2 of the present invention.

Detailed ways

Example 1

As shown in Figure 1, the present embodiment provides a power quality control system for a subway power supply system, which may include:

The collection device (not shown in FIG. 1 ) is used to collect the voltage and current of the high-voltage side and the low-voltage side.

As a specific implementation, the collection device may specifically include: a high-voltage collection unit for collecting three-phase voltages u _a1 , u _b1 , u _c1 and three-phase currents i _a1 , i _b1 , i _c1 on the high-voltage side; a low-voltage collection unit , used to collect three-phase voltages u _a2 , u _b2 , u _c2 and three-phase currents i _a2 , i _b2 , i _c2 of the low-voltage side load. Among them, the voltage signal and current signal are collected synchronously. Both the high-voltage acquisition unit and the low-voltage acquisition unit can realize the required voltage and current acquisition through voltage sensors and current sensors.

The active filter is used to calculate the harmonic current compensation value and reactive current compensation value based on the collected voltage and current. The harmonic current compensation value is equal to the harmonic current component of the high voltage side and the harmonic current component of the low voltage side The opposite number of the sum, the reactive current compensation value is equal to the opposite number of the sum of the reactive current component of the high voltage side and the reactive current component of the low voltage side.

As a specific implementation, the active filter may specifically include:

The unit for calculating harmonic components and reactive components is used to calculate the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side and the high-voltage side The reactive components i _aq1 , i _bq1 and i _cq1 of the three-phase current are also used to calculate the harmonic components i _ah2 and i _bh2 of the three-phase current on the low-voltage side based on the collected three-phase voltage and three-phase current on the low-voltage side and i _ch2 , and the reactive components i _aq2 , i _bq2 and i _cq2 of the low-voltage side three-phase current.

Calculation of harmonic current compensation value and reactive current compensation value unit, used to obtain harmonic current compensation value according to the harmonic components of the three-phase current at the high-voltage side and low-voltage side: i ^* _cah = -i _ah1 -i _ah2 , i ^* _cbh ＝-i _bh1 -i _bh2 and i ^* _cch ＝-i _ch1 -i _ch2 ; according to the reactive components of the three-phase current at the high-voltage side and low-voltage side, the reactive current compensation value is obtained: i ^* _caq ＝-i _aq1 -i _aq2 , i ^* _cbq = -i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 .

The monitoring device is used to determine the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter; it is also used to determine the working mode of the active filter according to the working mode, harmonic current The compensation value and the reactive current value generate a current compensation command and send it to the active filter.

As a specific implementation, the monitoring device may specifically include:

Generate current compensation instruction unit, used to generate current compensation instruction according to the active filter’s working mode, harmonic current compensation value and reactive current compensation value and send it to the active filter, the current compensation instruction is: i ^* _ca = A ×i ^* _cah +B×i ^* _caq ; i ^* _cb =A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc =A×i ^* _cch +B×i ^* _ccq , wherein, 0≤A≤1 , 0≤B≤1, the specific values of A and B are determined by the active filter working mode determination unit;

The active filter working mode determination unit is used to calculate the harmonic ratio Kh according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter (the required compensation harmonic capacity and the rated capacity of the active filter capacity ratio) and reactive power ratio Kq (required compensation reactive power capacity and active filter rated capacity ratio) and determine the mode of operation of the active filter, wherein,

When the harmonic ratio Kh ≥ 100%, the active filter works in the harmonic compensation mode only, and the values of A and B are: A=1, B=0;

When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1; wherein, the value of the first threshold can be 70%.

When the harmonic ratio first threshold ≥ Kh ≥ second threshold and reactive power ratio Kq> third threshold, or when harmonic ratio Kh<second threshold and reactive power ratio Kq<100%, the active filter works at In the reactive priority mode, the values of A and B are: 0<A<B<1; wherein, the second threshold may be 10%; the third threshold may be 70%.

When the first threshold of the harmonic ratio≥Kh≥the second threshold and the reactive power ratio Kq≤the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A=1, B=1.

When the harmonic ratio Kh<the second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power only compensation mode, and the values of A and B are: A=0, B=1.

The power quality control system of the subway power supply system provided in this embodiment collects the voltage and current of the high-voltage side and the low-voltage side at the same time, so that the final current compensation command is more accurate; at the same time, the fundamental wave in the high-voltage side and low-voltage side load signals The reactive and harmonic signals are extracted separately, and the working mode (compensation mode) of the active filter is determined according to the load working state (harmonic current compensation value and reactive current compensation value) and the rated capacity of the active filter, and Generate current compensation commands according to the working mode, harmonic current compensation value and reactive current value. The system and method comprehensively consider the reactive power and harmonic signals existing in the power grid, and comprehensively manage them according to a unified physical model, with high reliability; at the same time, the system and method can automatically adjust the working mode according to the load working state, The power distribution system has a high power quality throughout the operation stage, and the safety and reliability of power consumption are improved.

The process of generating the current compensation command will be specifically described below with reference to FIG. 2 , FIG. 3 and FIG. 4 .

In the following example, the voltage on the high-voltage side is 35kV, and the corresponding three-phase voltages u _a1 , u _b1 , u _c1 on the high-voltage side are: u _a35kV , u _b35kV , u _c35kV ; the three-phase currents i _a1 , i _b1 on the high-voltage side , i _c1 are: i _a35kV , i _b35kV , i _c35kV ; the harmonic components i _ah1 , i _bh1 , i _ch1 of the three-phase current at the high voltage side are: i _ah35kV , i _bh35kV , i _ch35kV ; the reactive power of the three-phase current at the high voltage side Components i _aq1 , i _bq1 , and i _cq1 are: i _aq35kV , i _bq35kV , i _cq35kV ;

The voltage on the low-voltage side is 1140V, and the corresponding three-phase voltages u _a2 , u _b2 , u _c2 on the low-voltage side are: u _{a1 140V} , u _{b1 140V} , u _{c1 140V} ; the three-phase currents i _a2 , i _b2 , i on the low-voltage side _c2 is: i _{a1 140V} , i _{b1 140V} , i _{c1 140V} ; the harmonic components i _ah2 , i _bh2 , i _ch2 of the three-phase current on the low-voltage side are: i _{ah1 140V} , i _{bh1 140V} , i _{ch1 140V} ; the three-phase current on the low-voltage side The reactive components i _aq2 , i _bq2 and i _cq2 of the current are: i _{aq1 140V} , i _{bq1 140V} , i _{cq1 140V} .

Currently known harmonic detection methods include: band-stop filter method, FFT transform method, band-pass frequency selection method, adaptive detection method and instantaneous reactive power theory method, etc. Among them, the circuit based on the theoretical method of instantaneous reactive power has simple structure, good performance, high feasibility, and good real-time performance. Therefore, the harmonic component and reactive component are calculated based on the theoretical method of instantaneous reactive power in this system.

The following describes the specific process of obtaining the harmonic current compensation value in combination with Figure 2, and uses the d-q method to detect the harmonic current on the high voltage side:

The three-phase currents i _a35kV , i _b35kV , and i _c35kV on the high-voltage side are transformed by CLARKE and PARK to obtain i _d and i _q , and the specific transformation is as follows:

In formula (1),

After i _d and i _q are filtered by a low-pass filter (LPF), the DC component is obtained and then and The fundamental wave components i _af , i _bf , and i _cf of the detection current can be obtained by inverse transformation.

Subtract i _af , i _bf , i _cf from i _a35kV , i _b35kV , i _c35kV to obtain the harmonic components i _ah35kV , i _bh35kV , i _ch35kV of the high voltage side three-phase current i _a35kV , i _b35kV , i _c35kV ;

Similarly, the harmonic components i _{ah1 140V} , i _{bh1 140V} , i _{ch1 140V} of the low-voltage side load three-phase current i _{a1 140V} , i _{b1 140V} , i _{c1 140V} can be obtained;

According to the harmonic components of the three-phase current at the high-voltage side and the low-voltage side, the harmonic current compensation value is obtained as:

The negative sign in formula (3) indicates that the amplitude of the compensation current and the harmonic current are equal, and the direction is opposite.

The following describes the specific process of calculating the reactive current compensation value in combination with Figure 3. The reactive current compensation value is also obtained by the instantaneous reactive method. First, the reactive current component on the high-voltage side is calculated:

According to Fig. 3, the reactive components i _aq35kV , i _bq35kV and i _cq35kV of the three-phase currents i _a35kV , i _b35kV and i _c35kV on the high voltage side can be obtained;

Similarly, the reactive components i _{aq1 140V} , i _{bq1 140V} , i _{cq1 140V} of the low-voltage side load three-phase current i _{a1 140V} , i _{b1 140V} , i _{c1 140V} can be obtained;

According to the reactive components of the three-phase current at the high-voltage side and the low-voltage side, the reactive current compensation value is obtained as:

The negative sign in formula (4) means that the amplitude of the compensation current and the reactive current are equal, but the direction is opposite.

As shown in Figure 4, the total current compensation command is composed of harmonic compensation command and reactive power compensation command, specifically:

A and B in formula (5) are real variables between 0 and 1, which are determined by the working mode of the active filter, as shown in Table 1, where Kh is the required compensation harmonic capacity and active The ratio of the rated capacity of the power filter; Kq is the ratio of the required compensation reactive capacity to the rated capacity of the active power filter; "×" indicates that it is not considered.

Table 1:

Operating mode Harmonic ratio Kh Reactive power ratio Kq Relationship between A and B Harmonics only Kh≥100% x A=1, B=0 Harmonic Priority 100%>Kh>70% x A > B Reactive priority 70%≥Kh≥10% Kq > 70% A<B full compensation 70%≥Kh≥10% Kq≤70% A=1, B=1 Only make up for nothing Kh<10% Kq≥100% A=0, B=1 Reactive priority Kh<10% Kq<100% A<B

It can be seen from Table 1 that:

When A=1, B=1, the filter works in full compensation mode;

When A＝0, B＝1, the filter works in only reactive power compensation mode;

When A=1, B=0, the filter works in only harmonic mode;

When A<B, the filter works in reactive power priority mode;

When A>B, the filter works in harmonic priority mode;

For the subway power supply system, when the system load is heavy, the active filter works in the harmonic priority mode; when the system load is light, the active filter works in the reactive power priority mode; when the system harmonic content is high When it is possible that the electrical equipment cannot work normally, the active filter can work in the state of only compensating harmonics; when the system has a lot of capacitive reactive power, which not only leads to waste of electric energy, but also may affect the stability of the system, the active filter can Work in the state of only making up reactive power. It can be seen that the active filter in the system provided by this embodiment has a variety of working modes, and can automatically adjust the working mode according to the load working state instruction, so that the power distribution system has a higher power quality during the entire operation stage. Improve the safety and reliability of electricity.

Example 2

As shown in Figure 5, the present embodiment provides a method for power quality control of a subway power supply system, which may include the following steps:

S1: Obtain the voltage and current of the high-voltage side and the low-voltage side. This step may specifically include: acquiring three-phase voltages u _a1 , u _b1 , u _c1 and three-phase currents i _a1 , i _b1 , i _c1 on the high-voltage side; acquiring three-phase voltages u _a2 , u _b2 , u _c2 of the load on the low-voltage side and the three-phase current i _a2 , i _b2 , i _c2 ; where the voltage signal and the current signal are collected synchronously.

S2: Calculate the harmonic current compensation value and reactive current compensation value according to the obtained voltage and current, and the harmonic current compensation value is equal to the opposite number of the sum of the harmonic current component on the high voltage side and the harmonic current component on the low voltage side , the reactive current compensation value is equal to the inverse of the sum of the reactive current components on the high voltage side and the reactive current components on the low voltage side. This step can calculate the harmonic component and reactive component based on the instantaneous reactive power theory, which can specifically include:

First, according to the acquired three-phase voltage and three-phase current on the high-voltage side, the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side are calculated, and the reactive components i _aq1 , i _bq1 and i _cq1 ; and according to the acquired three-phase voltage and three-phase current at the low-voltage side, calculate the harmonic components i _ah2 , i _bh2 and i _ch2 of the three-phase current at the low-voltage side, and the non-conductive components of the three-phase current at the low-voltage side Work components i _aq2 , i _bq2 and i _cq2 ;

Secondly, according to the harmonic components of the three-phase current at the high-voltage side and the low-voltage side, the harmonic current compensation value is obtained: i ^* _cah = -i _ah1 -i _ah2 , i ^* _cbh = -i _bh1 -i _bh2 and i ^* _cch =- i _ch1 -i _ch2 ; According to the reactive components of the three-phase current at the high-voltage side and the low-voltage side, the reactive current compensation value is obtained: i ^* _caq ＝-i _aq1 -i _aq2 、 i ^* _cbq ＝-i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 .

S3: Obtain the rated capacity of the active filter.

S4: Determine the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter.

S5: Generate a current compensation instruction according to the working mode of the active filter, the harmonic current compensation value, and the reactive current value, and send it to the active filter.

Steps S4 and S5 may specifically be:

The current compensation command in step S5 is: i ^* _ca =A×i ^* _cah +B×i ^* _caq ; i ^* _cb =A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc =A×i ^* _cch +B×i ^* _ccq , where, 0≤A≤1, 0≤B≤1, the specific values of A and B are determined by the working mode of the active filter.

The process of determining the working mode of the filter in step S4 is:

Calculate the harmonic ratio Kh and reactive power ratio Kq;

When the harmonic ratio Kh ≥ 100%, the active filter works in the harmonic compensation mode only, and the values of A and B are: A=1, B=0;

When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1;

When the harmonic ratio first threshold ≥ Kh ≥ second threshold and reactive power ratio Kq> third threshold, or when harmonic ratio Kh<second threshold and reactive power ratio Kq<100%, the active filter works at In reactive power priority mode, the values of A and B are: 0<A<B<1;

When the first threshold of the harmonic ratio≥Kh≥the second threshold and the reactive power ratio Kq≤the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A=1, B=1;

When the harmonic ratio Kh<the second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power only compensation mode, and the values of A and B are: A=0, B=1.

The power quality control method of the subway power supply system provided in this embodiment collects the voltage and current of the high-voltage side and the low-voltage side at the same time, so that the current compensation command obtained finally is more accurate; at the same time, the fundamental wave in the load signal of the high-voltage side and the low-voltage side The reactive and harmonic signals are extracted separately, and the working mode (compensation mode) of the active filter is determined according to the load working state (harmonic current compensation value and reactive current compensation value) and the rated capacity of the active filter, and Generate current compensation commands according to the working mode, harmonic current compensation value and reactive current value. The system and method comprehensively consider the reactive power and harmonic signals existing in the power grid, and comprehensively manage them according to a unified physical model, with high reliability; at the same time, the system and method can automatically adjust the working mode according to the load working state, The power distribution system has a high power quality throughout the operation stage, and the safety and reliability of power consumption are improved.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (8)

1. A subway power supply system electric energy quality control system, is characterized in that, comprises: A collection device, used to collect the voltage and current of the high-voltage side and the low-voltage side; The active filter is used to calculate the harmonic current compensation value and the reactive current compensation value according to the collected voltage and current, and the harmonic current compensation value is equal to the harmonic current component of the high-voltage side and the harmonic of the low-voltage side The opposite number of the sum of the current components, the reactive current compensation value is equal to the opposite number of the sum of the reactive current components of the high-voltage side and the reactive current components of the low-voltage side; A monitoring device, used to determine the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter; The working mode of the source filter, the harmonic current compensation value and the reactive current compensation value generate a current compensation command and send it to the active filter; The monitoring device includes: A generating current compensation command unit, configured to generate a current compensation command according to the working mode of the active filter, the harmonic current compensation value and the reactive current compensation value and send it to the active filter, the current compensation The instruction is: i ^* _ca ＝A×i ^* _cah +B×i ^* _caq ; i ^* _cb ＝A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc ＝A×i ^* _cch +B×i ^* _ccq , wherein, 0≤A≤1, 0≤B≤1, the specific values of A and B are determined by the active filter working mode determination unit; Among them: i ^* _cah , i ^* _cbh , i ^* _cch are harmonic current compensation values; i ^* _caq , i ^* _cbq , i ^* _ccq are reactive current compensation values; The active filter working mode determination unit is used to calculate and determine the harmonic ratio Kh and reactive power ratio Kq according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter The working mode of the active filter, wherein, When the harmonic ratio Kh≥100%, the active filter works in the harmonic-complement-only mode, and the values of A and B are: A=1, B=0; When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1; When the first threshold value of the harmonic ratio≥Kh≥the second threshold value and the reactive power ratio Kq>the third threshold value, or when the harmonic ratio Kh<second threshold value and the reactive power ratio Kq<100% , the active filters are all working in reactive power priority mode, and the values of A and B are: 0<A<B<1; When the first threshold of the harmonic ratio≥Kh≥the second threshold and the reactive power ratio Kq≤the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A= 1,B=1; When the harmonic ratio Kh<second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power-only mode, and the values of A and B are: A=0, B =1. 2. The system according to claim 1, wherein the acquisition device comprises: a high-voltage collection unit, used to collect three-phase voltages u _a1 , u _b1 , u _c1 and three-phase currents i _a1 , i _b1 , i _c1 on the high-voltage side; and A low-voltage collection unit, used to collect three-phase voltages u _a2 , u _b2 , u _c2 and three-phase currents i _a2 , i _b2 , i _c2 of the low-voltage side load; Among them, the voltage signal and current signal are collected synchronously. 3. The system according to claim 2, wherein the active filter comprises: The unit for calculating harmonic components and reactive components is used to calculate the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side and the high-voltage side The reactive components i _aq1 , i _bq1 and i _cq1 of the three-phase current are also used to calculate the harmonic components i _ah2 and i _bh2 of the three-phase current on the low-voltage side based on the collected three-phase voltage and three-phase current on the low-voltage side and i _ch2 , and the reactive components i _aq2 , i _bq2 and i _cq2 of the low-voltage side three-phase current; The unit for calculating harmonic current compensation value and reactive current compensation value is used to obtain the harmonic current compensation value according to the harmonic components of the three-phase current at the high-voltage side and the low-voltage side: i ^* _cah =-i _ah1- i _ah2 , i ^* _cbh =-i _bh1- i _bh2 and i ^* _cch =-i _ch1 -i _ch2 ; according to the reactive components of the high-voltage side and low-voltage side three-phase currents, the reactive current compensation value is obtained: i ^* _caq =- i _aq1 -i _aq2 , i ^* _cbq = -i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 . 4. The system according to claim 3, wherein the unit for calculating harmonic components and reactive components calculates harmonic components and reactive components based on instantaneous reactive power theory. 5. A method for controlling power quality of subway power supply system, is characterized in that, comprises the steps: Obtain the voltage and current of the high-voltage side and the low-voltage side; According to the obtained voltage and current, the harmonic current compensation value and the reactive current compensation value are calculated, and the harmonic current compensation value is equal to the inverse number of the sum of the harmonic current component on the high voltage side and the harmonic current component on the low voltage side , the reactive current compensation value is equal to the opposite number of the sum of the reactive current component on the high voltage side and the reactive current component on the low voltage side; Obtain the rated capacity of the active filter; determining the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter; generating a current compensation instruction according to the working mode of the active filter, the harmonic current compensation value and the reactive current compensation value and sending it to the active filter; The step of generating the current compensation instruction according to the working mode of the active filter, the harmonic current compensation value and the reactive current compensation value includes: the current compensation instruction is: i ^* _ca =A×i ^* _cah +B×i ^* _caq ; i ^* _cb ＝A×i ^* _cbh +B×i ^* _cbq ; i ^* _cc ＝A×i ^* _cch +B×i ^* _ccq , among them, 0≤A≤1,0≤B ≤1, the specific values of A and B are determined by the working mode of the active filter; Among them: i ^* _cah , i ^* _cbh , i ^* _cch are harmonic current compensation values; i ^* _caq , i ^* _cbq , i ^* _ccq are reactive current compensation values; The step of determining the working mode of the active filter according to the harmonic current compensation value, the reactive current compensation value and the rated capacity of the active filter includes: Calculate the harmonic ratio Kh and reactive power ratio Kq; When the harmonic ratio Kh≥100%, the active filter works in the harmonic-complement-only mode, and the values of A and B are: A=1, B=0; When the harmonic ratio is 100%>Kh>the first threshold, the active filter works in the harmonic priority mode, and the values of A and B are: 0<B<A<1; When the first threshold value of the harmonic ratio≥Kh≥the second threshold value and the reactive power ratio Kq>the third threshold value, or when the harmonic ratio Kh<second threshold value and the reactive power ratio Kq<100% , the active filters are all working in the reactive power priority mode, and the values of A and B are: 0<A<B<1; When the first threshold of the harmonic ratio≥Kh≥the second threshold and the reactive power ratio Kq≤the third threshold, the active filter works in the full compensation mode, and the values of A and B are: A= 1,B=1; When the harmonic ratio Kh<second threshold and the reactive power ratio Kq≥100%, the active filter works in the reactive power-only mode, and the values of A and B are: A=0, B =1. 6. The method according to claim 5, wherein the step of obtaining the voltage and current of the high-voltage side and the low-voltage side comprises: Obtain the three-phase voltages u _a1 , u _b1 , u _c1 and the three-phase currents i _a1 , i _b1 , i _c1 of the high-voltage side; and Obtain the three-phase voltage u _a2 , u _b2 , u _c2 and three-phase current i _a2 , i _b2 , i _c2 of the low-voltage side load; Among them, the voltage signal and current signal are collected synchronously. 7. The method according to claim 6, wherein the step of calculating the harmonic current compensation value and the reactive current compensation value comprises: According to the obtained three-phase voltage and three-phase current on the high-voltage side, calculate the harmonic components i _ah1 , i _bh1 and i _ch1 of the three-phase current on the high-voltage side, and the reactive components i _aq1 and i _bq1 of the three-phase current on the high-voltage side and i _cq1 ; and according to the obtained three-phase voltage and three-phase current at the low-voltage side, calculate the harmonic components i _ah2 , i _bh2 and i _ch2 of the three-phase current at the low-voltage side, and the reactive components of the three-phase current at the low-voltage side i _aq2 , i _bq2 and i _cq2 ; According to the harmonic components of the three-phase currents at the high-voltage side and the low-voltage side, the harmonic current compensation value is obtained: i ^* _cah = _{-iah1 -iah2} , i ^* _cbh = _{-ibh1-ibh2 and} i ^* _cch =- i _ch1 -i _ch2 ; According to the reactive components of the three-phase current at the high-voltage side and the low-voltage side, the reactive current compensation value is obtained: i ^* _caq = -i _aq1 -i _aq2 , i ^* _cbq = -i _bq1 -i _bq2 and i ^* _ccq = -i _cq1 -i _cq2 . 8. The method according to claim 7, characterized in that harmonic components and reactive components are calculated based on instantaneous reactive power theory.