An expert display system and nuclear power plant control rooms

  • Published on
    22-Sep-2016

  • View
    216

  • Download
    2

Embed Size (px)

Transcript

  • IEEE Transactions on Nuclear Science, Vol. 35, No. 2, April 1988 991

    AN EXPERT DISPLAY SYSTEM AND NUCLEAR POWER PLANT CONTROL ROOMS

    Leo Be l t r a c c h i U.S. Nuc lear R e g u l a t o r y Commission

    Washington DC, 20555

    ABSTRACT

    .An e x p e r t d i s p l a y system c o n t r o l s a u t o m a t i c a l l y t h e d i s p l a y o f segments on a cathode r a y t u b e ' s sc reen t o fo rm an image o f p l a n t o p e r a t i o n s . The image c o n s i s t s o f an i c o n o f : 1) t h e process ( h e a t eng ine c y c l e ) , 2) p l a n t c o n t r o l systems, and 3) s a f e t y systems. A s e t o f d a t a - d r i v e n , f o r w a r d - c h a i n i n g computer s t o r e d r u l e s c o n t r o l t h e d i s p l a y o f segments. As p l a n t o p e r a t i o n changes, measured p l a n t d a t a a r e p rocessed t h r o u g h t h e r u l e s , and t h e r e s u l t s c o n t r o l t h e d e l e t i o n and a d d i - t i o n o f segments t o t h e d i s p l a y fo rmat . The i c o n con- t a i n s i n f o r m a t i o n needed by c o n t r o l rooms o p e r a t o r s t o m o n i t o r p l a n t o p e r a t i o n s .

    One example o f an e x p e r t d i s p l a y i s i l l u s t r a t e d f o r t h e o p e r a t o r ' s t a s k o f m o n i t o r i n g leakage f rom a s a f e t y v a l v e i n a steam l i n e o f a b o i l i n g w a t e r r e a c t o r (BWR). p l a y t o m o n i t o r p l a n t o p e r a t i o n s d u r i n g p r e - t r i p , t r i p , and p o s t - t r i p o p e r a t i o n s i s d iscussed as a u n i v e r s a l d i s p l a y .

    The v i e w p o i n t s and o p i n i o n s expressed h e r e i n a r e t h e a u t h o r ' s persona l ones, and t h e y a r e n o t t o be i n t e r - p r e t e d as Nuc lear R e g u l a t o r y Commission c r i t e r i a , r e - qu i rements , o r g u i d e l i n e s .

    INTRODUCTION

    Graph ics speak f a s t e r t h a n words and numbers. I n t e r - a c t i v e computer g r a p h i c techn iques f a c i l i t a t e t h e pro- cess ing , d i s p l a y , and communicat ion o f da ta . P r o p e r l y des igned g r a p h i c s , such as i c o n s , may be used t o convey l a r g e q u a n t i t i e s o f i n f o r m a t i o n t h a t i s easy t o read, easy t o unders tand, and f r e e o f c l u t t e r .

    For example, a t r e n d p l o t o f a p rocess v a r i a b l e on t h e screen o f a ca thode- ray t u b e (CRT) i s much e a s i e r t o unders tand t h a n two columns o f numbers, one r e p r e s e n t - i n g t ime, and t h e o t h e r t h e magnitude o f t h e process v a r i a b l e .

    F o l e y (Ref. 1) s t a t e s t h a t t h e system d e s i g n e r must f i r s t develop i n t e r a c t i o n techn iques t h a t min imize t h e work r e q u i r e d by t h r e e b a s i c human processes: percep- t i o n , c o g n i t i o n , and motor a c t i v i t y . To ach ieve t h i s g o a l , t h e d e s i g n e r must have a thorough unders tand ing o f t h e performance and c h a r a c t e r i s t i c s o f i n t e r a c t i v e dev ices . The d e s i g n e r must a l s o p e r f o r m f u n c t i o n and t a s k ana lyses t o i d e n t i f y t h e d a t a needed by humans t o p e r f o r m t h e i r ass igned work. One c r i t i c a l p rob lem f o r t h e d e s i g n e r i s how t o f o r m a t and p r e s e n t t h e d a t a and i n f o r m a t i o n needed w i t h a minimum number o f d i s p l a y pages. maximize communicat ion f rom a l a r g e d a t a base.

    The E l e c t r i c Power Research I n s t i t u t e (EPRI) p u b l i s h e d d i s p l a y des ign g u i d e l i n e s (Ref. 2) f o r t h e development o f computer-generated d i s p l a y systems. The g u i d e l i n e s s u p p o r t a t h r e e - s t e p d e s i g n process: 1) a n a l y s i s , 2 ) s y n t h e s i s , and 3 ) e v a l u a t i o n . i n c l u d e s f u n c t i o n and t a s k a n a l y s i s w i t h a goa l o f i d e n t i f y i n g i n f o r m a t i o n requ i rements . s t e p d i s p l a y formats a r e developed u s i n g t h e p r o d u c t s from t h e a n a l y s i s s tep . The e v a l u a t i o n s t e p i n c l u d e s t h e assessment o f computer-based o p e r a t o r a i d s , such as t h e c o m p a t i b i l i t y o f t h e d i s p l a y w i t h a u s e r ' s sensory and p e r c e p t u a l c a p a b i l i t i e s .

    I n another example, t h e use o f an e x p e r t d i s -

    The goal i s t o min imize human search t i m e and

    The a n a l y s i s s t e p

    I n t h e s y n t h e s i s

    W i t h CRTs as d i s p l a y dev ices , a d e s i g n e r may use c o l o r t o code i n f o r m a t i o n . Murch (Ref. 3) s t a t e s t h a t most o f t e n c o l o r is used i n a q u a l i t a t i v e r a t h e r t h a n a q u a n t i t a t i v e f a s h i o n t o show t h a t one i t e m i s d i f f e r e n t f rom another . However, t h e use o f c o l o r becomes more complex as t h e number o f b i t p l a n e s i n d i s p l a y systems i n c r e a s e a l l o w i n g f o r thousands o f c o l o r s . As Murch c o r r e c t l y no tes , t o maximize t h e p o t e n t i a l o f g r a p h i c s systems, a d e s i g n e r must draw upon s c i e n c e ' s under- s t a n d i n g o f how t h e human eye c r e a t e s c o l o r sensat ions . Because o f sensor l i m i t a t i o n s i n t h e human eye, o n l y a few c o l o r s may be used t o e f f e c t i v e l y code da ta . Murch 's g u i d e l i n e s on t h e use o f c o l o r a r e e x c e l l e n t .

    Hayes-Roth's t u t o r i a l (Ref. 4) on knowledge-based ex- p e r t systems s t a t e s t h a t computer -s to red s k i l l s o f s p e c i a l i s t s may be used t o a i d o p e r a t o r s i n s o l v i n g problems. A m a j o r b e n e f i t f rom such systems i s t h e c o n s i s t e n t a p p l i c a t i o n o f l o g i c and t i m e l y s o l u t i o n s t o problems. n u c l e a r i n d u s t r y i s i n a t e c h n i c a l paper by G i m m y (Ref. 5). I n t h i s example, t h e au tomat ic d i a g n o s i s o f m u l t i - p l e alarms by an e x p e r t system i s d iscussed. From t h e d e s c r i p t i o n p r o v i d e d by G i m m y , t h e knowledge base appears thorough, t h e i n f e r e n c e eng ine i s based upon t a b l e - d r i v e n l o g i c , and t h e u s e r ' s i n t e r f a c e appears t o be v e r y e f f e c t i v e . Gimmy's paper p r o v i d e s e x c e l l e n t g u i d e l i n e s on how t o implement e x p e r t systems i n n u c l e a r f a c i l i t i e s .

    Computer-dr iven cathode r a y tubes a r e used as d i s p l a y dev ices i n t h e c o n t r o l rooms o f n u c l e a r power p l a n t s . The fo rmat o f t h e d a t a on t h e screens takes many shapes. For example, v e r t i c a l b a r s , w i t h l a b e l s and process parameter va lues , mimic ana log meters on t h e c o n t r o l board. A l s o , t r e n d p l o t s o f p rocess parameters a r e c o l o r and shape coded t o f a c i l i t a t e t h e o p e r a t o r ' s use o f t h i s da ta .

    An example o f an e x p e r t system i n t h e

    The d i g i t a l computer may mimic t h e human o p e r a t o r by au tomat ing o p e r a t o r t a s k s and t h e n d i s p l a y i n g processed da ta . The e x p e r t d i s p l a y d iscussed i n t h i s paper i n t e - g r a t e s i n d i v i d u a l p rocess parameters f rom t h e p l a n t t o fo rm and d i s p l a y a model o f t h e process . I n d o i n g these t a s k s , t h e computer mimics an e x p e r t o p e r a t o r by i n t e g r a t i n g and s t r u c t u r i n g t h e d a t a t o s u p p o r t d e c i - s i o n making by t h e human. The s p e c i f i c d i s p l a y s i n t h i s paper a r e p r o t o t y p e s developed by t h e a u t h o r on a g r a p h i c s w o r k s t a t i o n . They serve t o i l l u s t r a t e a d i f - f e r e n t t y p e o f d i s p l a y d e s i g n and au tomat ion , b u t t h e y a r e by no means a complete des ign .

    To p r o v i d e a b a s i s f o r a d i s c u s s i o n , t h e f o l l o w i n g terms a r e d e f i n e d :

    Graph ic p r i m i t i v e s : 1. The g r a p h i c elements d i s p l a y e d on a t e r m i n a l ;

    d i s p l a y . 2. The fundamental u n i t s o f a

    Segment: 1. A combined s e r i e s o f g r a p h i c p r i m i t i v e s ; A r e u s a b l e c o l l e c t i o n o f g r a p h i c p r i m i - t i v e s and p r i m i t i v e a t t r i b u t e s s t o r e d i n memory.

    2 .

    A t t r i b u t e : A c h a r a c t e r i s t i c o f a p r i m i t i v e , such as c o l o r , w i d t h , e t c .

    U.S. Government work not protected by US. Copyright

  • 992

    Dynamic

    Panel :

    a t t r i b u t e : Those a t t r i b u t e s t h a t can be changed a f t e r t h e segment i s d e f i n e d .

    The s e t o f p i x e l s t h a t l i e i n s i d e a c l o s e d boundary on a d i s p l a y s u r f a c e . A "panel d e f i n i t i o n " i s a s e r i e s o f MOVES and DRAWS t h a t fo rm a pane l boundary. A "pane l " may be i d e n t i f i e d as a segment.

    I con : An image composed f rom segments. A "process i c o n " models t h e process w i t h i n t h e p l a n t . "system i c o n " mimics p l a n t systems.

    A

    Ob jec t : A computer-generated g r a p h i c element t h a t can be a c t e d upon by t h e human user .

    Background elements: The t i m e i n v a r i a n t segments i n an i c o n .

    A c t i v e elements: The t i m e v a r i a n t segments i n an icon .

    Graph ic p r i m i t i v e s a r e t h e b a s i c g r a p h i c elements t h a t a t e r m i n a l d i s p l a y s i n response t o a command. One g r a p h i c p r i m i t i v e i s a v e c t o r , a s t r a i g h t l i n e drawn between two p o i n t s on a d i s p l a y s u r f a c e . A s e r i e s o f v e c t o r s i s used t o fo rm a c i r c l e , a r e c t a n g l e , o r a pane l . A t t r i b u t e s o f a g r a p h i c p r i m i t i v e may i n c l u d e c o l o r , l i n e s t y l e ( s o l i d , dashed, e t c . ) , and w i d t h . For example, a tempera ture-en t ropy diagram o f two-phase w a t e r ( l i q u i d and vapor) may be shown on a CRT as a s e r i e s o f v e c t o r s t h a t fo rm a pane l . The c o l o r o f t h e s u r f a c e , such as w h i t e , i s a d e s i g n e r - s p e c i f i e d a t t r i - b u t e o f t h e pane l .

    A segment i s a c o l l e c t i o n o f g r a p h i c p r i m i t i v e s and t h e i r a t t r i b u t e s t h a t t h e d i s p l a y t e r m i n a l t r e a t s as a s i n g l e o b j e c t . s i n g l e g r a p h i c p r i m i t i v e , o r as much as an e n t i r e d i s p l a y . An example o f a segment i s a symbol f o r a v a l v e , wh ich i s composed o f s e v e r a l s t r a i g h t l i n e s ( p r i m i t i v e s ) .

    A segment may c o n t a i n as l i t t l e as a

    I n t h e f o l l o w i n g d i s c u s s i o n , segments a r e used t o code d a t a and i n f o r m a t i o n f o r p rocess f u n c t i o n s and f o r p l a n t systems. Severa l segments a r e t h e n used t o com- pose an i c o n t h a t models p l a n t o p e r a t i o n s . Some seg- ments a r e used t o compose t h e background elements i n t h e d i s p l a y fo rmat . The use o f a c t i v e segments i n t h e d i s p l a y fo rmat i s c o n t r o l l e d by pre-de termined r u l e s s t o r e d i n t h e memory o f a computer. d r i v e n , w i t h t h e d a t a o b t a i n e d f rom sampl ing p l a n t sensors. For example, when a measured process v a r i - a b l e , such as pressure , exceeds a s e t p o i n t f o r a v a l v e t o open, a new segment f o r t h e v a l v e ( i n d i c a t i n g an open v a l v e ) i s added t o t h e d i s p l a y . T h i s overv iew p r o v i d e s an i n t r o d u c t i o n t o an e x p e r t d i s p l a y .

    EXPERT SAFETY VALVE MONITOR

    An i m p o r t a n t t a s k ass igned o p e r a t o r s i s m o n i t o r i n g s a f e t y v a l v e s f o r leakage a f t e r a s a f e t y v a l v e has l i f t e d and t h e n c losed. Many t i m e s these v a l v e s do n o t f u l l y c l o s e and leakage occurs . G e n e r a l l y , a s a f e t y v a l v e serves as a s i n g l e component and i s n o t backed up by a b l o c k va lve . Thus, leakage o f c o o l a n t f rom a s a f e t y v a l v e i s a f a u l t i n t h e p r e s s u r e boundary and a concern i n m a i n t a i n i n g s a f e p l a n t o p e r a t i o n .

    D u r i n g normal o p e r a t i o n o f a BWR, t h e s a f e t y v a l v e i n t h e steam l i n e i s c losed. Should a l a r g e i n c r e a s e i n p r e s s u r e occur d u r i n g a t r a n s i e n t and t h e p r e s s u r e i n t h e steam l i n e exceed t h e s e t p o i n t f o r t h e s a f e t y v a l v e , t h e v a l v e opens. The s e t p o i n t f o r t h e s a f e t y v a l v e i s t y p i c a l l y 1230 p s i g . When t h e v a l v e i s open, steam escapes t o t h e d i s c h a r g e p i p e , t h e n t o t h e d r y - w e l l , and u l t i m a t e l y t o t h e suppress ion p o o l .

    The r u l e s a r e d a t a

    O b e r t (Ref. 6) d e f i n e s a t h r o t t l i n g process as one t h a t occurs when a f l u i d expands f rom a r e g i o n o f h i g h p r e s s u r e t o a r e g i o n o f lower p ressure . t h e f l u i d d i s s i p a t e s energy t h a t c o u l d have been t r a n s - formed i n t o work. s a f e t y v a l v e ach ieves a h i g h v e l o c i t y , wh ich i s d i s - s i p a t e d i n a imless t u r b u l e n c e i n t h e d i s c h a r g e p i p e . Thermodynamical ly, t h e e n t h a l p y o f t h e d i s s i p a t e d steam i n t h e d i s c h a r g e p i p e i s t h e same as t h e e n t h a l p y o f t h e steam i n t h e steam l i n e . However, t h e e n t r o p y o f t h e d i s s i p a t e d steam i s much g r e a t e r t h a n t h e e n t r o p y o f t h e steam i n t h e steam l i n e . The amount o f e n t r o p y i n c r e a s e d u r i n g t h e t h r o t t l i n g process i s a measure o f t h e d i s s i p a t e d energ...

Recommended

View more >