CN205610208U - Fault handling system based on unified power flow controller - Google Patents

Abstract

The utility model discloses a fault processing system based on a unified power flow controller. The inverter exit unit is connected, the inverter exit unit is connected to the fault location judgment unit, and the fault location judgment unit is connected to the inverter restart unit; the fault detection unit judges whether If a fault occurs, the signal is transmitted to the inverter exit unit, and then the inverter exit unit controls the bypass device to bypass the inverter and transmits the signal to the fault location judging unit, and then the fault location The judging unit determines whether the fault location is on the side of the AC line and transmits the signal to the inverter restart unit, and finally the inverter restart unit judges that the line fault is cleared and then restarts the inverter.

Description

A Fault Handling System Based on UPFC

technical field

The utility model relates to a fault processing system based on a unified power flow controller, which belongs to the technical field of flexible power transmission in electric power systems.

Background technique

With the interconnection of large-scale power systems and the use of various new equipment, the scale and complexity of the power system have also increased while making power generation and transmission more economical and efficient; coupled with a large number of distributed power generation systems connected to the grid , so that the traditional fixed power flow transmitted from the transmission network to the distribution network is reversed; the continuous growth of user load requires power flow control means to improve the existing power transmission capacity; the complex power exchange between the booming smart grid and the power market requires Frequent flow optimization control.

Unified Power Flow Controller, also known as UPFC (Unified Power Flow Controller), is the most versatile power flow control device so far. The simplest UPFC is connected by two identical voltage source converters through the DC common terminal, which can be regarded as a static synchronous compensator (STATCOM) and A Static Synchronous Series Compensator (SSSC) is connected in parallel. Only by changing the control law, different control functions such as parallel compensation, series compensation and shifting can be realized separately or simultaneously and quickly, and the performance of the power system can be improved.

UPFC includes parallel-side converter, series-side converter, parallel-side transformer, series-side transformer, parallel-side transformer incoming switch, series-side transformer bypass switch, etc. Its basic structure is shown in Figure 1. In the figure, 1 is a parallel converter, 2 is one or more series side converters, 3 is a parallel transformer, 4 is a series transformer, 5 is a line switch, 6 is a bypass device connected in parallel with the primary winding of the series transformer, 7 is a A bypass device connected in parallel with the secondary side winding of a series transformer. The above bypass device is a controllable conduction device, including but not limited to mechanical switches, power electronic switches, spark gaps and their combinations. UPFC can realize multi-objective coordinated control such as AC grid-connected point voltage or reactive power control, line terminal voltage control, phase shift control, impedance control, and direct power flow control.

When a fault occurs on the line side, a large fault current may be generated, which will be coupled to the series-side converter through the series-side transformer, resulting in damage to the series-side converter. Therefore, the series transformer must be quickly bypassed through the bypass device, or Short-circuit the outlet of the secondary side of the series transformer to protect the converter. However, temporary faults account for most of the line faults, so the fault reclosing strategy will be configured on the line to improve the reliability of operation. At this time, the fault control strategy of UPFC should cooperate with the line reclosing strategy to improve the reliability of the transmission system .

Utility model content

The purpose of this utility model is to propose a fault handling system based on a unified power flow controller, which can protect the safety of the main equipment of the unified power flow controller and the power system by cooperating with the line fault handling strategy, and at the same time can take into account the requirements of the power grid for power transmission reliability. Suitable for engineering applications.

The utility model proposes a fault processing system based on a unified power flow controller, which is characterized in that it includes a fault detection unit, a converter exit unit, a fault location judgment unit, and a converter restart unit, and the fault detection unit and the The inverter exit unit is connected, the inverter exit unit is connected to the fault location judging unit, and the fault location judging unit is connected to the inverter restart unit; the fault detection unit judges whether there is When a fault occurs, the signal is transmitted to the inverter exit unit, and then the inverter exit unit controls the bypass device to bypass the inverter and transmits the signal to the fault location judgment unit, and then the fault location judgment The unit determines whether the fault location is on the side of the AC line and transmits the signal to the inverter restart unit, and finally the inverter restart unit judges that the line fault is cleared and then restarts the inverter.

The beneficial effects achieved by the utility model: the utility model can protect the safety of the main equipment of the unified power flow controller and the power system, and better utilize the advantages of the unified power flow controller to optimize the system power flow; the method is simple and reliable, and can be used with existing line protection The actions are coordinated to achieve the function of accurately and quickly isolating faults to protect the main equipment of the unified power flow controller and improving the operating reliability of the unified power flow controller system.

Description of drawings

Figure 1 is the equivalent diagram of the basic structure of the unified power flow controller.

Fig. 2 is a method flow chart of a fault handling system based on a unified power flow controller of the present invention.

Fig. 3 is a structural schematic diagram of a fault handling system based on a unified power flow controller of the present invention.

detailed description

Below in conjunction with accompanying drawing, the utility model is further described. The following examples are only used to illustrate the technical solution of the utility model more clearly, but not to limit the protection scope of the utility model.

Fig. 1 is an equivalent diagram of the basic structure of a unified power flow controller. In this specific embodiment, the unified power flow controller includes a parallel-side converter 1, one or more series-side converters 2, and each series-side converter 2 One end of the converter 2 is connected in series to different AC transmission lines through the series-side transformer 4, and the other end is connected in parallel with the parallel-side converter 1 through the DC system; the aforementioned parallel-side converter 1 and the series-side converter The converter 2 can be a voltage source converter with multiple transformers, two-level, modular multi-level or other topological structures. The line switch 5 is connected in series in the line, and the primary side bypass switch 6 of the series side transformer and The secondary side bypass switch 7 is connected in parallel with the primary side winding and the secondary side winding of the series transformer respectively, and the bypass switches 6 and 7 can be mechanical switches or switches composed of power electronic devices.

The working principle of the utility model: when the line fault occurs, the unified power flow controller is bypassed, and the fault situation and fault location are judged by using the abnormal voltage and current and the line switch position signal. When the fault location is on the side of the AC line, it is judged that the line fault has disappeared After that, the unified power flow controller is automatically restarted; FIG. 2 is a flow chart of a method for a fault handling system based on the unified power flow controller of the present invention, including the following four steps.

Step SS1 detects and judges whether there is a fault according to the electrical quantities and switch position signals of the line side and the unified power flow controller, and enters step SS2 if a fault occurs.

Step SS2 blocks the converter where the UPFC fails, and isolates the converter from the line by bypassing the primary side bypass switch and the secondary side bypass switch of the series transformer.

Step SS3 judges whether the fault occurs on the line side, if judged to be a line fault, then enters step SS4, otherwise enters the blocking fault restart function, and does not restart the series side converter; the line fault judgment method described in the step SS3 is: Partition protection is carried out for the unified power flow controller. When only an overcurrent fault occurs in the equipment area of the unified power flow controller and no other fault phenomena occur, it is judged that the fault occurs on the line side.

Step SS4 cooperates with the line reclosing function. After the line reclosing time has elapsed, judge whether the line fault is cleared. If it is judged that the line fault has been cleared, restart the input series side converter to control the line power flow; if it is judged that If the line is not restored, the series-side converter will not be restarted; the method for judging whether the line fault is cleared in the step SS4 is: after waiting for the line reclosing time, if the line switch is closed, and judging the line side voltage and current If it is in the normal range, it is considered that the line fault has been cleared.

Fig. 3 is a schematic structural diagram of a fault handling system based on a unified power flow controller of the present invention. The utility model also proposes a fault handling system based on a unified power flow controller, which is characterized in that it includes a fault detection unit, a The inverter exit unit, the fault location judging unit, and the inverter restart unit, the fault detection unit is connected with the inverter exit unit, the inverter exit unit is connected with the fault location judging unit, the The fault position judging unit is connected to the inverter restart unit; the fault detection unit judges whether there is a fault and then transmits a signal to the inverter exit unit, and then the inverter exit unit controls the bypass device Bypass the converter and transmit the signal to the fault location judging unit, then the fault location judging unit determines whether the fault location is on the AC line side and transmits the signal to the converter restart unit, and finally the commutation The converter restart unit restarts the converter after judging that the line fault is cleared.

The bypass device controlled by the inverter exit unit is a controllable conduction device, including but not limited to mechanical switches, power electronic switches, spark gaps and their combinations. The installation location can be installed on the primary side of the series transformer or the series transformer On the secondary side, the series side of the unified power flow controller is bypassed by turning on the bypass device.

The utility model proposes a fault handling system based on a unified power flow controller, which can be used in a system in which a static synchronous series compensator (SSSC), an interline power flow controller (IPFC), etc. are connected in series in the line and have a bypass device; It can also be used as an independent device or as a module in general control and protection equipment.

The above is only the preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the utility model, some improvements and deformations can also be made. And deformation should also be regarded as the protection scope of the present utility model.

Claims (1)

1. A fault processing system based on a unified power flow controller, characterized in that it includes a fault detection unit, a converter exit unit, a fault location judgment unit, and a converter restart unit, and the fault detection unit and the converter The inverter exit unit is connected, the inverter exit unit is connected to the fault location judging unit, and the fault location judging unit is connected to the inverter restart unit.