CN203119751U - Third triple tuned AC filter - Google Patents

Abstract

The utility model relates to a three-tuning AC filter, which is composed of three low-voltage capacitors C1, C2, C3, three reactors L1-Ztr, L2, L3, two resistors R1, R2 and a reactor arrester F1 constitutes; among them, the reactor L1-Ztr is a high-voltage reactor; the low-voltage capacitor C2, the reactor L2, and the resistor R1 are connected in parallel to form the first resonant circuit, and the low-voltage capacitor C3, the reactor L3, and the resistor R2 are connected in parallel to form the second resonant circuit ; The first and second resonance circuits and the high-voltage reactor L1-Ztr are connected in series in sequence and then connected in parallel with the reactor arrester F1 to form a circuit loop, and one end of the circuit loop is connected in series with the low-voltage capacitor C1. The filter can be used in the converter station where the UHV DC is connected to the UHV AC grid, and filters out various harmonics generated by the converter, while controlling the system harmonics within an acceptable range, and providing The reactive power required by the phases ensures the normal operation of the AC and DC systems.

Description

A Tri-tuned AC Filter

technical field

The utility model relates to an AC filter for connecting ultra-high voltage direct current to an ultra-high voltage AC power grid converter station, in particular to a three-tuned AC filter used in combination with a transformer for filtering in the ultra-high voltage converter station.

Background technique

The AC filters used in traditional converter stations are directly connected in parallel to the AC bus with the help of a small group switch to achieve harmonic filtering and reactive power balance of the converter, and control the harmonics injected into the AC grid within the standard requirements to ensure that the AC grid power quality. Since the busbar voltage of the AC field of the converter station of the traditional DC power transmission project is up to 500kV, the project is usually equipped with a 500kV filter group switch.

With the rapid development of my country's national economy and power grid construction, it is an inevitable trend to connect UHV DC to UHV AC in the construction of large power grids: by using AC UHV grids with high power and long-distance transmission capabilities, the short-circuit current of the 500kV power grid exceeds the standard , the problem of tight line corridors, and at the same time, it can improve the safe and stable operation level of the large power grid and promote the safe and stable operation of the power grid. Since the voltage of the AC field bus in the converter station in the direct connection of UHV DC to the UHV AC scheme rises to 1000kV, the original complete filter technical solution needs to be equipped with a filter group switch suitable for the 1000kV AC bus. However, there is no filter group switch that meets this requirement in the market at present. If a new research and development design is carried out for the filter group switch, the investment cost of the filter set will be greatly increased.

In order to reduce the investment cost of a complete set of filter for UHV DC connected to UHV AC converter station, ensure that the overall investment cost of the converter station is reasonable and feasible, and at the same time meet the requirements of harmonic control and reactive power compensation, this utility model proposes a new AC filter.

Contents of the invention

In view of the above problems, the purpose of this utility model is to provide a three-tuned AC filter, which can be used in combination with a transformer in an UHV converter station to filter out various harmonics generated by the converter, and at the same time control the harmonics of the system The wave is within the acceptable range, and provides the reactive power required for the commutation of the converter to ensure the normal operation of the AC and DC systems.

To achieve the above object, the utility model takes the following technical solutions:

A three-tuned AC filter, characterized in that it consists of three low-voltage capacitors C1, C2, C3, three reactors L1-Ztr, L2, L3, two resistors R1, R2 and a reactor lightning arrester F1 ; Wherein, the reactor L1-Ztr is a high-voltage reactor; the low-voltage capacitor C2, the reactor L2, and the resistor R1 are connected in parallel to form a first resonant circuit, and the low-voltage capacitor C3, the reactor L3, and the resistor R2 are connected in parallel to form a The second resonant circuit: the first and second resonant circuits and the high-voltage reactor L1-Ztr are connected in series in sequence and then connected in parallel with the reactor lightning arrester F1 to form a circuit loop, and one end of the circuit loop is connected in series with the low-voltage capacitor C1 .

The utility model has the following advantages due to the adoption of the above technical scheme:

1. The utility model is connected in series with the transformer of the converter station on the AC bus, and is switched as a group filter, which can effectively reduce the number of switches used in the filter group, and solve the problem of direct connection of UHV DC to UHV AC power grid The problem of high investment cost of harmonic control in the post-converter station.

2. The reactive power compensation capacitors connected in parallel at both ends of the utility model can use the original switching control strategy of the converter station to complete harmonic filtering and realize reactive power balance compensation of the converter station, which can effectively reduce the AC field filtering of the converter station. The investment cost of a complete set of appliances.

The utility model has the advantages of simple structure and convenient control, and can be widely used in the scheme of direct connection of ±800kV/±1100kV UHV DC to 1000kV AC power grid via conventional structure transformer.

Description of drawings

Figure 1 is a schematic diagram of the utility model connected to the AC bus of the converter station;

Fig. 2 is a schematic diagram of the composition circuit of the present utility model.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in detail.

As shown in Figure 1, the utility model three-tuned filter is composed of three low-voltage capacitors C1, C2, C3, three reactors L1-Ztr, L2, L3, two resistors R1, R2 and a reactor lightning arrester F1 .

Among them, the reactor L1-Ztr is a high-voltage reactor; the low-voltage capacitor C2, the reactor L2, and the resistor R1 are connected in parallel to form the first resonant circuit, and the low-voltage capacitor C3, the reactor L3, and the resistor R2 are connected in parallel to form the second resonant circuit; the first , The second resonant circuit is connected in series with the high-voltage reactor L1-Ztr and then connected in parallel with the reactor lightning arrester F1 to form a circuit loop, and one end of the circuit loop is connected in series with the low-voltage capacitor C1.

As shown in Figure 2, when the utility model is in use, both ends of the reactive power compensation capacitor SC are connected in parallel, and one end of the low-voltage capacitor C1 is connected in series with the converter station transformer Ztr (shown in the dotted line box in the figure), and the other end of the transformer Ztr One end is connected to the AC bus, so that together with the transformer Ztr, it can be used as a group filter for overall switching.

Concrete parameters of the utility model can be selected according to the following methods:

1) Determine the order and magnitude of each harmonic generated by the converter in the converter station.

2) Preliminary design of the parameters of the three-tuned AC filter.

3) Optimize the capacity and short-circuit impedance of the filter connected to the converter, and determine the leakage reactance of the converter.

4) Build a three-tuned AC filter model and perform system simulation calculations in combination with the transformer to ensure that the harmonics of the AC system of the converter station are within an acceptable range.

5) Optimize the parameters of the three-tuned AC filter according to the simulation results.

6) Bring the optimized three-tuned AC filter into the system model again for calculation.

7) According to the principle of reactive power distribution and compensation of the system, determine the capacity of the reactive power compensation capacitor connected in parallel with the three-tuned AC filter.

8) According to the parameters of the optimized three-tuned AC filter, determine the stress of each component in it.

The above-mentioned embodiments are only used to illustrate the utility model, wherein the structure and connection mode of each component can be changed, and any equivalent transformation and improvement carried out on the basis of the technical solution of the utility model should not be excluded. Outside the scope of protection of the present utility model.

Claims (1)

1. A three-tuned AC filter is characterized in that: it consists of three low-voltage capacitors C1, C2, C3, three reactors L1-Ztr, L2, L3, two resistors R1, R2 and a reactor arrester F1 constitutes; wherein, the reactor L1-Ztr is a high-voltage reactor; the low-voltage capacitor C2, reactor L2, and resistor R1 are connected in parallel to form a first resonant circuit, and the low-voltage capacitor C3, reactor L3, and resistor R2 The second resonant circuit is formed in parallel; the first and second resonant circuits and the high voltage reactor L1-Ztr are connected in series in sequence and then connected in parallel with the reactor arrester F1 to form a circuit circuit, and one end of the circuit circuit is connected in series with the low voltage Capacitor C1.

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