CN205263529U - Controllable elimination three -phase ferroresonance's electric power system model based on DSP - Google Patents

Abstract

A DSP-based power system model for controllable elimination of three-phase ferromagnetic resonance, including a three-phase power supply and three-phase voltage transformers PT connected to three buses of the three-phase power supply, two of the three-phase voltage transformers PT A controllable switch S and a damping resistor R are connected in series in the secondary open triangle, and the controllable switch S is connected with a DSP for sampling the voltage of the open triangle and sending control signals. Due to the adoption of the above technical solution, the DSP-based power system model for the controllable elimination of three-phase ferromagnetic resonance of the utility model can not only distinguish ground faults and ferromagnetic resonance, but also quickly eliminate ferromagnetic resonance, and can also eliminate iron After the magnetic resonance, the open triangle is kept open, which does not affect the normal operation of the PT. The value of the damping resistance and the length of the connection time are set according to the actual situation of the substation.

Description

A Power System Model Based on DSP Controllable Elimination of Three-phase Ferromagnetic Resonance

technical field

The utility model relates to a power system model, in particular to a DSP-based power system model that can controlly eliminate three-phase ferromagnetic resonance.

Background technique

In the power system, in order to monitor the ground voltage of the power plant and substation bus, a voltage transformer is usually connected to the generator or substation bus, and its primary winding is connected in a star shape, and the neutral point is directly grounded. In this way, when the power grid is excited by some disturbances, the excitation impedance of the voltage transformer and the ground capacitance of the system form a nonlinear resonant loop. Due to the difference in loop parameters and external excitation conditions, it may cause frequency division, fundamental frequency or high frequency ferromagnetic resonance. Magnetic resonance overvoltage. According to statistics, the ferromagnetic resonance overvoltage caused by electromagnetic voltage transformer is the most common internal overvoltage in the neutral point ungrounded system, which causes the most accidents. On the one hand, resonance will cause overvoltage in the system, endanger weak insulation equipment, cause flashover tripping accidents, and even cause arrester explosions; on the other hand, resonance will generate a high multiple of overcurrent in the PT, which will lead to Fuse blown, PT overcurrent burning or explosion accident. The PT resonance problem has seriously threatened the safe and stable operation of the power grid, and is also one of the causes of some major accidents in the power system.

PT resonance problems in neutral point ungrounded systems have been reported from time to time across the country. For example, PT resonance overvoltage frequently occurred in Chongqing Shiping substation, and PT high-voltage fuses were blown dozens of times. PT resonance accidents also occurred in Wanzhou Station. Chongqing Power Grid The 10kV and 35kV systems of the power supply bureaus have also repeatedly experienced PT resonance overvoltages, resulting in PT burnout accidents, and PT resonance accidents in the power systems of various grid provinces have also been reported from time to time. The PT resonance problem seriously threatens the safe and stable operation of the power grid, affects the reliability of power supply, and is a hidden danger to the stable operation of the power system, which has attracted great attention from the power sector and researchers.

In order to solve the above problems, eliminate potential safety hazards in distribution network operation, and improve system reliability, a simulation study on PT resonance and suppression measures is carried out.

Utility model content

The purpose of the utility model is to solve the deficiencies of the existing technical problems, and provide a DSP-based power system model that can controlly eliminate three-phase ferromagnetic resonance.

The purpose of this utility model is achieved by such a technical solution: a DSP-based power system model that can controlly eliminate three-phase ferromagnetic resonance, including three-phase power supply and three-phase voltage connected to the three busbars of the three-phase power supply Transformer PT, the secondary open delta of the three-phase voltage transformer PT is connected with a controllable switch S and a damping resistor R in series, and the controllable switch S is connected with a DSP for sampling the open delta voltage and sending control signals.

Further, the model of the voltage transformer PT is JDZX16-10RG.

Preferably, the rated capacity of the voltage transformer PT is 20VA, the rated frequency is 50 Hz, the rated current is 2.8 mA, and the rated phase voltage is 5.77 kV.

Control strategy: DSP samples the open triangle voltage of the secondary open triangle of the three-phase voltage transformer PT, and sets the threshold in the DSP. When the processed sampling voltage reaches the threshold, the DSP sends a signal to control the controllable switch S, and connects the damping resistor R for a period of time, after which the controllable switch S is turned off.

Due to the adoption of the above-mentioned technical scheme, the utility model has the following advantages: the DSP-based controllable elimination three-phase ferromagnetic resonance power system model of the utility model can not only distinguish the ground fault from the ferromagnetic resonance, but also can quickly eliminate the ferromagnetic resonance. Magnetic resonance can also keep the open triangle open circuit after eliminating ferromagnetic resonance, without affecting the normal operation of PT. The value of damping resistance and the length of access time are set according to the actual situation of the substation; the controllable elimination of three-phase ferromagnetic resonance based on DSP The power system model is consistent with the smart grid. With the development of the smart grid, all kinds of equipment in the substation are gradually developing in the direction of intelligence, making the operation of the power system more efficient, reliable and safe.

Other advantages, objectives and features of the present utility model will be set forth in the following description to some extent, and to some extent, based on the investigation and research below, it will be obvious to those skilled in the art, or can be Get teaching from the practice of the utility model. The objectives and other advantages of the utility model can be realized and obtained by the following description and claims.

Description of drawings

The accompanying drawings of the utility model are as follows:

Fig. 1 is the control train of thought diagram of the present utility model;

Fig. 2 is a schematic diagram of the utility model;

Fig. 3 is the frequency-division resonance zero-sequence voltage waveform when the damping resistor R is not connected in this embodiment;

Figure 4 shows the zero-sequence voltage waveform when a 10Ω damping resistor R is connected at 1.5s in this embodiment and the on-time is 6ms;

Figure 5 shows the zero-sequence voltage waveform when a 100Ω damping resistor R is connected at 1.5s in this embodiment and the on-time is 6ms;

Fig. 6 is a zero-sequence voltage waveform of a 10Ω resistor connected at a time of 0.5s in this embodiment.

detailed description

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

As shown in Figure 1 and Figure 2, in Figure 2, EA, E _B and E _C are three _- phase power supply potentials, the power system model based on the DSP controllable elimination of three-phase ferromagnetic resonance of the present embodiment includes three-phase The power supply and the three-phase voltage transformer PT connected to the three busbars of the three-phase power supply, the secondary opening triangle of the three-phase voltage transformer PT is connected in series with a controllable switch S and a damping resistor R, and the controllable switch S is connected to There is a DSP for sampling the open triangle voltage and sending control signals. The model of the voltage transformer PT is JDZX16-10RG. The rated capacity of the voltage transformer PT is 20VA, the rated frequency is 50Hz, the rated current is 2.8mA, and the rated phase voltage is 5.77 kV.

The DSP samples the open triangle voltage of the secondary open triangle of the three-phase voltage transformer PT, and sets the threshold in the DSP. When the processed sampling voltage reaches the threshold, the DSP sends a signal to control the controllable switch S, and connects the damping resistor R for a period of time. , and then disconnect the controllable switch S.

Figure 3 is the frequency-division resonance zero-sequence voltage waveform when the damping resistor R is not connected, and Figures 4 and 5 are the zero-sequence voltage when the resistor is connected at 1.5s, the on-time is 6ms, and the damping resistance R is 10Ω and 100Ω respectively Waveform, Figure 6 is the zero-sequence voltage waveform connected to a 10Ω resistor at 0.5s.

Figure 4 and Figure 5 show that the resistance is connected for 6ms during the frequency division resonance process, and the resonance disappears. Figure 6 shows that the resistance is connected during the ground fault period, and the ground fault continues. It can be seen that the connection of the control damping resistor R can distinguish between ferromagnetic resonance and ground fault, and when it is ferromagnetic resonance, it can eliminate the resonance and restore the system to the normal state. When it is a ground fault, it needs to be combined with other protection devices in the system to eliminate the ground fault.

Figure 4 and Figure 5 have different damping resistance values. It can be seen from the figure that the damping resistance R of 10Ω is better than the damping resistance R of 100Ω, which is consistent with the theoretical analysis conclusion that the damping resistance R is small and the effect is good.

From the analysis, it can be known that the DSP-based controllable anti-coordination measures can not only distinguish the ground fault and ferromagnetic resonance, but also keep the open triangle open after eliminating the ferromagnetic resonance, without affecting the normal operation of the PT. The value of damping resistance R and the length of connection time are set according to the actual situation of the substation. The controllable consumer association measures are consistent with the smart grid. With the development of the smart grid, all kinds of equipment in the substation are gradually developing in the direction of intelligence, making the operation of the power system more efficient, reliable and safe.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present utility model without limitation. Although the utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the utility model can be Modifications or equivalent replacements of the technical solutions without departing from the spirit and scope of the technical solutions shall be covered by the claims of the present utility model.

Claims (3)

1. an electric power system model for the controlled elimination three-phase ferromagnetic resonance based on DSP, comprises three phase mains and is connected to three-phaseThreephase potential transformer PT on three buses of power supply, is characterized in that: the secondary opening of described threephase potential transformer PTTriangle is in series with controllable switch S and damping resistance R, described controllable switch S be connected with for sample open-delta voltage and send outSend the DSP of control signal.

2. the electric power system model of a kind of controlled elimination three-phase ferromagnetic resonance based on DSP as claimed in claim 1, its featureBe: the model of described voltage transformer pt is JDZX16-10RG.

3. the electric power system model of a kind of controlled elimination three-phase ferromagnetic resonance based on DSP as claimed in claim 1, its featureBe: the rated capacity 20VA of described voltage transformer pt, rated frequency 50Hz, rated current 2.8mA, specified electricity mutuallyPress 5.77kV.