WO2014121636A1

WO2014121636A1 - Resonant current limiter based on insulator-metal phase change resistor

Info

Publication number: WO2014121636A1
Application number: PCT/CN2013/088997
Authority: WO
Inventors: 肖立业; 邱清泉; 张志丰; 戴少涛; 林良真; 屈飞
Original assignee: 中国科学院电工研究所
Priority date: 2013-02-06
Filing date: 2013-12-10
Publication date: 2014-08-14
Also published as: CN103117538B; CN103117538A

Abstract

Provided is a resonant current limiter based on an insulator-metal phase change resistor. The resistor (R_PC) made of an insulator-metallic phase change material is in parallel connection with a capacitor (C), and then is in series connection with a reactor (L). While in normal operation, the phase change resistor (R_PC) is in a high-resistance state, the current passing therethrough is low, the temperature rise is low, the current mainly flows through a circuit formed by the reactor (L) and the capacitor (C) in series connection, and the reactor (L) and the capacitor(C) form a serially connected resonant circuit which is in a low-impedance state and has small influence on a power grid system. When the power grid system breaks down and is short-circuited, the current flowing through the phase change resistor (R_PC) is increased, the temperature is rapidly increased, and the insulator-metal phase change material undergoes phase change and enters a low-resistance state. The short-circuit current is transferred to the phase change resistor (R_PC) branch from the capacitor (C) branch, the impedance of the power grid system is increased, and the short-circuit current is reduced. The insulator-metal phase change material is a negative-temperature coefficient insulator-metal phase change material of VO₂, V₂O₃ and the like.

Description

Resonance type current limiter based on insulator-metal phase change resistor

The invention relates to a series resonance type current limiter. Background technique

With the rapid development of the national economy, the society's increasing demand for electricity has led to the continuous development of power systems. The capacity of single and power plants, the capacity of substations, and the increasing load of urban and industrial centers have made the interconnection of power systems. The level of short-circuit current in all levels of power grids continues to increase, and the short-circuit faults are becoming more and more destructive to the power system and its connected electrical equipment. Moreover, while the demand for electrical energy is increasing, people have put forward higher requirements for power quality, power supply reliability and safety. However, the transient stability problem of large power grids is more prominent. One of the most important reasons is the lack of effective short-circuit fault current limiting technology due to conventional power technology. At present, the circuit breaker is widely used in the world to break the short-circuit current. Since the short-circuit current level is directly related to the capacity of the system, when the rated breaking current level of the circuit breaker is constant, the full-breaking short-circuit current will be used. The capacity of the power system is limited to increase, and the circuit breaker is expensive and its price rises rapidly as its rated breaking current increases. With the expansion of grid capacity and scale, the breaking capacity of circuit breakers has become increasingly difficult to adapt to the needs of grid operation. The short-circuit fault current limiter provides a new idea for solving this problem. At present, the more mature fault current limiter technologies mainly include series current limiting reactors, series resonance type current limiters, and controllable series compensation current limiters. The fault current limiter technology in the research stage is mainly realized by applying new materials. Current limiting technology, including superconducting current limiters, PTC thermistor current limiters.

Repetitive current limiter based on polymeter PTC resistor. IEEE Trans on Power Delivery, 1998, 13(2): 489-494. is a resistance type based on insulator-metal phase change material. Current devices, currently used insulators - metal phase change materials mainly include heat-sensitive materials such as BaTiO ₃ and organic high molecular polymers. China Patent 200710036527 "Restrictor based on sulfur-based compound phase change material and its manufacturing method" also proposes a current limiter based on a sulfur-based compound phase change material and a manufacturing method thereof. In addition, the superconducting resistor type current limiter is also a current limiting device based on phase change material. A thermistor made of PTC insulator-metal phase change material can undergo a phase change under temperature, causing a huge change in its resistance performance. It is in a low resistance state below the phase transition temperature and above the phase transition temperature. At high impedance, the resistance difference between the two states can be more than five orders of magnitude. Based on the current limiter of PTC material and superconducting material, in the event of a short circuit fault, since the resistance of the resistor increases and at the same time withstands a large current, the heat generation and loss of the resistor are very large, which is very high for manufacturing the resistor. Requirements have restricted its large-scale development. In the current current limiter technology, the series resonant type current limiter has mature technology and high reliability. The series resonant current limiter has no reactive power loss and has great application prospects. For series resonant current limiters, the capacitor bypass circuit is a key technology, mainly including the following bypass circuits: bypass circuits based on saturated reactors (comparison of the operating characteristics of two economical fault current limiters, Journal of Electric Power Systems and Automation, 2005, 17 ( 4 ) : 71-75 ), Surge Circuit Based on Arrester (The Effect of Zinc Oxide Arrester Fault Current Limiter on Power System Transient Stability, Power Automation Equipment, 2007, 27 ( 8 ) : 51 -54 ). The arrester is used as a bypass circuit. Although the response speed is fast, the arrester has a certain residual voltage, and the loss is large when the short-circuit current is passed. Summary of the invention

In order to overcome the disadvantages of the conventional series resonance type current limiter, the present invention proposes a resonance type current limiter based on an insulator-metal phase change resistor. The current limiter based on the insulator-metal phase change resistor is formed by series and parallel combination of resistor blocks made of sheets, blocks or films of negative temperature coefficient phase change materials such as VO ₂ and V ₂ O ₃ . The insulator-metal phase-change resistor is used as a bypass circuit for the capacitor, or an insulator-metal phase-change resistor is used in combination with the arrester to further speed up the response of the capacitor bypass circuit and effectively protect the arrester. Limit of insulator-metal phase change resistance proposed by the present invention The flow device is flexible and easy to implement, and can be applied to various power system systems with different voltage levels and different capacities. Taking the VO ₂ insulator-metal phase change material as an example, as the temperature increases, the crystal transition of the monoclinic structure and the rutile structure occurs near 68 ° C, and at the same time, the semiconductor state changes to the metallic state. Occurs in the nanosecond time range, followed by reversible mutations in resistivity, magnetic susceptibility, light transmission, and reflectivity. The use of VO ₂ insulator-metal phase change material makes it easier to fabricate an insulator-metal phase change resistor unit module. This new type of current limiter can be repeated because the high and low resistance states of the phase change material are reversible. Use, has a very broad application prospects in the field of power systems and electrical and electronic circuits. In order to achieve the above object, the present invention can adopt the following two technical solutions. The first phase-limiting material-based current limiter uses an insulator-metal phase change resistor in parallel with the capacitor and then in series with the reactor. When the grid system is working normally, the insulator-metal phase change resistor is in a large resistance state, and the current mainly flows through the circuit composed of the reactor and the capacitor in series. The reactor and the capacitor form a series resonant circuit, which is in a low impedance state and affects the power grid system. Very small. In the event of a faulty short circuit in the grid system, the insulator-metal phase change resistance reacts quickly to a small resistance state, and the short-circuit current is transferred from the capacitor branch to the insulator-metal phase change resistor branch, and the impedance of the entire grid system increases, and the short-circuit current decreases. The second type of current limiting device based on phase change material adopts an insulator-metal phase change resistor, and the arrester is connected in parallel with the capacitor, and then connected in series with the reactor. When the grid system is working normally, the insulator-metal phase change resistor is in a large resistance state, and the current mainly flows through the circuit composed of the reactor and the capacitor in series. The reactor and the capacitor form a series resonant circuit, which is in a low impedance state and affects the power grid system. Very small. When the grid system fails, the arrester responds quickly, and the short-circuit current is transferred from the capacitor branch to the arrester branch. The impedance of the entire grid system increases and the short-circuit current decreases. Next, the temperature rise of the insulator-metal phase change resistor increases. In the resistance state, the short-circuit current is transferred from the capacitor branch and the arrester branch to the insulator-metal phase change resistor branch, and the impedance of the grid system is further increased, and the short-circuit current is further decreased. The current limiter exhibits low impedance during normal operation and has little effect on the grid system. In the case of a short circuit fault, it exhibits a large impedance, which effectively limits the short circuit current. The invention has the following main advantages:

1) The current limiter of the present invention has a small steady-state influence on the power grid. In normal operation, the steady-state impedance of the fault current is small and does not increase the system reactive power.

2) The present invention applies the resistance change of the insulator-metal phase change resistor to suppress the fault current, enables automatic response and fast response speed, and has a simple structure and high reliability.

3) The present invention can be used to construct a large-capacity current limiter. The use of multiple phase-change resistors in series and parallel as the bypass circuit of the capacitor has low loss during normal operation and low heat generation when passing short-circuit current, which can effectively reduce the technical difficulty of resistor fabrication. DRAWINGS

The invention is further described below in conjunction with the drawings and specific embodiments. Figure 1 is a graph showing the change in resistivity of VO ₂ material with temperature;

2 is a circuit diagram of a resonant type current limiter based on an insulator-metal phase change resistor according to Embodiment 1 of the present invention;

Fig. 3 is a circuit diagram showing a resonance type current limiter based on an insulator-metal phase change resistor and a lightning arrester according to Embodiment 2 of the present invention. detailed description

The invention adopts a resistor module made of a sheet, a block or a film of a negative temperature coefficient phase change material such as VO ₂ , V ₂ O ₃ and the like to form an insulator-metal phase change resistor Rpc, which is applied to a series resonance fault current limiter. Improve the speed and reliability of the response. Figure 1 shows the resistivity of VO ₂ material as a function of temperature. It can be seen that the phase transition temperature of VO ₂ is between 320K and 340K. When the temperature is higher than the phase transition temperature, the resistivity of VO ₂ can be decreased. 5 orders of magnitude, from semiconductor to good conductor. 2 is a resonance type current limiter based on an insulator-metal phase change material according to Embodiment 1 of the present invention. The current limiter is first connected in parallel with the capacitor C by using an insulator-metal phase change resistor Rpc, and then connected in series with the reactor L. When the grid system is working normally, the insulator-metal phase change resistor Rpc has a large resistance state, and the current mainly flows through the circuit composed of the series connection of the reactor L and the capacitor C. The reactor L and the capacitor C form a series resonant circuit, which is in a low impedance state. , has little impact on the grid system. When the grid system fails, the voltage on the insulator-metal phase change resistor Rpc increases, the temperature rise also increases, the insulator-metal phase change resistor Rpc produces a phase change in a small resistance state, and the short-circuit current is transferred from the capacitor C branch to the insulator. - Metal phase change resistor Rpc branch, the impedance of the entire grid system increases, and the short circuit current decreases. The insulator-metal phase change resistor can be used alone or in combination with other mating switching elements. Fig. 3 shows a series resonance type current limiter based on the insulator-metal phase change resistor Rpc and the arrester MOV of the second embodiment. The current limiter adopts an insulator-metal phase change resistor Rpc, and the arrester MOV is connected in parallel with the capacitor C, and then connected in series with the reactor L. When the grid system is working normally, the insulator-metal phase change resistor Rpc and the arrester MOV are in a large resistance state, and the current mainly flows through the circuit composed of the series connection of the reactor L and the capacitor C, and the reactor L and the capacitor C form a series resonance circuit. In the low impedance state, it has little effect on the grid system; in the case of a sudden short circuit fault, overvoltage is easily generated at both ends of the capacitor. In order to protect the capacitor and reduce the cost of the capacitor, the arrester MOV is used together with the insulator-metal phase change resistor Rpc. It can effectively control the voltage drop of the capacitor. Since the arrester MOV has residual voltage, a lot of heat is generated when the short-circuit surge current flows, which is one of the factors restricting the development of the large-capacity arrester. The insulator-metal phase change resistor Rpc and the lightning arrester MOV are connected in parallel, which can effectively solve the problem that the arrester cannot pass the short-circuit current for a long time. When the insulator-metal phase change resistor flows through the short-circuit current, the resistance phase is changed into good. The conductor generates less heat when the short-circuit current passes, and can effectively protect the lightning arrester MOV from long-term overcurrent.

Claims

A resonant type fault current limiter based on an insulator-metal phase change resistor, characterized in that the current limiter is connected in parallel with a capacitor (C) using an insulator-metal phase change resistor (Rpc), and then The reactor (L) is connected in series; when the grid system is working normally, the insulator-metal phase change resistor (Rpc) is in a large resistance state, and the current mainly flows through the power path composed of the series connection of the reactor (L) and the capacitor (C). Reactor (L) and capacitor (C) form a series resonant circuit, which has a low impedance state and has little effect on the grid system. In the event of a faulty short circuit in the grid system, the insulator-metal phase change resistor (Rpc) reacts quickly to a small resistance state. The short-circuit current is transferred from the capacitor (C) branch to the insulator-metal phase change resistor (Rpc) branch, and the impedance of the entire grid system increases, and the short-circuit current decreases.

2. The flow restrictor according to claim 1, wherein the current limiter is used for collecting

Insulator-metal phase change resistor (Rpc), arrester (MOV) and capacitor (C) are connected in parallel first, then in series with reactor (L); in the normal operation of the grid system, insulator-metal phase change resistor (Rpc) and The arrester (MOV) has a large resistance state, and the current mainly flows through a circuit composed of a series connection of the reactor (L) and the capacitor (C), and the reactor (L) and the capacitor (C) form a series resonance circuit, which is in a low impedance state, The grid system has little impact; in the event of a faulty short circuit in the grid system, the arrester (MOV) responds quickly, and the short-circuit current is transferred from the capacitor (C) branch to the arrester (MOV) branch, the impedance of the entire system increases, and the short-circuit current decreases; , insulator-metal phase change resistor (Rpc) temperature rise increases, in a small resistance state, short-circuit current is transferred from capacitor (C) branch and arrester (MOV) branch to insulator-metal phase change resistor (Rpc) branch, grid The impedance of the system is further increased and the short-circuit current is further reduced.

3. The current limiter according to claim 1, wherein the insulator-metal phase change resistor (Rpc) is formed by series and parallel combination of resistor modules made of an insulator-metal phase change material; When the current is small, the temperature of the insulator-metal phase change resistor (Rpc) is lower than the phase transition temperature, the insulator-metal phase change material is in a semiconductor state, and the resistivity is large; when a large current is passed, High temperature of insulator-metal phase change resistor (Rpc) At the phase transition temperature, the phase change material is in a metallic state, and the resistivity is reduced by more than three orders of magnitude.

4. The current limiter according to claim 3, wherein the insulator-metal phase change material is a sheet or block or film made of a VO ₂ , V ₂ O ₃ negative temperature coefficient phase change material. .