技术
SELECTING, UPGRADING, AND RETROFITTING
SWITCHING SYSTEMS FOR SUBSTATIONS
IN THE 21ST CENTURY
By Jeff Rogers, Electroswitch
It’s long been a given that automated, unmanned substations are the wave of the future. However, with all the convenience and cost-effectiveness they bring, there is still the need for manual backup controls, and for a very good reason:worker safety. For protection of onsite personnel there is nothing like the familiar trip handle of a Breaker Control switch for peace of mind during maintenance or repairs. And with the ever- present possibility of wide-scale system failures, or even terrorism, maintaining the capability for local manual control makes more sense than ever.
SUBSTATION UPGRADES SHOULDN’T SACRIFICE LOCAL CONTROL FOR REMOTE OPERATION
Even with the wide variety of sophisticated yet affordable relays and protective devices on the market today,the Power Industry continues to recognize the need for cost-effective, relatively fail-safe, manual controls.
For state-of-the-art new designs as well as piecemeal retrofits of existing systems, it remains imperative to allow local operators to safely and effectively override a SCADA or other supervisory control system.There are many directions a utility can take to upgrade a substation, depending on needs and budget. Piecemeal “mix and match” improvements are common,partly because so many new switching devices are backward -compatible with older equipment. Some of the more versatile devices provide compatibility with modern supervisory control systems yet are engineered not to be software-dependent. Lock-Out Relays,Control Switch Relays, and Latching Switch Relays, for instance, provide the familiarity of a manual switch while allowing complete remote control capability.Versions of these rugged, reliable devices have long been available with a solenoid drive that can be hardwired to a pair of RTU control points. Newer models now coming to market acknowledge the industry’s trend toward serial communications,in which each of several switching devices can be easily configured with a distinct address, allowing supervisory control through a local or wide-area network. These networked devices typically operate with either DNP3 or MODBUS® software protocols.
SWITCHING DEVICES THAT MAKE SENSE FOR THE FUTURE
Let’s take a look at some of the proven switching devices that bridge the gap between manual operation and full software automation while preserving fail-safe operator intervention.
LOCK-OUT RELAYS (LORS)
Critical to almost every protection scheme, the Lock-Out Relay is usually slaved to an IED, protective relay, or other command device. When this device detects a fault parameter sufficient to warrant equipment shutdown, it sends a signal to the LOR, which immediately “trips,” toggling its internal
CONTROL SWITCH RELAYS (CSRS)
Control Switch Relays, which combine the functions of a control switch and a SCADA-controlled interposing relay, are available with three basic control circuits, multiple-voltage capability, and a wide choice of contact configuration that allows the automation of virtually any breaker control switch function. When converting a manual substation to supervisory control, a CSR duplicating the existing manual control switch contacting replaces both the switch and the interposing relay without the need for special wiring or extra panel space. Blade-and-terminal construction and simple stacking procedures allow two independent low-resistance contacts per deck. Because the handle moves on SCADA operation, target flag agreement is always true regardless of manual or electric trip. The target always shows the last active position. CSRs are also protected to withstand control-bus transients up to 3.5KV.
On some CSRs, a push on the handle disables remote operation, allowing only local /manual control so that testing or service can be performed safely. In addition, these models provide push-activated N/O and N/C auxiliary contacts that can be used as SCADA feedback or local indication of status.
LATCHING SWITCH RELAYS (LSRS)
Versatile Latching Switch Relays can be slaved to IED relays as contact multipliers, configured to control local or remote latching or reclosing, or can serve as programming relays for local or SCADA -compatible switches. Because their low-resistance blade -and-terminal design allows for up to forty contacts, LSRs can be configured for manual and remote control of a wide variety of specific applications.
ANNUNCIATOR TARGET RELAYS (ATRS)
Microprocessor-based Annunciator Target Relays (ATRs) are used to replace electromechanical annunciators to identify the source of an incoming trip signal quickly (microseconds). Developed in response to industry demands to replace older relays that could not keep up with modern high-speed LORs, these compact, reliable solid-state units offer adjustable trip-response times and can accept an input signal from a variety of devices. In a standard 3-hole panel installation, an ATR can (A) illuminate a bright LED to indicate a trip event and (B) send signals to activate up to two other devices within the system, such as alarms or other relays. Once a trip signal has been detected, the two auxiliary contacts either latch or slave to the source, depending upon model. The LED will stay lit until the reset button is pushed.
TAGGING RELAYS (TRS)
Worker-safety Tag-Out rules require the placement of a warning tag on every switch that could be used to energize a piece of out-of-service equipment being maintained or repaired. Modern Tagging Relays allow a remote operator to place and remove such tags, thus optimizing automated breaker control schemes in new or existing power distribution systems. Recently available with serial communications capability for network control, TRS can control remote reclosure cutoff and facilitate the expansion of a remote control SCADA system beyond a substation to distribution feeders. These compact units have multiple contacts and are available with two or three positions. Two-position models offer “Normal” and “Tagged” positions, while three-position models have “Closed,” “Open,” and “Tagged” positions. The best models allow bi- directional operation.
CONTROL INDICATOR MODULES (CIMS)
“A breaker control panel in a box” is what some call the versatile Control Indicator Module. Designed for highly automated environments, this device works with RTU points or serially, using MODBUS, DNP3, or other communications protocols. It enables an electric utility to trip and close a station breaker as well as monitor up to three trip coils for continuity. The unit also replaces the SCADA interposing relay, accepting signals from protective relays to control breaker function. Switches on the unit’s front panel permit manual control of breakers and reclosers even during software failures. Time stamping provides a precise record of recent events. The CIM can communicate directly with up to 32 separate computer workstations, printers,etc. through its RS-485 interface. A simple 8-bit parallel interface is also available. The CIM’s front panel contains red, amber, and green LEDs that indicate breaker trip coil operation, trip signals and their sources, and the status of both the external reclose relay and the interface to the supervisory control system. Taking up less than 13 square inches of panel space (either horizontal or vertical), the unit is easily incorporated into a new or existing substation and is compatible with virtually all other electronic or electromechanical protective equipment. The CIM meets IEEE standards C37.90.1 and C37.90.2.
“SMART NAMEPLATES”
Another development worth noting is the availability of “Smart Nameplates,” which are especially useful at hybrid substations in transition from manual to automated operation. Whether a control switch is operated manually or remotely, critical warning and status information is still best presented through panel- mounted indicator lamps. The most common lamp applications are local indication of breaker status, trip coil integrity, and LOR trip signal detection, each traditionally monitored with separately mounted incandescent bulbs. The “Smart Nameplate” incorporates these functions into the pertinent switch or relay itself.
By utilizing very bright, low-power light-emitting diodes (LEDs) “Smart Nameplates” match the candlepower of the brightest incandescent bulbs while saving energy, heat, and panel space. They monitor and annunciate faults so economically they eliminate the need for a separate coil monitor relay or system voltage monitor. Better yet, they are equipped for SCADA-compatible remote annunciation of critical functions by way of solid-state dry contacts. A standardsize nameplate can contain up to three indicator LEDs and one output contact, monitoring and displaying the status of multiple events and triggering annunciation or device activation. These nameplates are available with or without mechanical targets.
A “Smart Nameplate” for an LOR, for example, monitors the integrity of the LOR trip coil and the presence of a trip signal.
The all-important “health” of the LOR trip coil, which translates the input signal into the change-of-state of the LOR contacts, is effectively monitored by internal circuitry that trickles a pilot current through the coil and lights an LED at the top left of the nameplate. This unmistakably bright LED gives local indication that the coil is intact and ready to operate. Should the coil burn out for any reason, the LED extinguishes and an on-board solid-state contact (100mA/125VDC) closes, allowing SCADA-compatible remote annunciation.
Additional circuitry in the LOR “Smart Nameplate” is designed to further protect the coil by preventing the most common failure mode: an operator resetting the LOR into a standing trip signal and heating the coil to failure. As long as the trip signal is present at the coil inputs, a second LED glows to warn against resetting. Only when the trip signal is removed does this warning LED extinguish, indicating it is safe to reset the LOR.
When adapted for breaker control, the “Smart Nameplate” can be mounted on a standard manual control switch or a remotely operable, SCADA-compatible Control Switch Relay. In this application, one, two, or three LEDs are arrayed across the top of the nameplate for easy visibility, typically indicating breaker status (open/closed) and/or breaker trip coil integrity.
Recent improvements in LED technology have produced long life (100,000+ hours vs. 2,000 hours for incandescent bulbs) and impressive resistance to vibration. The newest generation of LEDs has come to market in a variety of brilliant colors, each capable of producing more light than older devices by at least an order of magnitude. Today’s LEDs emit light over a wide viewing angle, so they are visible when seen from the side, even under the brightest ambient lighting conditions.
In other words, the “Smart Nameplate” brings many advantages to the modern control panel:
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#8226; Visibility — extraordinary brightness from all viewing angles.
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#8226; SCADA-Compatible Annunciation — solid-state dry contact linked to LED.
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#8226; Backward Compatibility — retrofit kits available.
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#8226; Long Life — LEDs rated for 100,000+ hours.
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#8226; Easy LED Replacement — socketed LEDs removable from front, without disturbing wiring.
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#8226; Low Power Consumption — less than 12 mAmp per lighted LED.
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#8226; Self-contained — all current-limiting and remote-annunciation circuitry included.
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#8226; Five Brilliant Colors — green, red, amber, blue, and white available.
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#8226; Space Savings — up to three LEDs inside the standard nameplate footprint.
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#8226; Low Cost — save on initial cost, wiring labor, and replacement intervals.
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#8226; Built-in Terminal Block — extra switch deck provides termination for leads.
In the midst of all this talk about high-tech features, it is reassuring to note that all these switches are still available with handles fashioned into familiar shapes for human hands —oval, knurled, and pistol-grip.
The best of today’s switches and relays have low-resistance contacts and other features that enable them to work well with automated supervisory control systems, yet they permit an on-site operator to quickly take over if computers fail, even in brownout conditions. When nobody is present, a substation can be monitored and operated remotely. And if the devices that facilitate this are, at their cores, still the same proven devices the industry has depended upon for a century, so much the better.
REDUNDANCY IS GOOD, MANUAL BACKUP IS
Summing up, automation should not mean the elimination of easily accessible manual control. Using cost-effective devices that bridge the analog/digital gap to upgrade equipment does not require a choice between complete remote operation and manual capability. Versatile products are available today to provide the best of both worlds. As substation equipment continues to evolve, the human safety element should not be neglected along the way. Reliable products retaining safe and easy manual operation make welcoming new technology a net gain, not a trade-off.
Jeff Rogers is a Regional Sales Manager for Electroswitch, a leading supplier of rotary switches and relays to the utility, industrial, military, and electronics marketplaces.
Electricity Today Issue 6, 2005
www.electricityforum.com
21世纪变电站的选择、升级及改型的开关系统
无人操控的自动化变电站是未来的趋势，然而，随着它们所带来的所有便利和成本效益，人工控制还是有必要的，并且有一个充足的理由：工作者安全。运行人员的保护与在维护或检修期间断路控制开关所起的作用并不相似，并且以宽比例系统故障的老在可能性，地方人工控制的维护能力发挥了更大的作用。
变电站升级不应该为遥控操作牺牲地方控制
在当今的市场上既使有各种先进的继电器及保护装置，电力工业仍然看重成本效益万无一失和人工控制。
为最新型的新设计，以及现有系统的翻新件，仍允许当地经营者安全有效的推翻SCADA或其它监控系统，根据需要和预算，有许多可利用的方向提升了变电站，逐渐“调制和配合”共同改善，部分原因是许多新的开关设备与旧的设备向后兼容。部分装置提供更多元化的现代监控系统的配合，但却不能以软件设计为主。以闭锁继电器，控制开关继电器和开关构件继电器为例，当有完全遥控能力时，提供一个系统开关的熟悉，这些坚固的可靠装置，已经被硬联 一个对RTU控制点的螺线管驱动。现在新的模式来认识市场的产生趋势系列通信，通过本地或广域网的监控，每种开关设备都可以配置一个明确的地址，这些网络设备通过DNP3或MODBUS协议进行操作。
未来的开关设备（转换装置）
让我们来看一些弥补人工操作和软件自动化差距的转换装置，它是操作员干预时的交换设备。
停工中转
对没一个重要保护，停产中继通常都取决于IED，继电保护或其它装置。当该装置发现鼓掌并将其切除，它会发出LOR信号，并立即跳闸，其内部
控制开关
控制开关继电器，把控制开关的作用和SCADA的中转作用结合在一块，用三条可利用的基本电路控制，多电压能力，并且接触点配置有一个很大的选择欲度让断路器自动的控制开关。当一个人工变电站过渡为监控变电站时，CSR将复制现有的手工控制开关触点替换开关和插话的中转，不用特别的接线或嵌入压板。刀闸和终端的结构简单且允许每个面板只能有两个独立的低阻抗元件相连。SCADA的操作移动是靠手柄来实现的，不管是人工还是电动，最终的目的还是一致的，目标总是在最显眼的地方显现。CSRS的控制母线可承受短暂的超过35KV的电压
对某些CSRS而言，拉把柄会导致遥控失去能力，所以仅允许手动操作，以便测试或服务能在安全的情况下进行，此外，这些模式还将启动N10；N、C辅助触点，用于监控及数据采集，体现自身的作用。
构件转换
构件转换型继电器取决于IED继电器的触点倍增器，它拥有或控制的本地控件和远程控件可作为本继电器监控及数据搜集的兼容开关。由于他们的低阻抗刀片和终端设计的触点最多不超过40个，所以LSRS可作为手动和遥控的具体应用配置。
告警继电器
基于微处理器的告警继电器被用作取代机电告警，主要用来快速辨别跳闸信号的来源（微秒）。由于产业需求的发展，从取代那些不能跟上现代高速的LORS的旧型继电器，这些结实的固态单位提供适当的跳闸反应时间和可接受的输入信号，在标准孔盘区安装ATR照明设备，ATR能照亮LED并发出信号，激活系统内的其他两个装置，例如报警装置或继电器。一旦发现跳闸信号，两个辅助触点或闭合或决定于故障源，都根据模型的不同而取舍。LED将保持点燃状态，直到复位按钮复归。
标记中转
工作人员安全规程要求每个开关的提醒标志的位置应处在能被维护或修理的范围内。现代标记中转允许远程操作人员安置或去除这种标记，因而自动断路器尽可能的把计划控制在新的或现有的分配系统中。目前，可利用串行通信为网络服务。TRS能控制远程切除故障，并且能促进SCADA系统的远程控制在变电站之外的分配供应。这些紧凑的结合点有大量的触点并且有两三个点可利用，两点模型有“正常”和“警戒”状态，三点模型有“开”“关”“警戒”状态，最佳模型允许双向操作。
控制显示模块
“断路器控制压板”是人们所说的控制显示模块。高度自动化设计环境，这个设备与RTU点一起使用，从MODBUS，DNP3作为交流工具，它能使电力设备跳闸并合上断路器。
控制显示模块（CIMS）
“控制板开关箱”是人们所称的控制指标型模块。设计高度自动化的环境，这个装置通过MODBUS，DNPS或其他通信协议与RTU点一起使用，它操作电力效用发现错误并且关闭断路器，同时监测到三旋管程连续性。中介单位也取代SCADA中转继电器，接受从保护继电器发出的信号来控制断路器动作，在该单位前排面板上的开关允许人工打开或合上，甚至是在发生软件故障的情况下，时间继电器提供近期事件的精确记录。CIM可以通过它的RS-485接口直接与32台独立计算机工作站，打印机等联络。一个简单的8位平行接口也是可利用的，CIM面板包含以显示开关线圈操作、报警信号及信号源，重合继电器和连接到监控系统的状态，、它占了不到3平方英寸盘区空间（横向或纵向），单位很容易被合并到一个新的或现有的变电站并且与其他几乎所有的电子、机电设备的保护兼容。（CIM符合IEEE标准C37.90.1和C37.90.2）。
一个值得注意的发展是“智能牌”的利用，它在各变电站中由手动到自动操作的转换中是非常有用的。无论控制开关是人工操作或是遥控，预警和状态信息仍然会通过标志灯很好的显示出来。最常见的应用信号是当地断路开关的状况，线圈完整性，以及LOR错误信号检测，每一传统监测都通过各自的白炽灯泡完成。“智能牌”通过相关的开关和继电器本身来完成这些职能。
通过运用明亮的、低功率发光二极管（LEDS），“智能牌”在保存能量、热能和盘区空间时，匹配最明亮的白炽灯泡的烛光。他们能很经济的监测并报告故障，没有必要再用单独的线圈监测继电器或电压监测系统。更好的是，他们通过固体方式接点为SCADA安装重要功能兼容遥控的通告，一个标准的、标识0牌可能包含三个显示LEDS和一个输出的联络，监测和显示多个事件和触发通告或设备活化作用的状况。这些标识牌是可利用的或没有机械目标。
LOR“智能牌”，例如完整的监测LOR线圈和现场行程信号
LOR线圈最重要的将输入信号转变为LOR联络状态的改变的标志是通过LED左上角名牌上的线圈和灯光来有效监督内部线路。这无误的明亮的LED指示线圈是完好的并且做好了运行的准备。如果由于某种原因线圈烧了，LED熄灭并在机上的固体联络（100MA/125VDC）关闭，允许SCADA兼容并发出遥控通告。
LOR中的新线路“智能牌”旨在进一步保护线圈，防止最常见的失败模式：复位操作使LOR变为线圈信号，加热线圈则出现失败模式。只要在线圈投入时出现线圈信号，第二个LED发出重新设置警告。只有线圈信号被排除，告警LED确实熄灭，才表明重新设置LOR是安全的。
为适应开关控制，“智能牌”可以装在一个标准的人工控制开关或遥控操作，SCADA兼容控制开关继电器上。在这种应用中，一、二或三LEDS为易见性会横跨在标识牌的上面，以表明断路器状态（开/关）或开关线圈的完整性。
近期，随着LED技术上的改善，已经生产出了长寿命（白炽灯泡工作时间100，000+几小时对2，000个小时）和抗振性能的产品。最新一代的LEDS以各种各样的形式来销售，每种新型设备会比旧设备产生更多的光。如今的LEDS从一个宽视角散发光，因此，当从边缘上看时，甚至在四周有明亮照明的情况下也能看见它们。
换句话说，“智能牌”给现代控制板带来许多好处：
可见性—从任何角度都能看到亮光。
SCADA兼容通告—固体干式接点与LED连接。
逆兼容性—更新工具包可利用。
寿命长—LEDS估计能工作10万多小时。
LED容易替换—插座LEDS可以从前面移动，不会干扰接线。
功率消耗低—每被点燃的LED少于12MAMP。
独立性—包括所有当前限制和遥控通告电路。
五种色彩—绿色、红色、琥珀、蓝色和白色。
节省空间—最多三个LEDS在标准标识牌脚印里面。
低成本—节省初始成本、线损和更换间隔时间。
固定接线盒—额外开关为线路提供终止点。
在谈论这些高科技的特点时，令人欣慰的是，这些开关通过塑造成人手、椭圆形、隆起和手枪把握等常见形状的把柄，仍然是可利用的。
如今最好的开关和继电器有低接触阻抗和其他特点，使它们能很好的与自动监控系统结合，但如果计算机故障了，甚至在停电情况下，允许现场进行操作来快速切除故障。如果没人在现场，变电站可以通过遥控进行操作和管理。如果这些装置的核心便于操作，同样证明工业装置能依靠百年，这点非常好。
信息详细是好的，更重要的是备份手册
总之，自动化不等于取消人工控制。用成本效益装置填补类比/数位差距，提高了设备的选择性，完全不需要人工操作和远程能力。今天可提供多种两全其美的产品，容易使手工操作带来净收益和迎接新技术，而不是顾此失彼。
杰夫&
#12539;罗杰斯是一个区域销售经理，扶轮开关、通用继电器、工业、军事、电子市场的主要供应商。
摘自“今日电力”第六期，2005
www.electricityforum.com
