WO2013075754A1

WO2013075754A1 - A hvdc thyristor valve assembly

Info

Publication number: WO2013075754A1
Application number: PCT/EP2011/071025
Authority: WO
Inventors: Robert Elliott
Original assignee: Alstom Technology Ltd
Priority date: 2011-11-25
Filing date: 2011-11-25
Publication date: 2013-05-30
Also published as: CN104011859A; EP2783394A1

Abstract

A HVDC thyristor valve assembly(10; 80; 90; 100) comprises a plurality of series-connected thyristor valve modules (30, 36, 58, 60). Each valve module (30, 36, 58, 60)has two opposed ends(14, 16). One end of a first valve module (30)in an adjacent pair(32, 54, 56)of valve modules is movably and electrically interconnected by a coupling(34)member to an end of the second valve module (36)in the said adjacent pair(32, 54, 56)of valve modules. Relative movement between the interconnected ends of the first and second valve modules(30, 36)is damped by at least one damping member(40, 42).

Description

A HVDC THYRISTOR VALVE ASSEMBLY

This invention relates to a High Voltage Direct Current (HVDC) thyristor valve assembly.

Thyristors form the centre of most HVDC conversion processes, and typically a number of them are clamped in series between heatsinks in a Thyristor Clamped Assembly (TCA).

Normally one or more such TCAs and other associated components such as reactor, resistor and capacitor assemblies are connected together to form a thyristor valve module.

A conventional thyristor valve assembly includes a plurality of such thyristor valve modules fixedly secured on top of one another in a stacked configuration.

Such conventional thyristor valve assemblies are perfectly adequate in normal operating conditions. However they are not well suited to installation in seismic regions, i.e. regions that are subject to tremors and earthquakes, since during a seismic event they undergo large displacements which damage both the valve assemblies themselves and external components with which they are interfaced.

According to a first aspect of the invention there is provided a HVDC thyristor valve assembly comprising a plurality of series-connected thyristor valve modules, each valve module having two opposed ends, one end of a first valve module in an adjacent pair of valve modules being movably and electrically interconnected by a coupling member to an end of the second valve module in the said adjacent pair of valve modules, and relative movement between the interconnected ends of the first and second valve modules being damped by at least one damping member.

Movably interconnecting respective ends of first and second valve modules in an adjacent pair of valve modules via a coupling member allows the valve modules to move relative to one another so as to accommodate disturbances caused by a seismic event.

Electrically interconnecting the same ends, via the same coupling member, removes the need for inter-module busbars and reduces the number of inter-module insulators required. Such busbars prevent movement of one valve module relative to another valve module within a said adjacent pair of valve modules, and so increase the risk of damage occurring to the valve assembly and/or the external components to which it is connected during a seismic event. Meanwhile inter-module insulators are expensive and relatively fragile components and so reducing their number reduces costs and the risk of damage or other failure occurring during a seismic event.

Furthermore, the inclusion of at least one damping member to dampen relative movement between the ends of the first and second valve modules that are interconnected by the coupling member, reduces the amplitude of relative oscillation between adjacent valve modules and so reduces further the risk of the valve assembly and/or the external components to which it is connected being damaged during a seismic event.

As a result the thyristor valve assembly of the invention is well-suited to installation in seismic regions.

Preferably the thyristor valve assembly includes a first damping member extending between the ends of the first and second valve modules interconnected by the coupling member.

The inclusion of such a first damping member helps to ensure that the damping member need only accommodate a minimal degree of relative movement between the adjacent valve modules for a given degree of damping.

In a preferred embodiment of the invention the first damping member is defined by a first fluid conduit. Such a fluid conduit is able to convey fluid around the thyristor valve assembly in order to provide necessary cooling of the thyristors within each thyristor valve module. An arrangement of this kind helps to provide a coolant path that does not involve inter-module voltage stresses and avoids the need to span inter-module insulators with fluid conduit.

Optionally the thyristor valve assembly further includes a second damping member extending between the ends of the first and second valve modules interconnected by the coupling member.

The inclusion of such a second damping member, positioned in a similar manner to the first damping member, provides additional damping for more severe seismic events.

In another preferred embodiment of the invention the second damping member is defined by a second fluid conduit. The inclusion of a second fluid conduit allows the recycling of used coolant fluid conveyed by the first fluid conduit to a cooling facility.

The HVDC thyristor valve assembly may include first and second fluid conduits in which:

(i) the first fluid conduit extends along a first side of both the first and second valve modules in an adjacent pair of valve modules and the second fluid conduit extends along a second side of both the first and second valve modules;

(ii) the first fluid conduit extends along a first side of the first valve module and along a second side of the second valve module and the second fluid conduit extends along a second side of the first valve module and along a first side of the second valve module;

(iii) the first and second fluid conduits extend along the same side of both the first and second valve modules; or

(iv) the first and second fluid conduits extend within each of the first and second valve modules.

Such arrangements provide desirable flow and return conduits for circulating coolant fluid around the individual thyristors in the thyristor valve assembly and a desired degree of damping between adjacent pairs of thyristor valve modules. They also remove the requirement for additional fluid conduits between valve modules.

In still further embodiments of the invention the coupling member is or includes a damping member. Such an arrangement can help simplify the provision of damping between adjacent pairs of thyristor valve modules while providing additional options for the routing of flow and return conduits around the thyristor valve assembly.

Preferably in normal use the or each damping member holds the first and second valve modules in an adjacent pair of valve modules at an angle to one another. Holding adjacent valve modules at an angle to one another helps to ensure a necessary operating clearance between various components within the adjacent valve modules, e.g. between reactor modules arranged at or near the ends interconnected by the coupling member and between voltage modules arranged at or near the other ends of the valve modules.

In a further preferred embodiment of the invention the coupling member includes a corona shield secured thereto. Securing a corona shield to the or each coupling member redistributes the electrostatic lines of force emanating from the high potential region at the movably interconnected ends of adjacent valve modules, while reducing the likelihood of the shield being dislodged from the thyristor valve assembly during a seismic event.

The interconnected ends of the first and second valve modules in an adjacent pair of valve modules may lie directly opposite one another. Such an arrangement results in a compact thyristor valve assembly with a relatively simple interconnecting structure.

Optionally in an installed configuration the valve modules are arranged one above another in a valve stack. Such a stack arrangement, or Multiple Valve Unit (MVU), results in a minimal footprint for a given string of series-connected valve modules and so provides installation benefits, particularly when the overall space available for a HVDC installation is limited.

The first and second valve modules in an adjacent pair of valve modules may have the same orientation as one another. Such an arrangement allows each valve module to have essentially the same configuration which simplifies the manufacture of each valve module.

In other embodiments of the invention the first and second valve modules in an adjacent pair of valve modules have a different orientation to one another.

In each of the aforementioned arrangements current flows in opposite directions within adjacent valve modules, and so the electric field generated by the current flowing in one valve module has a tendency to cancel out the electric field generated by the other valve module. Such cancellation of the respective electric fields reduces, and sometimes eliminates, the need for a bevel within an associated stress shield which simplifies production of the stress shield.

There now follows a brief description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the following figures in which:

Figure 1 shows a HVDC thyristor valve assembly according to a first embodiment of the invention;

Figure 2 shows a HVDC thyristor valve assembly according to a second embodiment of the invention;

Figure 3 shows a HVDC thyristor valve assembly according to a third embodiment of the invention; and Figure 4 shows a HVDC thyristor valve assembly according to a fourth embodiment of the invention.

A HVDC thyristor valve assembly according to a first embodiment of the invention is designated generally by the reference numeral 10.

In the embodiment shown the valve assembly 10 includes four series- connected thyristor valve modules 12. Other embodiments of the invention may include more than or less than four thyristor valve modules 12.

Each valve module 12 has two opposed ends 14, 16 and includes first and second thyristor clamped assemblies 18, 20, each with associated resistor and capacitor assemblies 22, 24 and first and second reactor modules 26, 28.

A first end 14a of a first thyristor valve module 30 in a first adjacent pair 32 of valve modules is movably and electrically interconnected by a coupling member 34 to a first end 14b of a second thyristor valve module 36 in the first adjacent pair 32. In particular, in the embodiment shown, each of the first ends 14a, 14b is pivotally connected to one another by the coupling member 34. Moreover the first ends 14a, 14b lie directly opposite one another. In other embodiments of the invention, however, the first ends 14a, 14b may lie diagonally opposite one another.

The second end 16a of the first valve module 30 is interconnected by first and second insulating members 38 to the second end 16b of the second valve module 36. Each insulating member 38 is sufficiently flexible to accommodate some movement of the second ends 16a, 16b relative to one another.

Such movement of the second ends 16a, 16b, and movement of the first ends 14a, 14b, relative to one another is damped by first and second damping members 40, 42 (only the first damping member 40 is shown in Figure 1).

The first damping member 40 extends between the first ends 14a, 14b of the first and second valve modules 30, 36 and more particularly, in the embodiment shown, extends along a first side 44 of each of the first and second valve modules 30, 36.

The first damping member 40 is defined by a first fluid conduit 46. The first fluid conduit 46 is defined by a hose that is formed from a resiliently deformable material such as cross-linked polyethylene (XLPE), polyvinylidene fluoride (PVDF), or polysulfone (PSU), for example. The second damping member 42 (not shown) also extends between the first ends 14a, 14b of the first and second valve modules 30, 36 but, in the embodiment shown, on a second side 48 of each of the first and second valve modules 30, 36.

The second damping member 42 is defined by a second fluid conduit 50

(not shown in Figure 1) which is also formed from a resiliently deformable material.

The first and second fluid conduits 46, 50 together define respective flow and return paths for a coolant fluid used to cool respective thyristors in each thyristor clamped assembly 18, 20.

Fibre optic control lines (not shown) which are used to control operation of the various valve modules 12 may follow the same path as one or both of the first and second fluid conduits 46, 50.

In other embodiments of the invention (not shown) the coupling member 34 may itself be formed from a resiliently deformable material so as to define a further damping member, or it may include a damping member in the form of, e.g. a resiliently deformable bush lying between the coupling member 34 and one or both of the first and second valve modules 30, 36.

In the embodiment shown the first and second damping members 40, 42 hold the first and second valve modules, in normal use, at an angle to one another. More particularly, when the thyristor valve assembly 10 is in an installed configuration, as shown in Figure 1 , the first and second valve modules 30, 36 are arranged one above the other in a valve stack, and the first and second valve modules 30, 36 are held in an inclined position relative to one another.

Preferably the angle subtended between the first and second modules

30, 36 is typically more than 10°and/or less than 20°.

The coupling member 34 also includes a corona shield 52 (omitted from the coupling member 34 lying between the first and second valve modules 30, 36 shown in Figure 1 for clarity) which is secured thereto.

AC and DC take-off connections (not shown) can extend through each respective corona shield 52. Alternatively such connections could be taken from a mid-point along the length of each valve module 30, 36, or any intermediate point along the length of each valve module 30, 36. The first and second valve modules 30, 36 have the same orientation as one another, i.e. the first and second thyristor clamped assemblies 18, 20 lie on the same, first side 44 of each valve module 30, 36.

The thyristor valve assembly 10 also includes second and third pairs 54, 56 of valve modules.

The second pair 54 includes the second valve module 36 described hereinabove together with a third valve module 58 which is essentially identical to the second valve module 36.

In this pair 54 the second end 16b of the second valve module 36 is pivotally connected and electrically interconnected with a second end 16c of the third valve module 58 by a coupling member 34, while the first ends 14b, 14c of the second and third valve modules 36, 58 are interconnected by two flexible insulating members 38.

The first and second damping members 40, 42, i.e. the first and second fluid conduits 46, 50 also extend between the second ends 16b, 16c to provide the same degree of damping as between the first ends 14a, 14b of the first and second valve modules 30, 36.

The third pair 56 of valve modules includes the third valve module 58 and a fourth valve module 60. The third and fourth valve modules 58, 60 are interconnected in the same manner as the first and second valve modules 30, 36, i.e. their first ends 14c, 14d are pivotally connected and electrically interconnected by a coupling member 34, and their second ends 16c, 16d are interconnected by two flexible insulating members 38.

The first and second damping members 40, 42 also similarly extend between the first ends 14c, 14d of the third and fourth valve modules 58, 60.

In this manner the various valve modules 30, 36 adopt a zig-zag configuration in which each valve module 30, 36 is inclined relative to the adjacent module.

The thyristor valve assembly 10 also includes upper and lower stress shields 62, 64, and each valve module 30, 36, 58, 60 has a plurality of module stress shields 66 arranged on each of the first and second sides 44, 48 thereof.

In use the thyristor valve assembly 10 is normally hung from a ceiling in a valve building (not shown). During normal operation, i.e. under non-seismic conditions, the respective coupling members 34 and insulating members 38 combine to suspend the valve modules 30, 36, 58, 60 one below another in a valve stack, i.e. a multiple valve unit.

During a seismic event the coupling members allow the valve modules

30, 36, 58, 60 in adjacent valve module pairs 32, 54, 56 to pivot relative to one another so as to accommodate disturbances caused by the seismic event.

Meanwhile the first and second damping members 40, 42, i.e. the first and second fluid conduits 46, 50, dampen the relative movement between the first ends 14a, 14b of the first and second valve modules 30, 36, between the first ends 14c, 14d of the third and fourth valve modules 58, 60, and between the second ends 16b, 16c of the second and third valve modules 36, 58. This reduces the amplitude of relative oscillation between adjacent valve modules to lower the risk of the valve assembly 10 and/or the external components to which it is connected being damaged during the seismic event.

A thyristor valve assembly 80 according to a second embodiment of the invention is shown in Figure 2.

The second thyristor valve assembly 80 is very similar to the first thyristor valve assembly 10 and like features share the same reference numerals.

However, in the second thyristor valve assembly 80 both of the first and second damping members 40, 42, i.e. the first and second fluid conduits 46, 50, extend along the first side 44 of each valve module 30, 36, 58, 60.

A third thyristor valve assembly 90 according to a third embodiment of the invention is illustrated schematically in Figure 3.

The third thyristor valve assembly 90 is similar to each of the first and second thyristor valve assemblies 10; 80 and like features again share the same reference numerals.

One way in which the third thyristor valve assembly 90 differs, however, is that the first and second damping members 40, 42, i.e. the first and second fluid conduits 46, 50, extend along a central axis A_c of each valve module 30, 36, 58, 60. Such an arrangement is beneficial because it allows the orientation of alternate valve modules 30, 36, 58, 60 to vary from one another without a need to re-route the first and second fluid conduits 46, 50.

A fourth thyristor assembly 100 is shown in Figure 4. The fourth thyristor assembly 100 is similar to each of the first, second and third thyristor valve assemblies 10; 80; 90 and like features are designated using the same reference numerals.

However, in the fourth thyristor valve assembly 100 the valve modules 30, 36, 58, 60 in each module pair 32, 54, 56 have opposite orientations to one another, i.e. the thyristor clamped assemblies 18, 20 are on different sides of the said valve modules 30, 36, 58, 60 in each module pair 32, 54, 56.

In addition the first fluid conduit 46 extends along the first side 44 of the first and third valve modules 30, 58 and along the second side 48 of the second and fourth valve modules 36, 60. Meanwhile the second fluid conduit 50 extends along the second side 48 of the first and third valve modules 30, 58 and along the first side 44 of the second and fourth valve modules 36, 60. As such the first and second fluid conduits 46, 50, i.e. the first and second damping members 40, 42, cross over one another as they extend between the valve module ends that are interconnected by a respective coupling member 34.

Each of the second, third and fourth valve assemblies 80; 90; 100 functions in essentially the same manner as the first valve assembly 10.

The various first and second damping member 40, 42 paths described hereinabove with respect to the valve modules 30, 36, 58, 60 may be combined with valve modules 30, 36, 58, 60 that have a different orientation to one another, and other damping member paths between respective valve modules 30, 36, 58, 60 are also possible.

Claims

1. A HVDC thyristor valve assembly comprising a plurality of series- connected thyristor valve modules, each valve module having two opposed ends, one end of a first valve module in an adjacent pair of valve modules being movably and electrically interconnected by a coupling member to an end of the second valve module in the said adjacent pair of valve modules, and relative movement between the interconnected ends of the first and second valve modules being damped by at least one damping member.

2. A HVDC thyristor valve assembly according to Claim 1 including a first damping member extending between the ends of the first and second valve modules interconnected by the coupling member.

3. A HVDC thyristor valve assembly according to Claim 2 wherein the first damping member is defined by a first fluid conduit.

4. A HVDC thyristor valve assembly according to Claim 2 or Claim 3 further including a second damping member extending between the ends of the first and second valve modules interconnected by the coupling member.

5. A HVDC thyristor valve assembly according to Claim 4 wherein the second damping member is defined by a second fluid conduit.

6. A HVDC thyristor valve assembly according to Claim 5 including first and second fluid conduits, wherein:

(ii) the first fluid conduit extends along a first side of the first valve module and along a second side of the second valve module and the second fluid conduit extends along a second side of the first valve module and along a first side of the second valve module; (iii) the first and second fluid conduits extend along the same side of both the first and second valve modules; or

7. A HVDC thyristor valve assembly according to any preceding claim wherein the coupling member is or includes a damping member.

8. A HVDC thyristor valve assembly according to any preceding claim wherein in normal use the or each damping member holds the first and second valve modules in an adjacent pair of valve modules at an angle to one another.

9. A HVDC thyristor valve assembly according to any preceding claim wherein the coupling member includes a corona shield secured thereto.

10. A HVDC thyristor valve assembly according to any preceding claim wherein the interconnected ends of the first and second valve modules in an adjacent pair of valve modules lie directly opposite one another.

1 1. A HVDC thyristor valve assembly according to any preceding claim wherein in an installed configuration the valve modules are arranged one above another in a valve stack.

12. A HVDC thyristor valve assembly according to any preceding claim wherein the first and second valve modules in an adjacent pair of valve modules have the same orientation as one another.

13. A HVDC thyristor valve assembly according to any of Claims 1 to 1 1 wherein the first and second valve modules in an adjacent pair of valve modules have a different orientation to one another.